Autumn 2011 by Tim Walker

Volume 25 No 1 – Autumn 2011

The world’s best salmon? Biofloc boost for prawn farms Barra Gold wins medals and fans Flat oysters’ expanding markets Native fish’s thinking pioneer Tropical rock lobsters’ 2nd generation Sand filtration by marine worms Microalgae biotechnology push

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Contents Editor-in-chief Dr Tim Walker Regular contributors David O'Sullivan John Mosig Subscription/editorial Austasia Aquaculture PO Box 658, Rosny, Tas. 7018 Ph: 03 6245 0064 Fax: 03 6245 0068 Email: AustasiaAquaculture@netspace.net.au Advertising Megan Farrer Design/typesetting Coalface Production Pty Ltd Prepress & Printing Geon Group Copyright © by Austasia Aquaculture. Contents cannot be reproduced without permission. Statements made or opinions expressed are not necessarily those of Turtle Press Pty Ltd (ABN 98 506 165 857). Austasia Aquaculture magazine (ISSN: 0818 552) is published by Turtle Press Pty Ltd (ABN 98 506 165 857) for the promotion of aquaculture in the Australasian and Asian regions – inclusive of farming in marine, freshwater, brackish and hypersaline waters. Reader's contributions are encouraged on the clear understanding they will be subject to editorial control and, if accepted, will appear in both printed and online versions.

Cover photo A montage of photos taken from stories contained in this issue. Captions and photo credits as per the details inside.

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The World’s Best Salmon? Environmental certification and biofloc technology boost prawn farm profitability

RESEARCH

Quality and service wins for Barramundi Gold

Flat oysters finding expanding markets

F E AT U R E

Thinking out of the square with native fish

Microalgae biotech provides ‘green’ diversification

Second generation tropical rock lobster produced in Australia

Marine worms to assist sand filtration of mariculture effluents

Quantification of alkaline phosphatase in phosphate limited barramundi ponds

22 TECHNOLOGY

Seafood High Schools prepare students for a fishy career

Trout fishers work to support endangered native fish

Aquasonic is focused on energy efficient technology

Autumn 2011 | Austasia Aquaculture 1

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Inside Front Cover

Inside Back Cover

FA R M P R O F I L E Beautiful fresh, premium Huon salmon. These fish are around 3-4kg.

The World’s Best Salmon? Peter and Frances Bender, owners and operators of Huon Aquaculture, producing some of the best Atlantic Salmon in the world.

wned and managed by Peter and Frances Bender, Huon Aquaculture (HA) is a great success story for aquaculture in Australia. Established in 1985, HA now produces each year more than 10,000 tonnes of Atlantic Salmon (Salmo salar) and around 1,000 tonnes of Ocean Trout (Oncorhynchus mykiss). Over the past five years the business has grown at an average rate of 25 per cent per annum and now employs more than 350 people across Australia. Like most other salmon farmers, they mostly ‘just kept their heads above water’ during the period 1998-2002 when all of the industry suffered from poor salmon growth. Selective breeding and an R&D

program focussed on improving health and nutrition has seen salmon growth and survival rates increase significantly at HA. The farm originally focussed on contract growing for other salmon companies in Tasmania specialising in ‘early fish’, providing large fish earlier than the other companies could achieve. The market demand for HA fish grew strongly and in 2004 the Benders introduced their own Huon Aquaculture Company label. In 2006 they bought the existing Springs Smoked Seafood business and started supplying branded salmon products through to the end consumer. In 2008 all company products were relaunched under the Huon brand.

Through this period of rapid business growth, Huon has maintained its reputation for growing the biggest (5+kg headon-gutted, HOG) and best Atlantic salmon. State-of-the-art technology & facilities One of the hallmarks of the company has been its reinvestment of profits back into the business. HA has seventy-one 100/120m and fifty-six 160/168m circumference Plastic Fabrications pens in over 600ha of leases located in the Huon River and D’Entrecasteaux Channel (south-east Tasmania) and in Autumn 2011 | Austasia Aquaculture 3

All images courtesy Huon Aquaculture.

Huon Aquaculture is Australia’s second-largest producer of salmon, supplying both national and international markets with over 10,000 tonnes of consistently high-quality product. The company’s operations have many examples of world’s best practice and the premium prices show the respect the market has for the Huon Aquaculture Company labelled products.

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Management Metrics Key Management Decisions for Huon Aquaculture include: • Certification: BRC (international) Food Safety certification, GlobalGAP (under application), AQIS (Export) • Fully integrated from hatchery, smolt, growout, primary processing and value adding • Reinvestment of profits to achieve goals through innovative technology. Key Performance Indicators (KPIs) include: • Culture or Holding System utilised: Plastic Fabrications sea pens • Growth rate (from stocking to market): 12-14 months (100g to 4.5kg) • Survival rate: 90% from first stocking to sale size • Av. stocking density: 8kg/m3 in summer, 12kg/m3 in winter • Annual harvest: 10,000 tonnes • Production rate: 30 tonnes/ha (growout system area) per year • FCR: 1.4 (number of kg of food to produce 1kg stock) • Productivity: 30 tonnes per Effective Fulltime Unit (240 days, 48wk x 40hr).

Macquarie Harbour (western Tasmania). Since 1992 AQ1 automated feeding systems have been used exclusively on all production pens. Gill amoeba is one of the continuing challenges to farming salmon in the south of Tasmania. This single celled animal clogs up the gills preventing the fish from efficiently obtaining oxygen. If left untreated Amoebic Gill Disease (AGD) can result in stock losses of 80-90% in summer. The remedy is to bathe the fish in freshwater every 30-100 days depending on the time of year, a total of 6-8 times over the production cycle. This is an expensive process – of 100 people employed on HA farms, 60 are involved in bathing and support infrastructure. It is also stressful for the fish and will reduce their feeding activity and increase the risk of mortality. HA have developed a novel fish lift system for use during freshwater bathing. Their Fish Race allows up to 1.2 tonnes of fish to be lifted 2m so they can be ‘gravity fed’ into a new pen lined with tarpaulins holding freshwater. The fish are gently lifted out of water; they are in the air for less then 12 seconds, before sliding into the freshwater bath where they remain for up to four hours. Built with the aid of 50% AusIndustry grant funding, HA believe it is the largest 4 Austasia Aquaculture | Autumn 2011

fish elevator in the world. With the special HA raceway, up to 100t/hr of fish can be moved versus only 60t/hr with a fish pump. For 25,000 fish moved, the Fish Race will only lose 1 or 2 fish, with other systems 30-40 fish can be lost and even more damaged. HA has a 18% share holding in the SALTAS salmon hatchery located at Wayatinah in central Tasmania. But it has its own stateof-the-art freshwater hatchery too a short trip away from the sea pen farm; this includes an ultra-modern recirculation unit designed by Billund Aquaculture. Bore water is used and the small amount of waste water is sent to irrigate adjacent plantation land. The facility can produce more than 1.8 million smolts (100g, range 80-130g) per year; usually available from around April to November. In 2009 HA bought the Springfield hatchery group (northern Tasmania) adding a further capacity of 1.6 million smolts. At 11-18°C the Tasmanian growing waters are the warmest in the world for salmonid culture, so a fast growout time is achieved. HA aim for an average market size fish of 4kg (3-5kg) which can be grown from smolt-stage in 12-14 months. There have been some problems with early maturity of stock, so the farmers prefer to harvest fish before their second summer in the sea. R&D has shown that photoperiod manipulation can delay maturation by

naturally convincing the fish that it is the wrong time to breed. The fish then continue to grow and do not produce secondary sexual characteristics that can downgrade flesh quality. HA always has two year classes in the growout phase. This allows continuous year round supply. The year classes are kept geographically separate to best utilise lease space and maximise biosecurity. Environmental and risk management HA don’t have a formal EMS in place; however, they use a range of measures to manage environment related issues associated with its operations. This includes best practice in: • fish health and feeding management; • fallowing of sites between growing cycles, usually for at least six months so any build up of fish wastes are broken down, and • careful control of the use of antibiotics – usage rates are provided to the DPI. HA also participate in the Tasmanian Broad-Scale Environment Monitoring Program, which provides for independent assessment of water and sediment quality in reference sites close to their marine finfish farms. The smolts are either stocked in upriver (brackish water) sites or directly into the marine sites in cohorts of 50,000 fish . As the fish grow and their feed demands increase, they are transferred into larger pens and moved down river to open water leases (the fish can be moved up to 90km during the production cycle). The large growout pens can hold over 200 tonnes of fish. This innovative strategy ensures appropriate nutrient input in the lower energy upriver environments that are not scoured so regularly with tidal movement. The highest nutrient inputs are in the largest fish classes located in the deeper waters near the river mouth where ocean swells provide substantial scouring on the river bottom. HA have developed strong in-house fish health monitoring and management protocols overseen by fish vet Dr Steve

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Percival, which means that they can undertake their own screening for AGD and other pathogens. Fish samples can be also sent to DPI’s Mt Pleasant Labs (Launceston) or other analytical labs for specialist screening for virus or other potential pathogens.

Aerial shot of part of Huon Aquaculture’s salmon farming operation.

A series of eighteen trial pens (5m x 5m) are in continual use to undertake experiments on diet formulation, vaccines, other fish species (eg. Striped Trumpeter Latris lineata), light and dark regimes for combating maturation, and so on. Whilst operating these units increases costs, the benefit is having the facilities that allow research in an identical environment to HA production fish. The small numbers of fish in each pen means that work that would be too risky or complex to attempt in full scale production can be confidently undertaken. The beautiful waters of southern Tasmania – where Huon salmon is grown.

Selective breeding has been a late development for the Tasmanian Atlantic Salmon industry. The delay in implementing this approach to improving production efficiency was primarily due to concerns over in-breeding as a result of the relatively small number of stock introduced into Tasmania during the 1980s to start the industry. HA started their mass-selection breeding program in 2002 and the industry (SALTAS/CSIRO) program started in 2004. The initial generations from these programs are showing improved resistance to AGD and better growth performance. Seal predation has been a major problem for stock in sea pens. One seal can kill 300-500 fish in a single day by simply sucking out the livers of fish caught through loose netting; the most vulnerable time is when fish are in the swim-through tunnel from their ongrow pen to harvest raceways. Seals are protected so the farmers can’t harm them; in the past they have been trapped and relocated to Bass Strait, however, this was not successful as the seals quickly returned to the pens.

the defences. Underwater HA deploys very tight, very thick, dual net layers with a thick (40mm) anti-predator ‘China’ net to prevent the seals from pushing in the netting and catching fish. Above water 2.4 metre tall outward leaning fences prevent seals from climbing into the pens.

A number of non lethal measures have been tested to minimise fish losses. Exclusion methods are continually being improved as seals find their way around

To reduce the need for regular net changing, copper-based antifouling is used on all predator netting which can mean an additional usage time of four to

six weeks. The nets can be cleaned in situ by a specialised Tasmaniandesigned net cleaning boat. Alternatively the fouled net is taken ashore and soaked in freshwater pits to reclaim the copper and wash off the fouling. This work is now undertaken by a local contractor which has reduced the cost of antifouling the nets by 30%. Trials are underway to reduce and eliminate the use of antifouling paint whilst maintain the benefits of improved water Autumn 2011 | Austasia Aquaculture 5

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flow and low structural weight.

The first near-shore water temperature forecasts are being developed to assist Australia’s aquaculture farm managers contend with rising ocean temperatures.

Trialling ocean temperature forecasts for fish farms Marine scientists are trialling the first near-shore water temperature forecasts to assist Australia’s aquaculture farm managers contending with rising ocean temperatures. While land farmers have used seasonal forecasting for nearly a decade, marine farmers in south-east Australia have sought the technology for a region identified as a climate change hotspot, with rates of ocean warming up to four times the global average. CSIRO Climate Adaptation Flagship scientist, Dr Alistair Hobday, said the project, funded through the Fisheries Research and Development Corporation, is a response to requests by Tasmania’s four major salmon companies for shortterm ocean forecasts for their farm sites. “Marine farms in this region, particularly south-east Tasmania, want to use all available resources to ensure proper planning and response measures are in place to combat against the warmer summer months which can have adverse effects on fish performance,” Dr Hobday said. “While adaptation to long-term change is seen as important by the sector, dealing with climate variability exacerbated by ongoing climate change is a more immediate need. “Our objective is to provide marine farmers with forecasts at their salmon farming 6 Austasia Aquaculture | Autumn 2011

sites up to four months ahead. This will enable management to consider a number of responses that will help maintain industry profitability in an uncertain environment. It should also help this valuable industry to come to terms with long-term climate change and begin formulating adaptation strategies.” The trials began in September last year, with forecasts provided to Tasmania’s four major salmon farmers each month. Historical data back to 1990 and a seasonal ocean-atmosphere model developed by the Bureau of Meteorology are being used in the predictions. An associated cost-benefit analysis of the predictions applied to each site also will be generated. The project involves trialling advanced statistical techniques to determine how well scientists can resolve the variations at the different time scales. Dr Hobday said warm summers can significantly impact farm production through an increase in operational expenses and direct impacts on salmon, while cool winters slow growth in salmon. He said validation of the forecasts using historical data is improving their accuracy and illustrating the likely benefits to the industry. For further Information contact Dr Alistair Hobday, CSIRO Marine & Atmospheric Research. Ph: 03 6232 5310 Email: Alistair.Hobday@csiro.au

Optimal feeding is vital for good fish growth; large fish need one feed/day whilst the smolts require up to six per day – this means that HA can be feeding more than 700t/week at peak biomass. Using pellet sensors, backed up with underwater cameras and solar powered smart feeders, HA feed to satiation to get the best growth; they don’t focus on FCR, although they regularly have FCRs between 1.3–1.45 using a 20MJ diet with varying protein content to match fish requirements. The farm uses Ridley and Biomar feeds. HA have found the best strategy is to have good water flow through larger mesh nets, regularly cleaned and a lower fish density. As water temperature increases and dissolved oxygen falls below 5.5mg/L in the centre of the pens, the feeders can add bottled oxygen through perforated grid inside the pens to support metabolic requirements of the fish and allow feeding. The AQ1 Smart feeding technology is used to optimise fish feed consumption and reduces the wastage of aquaculture feeds. These units consist of a floating silo which can hold up to 6 tonnes of feed with spinner and underwater sensor. The pens are all bird netted to prevent birds taking pellets. A 168m pen full of fish can use up to 3 tonnes of feed a day. In mid 2007 a new 100 tonne feed boat, Zeus, was introduced. Zeus can resupply 10-16 pens each trip. Feed is stored at Port Huon pier which is also the location of HA’s workshop where Zeus was built. Harvest and processing For harvest, the growout pens are towed in at one knot into the more sheltered Hideaway Bay; some pens might take 60hrs to reach their destination. The tow boat is set several 100ms away from the pen to avoid the wash from the propellers stressing the fish. The fish are transferred into either of two 480m3 raceways; together these can hold 200 tonnes of fish which are purged for 2-4 days. These harvest raceways have thick knotless nets to keep out the seals

and also prevent damage to the fish. They are also supplied with aeration to maintain dissolved oxygen levels. The actual harvest takes place at night. The salmon are sucked through a 40cm wide intake pipe of the Transvac triple chamber vacuum fish pump (this model is the largest in world). Over the night there is a continuous flow of up to 100 tonnes of fish into a battery of automatic stunner machines (made by Seafood Innovation, Qld) which humanely kill the harvested fish and then automatically bleed them to maximise quality. This system means that the fish are killed with little stress and it takes about eight hours before rigor sets in. The fish are transported in ice slurryfilled, 1-tonne plastic insulated bins on trucks for the five hour trip to their primary processing factory at Parramatta Creek near Devonport; this facility has a daily capacity of 150 tonnes of HOG, 25 tonnes of fillets. Fish are gutted using a Baader vacuum type system, a manual ‘hand’ line is also used when caviar is being collected during late summer. A Marel weighing system that links a computer with the daily orders to a scale and label printing machine allows for easy packing and tracking of order fulfilment. The HOG fish packed in plastic bags and ice are sent to market in Huon labelled boxes. Harvesting at night coupled with same day processing and sea freight means fish are available for sale in Melbourne or Sydney the next day, the freshest salmon in the world. Second quality fish are graded for filleting. A Carnitec automatic filleting machine and Marel trimming machine enables four tonnes of fillets to be produced per hour of operation. The fillets are either individually vacuum packed or sold loose in 18kg cartons; most go to HA’s value-adding smoked salmon operation but an increasing amount go to domestic and export customers. The internationally recognised BRC’s (British Retail Corporation) food safety certification is difficult to achieve, and few companies are certified at their first

audit. However in August 2010 a BRC auditor checked the systems and processes at the processing facility at Parramatta Creek and found they complied with every one of the 332 items in this most rigorous standard. HA are the only ‘A’ rated seafood processor in Australia. To receive this world class A rating with no non-conformances within four months of opening a new facility is something HA and its staff are justifiably proud of. HA are lining up further accreditation with GlobalGAP – this certification will cover the farming operations from egg through to harvest fish embodying Huon’s commitment to continuous improvement and quality. Awards, awards, more awards Throughout the years HA has been continually successful with its range of fresh and value added products. In 2010 HA was selected as a finalist in the prestigious ‘President’s Medal’ section of the Sydney Royal Show. The field of 5,000 food and beverage products was narrowed down to just six products. HA’s unique Banquet Slice (a fillet length slice of premium cold smoked salmon) was judged against such Australian food giants as The Yalumba Winery, Bulla Diary, Peter Lehmann Wines, T& R Pastoral and Holy Goats Cheese. This same product went on later to win the Perpetual ‘Richard Langdon’ Trophy at the Hobart Royal Fine Food show with a perfect score of 100 points. In 2007 Peter was one of the Australian winners of the Ernst & Young Entrepreneur of the Year Award. Peter received the award in the Retail, Consumer & Industrial Products category. The Entrepreneur of The Year celebrates entrepreneurs who are building and leading, recognising them through regional, national and global award programs in over 100 cities and more than 40 countries. Peter dedicated the award to his wife Frances and all Huon Aquaculture staff, and said the company’s success had been built on attention to detail and innovation. “Since inception, we have maintained a

Huon Hot Smoked Salmon Italian Frittata.

strong commitment to ongoing Research & Development as an essential tool for peak performance,” he said. “We constantly strive to turn our research into practical on-farm innovations, to keep us ahead of our competitors.” A major focus of the company was to become vertically integrated. “We are no longer reliant on others for seed stock, and our purchase of Springs Smoked Seafoods in 2005, has seen the company enter new market segments that previously weren’t open to us.” “With the catch of all wild fish declining around the world, while the demand for fish and seafood continues to rise, Huon Aquaculture’s future looks bright,” Peter said. The Huon product is particularly sought in Japan where it is sold branded in many large Japanese department store food halls and supermarkets. It is recognised in Australia as the premium fresh product by wholesalers, retailers and chefs throughout the country and appears on many significant restaurant menus by name. There is no doubt that HA will continue to be a successful, growing and dynamic business. By Dos O’Sullivan For more information contact Frances & Peter Bender, Huon Aquaculture Company, PO Box 1, Dover 7117. Tel: 03 6295 8111, Fax: 03 6295-8161 email: huonaqua@huonaqua.com.au Autumn 2011 | Austasia Aquaculture 7

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The proud ‘boys’ at Australian Prawn Farms show off their award winning prawns. Photo courtesy of Aust Prawn Farms.

Environmental certification and biofloc technology boost prawn farm profitability A north Queensland prawn farming company has been leading the charge for Aussie prawn farms to be more sustainable. In 2006 it attained ISO 14001 certification for environmental management; one of the first prawn farms in the world to achieve such recognition. Applied research into the use of biofloc in their ponds has also contributed to considerable increases in profitability.

three-year research project funded by the FRDC and the Seafood Cooperative Research Centre through the Australian Prawn Farmers Association (APFA) examined the use of bioflocs to allow low water exchange culture of prawns. Biofloc technology combines the control of water quality – by removing waste nutrients from the ponds – with the production of a microbial community which can be used by the culture species as an additional food source. 8 Austasia Aquaculture | Autumn 2011

The main focus of this research was to determine if these innovative methods increased on-farm profitability. Did it ever! The results are extraordinary: • an 80% decrease in pumping costs • FCR reduced by 25% from 1.8 to 1.2 • Saving with a good floc can be 3 tonnes of feed/ha • Nutrient discharge down 65% • Productivity increase from 8t/ha/crop to 12t/ha/crop. This remarkable research was

undertaken at Australian Prawn Farms (APF), an hour south of Mackay in north Queensland. In November 2006 APF became the first Australian prawn farm to achieve ISO 14001 (environmental) certification, one of the first to do so in the world. According to Farm Manager Matt West, APF was one of the five farms involved in an eco-efficiency program funded by the Federal Department of Environment & Heritage and coordinated by the APFA. “We believed this was an

Management Metrics important initiative to help us improve our environmental management practices. It shows how committed APF are to environmental sustainability. And even though there are no current financial benefits of having ISO 14001 accreditation, it does open up potential future markets,” he says. The farm grows Black Tiger Prawns (Penaeus monodon) in 33 one-hectare ponds; the facility also includes a large modern hatchery, a HACCP-certified onsite processing plant and a 20ha settlement system built to reduce the release of suspended solids, total nitrogen, and total phosphorous. As part of the EMS, fortnightly tests on effluent are carried out to ensure the efficiency of the settlement ponds and compliance with Government regulations. APF has built up a good rapport with the regulatory agencies and prides itself on constantly improving its system to better the environment. “Our company’s approach to reduce environmental pressures is very proactive, which is why implementing an EMS (environmental management system) to achieve and maintain our ISO 14001 accreditation was very important,” Matt explains. “The system gives us an important tool to undertake a comprehensive review of our efficiency throughout the entire workplace, through identifying certain environmental risks and having a documented approach to deal with them.” Biofloc production This management system put the company in an excellent position to critically examine options for innovative production practices and the environmental risks associated with these. “I was forced into alternative methods of culture at a site with good water quality but limited availability at times. This led to limited water exchanges with an ever increasing pressure of higher production.”

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Key Management Decisions for Australian Prawn Farms include: • Certification: Environment ISO 14001, HACCP • Use of EMS systems to improve environmental performance as well as assess other innovative process • Commercial scale research into biofloc production • Time spent in providing extension of the research to industry. Key Performance Indicators (KPIs) for biofloc ponds include: • Culture or Holding System utilised: 1ha earthen ponds with biofloc • Growth rate (from stocking to 20g): 1.4g/week • Survival rate: 80% from first stocking to sale size • Av. stocking density: 50-60 PL/m2 (first stocking) • Production rate for test ponds: 12t/ha/crop, average farm production: 11t/ha • Water use: significant recycling, nutrient discharge down 65% • Power use: 80% decrease in pumping costs • FCR: 1.2 (number of kg of food to produce 1kg stock), savings up to 3 tonne of feed/ha Mixing up the biofloc in the prawns ponds. Photo by David Smith, CSIRO

Aerial view of the growout and settlement ponds at Australian Prawn Farms. Photo courtesy of Aust Prawn Farms.

Dr Dave Smith, as part of the CSIRO Food Futures Flagship, oversaw the research at APF which used five of APF’s commercial ponds operating under an Autumn 2011 | Austasia Aquaculture 9

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Silica was added at rates to maintain levels greater than 1mg/L after week 2 when the PLs are introduced. Given the importance of the phosphorus for primary production, the levels of this nutrients were kept at >0.1 mg/L. With sunlight this process resulted in very high blooms of large diatoms, a favourite feed of the prawns and an excellent seed for floc development.

Above: Some of the settled biofloc sampled from a growout pond. Left: A drained biofloc pond showing the clean substrate left following harvest. Photos by David Smith, CSIRO.

Annual Review APF conducts annual reviews which include assessment of the following practices and procedures: • Maintenance records (eg vehicles, equipment, bins, down time, accidents, fuel usage and electricity) • Feed use and feed use monitoring systems • Water usage and water monitoring • Communications (e.g. on the farm and between farms) • Disease management and monitoring • Disease response • Emergency Action and Response Planning • Daily task lists • Induction and training verification systems • Administration efficiencies • Recycling and re-use.

10 Austasia Aquaculture | Autumn 2011

intensive monitoring program. The project had six aims: 1. Confirm nutrients needed to establish and maintain the floc. 2. Establish the effects of different sources of carbon for the floc. 3. Determine the nutritional benefits to the prawns using FCR. 4. Assess changes in the levels of nutrients in farm discharge. 5. Calculate the influences on farm profitability. 6. Extension to industry. The results were presented at the 2010 annual APFA conference and exhibition to an engrossed audience. A range of phosphorus and silicate fertilisers were tested to determine which was the most efficient at establishing early diatom blooms, the key to floc production. A process was developed which started with the addition of 20kg Urea and 7kg MAP per hectare in a recently filled pond. This resulted in an increase in pH to 9 within two weeks.

Both inorganic and organic sources of carbon are important for the bioflocs. Crushed limestone, or sodium bicarbonate, provides an inorganic carbon for microalgae (such as the diatoms) and autotrophic (self-feeding) bacteria. Measured as Total Alkalinity, the best range is between 80-120 mg/L. The project found that neither hydrated lime nor sodium carbonate is directly suitable for the maintenance of bioflocs, but hydrated lime is used to keep pH in the range suited for good autotrophic bacterial growth. Matt said that a good floc would cause Total Alkalinity to drop so the farmer needs to keep adding sodium bicarbonate to maintain the optimum levels. Heterotrophic bacteria don’t use sunlight; rather they use ammonia for their energy production. Thus organic carbon sources such as molasses, bagasse (cellulose-based by-product of sugar cane production) or even dead algae can be used to increase their production; however, the best results were achieved with molasses. “Care needs to be undertaken with the addition of molasses as it is expensive and it can result in heterotrophic bacterial blooms which in turn can lower dissolved oxygen.” If a stable environment is maintained then there can be great nutritional benefits for the prawns as they exhibit less stress and use less energy. Matt found that FCRs around 1.2 to 1.3 were recorded; a poor floc or normal feeding usually results in FCRs in excess of 1.6. “This can mean that with a well maintained floc the savings in a one hectare pond can be over three tonnes of feed during a 136 day production cycle. The

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normal feed amount is around 16 tonnes/ ha/crop, so the farmer can reduce his feed bill by over $6,000/ha/crop.” Significant decreases in nutrients discharged were also recorded. For example Total Nitrogen discharge in 2003/04 was 41kg for every tonne of prawns harvested; the floc reduced this to 9.4kg/tonne in 2008/09. Matt says that the floc also increases the management options for the farmer. “During heavy rain the prawn farmer can’t exchange water even though this can lead to increased ammonia levels which in turn reduce production in a normal pond. In a floc pond the ammonia is used by the bacteria which in turn become food for the prawns.” Significant increase in profitability The five test ponds performed significantly better than the other ponds that were operated using conventional prawn farming techniques. Average harvest increased from 8t/ha/crop to 12t/ha/ crop. At a farm gate price of $10/kg, this results in an increase in market sales of $40,000/ha; at $15/kg the extra profits could be greater than $60,000/ha/crop.

leads to reduced stocking densities and thus lower nutrient loads (for Monodon ponds) which require a slightly different way of ‘low water exchanges’.”

identify the challenges to implementing the strategies needed to undertake Biofloc technology.” At least three major farmers are now using bioflocs on their farms.

Industry workshops Matt and APFA have been extremely active in ‘spreading the word’ through phone calls to answer questions to farm visits to demonstrate the process or trouble shoot. Presentations have been made at the annual APFA conferences from 2008 to 2010.

Research is now underway to fine-tune the process as there are a number of things which still need to be worked out. The first is the uncertainty about how best to establish the diatom bloom at the start of the crop. The application of molasses is another area as well as the continual maintenance of the appropriate levels of silicates and phosphates.

In conjunction with the Sunshine Coast Institute of TAFE (SCT), a two day industry workshop on Biofloc was run in Townsville in May, 2010. Attended by many farm and pond managers and technicians, the workshop aimed to develop changed management strategies for the implementation of Biofloc techniques on prawn farms.

As with the previous results, this highly successful research will be communicated quickly to industry. By Dos O’Sullivan. For more information contact Matt West, Australian Prawn Farms Pty Ltd 12, Lot 12, Notch Point Rd, Ilbilbie, QLD, 4738, T: (07) 4950-3111, 0428 457-787, E: apffarm@bigpond.com

Organiser Stuart Whitney said the workshop demonstrated the management practices implemented and lessons learned during APF’s Biofloc grow out cycles. “The delegates were able to assess the capacity of their farms and

Dr David Smith, CSIRO, 07 3826-7239, E: david.m.smith@internode.on.net

Matt found that slightly more labour was required to initiate and maintain the flocs as well as analysing water quality; the extra cost was around $1-2,000/ha. “On a large farm (say 40-60ha) this job could not be handled by one person.” Stocking densities of PLs have also been increased from 30-35/m2 to 50-60/m2, which Matt says also boosted pond productivity. “In Belize, where this technology was developed in the early 2000s, they stock white shrimp (Litopenaeus vannamei) at 180PL/m2; however, they produce 25g prawns, whereas our Black Tigers average closer to 30g.” Matt is well aware that different species exhibit different behavioural characteristics which is important when considering adopting different techniques. “Vannamei inhabit more of a 3-dimensional space, whereas Monodon are more 2-dimensional bottom dwellers. This difference

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A Q U A C U L T U R E TA N K S Autumn 2011 | Austasia Aquaculture 11

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Quality and service wins for Barramundi Gold Barramundi Gardens, winner of a gold medal for large Barramundi at the Spring 2010 Sydney Royal Show Fine Foods competition, is reaping the benefits of a focus on quality products and customer service that’s ‘second to none’. The farm has just launched the Barramundi Gold brand name and is gaining more customers for its delicious Barramundi spring roll.

“Of course we’re also locally famous for our ‘Barramundi Spring Rolls’ which are distributed nationally. “Our hydroponic lettuce, Asian greens and herbs are grown for local wholesalers, retailers and restaurants. Growing our own produce to include in our spring rolls is the added bonus which not only cuts costs but gives us total confidence in our ingredients.” The barramundi growing process begins with 25mm fingerlings purchased from hatcheries around north Queensland. The fingerlings are grown to around 100-130mm (10-25g) over 8-10 weeks in the nursery – consisting of 48 x 400 litre tanks, four1,000 litre tanks and six 5,000 litre tanks. These small fish are fed GroBest barramundi pellets three times a day. “Our fingerling nursery is a fully closed recirculation system that pumps 50,000L/ hr. We have a drum filter to remove solid waste, a 5,000L capacity biofilter to remove ammonia and nitrites, a polygeyser, ozone and oxygen generators which inject ozone into the system and UV lights for sterilisation. We purchased this system from Aquasonic.” The pond water comes in through 6 inch PVC pipe from a header dam which is topped up for evaporation losses by a spring fed creek flowing from neighbouring rainforests.

Looks good enough to eat a dozen! The famous Barramundi Spring Roll.

im and Gail Thiele, along with their extended family and three young boys,

have been running Barramundi Gardens since 2002. Located in the Port Douglas hinterland, only 25 minutes drive from the vibrant tourist town, the six hectare property offers a diverse range of products and activities. The farm was featured in AA in March ’09 (Vol 23.1). 12 Austasia Aquaculture | Autumn 2011

“We’re constantly working to improve the quality of our products, expand our range and ensure a friendly customer service,” explains Tim. “We have a commercial 2ha aquaculture farm, a 50m2 fingerling nursery and a 150m2 hydroponic produce complex. Each year we can produce up to 45 tonnes of Barramundi from pan size to large whole (and fillets) and sell over 200,000 fingerlings to local farms.

There are12 growout ponds, each 0.1ha in size and up to 2m deep. Each pond has a 2.5HP double paddlewheel to maintain water circulation. Water quality is maintained by a weekly 20% water exchange into a settling ponds. “The settling pond acts as a natural wetland ecosystem which purifies the water before being held in the header dam.” After the nursery stage the fish are first stocked in 6 x 3m floating PVC pontoons with a 1-1.5m deep hanging net. Once

All photos courtesy Barra Gardens.

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the fish reach 100-150g (200mm+), they are released to free range in the ponds. To prevent predation from shags and night herons, the ponds are netted with bird netting held up with poles located in the centre of the pond and attached to the ground with star pickets. Tim says that the pond fish are fed Ridley’s floating barramundi pellets in the mornings. “We do this in the mornings to maximise the optimum dissolved oxygen level throughout the day.” Once the fish exceed 300g Tim removes the netting as the fish are now too big for most predators. However there is a local sea eagle that will take the occasional bigger fish.

Chris, Sandra and Tim in their popular Barramundi Gold stand at Master Chef Live Event held last December in Sydney.

Asian Greens and Lettuce are grown at the hydroponic facility.

Fish are harvested depending on orders with a 30 metre fish net. They are mustered to one end of the pond and then moved quickly to a bin with an ice slurry. These are transported to the packing facility. The Thieles once ran a sports fishing tourist facility in one of their ponds. “We started the Barramundi Sports Fishing Park back in 2004,” Gail says. “This proved to be extremely popular with people from all ages and parts of the world enjoying the opportunity to get up close and personal with the world renowned barra. Both professional fishermen and recreational fishers came here to enjoy the prospect of bringing home the big one (we stocked fish between 4-5kg) and making sure they don’t have a story to tell about ‘the one that got away.’” But they closed the fishing park two years ago to concentrate on growth of other aspects of the business. “The sports fishing/ tourism potential is an avenue that we intend to go back into in the future.” Processing plant Barramundi Gardens has a HACCP accredited processing plant. “We have been third party certified since 2002,” Gail says.

“We also are audited annually by Safe Food Queensland and have a food manufacturer’s licence with the Tableland Regional Council. So we can show that we are committed to all aspects of food safety.” The Thieles sell barramundi year round. Most of the fish are sold as whole chilled (0.2°C) fish to wholesalers in Sydney and Brisbane. “We also offer a 5kg shatter pack (fresh or frozen) of fillets between 800g and 1.2kg and pan size gut’n’gilled barramundi. Fish are packed in 20kg polystyrene foam boxes with ice packs

Healthy fingerlings grown in the nursery shed.

Autumn 2011 | Austasia Aquaculture 13

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Management Metrics Key Management Decisions for Barramundi Gardens / Gold include: • Certification: HACCP and consistent quality and customer service • Diversification into other high quality, high turnover products such as spring rolls, dumplings, etc. • Use of discharge water for hydroponics operations. – research more into aquaponics, to continue and enhance the links between aquaculture and the horticulture side of the business Key Performance Indicators (KPIs) include: • Culture or Holding System utilised: 0.1 ha earthen ponds, nursery tanks • Growth rate (from stocking to market): <18 months (2g to 3kg+) • Survival rate: 80% from first stocking to sale size • Annual harvest: 45 tonnes • FCR: 1.2 (number of kg of food to produce 1kg stock)

and the best’ Barramundi Spring Roll. “By combining locally grown produce and our own finest barramundi fillets we have created a unique Spring Roll that surpasses all taste expectations. The individually handmade, rolled and created spring roll cannot be matched with its superior quality ingredients, finest taste and uniform presentation. Our product is a must for every restaurant wanting to offer an Australian product of such high quality. “In 2004 our spring rolls were awarded the endorsement as one of Queensland’s Fine Foods through the Les Toques Blanches Queensland Chapter. Since then our spring rolls continue to offer the highest quality product in taste and presentation that Executive Chefs from many establishments are proud to offer on their menus throughout Australia. “Repeat customers and new restaurants show we have a great product.”

A delicious award winning Barramundi.

wholesales frozen Asian food around Australia. “In partnership with Crazy Dragon, we have built a state of the art processing facility,” Gail explains. Untitled-1 1

17/11/10 10:44:41 AM

Barramundi Gold Logo – award winning artwork for the brand.

or bulk half-tonne bins for transporting by road to customers.” Barramundi Gardens also manufactures a wide range of spring rolls and dumpling products for the Crazy Dragon Gourmet Food Company which 14 Austasia Aquaculture | Autumn 2011

“Using high grade machinery we are able to manufacture spring rolls and dumplings very efficiently. Part of the facility involves high speed blast tunnels for freezing of the products. Our facility allows us to produce approx 2,000 spring rolls per hour, with them being frozen and packed within 50 minutes of manufacture.” No surprise then that she reckons Barramundi Gardens makes the ‘original

Gail is quick to point to the synergies of these two parts of their business. “The processing is a part of the business which is continually developing and expanding and we are enjoying the ride that it is taking us on, diverging from the traditional primary producer and value adding our products at the same time. Both are successful due to our attention to quality and customer service. Our aim, as for is most small business, is to be able to get a better price at the farm gate for our aquaculture and its products.” Barramundi Gold & Master Chef Live The Thieles entered an 18month old barramundi in the Sydney Fine Foods Spring ’10 competition – the section was for 2-4kg whole fish. Fish from several farms were all steamed and judged on external appearance and eating quality – texture, sweetness, flavour and aftertaste. Their ‘entrant’ won gold; one other producer also received a gold medal in this category. “The judges described both gold medal-winning fish as being of ‘outstanding presentation with the highest quality’ and ‘very well fleshed’. “We were very happy with this,” Gail says.

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“The judges also remarked that there’d been significant improvement in the quality of fish supplied for judging over previous years.” The Gold Medal award underpins the Thieles’ new ‘Barramundi Gold’ brand. “Our aim is to get our fish well known as high quality in the market,” Gail continues. “Customers can have confidence in our fish as they are grown in rainforest-sourced water. We want to lift the profile of farmed barramundi not only with chefs and caterers but also with the average consumer. We want it to become the fish of choice for everyday Australians wanting to eat quality, great-tasting, Australiangrown fish on a regular basis.

Location, location, location – paradise at Julatten, north Queensland.

Tim has also exhibited their fish at Sydney’s three-day Master Chef Live show in Sydney last December. Tagged as the ‘Foodies Ultimate Day-out’, the event attracted more than 25,000 hungry and discerning food enthusiasts. “We were lucky enough to engage the services of Martin, 4th year chef from the Ochre Restaurant in Cairns to help us present our fish,” Gail says. “We sent down around a total of 300kg of fish (average size 2kg) of which some were baked with white wine and other special flavourings. “We also served Barramundi in a gougon style – deep fried Barramundi fillets in a tempura batter served with lime aioli – and offered a Barramundi ceviche – thin slices of Barramundi ‘cooked’ in a lime, vinegar, chilli, ginger and coriander sauce. “The Barramundi Spring Roll as usual was a resounding success with a lot of what we call ‘repeat offenders’, people returning for another bite.

Tim Thiele sending off a fine specimen of ‘Barramundi Gold’ to market.

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“Overall it was definitely worth doing and really raised the overall awareness of our products.” By Dos O’Sullivan. For more information contact Tim & Gail Thiele, Barramundi Gardens, P.O. Box 159, Mt Molloy Qld 4871, T: 07 4094-1293, F: 07 4094-1434, Email: barramundigardens@bigpond.com

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Autumn 2011 | Austasia Aquaculture 15

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Flat oysters finding expanding markets

An aerial view of part of the intertidal leases at Pristine Oysters. Courtesy of Pristine Oysters

Our native Flat oyster (Ostrea angasi) is also sometimes called the Mud oyster or Angasi oyster. Native oysters very closely resemble the Belon oyster (O. edulis), which was previously common in Europe and is now reported to be the most expensive oyster in the world. Our Flat oyster is popular for its fine textured meat, full-bodied taste and distinctive salty flavour. Thanks to hatchery production of spat, some NSW farmers have been growing Flat oysters commercially for about fifteen years and over the past few seasons a grower in SA has been growing award-winning Flats.

he Flat oyster is endemic to southern Australia, ranging from Western Australia (Albany) to southeast New South Wales (Newcastle) and around Tasmania. Also known as Angasi, Bluff, Mud and Belon oysters, Flat oysters are found in sheltered silty or sand bottomed estuaries at depths of between 1 and 30m. They actually attach themselves to hard substrates before later breaking free to settle on sand or soft mud. Like all other oysters they are filter feeders, feeding on, and taking in anything small enough to be filtered in their gills. This may include plankton, microalgae or inorganic material. Flat oysters, are being farmed alongside 16 Austasia Aquaculture | Autumn 2011

Sydney Rock Oysters (Saccostrea glomerata) on the south coast of NSW and with Pacific oysters (Crassostrea gigas) in South Australia. These oysters reach market size in about 18 months or half the time of Sydney rock oysters. They are also receiving a high farm-gate price of about $9-10 per dozen and are the preferred traditional oyster of people from Western Europe, Asia and New Zealand. Farmers are reporting increasing interest in the Flats by chefs at the top end restaurants in Melbourne and Sydney along with increasing prices. According to Steve Feletti of Moonlight Flat Oysters®, the Flat oyster is the oyster lover’s oyster. On his fantastic website (www.moonlightflatoysters.com.au/) he

writes that the flesh is usually a dull mushroom pinky brown with a chalky white in winter. In comparison to Sydney Rocks, he claims the Flats taste a little smoky, earthy, like duck compared with chicken and notes that, whilst some consumers may have previously found them challenging due to their texture and stronger taste, superb handling by some restaurants is increasing their popularity. The Batemans Bay oyster marketing supremo is also quick to point to its similarities to Europe’s famed Belon oyster, using recent DNA findings as research collateral. Surprisingly the Flat Oyster is closer to the Belon than to the New Zealand Bluff Oyster (Tiostrea chilensis).

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Hatchery basis Due to low numbers and an unreliable wild catch, the NSW Flat Oyster industry has been reliant on hatchery-produced spat (3-5m seed/yr) for the past six years. Most hatchery production comes from the Port Stephens Fisheries Institute (NSW Industry & Development) although a couple of farmers on the NSW south coast have also established small scale hatcheries to meet their own needs.

Ostrea angasi larvae at the crawling stage (note foot extended along shell grit particle) just prior to metamorphosis. Courtesy of S. O’Connor NSW Dep. Industry and Investment – Port Stephens Research Institute

According to PSFI scientist Stephen O’Connor, Flat oysters brood larvae in their gill cavity for 7-10 days, depending on food availability and water temperature. The larvae are then released for a planktonic stage of 7-10 days after which the larvae settle on a suitable surface, adhere and metamorphose into oyster spat. In the past hatchery production of O. angasi spat has relied on ground scallop shell as a settlement substrate. However this has proven problematic. Given PSFI research (published in Aquaculture Research Vol 40 Issue 14, 2009) showing that epinephrine successfully produces cultchless Flat Oyster spat, such chemical induction is now used for routine commercial production. Stephen has also been researching the effects of larval diets on the energy reserves of the Flat oyster larvae at settlement. “During this transitional stage of larval development (from free swimming to benthic) larvae loose the ability to feed and rely on energy reserves accumulated during larval growth,” he says. “Epinephrine treatment of larvae to induce larval metamorphosis has been used to examine the effects of different alga diets on the development rate of hatchery produced flat oyster larvae.” Stephen points to the importance of dietary assessment for hatchery culture of different bivalve species. “As an example many Pacific Oyster hatcheries have used an algal mix of up to 80% of the diatom Chaetoceros calcitrans, whereas the Flat oysters would not grow well on such a diet. We do know they grow well Pavlova lutheri and Tahitian Isochrysis galbana. However a mix of several algal species

have been identified that will maximise the diet’s nutritional value for the larvae.” He’s also developed a technique to remove larvae from adult oysters on the leases without damaging the larvae or the broodstock. “A 500mg/L solution of magnesium chloride is used to narcotise individual adult oysters; the process can take up to 2 hours to take effect. Once narcotised, the adult oyster gape open and the larvae can be easily rinsed from the oyster. The adult oysters are returned to fresh seawater and recover within an hour. The larvae are rinsed in fresh seawater and held in an aerated bucket of 1µm filtered seawater for transport back to the hatchery where they are on-reared in one tonne tanks.” The seed are ongrown until they are about 1mm shell length when they are sold to oyster farmers. Genetic research has found that the New South Wales estuaries represent a geographically homogeneous population (Hurwood et al. 2005, Marine & Freshwater Research, Vol. 56, no. 8, pp. 1099-1106). This essentially removes any potential genetic constraints on broodstock sourcing and spat translocation within this region. So hatcheries can produce seed which can be stocked in waterways up and down the NSW coast in accordance with NSW I&I translocation protocols.

From top: Flat Oysters in tray washed and ready for retail sale. Sales are either opened or unopened as requested by the customer.. Flat Oysters in 20mm mesh tray, in the finishing stages to gain depth and mature for sale. Flat oyster presented for retail sale. Hessian bags are used as they keep the oyster cool and extend the shelf life. Courtesy of Pearl Oyster Bar.

Autumn 2011 | Austasia Aquaculture 17

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product in other parts of Australia have been caused by the disease Bonamia, for which there is no known cure. Preliminary surveys by NSW DPI of five south coast estuaries have confirmed the presence of Bonamia. However, to date no mass mortalities of Flat oysters caused by Bonamia have been reported in NSW. R&D is underway to find a molecular test for diagnosing Bonamia. Low salinity and mud deposition can also cause troubles. Last year, at least one farmer lost his entire Flat oyster crop due to freshwater flooding along the river where his farm was located. Stefan Paschailidis has been farming oysters on the Clyde and Tomago Rivers for over 35 years and currently operates 25ha of leases. His family business has been selling Sydney Rocks through their retail store The Pearly Oyster Bar at Batemans Bay; it remains in the same location where it was established by family patriarch Christos in 1972.

Top: The oyster processing room at Pristine Oysters, South Australia. Above: Flat and Pacific Oysters growing in the beautiful waters of Coffin bay, South Australia. Images courtesy of Pristine Oysters

Farmer advice and assistance As part of the NSW Government’s continued commitment to aquaculture development, over the past decade NSW Fisheries has been providing farmers with advice on design, assembly and operation of Flat oyster nursery equipment as well as advice on care and handling of stock (three workshops were held between 2000 and 2002). Oyster farmers have established pump ashore field nurseries at sites in Pambula Lake, Merimbula, Bermagui, Narooma, Batemans Bay, Port Stephens and Camden Haven. They use upwellers 18 Austasia Aquaculture | Autumn 2011

which are compatible for a number of shellfish species. In most cases, results achieved by the farmers have exceeded expectations. Growth rate and survival of spat on a diet of wild phytoplankton have been far superior to that achieved in previous years with hatchery spat fed cultured microalgae. In NSW an average market size is achieved in 18-24 months when the Flat oysters are grown on existing intertidal rack and tray leases developed for Sydney Rocks and even faster if grown in suspended culture on deeper sub-tidal leases. Mass mortalities of wild and cultured

Stefan was the first farmer in the Clyde River to try growing Flat oysters and he has been doing this for more than 15 years. He purchases an average of 50,000 1mm-2mm seed from the NSW PSFI and grows them up in a pump ashore nursery upweller system for 2-3 weeks. They are then transferred into 2mm mesh trays that are floated in the surface waters under capped 100mm polypipes. “Every three weeks we lift the trays out, wash and grade the seed through sieves,” Stefan continues. “And then we thin them out into new larger mesh trays. When the oysters reach 30-50mm they are moved into 20mm mesh trays and are suspended in a pontoon system in 10 tray modules. All of the seed received should have reached this point by 17 weeks. At this point the oysters are still very thin; it can take several years to finish the oysters and provide them with the depth they require to be mature enough for sale. Fish predation – especially stingrays on the juvenile Flats – can be a problem so 20mm plastic mesh covers the trays to exclude the predators.”

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Fouling is an ongoing headache during growout, especially cunjevoi (sponges) and barnacles. “You can dry out the Sydney Rocks and kill the fouling, but you can’t do that with Flats. So we try to avoid the fouling settlements by moving the Flats up or down in the water column. We wash and grade the larger oysters every 6-8 weeks.” Stefan finishes his Flats in intertidal racks for around 3 months. “We gradually hold them higher and higher in the racks to harden them as they don’t like being out of water for more than three days, even when it is cool.” He says his Flats are quite different to the Sydney Rocks. “They are an unusual product. Some people love them and at our store we get a bit of interest from people wanting something out of the ordinary. We have tried selling them to restaurants but lack of knowledge about them can limit sales; the Flats have a much stronger taste. Whilst the Flats are only a small part of his business they do retail at $14/dozen for 75-100mm oysters for 2-3 year-old

product. And well worth it too he reckons. In 2008, Stefan won the Gold Medal for Flat oysters at the Sydney show (Fine Foods awards) as well as the Champion Oyster award.

longlines for the Flats, in much the same way as Pacifics are grown in the region. The brothers have used a range of baskets and are experimenting with stocking density and height in the water.

Culture in SA

The shell of a Flat is not as hard as that of the Pacific oyster so farmers need to take care with how the they are handled, especially during mechanical grading. “We can’t put them through the automatic SED oyster grader so we use the rotary (PVC tube) graders for them,” Brendan says.

Some seed has also been sent interstate under strict biosecurity protocols. Such income is considered vital to securing a commercial hatchery for NSW as sales for local producers are currently too low to underwrite such an operation. One customer is Pristine Oysters, located in Coffin Bay at the remote southern end of the Eyre Peninsula, run by brothers Tony, Brendan and Nick Guidera. In September 2008 they purchased 6,000 Flat Oyster seed from Shellfish Culture in Tasmania to trial. “We were happy with the results selling the majority of them at 75 to 80mm in 4-18 months,” says Brendan. “The only problem we had was sourcing more spat. It wasn’t until March 2010 that we managed to get 200,000 angasi spat from NSW.” Pristine Oysters uses adjustable

“It is important to get the small seed into the drink quickly. However, they are fairly robust. We don’t have a Bonamia problem here in SA perhaps due to our higher salinity or water temperatures. “The angasi has a much stronger lingering flavour than the Pacifics, so they don’t need to be overly large,” he continues. “We are finding chefs place more emphasis on a clean nicely shaped oyster shell rather than going for a large size.” Many of Australia’s leading judges believe the Flat oyster has a great future. Pristine’s

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Flat oysters won the Champion Oyster award at the 2010 Sydney Royal Fine Food Show plus that year’s Delicious magazine ‘Producer of the Year’ award as judged by Philip Johnson, Matt Moran, Neil Perry, Alla Wolf-Tasker, Maggie Bier and Cheong Liew. “The judges singled out our angasis for special mention at the awards,” Brendan adds.

Some of Pristine Oysters’ award winning Flat oysters. Courtesy of Pristine Oysters

Changing how oysters are sold Through broodstock selection in the hatcheries and innovative culture techniques on the leases, farmers hope to further develop Flats as a premium product line suitable for both local consumption and for export, especially into Asia and Europe.

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But a premium product requires very high standards and Steve Feletti of Moonlight Flay Oysters suggests – through his website – that oysters in Australia are generally “under-marketed, poorly handled and badly delivered”. He believes that Australians should lift the standard of oyster growing from the ground up and ensure product integrity and consistency in all aspects of cultivation and delivery right way through to the consumer. He follows up this assessment with compelling data on why the way in which we enjoy oysters in Australia doesn’t do them justice. “France produces 129,000 tonnes of table oysters per year,” he says. “Australia produces about 10,000 tonnes. In France not a single oyster is sold pre-shucked and tap rinsed – in Australia the bulk of product is pushed through opened and rinsed. “This is the challenge. If we are to create real demand for quality product then the grassroots of the industry have to change. I’m astonished that Australians will pay good money to eat pre-frozen imported oysters laid out on those groaning hotel buffet tables, or buy chilled, shucked oysters when it’s easier and cheaper to buy live oysters in their shell and open them at home.” By Dos O’Sullivan For more information contact: Stefan Paschailidis, Pearly Oyster Bar, 02 4472-7322 / 4472-4233, E: pearlyoysterbar@bigpond.com Stephen O’Connor, Port Stephens Fisheries Institute, E: stephan.oconnor@industry.nsw.gov.au

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Brendan Guidera, Pristine Oysters, 0427 292-430, E: info@pristineoysters.com.au Steve Feletti, Pelican Beach Oysterage 02 4472-9000, 02 4472-7186, Moonlight Flat Oysters, Batemans Bay, www.moonlightflatoysters.com.au/

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Autumn 2011 | Austasia Aquaculture 21

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Thinking out of the square with native fish The really big changes in technology often come when people work independently, think ‘out of the square’ and move away from the conventional thought processes. A NSW native fish hatchery operator has used his science background and practical experience to critically assess the biology of his fish. The results are some very interesting ideas which he has detailed in a 410 page book to be launched this year.

ince 1996 Greg Semple has owned and operated the Murray Cod Hatcheries (MCH) which was first developed by David ‘Pat’ McLaren in 1969. The 38.6ha facility is located within the suburbs of Wagga Wagga just 7km from the CBD and 270 km southwest of Sydney. The hatchery/farm and its production methods have been featured in Austasia Aquaculture in 2001 and 2006. Greg has earned a living from the production of Murray Cod (Maccullochella peelii), Silver Perch (Bidyanus bidyanus), Golden Perch (Macquaria ambigua), Freshwater Catfish (Tandanus tandanus) and Yabbies (Cherax destructor) but clearly his motivation has been more than only fiscal.

“For 15 seasons, most of the World’s endangered Tandanus tandanus production has been from MCH,” he explains. “I have dedicated a great deal of time, pond space and other resources to the preservation of six endangered Catfish strains. Many of the parental populations are now believed to be extinct in the wild. This has been undertaken with no formal Government stocking program and a limited private market, around 22,000 fingerlings a year.” The fish were being donated for stockings by the Wagga Wagga City Council, by children during Water Week and by local recreational fishing clubs. However, such programs were largely suspended because of a failure of the stocking groups to notify the Fisheries Authority, so the presence of young fish gave the false 22 Austasia Aquaculture | Autumn 2011

impression that the species was breeding and recruiting naturally. “Most fish have quite short effective productive lives. During my work I have culled in excess of 1.5 million fish to maintain the genetic diversity of my six catfish strains. These excess fish were fed to other game fish species such as broodfish cod and perch.” Scientific background Greg was university trained as a scientist, initially specialising in zoology and genetics. Later formal postgraduate studies in the USA were in Aquaculture and Aquatic Environmental Sciences. He has worked with, and consulted for, a wide range of government and private projects. One job was the supervising and upgrading of monitoring equipment (fish biosensors and electronic water quality monitors) used to safeguard the potable water supplies of the Sydney Basin. For a year and a half he helped study the catchment impoundment and even managed to spawn the Macquarie Perch (Macquaria australasica) in monitored glass races. From 1983 to 1990 – prior to becoming a full-time farmer – he was an author of over 80 scientific publications (Government reports and peer-reviewed papers). Greg has presented scientific papers to international conferences in Canada, USA and Australia and is often requested to give interviews to the media or to present lectures to

veterinary, biology or aquaculture groups. “During 50 years ears of independent fish keeping (Greg started keeping fish when he was 5 years old) and 35 years of study as a biologist and water quality analyst, I have long thought through my ideas on fish biology,” Greg continues. “I am publishing this information in my book ‘Fish Biology with emphasis on the Cod, Bass and Perches Maccullochella and Macquaria (Pisces: Percichthyidae)’. “My somewhat altruistic philosophy is that the roles of science should be to expand and nurture our knowledge and understanding, and to critically review and question the validity of earlier work. In my book I challenge our earlier understanding of native fish biology by re-examining fish biology and genetics, reinterpreting baseline data and reassessing scientific techniques.” In a wide ranging interview Greg gave Austasia Aquaculture some interesting insights to his views with some key messages on Australian native fish. Fisheries management strategies Greg believes that the scientists and fisheries managers will always have problems on reaching consensus. “Disagreement always existed in how to best manage and improve each fishery. This is not surprising when one considers the numerous different fractional self-interest groups and strong personalities involved.” He considers that at least some of the

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information represented as fact has simply managed to ignore basic fish biology, genetics, historic native fish distributions and changes in the natural carrying capacity of the waterways, particularly the Murray-Darling Basin (MDB). Growth rates and reproductive success “Whilst the growth rates, size and age at which any fish will commence and cease to reproduce is largely genetically predetermined, it is also conditional on its habitat. Precocious maturation and overstocking can reduce growth, creating stunted populations. The periodicity, spawn size, total number of batches, and lifetime fecundity of each fish are all very much functions of the environment in which it has lived.” Environmental change and habitat alteration “Habitat changes over 150 years have clearly altered the landscape of the Murray-Darling Basin (MDB). Lieutenant John Oxley in 1817 and Charles Sturt 1828-1835 gave very bleak accounts of the Basin. These expeditions noted either little water or saline water in many inland rivers and native forests dying from drought. Ironically, these same ephemeral rivers and wetland areas which never supported any continuous permanent finfish populations or water, are now considered to be suffering from overfishing and desiccation.” According to Greg, people have over estimated the amount of fish that were in the MDB. “Many people believe that the Basin once had a huge commercial fishery. Figures for the Commercial Fisheries of Inland Australia show that the maximum annual catch of native fish before weirs were used to regulate water in the Basin was only 147 tonnes in 1883. The creation of permanent water due to the weirs actually increased the commercial harvest of native species – in FY1976-77 some 290.7 tonnes were harvested in NSW (Water Resources Commission, 1996) and a maximum 340 tonnes in 1993 was reported for the MDB (Australian Bureau of Agricultural

Resources Economics annual fisheries report 1993). Recreational fishing is now being supported by the stocking of hatchery raised fingerlings. Government estimates suggest between 6 and 10 million native fish fingerlings are stocked each year by government and private groups into the more permanent waterways and farm dams within the MDB. The introduction of alien or exotic species has added pressure to the system. “Managed sports fisheries have been created for trout (mostly Rainbows [Oncorhynchus mykiss] and Browns [Salmo trutta]), and Carp (Cyprinus carpio) numbers have exploded in the Basin. For example, some 27,000 tonnes of Carp have been removed over 36 years by a single commercial fisherman.” Fish circadian rhythms, migrations & translocations “Australia’s hostile ephemeral aquatic habitat means that local extinction and recolonisation by immigrants is the norm rather than the exception.” Fortunately aquatic species are readily transported to allow these recolinisations. “The notion that fish in different bodies of water are isolated simply ignores the ease by which genetic material is moved long distances by water, the wind, birds and man. For example, all my ponds are filled with bore water so no other fish species can be introduced in the water. Yet last year I caught a 10kg Carp in one of my isolated Murray Cod broodstock ponds (0.2ha). The pond only had water in it for two growth seasons. The fish must have been introduced as an egg on bird’s legs or by some other manner. “In addition, wild freshwater species often move between river systems by means of diluted water in the coastal currents. “The general daily and seasonal movements of fish will often show some cyclic pattern of consistency for a population. However, the movements of each fish, or the same species in a different case scenario, are very much the ultimate functional response to a biological need at that

From top: A small ATV is a versatile and cost effective means of movement around the ponds. Greg Semple sexing mature Tandanus Catfish by examining their genital papillae. Returning conditioned brood Tandanus Catfish to a recently refilled and fertilised pond for spawning.

Autumn 2011 | Austasia Aquaculture 23

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Clockwise from top left: Once they are more than 70mm long Tandanus fingerlings become increasingly difficult to sell and ship. The aquarium trade prefers smaller fish. A 16 year old Murray Cod broodfish. Aquatic species are readily transported. This 10kg Carp grew a 0.2ha pond of mature Murray Cod in two growth season. As all his ponds are filled with bore water, Greg believe this fish was self sown, possibly through an egg being carried in on the legs or feet of a bird.

time. For example, these movements could involve environmental triggers and earlier experiences of a preferred feeding, resting or nest site. “Species which migrate thousands of kilometres may have individuals or populations which are quite sedentary. Inconsistency of movement is well demonstrated by most native fishes; a Murray Cod may live in a preferred deep hole for much of its life or it may make an extensive general movement either upstream or downstream. “A key message on the translocations of Australian native fish is that the species will expand its range to the limits of its physicochemical and competitive endurance.” Fish taxonomy & genetics “Many people don’t know that as few as 20 continuously variable genetic traits define the physical differences of an individual. The comparative ease by which a species can be selectively altered by nature or man must make one question the validity of short-term genetic studies in the management of wild fisheries. Even fish which have been selectively inbred 24 Austasia Aquaculture | Autumn 2011

for many generations produce throwback culls in each generation. Highly domesticated species will quickly revert to their native, green or wild type. Feral and wild strains of fish can sometimes breed together where wild stocks are depleted. However, the progeny of any spawns produced will be selected for the wild characteristics which are suited to the local habitat.”

Fish reproductive biology “Some of the commonly presented life histories of Australian fish make no sense. For example, the Australian Bass and Estuary Perch share their reproductive characteristics - physiology, timing and locality. These fish are clearly the same biological species – Macquaria colonorum. These fish are not catadromous,as they do not migrate to sea to reproduce and are known to recruit young within some freshwater environments. The oestrogenic responses that trigger reproduction in all fish require a drop in blood sodium levels. The only fish which move to sea to breed are the Anguillid Eels which then later move upwards from the salty ocean depths to less saline surface water before spawning. “A key message for fisheries managers is that much of the earlier research on Australian native fish has been undertaken by enthusiastic but inexperienced young scientists. The results and interpretation of the data are often based on a few case studies and are subject to reinterpretations and further later revisions.” MCH’s future – Fish or land development? With almost 40ha of land protected from flood events by approved levee banks and its proximity to Wagga Wagga, Greg says that his property is quite valuable and he is examining the option of selling.

Greg has proven that the jaw length and body colour in Australian native fish – like the Cod – are altered by age, growth, gender, maturation, nutrition, toxins and environmental stress. “These are invalid traits by which to identify Maccullochella sp. The head:body length ratio in Murray Cod decreases with growth and development and becomes noticeably smaller in biologically soft water populations. However, healthy aging, malnourished or sick fish can all shorten in length by >3%, making the head to body length ratio proportionally greater.”

“Wagga Wagga is the largest city in Inland NSW and the local topography has created a shortage of space. Local land values have quite consistently outperformed other safe investments. The MCH business is quite resilient and has continued operation for 41 years, including through the longest drought (1997 to 2010) on record when many other farms failed. The proximity of the airport and road freight depots has meant that fish continued to be shipped even at the height of the regional flooding (Dec ’10).”

The key message Greg is making is that the restriction of the stocking of certain biotypes or genotypes may actually have no positive benefits and may even have a gross negative impact.

“It would be nice, but naïve, to believe that the property could remain a farm. The location and approved local zoning as a Business Village makes the usage of the property highly flexible. With 360

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degrees of beautiful panoramic views, the MCH is a pretty amazing place to live and work. You feel as though you’re in the country alone, just surrounded by the incredible wildlife. It is only when you look at the town plans and go for a drive that you realise just how close the built-up areas and major city services really are. The property has full town services available, and four bore licences. Normally only one of the bore pumps is ever needed for operation at any given time. “I have no regrets about a lifetime working with fish. Fish keeping, commercial fishing and fisheries research haven’t just paid the bills. Fish have given me a passion, the means to travel and study, not to mention the great privilege to represent my country. I’ve met a lot of really nice people, had interesting experiences and visited terrific places. It is not over yet, with more adventures ahead.

Yabbies can be polycultured with Tandanus but few other native fish species, especially Percichthyids such as Murray Cod and Golden perch as invertebrates for the major portion of their diet.

“The MCH property is being under-utilised. Production was progressively cut back so that I could handle the work alone. The equipment is operational to again scale up production. However, I no longer have the stamina or competitive

need to produce up to two million fish a year as I once could largely on my own.” Perhaps the release of his thought provoking book may inspire some people to take up the reins of MCH. Nevertheless Greg’s legacy will survive at least with his book.

By Dos O’Sullivan. For more information contact Greg Semple, Murray Cod Hatcheries, 3681 Sturt Hwy, Wagga Wagga, NSW 2650. Tel: 02 6922-7360, fax: 02 6922-7619.

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Autumn 2011 | Austasia Aquaculture 25

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Seafood High Schools Prepare Students for a Fishy Career

Stuart High’s Seafood Facility

s the seafood industry continues to grow in specific regions of Australia, it becomes evermore interwoven into the fabric of these communities. These communities generally are not large state capitals but small tight knit centres of population – such as Port Lincoln in South Australia, Huonville in Tasmania and Cardwell in Queensland. The youth of these communities see fisheries and aquaculture as an attainable career and many grasp this opportunity.

However this has not happened by chance. One of the more successful mechanisms in promoting the plethora of careers around fisheries and aquaculture is its integration into high school programs. Future staff, researchers and managers of the seafood industry are currently within the Australian education system. Effectively communicating all of the career possibilities that the seafood industry has to offer to students while they are formulating decisions 26 Austasia Aquaculture | Autumn 2011

about their future is vital for the longevity of the industry. To acknowledge the vital role high schools play in the seafood industry, the Australian Seafood Cooperative Research Centre (Seafood CRC) has just completed a High School Engagement Initiative. The cornerstone of the initiative was to undertake three case studies of high schools that have implemented successful seafood programs. It was a definite challenge to find examples of high school programs of this nature in most states of Australia; however after scouring the country there were three high schools that stood out both in terms of program delivery and vision. All three were based in arguably the most famous seafood and aquaculture region in Australia, the Eyre Peninsula, South Australia. The three high schools that took part in the case study were:

• Stuart High, Whyalla; • Port Lincoln High School, Port Lincoln; and • Cowell Area School, Cowell. Each school delivers quality programs but were individual enough to offer unique learning and skills development opportunities. Stuart High is based in the northern region of the Eyre Peninsula in Whyalla. The precursors to the current aquaculture program were developed in 1993 when the school was looking at techniques to better engage students in science-based learning. It now has now a purpose built indoor recirculation facility that grows Barramundi, Murray Cod and trout. Other important points about Stuart High’s seafood program are use of the facility as a tourist attraction: students conduct the tours of the facility and it is now part of the South Australian Government’s Seafood and Aquaculture Tourist Trail. There is a commercial fish

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smoker onsite and the school sells its very tasty smoked kingfish; the fish is either its own home-grown product or bought off a nearby facility. Students can undertake a Certificate II in Aquaculture while at Stuart High. Port Lincoln High is fortunate enough to be situated in the epicentre of the region’s seafood industry and the school has had seafood-related programs for over ten years. It currently has a Seafood Industry Pathway Program allowing students to experience a diverse array of learning and practical experiences including deckhand skills, PADI diving, aquaculture, vessel operations in addition to having minimum of 20 days work experience with local commercial operators. The qualifications they can achieve range from a Certificate I level through to the commencement of Certificate III. For some of the maritime components of the program the students attend the Australian Fisheries Academy. Port Lincoln High also has a purpose-built seafood facility that grows Barramundi, Murray Cod and trout. The teaching staff at Port Lincoln have had extensive commercial experience and do everything they can to assist students to enter the seafood industry.

Above: Port Lincoln High School students working at the school’s facility. Right: Smoked kingfish ready for sale by the students

farm as part of their seafood program and the oysters they grow are recognised by the commercial sector as a quality product and have won a host of awards. The school also partners with the Australian Fisheries Academy to deliver some of the maritime components of their certificate level seafood courses.

Cowell Area School is situated in the central area of the Eyre Peninsula and caters for students from Reception to year 12. Set in a rural community, the principal industries in the area are aquaculture (specifically oysters), agriculture and mining. The school is considered one of the centrepieces of the tight-knit community of Cowell and is revered as an excellent example of rural schooling success by many. Cowell Area Schools seafood program is extremely diverse for such a small school. Its indoor facility has a strong focus on sustainability with fish such as Barramundi grown in an aquaponics system along with leafy green vegetables.

In conclusion, all three schools agreed that industry involvement was the key to ensuring the longevity of these programs and that was one factor they all would like to enhance in the future. The other common thread was that a core group of extremely devoted individuals within these schools ensure these programs run successfully and continuously improve. As long as individuals like these are around, the future of the seafood industry in the Eyre Peninsula looks bright.

Cowell Area School also has a commercial oyster farm which has its own full time manager. Students work on the

For any other schools wishing to embark on programs of this nature, some important points to consider are:

• It is crucial to gain support from the local commercial seafood industry; • To allow the local commercial seafood industry to advise on relevant learning experiences and skills development; • Having aquatic livestock on site requires at least 6 days a week monitoring; • Having individuals with plumbing/ construction skills is crucial; and • Relevant staff should undertake professional development focused on gaining the skills needed to run a program of this nature. If your school is interested in developing a seafood related program please don’t hesitate to Call Jan Potter of Cowell Area School on 08 8629 2150. She is more than happy to share with you how they developed and now manage their program. By Mark Oliver The Seafood CRC would like to thank the staff and management of the three schools for allowing our researchers access and for their wonderful hospitality during the whole process. Autumn 2011 | Austasia Aquaculture 27

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Trout fishers work to support endangered native fish Members of the Australian Trout Foundation, the leading organisation representing trout fishers, have worked with scientists from Vic DSE to support a population of the critically endangered Barred Galaxias.

he Barred Galaxias (Galaxias fuscus) is one of Australia’s most endangered – Victoria’s only endemic – freshwater fish. This species has a restricted distribution in eastern Victoria and is only known from a small number of mountain streams above 400m in elevation in the upper Goulburn River catchment. At least five populations are presumed to have become extinct since its description in 1936. Most of the remaining populations are effectively geographically isolated from each other by the presence of predators such as trout, redfin and other species.

Many of these populations were adversely affected during the February 2009 bushfires prompting a rescue (in March) of several hundred of these fish by scientists from Department of Sustainability & Environment (DSE). In April 2009 a major rain event occurred in the fire-affected areas in which large volumes of silt and ash flowed down

many of the Barred Galaxias streams. So the DSE scientists should be to be congratulated for their foresight and quick action. The ‘rescued’ fish were housed in secure aquaria at the Arthur Rylah Institute (ARI) research aquarium at Heidelberg. Each population was held in a separate tank, with a separate chilled recirculating water supply. Salinity and temperature control According to ARI’s Tarmo Raadik, 400 fish were held in water temperatures that closely mimicked those in the wild. “We held them at 5°C in winter and below 12°C in summer,” he says. “Even so they were pretty stressed so we kept them in a higher (slightly isotonic) salinity around 2-3,000 EC (~2.8ppt) than their normal 40 EC. This is a common method when holding or transporting stressed natives. The Barred Galaxias

have no scales and when stressed they are pretty susceptible to fungal infections, especially in the pits and pores of their lateral lines. In addition we gave them regular salt baths and treatments with Pimafix (a common antifungal treatment for aquarium fish).” Fish vet Jim Griffiths also prescribed some antibiotic treatments. “These fish live in very clean waters. We therefore needed to be very careful of nitrogen or ammonia spikes so we were kept busy cleaning tanks and undertaking water exchanges.” The fish ranged from around 50mm (about 3 years of age) up to 100mm (approx. 8-12yrs). “These fish grow very slowly. We fed them blood worms (larvae of the mosquito-like midge family Chironomidae) as closer to release times we fed them brine shrimp nauplii and small earthworms to get them foraging for feeds.” Whilst some populations have been returned to their natal streams in December ’09 and June ’10, others have been maintained in the aquaria for more than 12 months awaiting appropriate rehabilitation of their stream habitats. Rehab working bee According to DSE Native Fish Strategy Coordinator Fern Hames, it was an eclectic mix of over thirty people who gathered last June to reconstruct the

Members of the ATF, ARI DSE staff and young people from the district gather on the predator barrier in Leary’s Creek, Marysville, after revegetating the banks to support the resident Barred Galaxias population. Photo by DSE.

28 Austasia Aquaculture | Autumn 2011

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Biology and Habitat The Barred Galaxias is a rich orange-coloured fish growing up to 15 cm, but commonly reaches 7-9 cm long. It has 1-10 vertical ovoid black bars on its side and clear to reddish brown fins. Scales are absent. The Barred Galaxias occurs in cool (<11°C), clear, upland streams with stony or sandy substrates. Little is known of its ecology due to its highly threatened status and small population size. The preferred habitat is thought to be slowflowing (0-0.2 m/sec), deep pools adjacent to riffles and cascades. Spawning is triggered by an increase in day-length and water temperature in August–September. Average fecundity is about 500 eggs, which are large (unshed eggs are ~ 2.2 mm diameter) and adhesive. The eggs are laid on or under in-stream rocks and boulders when water temperatures are around 2–3°C. Time to hatching and size of larvae at hatching are unknown, but 12 mm long larvae are present in streams by December. Movement requirements are unknown, but the species is thought to be non-migratory and relatively sedentary, judging by recolonisation rates of streams where trout have been removed. The diet consists of drifting and benthic aquatic invertebrates taken at the upstream end of pools. The species is relatively long-lived for a small fish – individuals up to 13 years old have been recorded.

Arthur Rylah Institute (Vic DSE) staff releasing Barred Galaxias into a population site. Photo by Fern Hames (DSE).

bushfire affected area around Leary’s Creek, which runs through Marysville. “Trout anglers were working side by side with kids from the Marysville Youth Incorporated and with scientists from DSE and ARI. The work included planting of native vegetation and debris removal around the repaired man-made predator barrier on Leary’s Creek which was

badly damaged by the 2009 bushfires. “Revegetation around the creek will assist in maintaining water quality by reducing the amount of silt and ash which can be washed into the creek. It also forms important habitat and food sources for the rare fish,” Fern said. “We believe there are still some Barred Autumn 2011 | Austasia Aquaculture 29

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first of many. We would also like to congratulate the members of DSE, MDBA, and Arthur Rylah Institute who have gone out of their way to work side by side with the ATF; it truly is a great sign for the future.” Assistance for trout farm The ATF have also been active assisting a local trout farm which was badly damaged during the 2009 Black Saturday bushfires, lending a helping hand to rebuild the very popular Buxton Trout Farm.

Above: Tank systems at Arthur Rylah Institute (Vic DSE) holding the Barred Galaxias populations rescued from fire affected areas. Photo by Tarmo Raadik.

Left: Stuart Rees from the Australian Trout Foundation releasing fingerlings donated by Buxton Trout at Hepburn Lagoon, near Ballarat. Photo by Lyndon Webb (ATF).

Galaxias in Leary’s Creek but we need this type of revegetation work to occur to help the site recover sufficiently to support the return of the fish we removed more than a year ago. “This recovery action has been vital for the survival of this already rare species because 90 per cent of its known habitat has been affected by either the 2006 or the 2009 bushfires. “The fires also damaged the trout barrier in Leary’s Creek but this has since been repaired. The barrier stops predators from moving into the section of Leary’s Creek used by the Barred Galaxias and having an impact on this rare fish.” ATF’s vice-president Mick Hall said their members were enthusiastic participants in the work at Marysville. “The Australian Trout Foundation is committed to assist wherever possible to maintain the viability of our native fish species and we hope that this small yet significant project is the 30 Austasia Aquaculture | Autumn 2011

Recently owner/operator Mitch MacRae offered the ATF a gift of 20,000 Rainbow Trout fingerlings (8-10cm). To keep everything above board, the ATF in turn has offered these trout to Fisheries Victoria to assist in getting those once dry Western district lakes back on line for recreational fishing of trout. Over 10,000 of these fingerlings were stocked into Lake Hepburn on 15th December and the balance is to go in sometime in early 2011. “These fingerlings are only small,” said Mick, “However by spring next year they hopefully will be a lot bigger and the year after that, with the aquatic food chain already coming back on line, (see pictures) we can expect to see some of the best trout fishing this state has seen in many years. All we need to do is just keep on adding water.” By Dos O’Sullivan The Australian Trout Foundation is an independent, non-profit organisation, dedicated to ensure that all Australians can enjoy trout fishing now and for future generations to come. For more information contact Tom White (secretary) Australian Trout Foundation, P.O. Box 466, Mooroolbark, Vic 3138. T: 03 9726-7973, F: 03 9726-7961, Email: info@atfonline.com.au The ARI contact is Tarmo Raadik 03 9450-8600, tarmo.raadik@dse.vic.gov.au

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The NCRIS 3.5m3 Algelink Solutions photobioreactor at SARDI. Photo courtesy of SARDI Aquatic Sciences.

Microalgae biotech provides ‘green’ diversification The use of algae as biofuel is providing opportunity for savvy aquaculturists to ‘value add’ their production systems.

esearch into biofuels is now pioneering new technology in algal selection, culture, harvesting and processing (i.e. extraction of proteins, lipids or pigments).

That’s of immediate interest to aquaculturists. Growing microalgae is a key process in commercial and R&D hatcheries, providing an essential nutrients for the larvae/juveniles of prawns, mussels, oysters, pipis and scallops as well as feeding the zooplankton eaten by finfish larvae. 32 Austasia Aquaculture | Autumn 2011

As well, there are a number of higher value algal-derived products such as biofuels, omega-3 fatty acids and pharmaceuticals. Algae can also have a vital contribution in nutrient removal processes thereby increasing water availability recycling. And algae remove carbon dioxide too. Murdoch University’s Professor Michael Borowitzka estimates that 108 tonnes of CO2 are fixed per hectare of algae ponds each year. Important role of algae in water quality Fish and prawn farmers stimulate algal blooms in ponds to: • shade and shelter their stock;

• maintain oxygen levels; • reduce levels of ammonia and other toxins; • provide food for zooplankton eaten by culture stock; • provide benthic algal food for newly stocked juveniles or larvae, and • produce algal flocs in carbon added ponds as a food source. But culturing the wrong algae can be bad. TasUni’s Dr Gustaaf Hallegraeff lists some negatives: • ‘bad taste’ or odour problems in fish or mollusc flesh or in drinking water (e.g. cyanobacteria Microcystis and Anabaena); • kills of fish and invertebrates due to oxygen depletion or natural toxins;

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• damage or clogging of gills of culture stock; • potent toxins causing human gastroenteritis and neurological illnesses (e.g. PSP, DSP or Ciguatera), and • swimmer itch (sensitive skin). “All farmers need to carry out long-term routine monitoring of the many algal species is their ponds to develop a feeling for what are the good and what are the bad species.” Algal biotechnology opportunities Several projects spread around Australia are likely to provide opportunities for aquaculturists to diversify into algal biotechnology.

Culturing microalgae species in two of the outdoor 20m2 raceways at SARDI, Chaetoceros (left) and Nannochloropsis (right). Photo courtesy of SARDI Aquatic Sciences

As part of an Australian Research Council Linkage Grant, the Schenk Laboratory group at the University of Queensland (UQ) is investigating the use of microalgae lipids for biodiesel. Associate Professor Peer Schenk’s team (www.algaebiotech.org) aims to effectively scale-up a low-cost technology to a pilot-plant facility to facilitate further commercial evaluation. In addition to producing algal lipids for conversion to biodiesel, PhD student Steve Magarry told the recent APFA/ ABFA Conference that such technology could provide significant biomass for aquaculture nutrition. “We have more than 50 SE Qld strains of microalgae in the UQ collection,” Steve explained. “We are evaluating their omega-3 lipid content and production for further targeted use within the aquaculture industry for broodstock maturation and general nutrition enrichment.” Also at the APFA/ABFA conference, Ridley Aquafoods’ Richard Smullen noted that with some microalgae species containing 50-70% protein and 10-20% lipids, there’s a huge market opportunity to supply basic human nutritional needs. The production of high value omega-3 oils for human consumption provides another compelling opportunity.

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Call: 0409 727 853 Autumn 2011 | Austasia Aquaculture 33

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Thinner bags for growing algae Aquacultured larvae/juveniles and

500L ‘Bayes’ bag system to a

zooplanktons need different

‘thinner bag’ system. Mark Gluis,

combinations of microalgal species

SARDI’s Shellfish Hatchery Specialist

to meet their specific nutritional

has shown that the same physical

requirements at different

space can grow a more diverse

developmental stages. “Therefore,

range of species as well as boosting

the reliable provision of the right

cell densities within the bags used by

species at the right time and at the

two to fourfold.

required quantity and quality is

Mark is receiving such a high level

challenging to all the hatchery

of interest in his ‘thinner bag’ system

operators,” says Dr Xiaoxu Li,

that he’s proposing SARDI host a

Aquaculture Senior Scientist at SARDI.

national microalgal seminar

These challenges can be overcome to

including a system demonstration

a large degree by a move from the

seminar and training course.

traditionally used continuous flow

“There is a sense of urgency within the UQ team,” said Steve. “We believe it is only a matter of time before we can make the opportunity for an ‘Australian first’ commercial production of the EPA and DHA oils. “The global industry is worth around US$10 billion for these oils in health products and enriched infant formula. There are no algae-sourced omega-3 oils available in Australia right now although fish oil omega-3 sales exceed AU$200 million a year. Wholesale fish oil (with a ratio of EPA/DHA 18:12) sells for between $5-10/L and retails between $40-60/L. Refined and purified ALA/ EPA/ DHA wholesales for $80-120/L in some pharmaceutical markets.” A range of pharmaceutical quality chemicals as well as phytosterols (plant derived cholesterol, stigmasterol, campesterol, etc.) and antioxidants for human consumption can be manufactured algalderived fatty acid ethyl esters. But, as Steve quickly pointed out, not all these product lines are complimentary. “Typical commercial biodiesel manufacture uses methanol which limits the opportunity to produce for other market sectors.” UQ’s preferred mass algal production model incorporates a ‘split-system’ sequential approach. A photobioreactor (PBR) maintains the algae in its exponential growth phase with specific nutrient media dosed at intervals based on the weather and available solar energy. Next the algal biomass is harvested for transfer to open raceway ponds where nutrient concentrations are manipulated to boost lipid synthesis. “We have a built a low-cost 2,500L splitsystem consisting of a 1,500L airlift PBR and two 1,200L raceway tanks,” Steve continued. “There are plans for a 120,000L pilot-plant facility to be commissioned in 2011.”

Synchronised lipid production in Tetraselmis cells. Photo courtesy of Schenk Lab.

34 Austasia Aquaculture | Autumn 2011

Initial results are very promising. “We have achieved biomass productivity greater than 50 gm DW/m2/day which equates to the industry benchmark of

FA R M P R O F I L E

60 t/ha of DW/year. And we’ve had lipid accumulation at 10% DW biomass (equivalent to 7.5 t/ha DW/yr; the industry benchmark is 15 t/ha/y.” At least ten algal strains have been selected by the UQ Algae Biotechnology Group as having potential. These include the commonly used aquaculture species such as Chlorella, Nannochloropsis, Tetraselmis, Pavlova, Isochrysis, Scenedesmus, Chaetoceros and Skeletonema. Research is also underway for growth optimisation and using genetic selection (non-GM approach) of these algae to further increase production. The primary constraints to commercialising microalgae culture is the cost of energy to drive the dewatering (separation of microalgae and water), biomass drying and extraction of lipids. Steve said the solution may lie with novel methods of lipid extraction directly from the microalgae culture. Bolt-on Opportunities: UQ’s team reckons the new biotechnology offers aquaculturists the means to leverage facilities into further profit. “We call them the ‘bolt-on’ opportunities,” explained Steve. “Discharge ponds or channels, hatchery, processing and purging water discharge points, prawn or finfish hatcheries and algae / live feed facilities may not be not fully occupied for all of the year. “Many could be used off-season or for polyculture using floating (pond or drainage channels) or surface (bank or levee) based PBR’s. Another opportunity is to use the algal technology for better nutrient removal. “A PBR operating in full sunlight could take every 6 hrs -some 80-100 mg/L of nitrogen and 20-50 mg/L of phosphorus.” S.A. Aquaculture Program Dr Sasi Nayar heads the Algal Production Group at the South Australian Research & Development Institute (SARDI), West Beach, Adelaide. SARDI has been

Harvesting algae with flocculants used widely in the wastewater treatment industry. Photo courtesy of SARDI Aquatic Sciences.

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Autumn 2011 | Austasia Aquaculture 35

FA R M P R O F I L E Left: High performance Tetraselmis cells after selective breeding at UQ’s Schenk Laboratory.

between 80 and 95% of the algal biomass with the remainder used for gasification.

Below left: Tow tubes of the low cost 1,500L photobioreactor in operation at Schenk Laboratory (UQ).

Pilot Plant at Karratha

Photos courtesy of Schenk Lab.

bioprospecting and selecting native high lipid microalgal strains as a feedstock for biodiesel production and other applications for over six years. He said the cost of production of biofuels needs to be kept to around $1.00 per litre to be competitive with conventional petrochemical fuels. “Currently we are in the order of $5.00 to $300/L so we have to find systemic and economic improvements in production, harvesting, dewatering and extraction. There are two approaches to produce biomass – the open ponds such as raceways and the closed photobioreactors. Sasi estimates that it costs approximately $100/m2 for photobioreactors in contrast to about $30/m2 for raceways. When used in combination as a ‘hybrid system’ the benefits of both systems can be harnessed.

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The Algal Fuels ConsortiumTM (SARDI’s Algal Production Group together with Flinders University and CSIRO) are to develop a pilot and pre-commercial scale production facility on Torrens Island, just north of Port Adelaide. The pilot scale facility of 0.4 ha should be operational in 2011. It will use nutrient rich Port River seawater, carbon dioxide from adjacent power plants and Adelaide’s abundant sunshine. It has been designed to include a series of raceways between 3.5 m2 to 1000 m2 and PBRs all with control and monitoring systems for salinity, depth of water, dissolved oxygen, chlorophyll a, pH, flow and nutrient inputs. Flocculation and dewatering will enable concentrated algal biomass to be bioprocessed for high and low value co-products such as pigments, poly unsaturated fatty acids, proteins, carbohydrates and feedstock for aquaculture and livestock. The biorefinery is expected to use

Michael Borowitzka, Professor of Phycology at Murdoch University has worked for over 30 years on commercial culture of microalgae. With Adelaide Uni’s David Lewis and Peter Ashman, he heads up a Commonwealth on the production of biofuels from saline microalgae. “Our long-term (> 18 months) trials have proven reliable, high productivity culture in outdoor raceway ponds in Perth as well as Chennai, India, he said. “We have integrated harvesting and dewatering processes, and we have optimised lipid extraction techniques.” With modelling having confirmed the design and constructability of 50 km2 production plant, a $1.5m pilot plant at Karratha (Pilbara region) should be completed before the end of the year. The plant has two 20m2 intensive ponds and three 200m2 raceways, plus largescale harvesting and dewatering system. “People ask me, why the Pilbara,” he said. “The region has all what we need – appropriate sunshine and climate, inexpensive land, loads of saline water, many sources of CO2 (e.g. Rio Tinto’s Yurralyi Maya Power Station), plenty of infrastructure and a high local demand for diesel. We have achieved production rates of about 60 tonnes of algal biomass per hectare per year, over 40% of which is converted to oil. These high production rates are expected to increase at the new pilot plant due to the even better climatic conditions in Karratha.” By Dos O’Sullivan. For more information contact: Schenk Laboratory UQ, E: p.schenk@uq.edu.au W: www.algaebiotech.org Dr Sasi Nayar, SARDI, M: 0428 542-101, E: sasi.nayar@sa.gov.au Prof Mike Borowitzka, Murdoch Uni, E: m.borowitzka@murdoch.edu.au

FA R M P R O F I L E

Hatchery-reared tropical rock lobster broodstock (female and male)

Second generation tropical rock lobster produced in Australia Leading lobster aquaculture company Lobster Harvest (LH) has developed unique hatchery technology to propagate the high value lobster species such as Slipper Lobster (bugs) (Thenus australiensis and T. parindicus) and Tropical Rock Lobsters (Panulirus ornatus and P. versicolor). The WA-based company was featured in AA 24.1 (pp 49-52). In another ‘World First’ Lobster Harvest have produced F2 (second generation) P. ornatus.

ll spiny wild lobster fisheries are either fully exploited or overexploited, with many experiencing trends of catch declines over the past several years. Tropical Rock Lobsters are the most highly prized and most valuable of all tropical lobster, with wholesale live prices of Au$50-70/kg reaching as high as Au$100/kg at times. Increasing demand from China has outstripped supply. The solution to this imbalance clearly is lobster aquaculture. However, Tropical Rock Lobsters are widely recognised as one of the most difficult of all

aquaculture species and the most difficult crustacean to propagate. This is due to the protracted and complex larval phase, and extremely delicate larvae, also known as phyllosoma. First generation (F1) female P. ornatus from a cohort produced by MG Kailis technicians in Exmouth, WA, in 2006 were stocked in maturation raceways, together with first generation males from the 2007 cohorts (produced by LH technicians, also in Exmouth). In 2009 mating occurred, with ‘tar-spots’ observed on the females. Spawning of

these first generation females occurred in late December 2009, resulting in the first hatch of second generation (F2) larvae on the 24th January 2010. Three cohorts of the second generation P. ornatus have been successfully cultured through the larval phase to pueruli and the juvenile stage in 2010 – another ‘World First’ for the team in remote Exmouth, WA. A survival rate from Stage I newly-hatched larvae to juveniles of 9.6% was achieved using smallscale tanks, with concurrent production at survival rates near to rates deemed Autumn 2011 | Austasia Aquaculture 37

RESEARCH

Above: The world’s first hatchery-reared Tropical Lobster puerulus larvae (clear) and juveniles (mottled yellow and brown). Left: A F1 generation Tropical Lobster from the Exmouth hatchery.

fast-growing and robust P. ornatus, which relies on using wild-caught postlarvae and juveniles, with an estimated annual export value of $US80m.

commercially viable achieved in production-scale tanks. The company’s Commercial Development program is now focused on further developing the larval nutrition and scalingup of larviculture tanks in the hatchery. Commercial survival rates in the hatchery of 5 - 10% have already been achieved, albeit using small-scale tanks, in replicated experiments. Mean survival in the best feed formulation replicated experiment was 8.1% to the juvenile stage in 2010, with the highest tank survival in a smallscale tank of 9.6%. Scale-up to commercial scale began in 2010 with the unique LH larviculture custom-designed and built tanks. Production-scale tanks have

repeatedly produced juvenile lobsters (P. ornatus) in 2010, at survivals of 4.4%, 4.4% and 4.0% survival from Stage I to juvenile. Multiple hatchery production batches of first generation P. ornatus and the recent success in truly closing the life cycle with the production of second generation progeny are significant steps for the commercialisation of tropical spiny lobster aquaculture. The development of LH’s unique propagation technology places them in a strong unprecedented position to benefit from this situation and to expand the lucrative Rock Lobster market. Vietnam has an established grow-out industry, fattening the

These results will be presented to the World Aquaculture Society Meeting in New Orleans at the end of February 2011. By Roger M. Barnard, Aaron Turner, Travis Rumballe, Matthew Johnston and Bruce Phillips For further information contact Lobster Harvest Ltd, 50 Mews Rd, Fremantle, WA 6160. Technical Program Leader: Roger Barnard (LH Aquaculture Development Manager) E: rogerbarnard@lobsterharvest.com.au Business: Terry Burnage (LH General Manager), E: terryburnage@lobsterharvest.com.au Acknowledgements: Vaughan Hastie, Simon Harries, Bill Hamilton, Rhys Channing, Tim Quick, Clive Jone

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RESEARCH

All images by Paul Palmer.

Constructed beds at the Bullock Creek Prawn Farm.

Recently harvested Perinereis helleri.

Marine worms to assist sand filtration of mariculture effluents Demand is increasing for marine worms as feeds for aquacultured and aquarium animals, especially valuable broodstock. There are also markets for human foods and as bait. However, there are more uses for these intriguing worms – an innovative project in Queensland has found that these worms can also provide significant benefits in treating large volumes of low nutrient effluents typically discharged by brackish water aquaculture farms.

n addition to being popular as bait, marine worms are recognised internationally as one of the best diets for maturing prawns and fish. With a high fatty acid content – providing essential nutrition – and feeding attractants – which make them very palatable – a number of countries around the world use them as live, frozen or processed aquatic feeds. The worms are also used to flavour human foods and are considered a delicacy by many nations. However, these worms may have even greater uses. Dr Paul Palmer – Senior Biologist (Aquaculture) at the Queensland Department of Employment, Economic Development and Innovation’s (DEEDI) Bribie Island Research Centre (BIRC) – has been experimenting since 2005 with two species of marine polychaetes (the sandworms Perinereis nuntia and P. helleri) commonly found in Moreton Bay, near Brisbane. Both live in intertidal natural habitats and grow to relatively large sizes (>1g) and at moderate to high densities

(>400g/m2) in constructed sand beds. “I am particularly interested in their use for nutrient removal,” Paul says. “The worms’ appetites increase as they grow but they are happy to sit and wait for their next meal. This is great for aquaculture operations like prawn farms which produce seasonal crops and have varying levels of wastes during the crop. Nutrients in the water are generally bound up in very small algae and plankton which the worms can use after they lodge in the sand.”

needed to be for commercial prawn farms and also evaluate their productivity (at the end of the prawn crop the worms can be harvested and sold for bait or for fish or prawn broodstock feeds).”

He has been trialling the sandworms for their benefits in sand filters used for wastewater treatment at mariculture facilities. That research has been published recently in the internationally acclaimed scientific journal Aquaculture.

Water remediation trials “A two year pilot program conducted at BIRC won National Landcare Program innovation funding to test the concept at a commercial farm,” Paul continues. “In the 2006-07 culture season I conducted wastewater remediation trials using sandworms at the Bullock Creek Prawn Farm operated by Peter Spindler and Judy Butler (featured in AA 20.2 AprilMay ’06). The farm trial assessed the worms as a natural, low maintenance and environmentally friendly way to reduce the annual nutrients released from earthen prawn ponds.

“By working out how well the worms dealt with the range of conditions found in sand beds used to filter pond waters, I could determine how big the worm operations

“The aim was to test a series of treatment tanks which combine the worm’s specialisation as benthic feeders with the mechanical properties of a down flow

“The worms can also help to prevent sand filters blocking with organic debris.”

Autumn 2011 | Austasia Aquaculture 39

RESEARCH

Filter beds with (left) and without (right) worms living in the sand. Note the darker colour of the wormless filter beds showing more blockages and sometimes anaerobic conditions.

sand filter. Normally sand filters clog up over time with algae and debris. However, when worms are living in the sand they tend to eat the organic debris and create a network of burrows which allows the water to continue to pass through the layers.” Broodstock worms captured from Moreton Bay were spawned and cultured in nursery systems. “The worms were initially stocked at a range of sizes, ages and densities in a controlled process that could be applied in a farm environment. As they grew and migrated across the bed, the surface layers changed from green and fouled to a much cleaner appearance. The earlier trials clearly illustrated their feeding activities and the network of burrows they created substantially increased the sand bed’s filter-surface area and improved the condition of subsurface sediments.” The sand worms lowered the amounts of organic matter in the upper layers of sand and increased the percolation rates of water through the filtration beds. This has now been demonstrated in replicated

trials which was the focus of the recent scientific publication (see Figures 1 and 2 taken from Aquaculture 306: 369-377). Commercial applications tested In July 2008 a Department of Agriculture, Fisheries and Forestry grant allowed continued developmental work on the integrated sandworm filter technologies at a commercial scale. Two prawn farms and one fish farm in the SE Queensland and Burnett regions were selected for the studies. Different construction methods have been tested including low profile above-ground sand beds where the sides are supported by timber battens, as well as in-ground lined ponds similar to those currently used for aquaculture crops. HDPE plastic liners have been used to form the water proof bed enclosures. Medium bedding sand that is commonly used in the construction industry is then spread to a depth of 200mm over gauzecovered drainage pipes. This simple method of construction allows large beds to be built very cheaply. Work so far has shown that each square metre of sand

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ly ent nd epe ured y d In as or me borat a la y b

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bed can filter up to 1,500 L of wastewater per day, and this provides a guide to the scale that may be required at different establishments. In a prawn farm environment, the worms grow during the prawn crop whilst the pond wastewater is being discharged and treated. After the prawns are harvested, the worms are harvested for their respective uses. The sand beds are then dried, re-levelled and prepared for the next season. “The project was designed to investigate the efficacy of this new wastewater treatment system at a larger scale, in terms of construction methods, volumes of water able to be handled, and worm biomass productivity,” Paul explains. “The pilot trial demonstrated excellent solids and chlorophyll a removal (reductions >50% for both) (Figure 3) and maintenance-free operations. Nutrients are converted into bio-available dissolved forms and dissolved oxygen, redox and pH levels are also lowered significantly by the process.” Paul says that P. helleri appears to be better adapted to live in muddier environments than P. nuntia. “Although P. nuntia appeared

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RESEARCH

more suitable than P. helleri for stocking directly into sand filtration beds at a very young age, we found that the best growth rates were achieved by P. helleri so this species became the focus of our ongoing and future research.” Paul’s conclusion is that worms can act as natural vacuums for prawn-farm waste. “They can be an important component in an integrated marine farming system that captures waste and converts it into useful products. We achieved production of about 400g of worms per square metre of sand bed during the term of a prawn crop (16 weeks). “In Australia, settlement ponds are used to capture nutrients wasted in pond discharges prior to release. They often account for up to 30% of farm area yet they are generally non-productive parts of the operation. In the future we may see a portion of this area become worm production units that feed on organic waste from the farm. In this way they could assist in effluent treatment and also provide a secondary crop for on-farm use or off-farm sale. “Industrial expansion of this process is

Figure 1: Organic matter content (%) of surface and core sand samples from sand beds with various P. nuntia densities (n = 8). Data shown includes the linear fit for surface organic matter.

Figure 2: Mean (± se, n = 4) water depths above operating sand filtration beds 10 weeks after stocking with different densities of 1-mo-old P. helleri (low = 1000 m-2, medium = 2000 m-2, high = 4000 m-2).

Figure 3: Mean (± se) levels of Chlorophyll a (Chl a) and total suspended solids (TSS) in inflow and filtered discharge waters during mid-tide sampling in the farm trial in 2007 (n = 6).

high on the agenda for our future work in this area, and there are several other functional uses that we will be exploring to further utilise these interesting and unique animals.”

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Autumn 2011 | Austasia Aquaculture 41

RESEARCH

Quantification of alkaline phosphatase in phosphate-limited barramundi ponds P

Fig 1. This shows how PO4 responds to Phoslock application. On average over this period, 1 kg of Phoslock was applied for every 20 kg food added to the pond

Fig 2. Absorbance is a measure of the amount of enzyme present in the pond. For example an absorbance of 0.5 equals APase activity of about 70 uM PO4 liberated per hour

Fig 3. A strong relationship between enzyme activity and algal density suggests the algae is the source of the APase

Fig 4. APase activity is higher in the unfiltered samples indicating that most of the APase is closely associated with algae.

42 Austasia Aquaculture | Autumn 2011

hosphate (PO4) is an essential nutrient for life and is useful in aquaculture ponds where it helps promote algal blooms. As with many things, too much of a good thing can be hazardous and PO4 in ponds is no exception to this. During 2010 and into this year we have been learning about the impact of limiting PO4 in our saltwater barramundi ponds near Darwin in the Northern Territory. We initiated this work is response to harmful algal blooms that had caused us substantial losses in 2009. Some of the work we have been doing was reported in Austasia Aquacultureâ&#x20AC;&#x2122;s 2010 summer edition. This article reports on further information we have gathered over the past few months on how the ponds respond to PO4 limitation. A substantial amount of work has been done by researchers that shows that when PO4 is limited in the environment, algae respond by producing alkaline phosphatase (APase) which is an enzyme that works on (or hydrolyses) complex P-containing molecules to liberate PO4 . These researchers found that when PO4 was less than about 0.03 mg/L, algal cells began to produce APase. On our farm we were measuring PO4 levels at close to 0.00 mg per L after application of Phoslock and figured that there was a strong possibility that APase would be present. We figured this because we found that although the behaviour of the blooms and bloom composition was altered, the bloom densities (as measured by Chl

RESEARCH

a or by Secchi) stayed more or less the same. There had to be a reason for this, because with PO4 close to 0.00 the bloom density should be reduced. So we set about measuring whether or not APase was present, and if so, how much was present. To measure PO4 we used a compound called pNPP, which turns a yellow colour when it is hydrolysed by APase. The yellow colour can be measured with a spectrophotometer and so we can work out from this how much APase is in the sample. The data we collected are shown in Figure 1 and Figure 2. From these data we conclude that the ponds produce large amounts of APase when PO4 is limited. Is the APase coming from algae? Two sets of data indicate that it is. Figure 3 shows a strong relationship betweeen Chlorophyll a and APase. Figure 4 shows that most of the APase is associated with particles more than 1 um in size. These two sets of information suggests strongly

that the APase is closely associated with algal cells. What does this information mean for fish and prawn farmers? As mentioned earlier, limited PO4 impacts on the behaviour and composition of the blooms. In terms of the bloom behaviour, limitation of PO4 leads to less bloom volatility as measured by diurnal DO and pH. In terms of composition the blooms are dominated by very small (less than 7 um) algae of numerous genera with clear absence of blue green algae (cyanobacteria). It should be stated here that on our farm we hold pH at less than 7.7 as reported in the previous Austasia article, as we have found that this along with PO4 control is necessary to achieve the results we are seeking: stable and low risk blooms. Some water exchange is still required as the blooms can still exceed the densities we consider safe (about 25 cm water transparency) due to the action of the APase. In terms of

costs of Phoslock and molasses, our experience suggests that the 1 kg of Phoslock for every 20 kg of feed applied and 10 kg molasses per ha per day are adequate to keep PO4 levels under 0.03 mg per litre and pH under 7.7. By Adam Body For more information contact Adam at: Email - adambody@flickingfresh.com Phone - (08) 8988 6861 Web: www.flickingfresh.com

Plastic Mesh Supplied to the Aquaculture, Fishing and Oyster Industry. Mesh to suit oyster, prawn, marron and goldfish farming. Inquiries: HR Browne & Sons PL 32-34 Brownes Rd, Saltash NSW 2318 Email: hrbrowne@bigpond.com Mobile: 0408 688 461

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Autumn 2011 | Austasia Aquaculture 43

TECHNOLOGY

Aquasonic is focused on energy efficient technology R

ecent times have seen an exponential rise in energy costs across the board in Australia. This has hit the bottom line of all primary producers and in particular fish farmers who already work on tight margins. With this in mind, Aquasonic have been making a concerted effort to find ways to improve the efficiency of the aquaculture sector thus minimising the costs associated with electricity consumption. Pumping costs traditionally burn the biggest hole in a fish farmer or breeders pocket. With this in mind we embarked on an exercise to find a premium quality, low cost, low energy pump that would be able to be used for both fresh and saltwater applications. We have found a pump that we believe ticks all those boxes and have been marketing these pumps for about six months now, with very pleasing results. Our premium range of Performance Pro pumps made in the USA, have all those attributes and come with a diverse range of flow rates and head capabilities to suit most applications. They range in flow rates from 9,000lph @ 1.5m head (Cascade model) which uses 0.71amp (90watts), up to the 3HP Artesian (Pro High Flow model) pump which at 1.5m pump 70,860lph using just 7.9amps (1,480watts) of current. When comparing the wattage and amp draws to your existing pumps and you will see that substantial savings that can be made in running costs with these new pumps. Performance curves on all these models can be viewed on our website or in our catalogue supplement available on request. Aquasonic have also sourced a continuous use 12v pump which can move surprising amounts of water for applications where 240V is not an option. The smallest of these pumps is just 43watts, pulls 3.6amps and will pump 7300lph @0.5m head. The largest of these 44 Austasia Aquaculture | Autumn 2011

pumps is a 58watt unit which draws 4.8amps and will pump a whopping 10,000lph @ 0.5m . Maximum head for these pumps is 2m which still makes them excellent units for the steady transfer of water without the need to be attached to the grid. Oxygenation of water bodies is another area that Aquasonic have sought to cut costs for farmers. Running traditional mechanical aerators has always been a large component of farm budgets. To this end we have been involved in the development of Colorite Airlift Grids. Testing of these grids has proven that the SOTR can be more than 3 times more efficient than a typical paddle wheel in saltwater application. The use of a

blower also results in a significant reduction in the amount of power required to achieve that transfer of oxygen in the water. Maintenance is also reduced considerably â&#x20AC;&#x201C; no more changing or repairing reduction boxes, as blowers are typically reliable and require little maintenance. Aquasonic can assist with sizing the airlift grids to meet biomass requirements in either your tank or pond application. For more details and pricing, please contact Aquasonic, 14 Commerce St (PO Box 311), Wauchope, NSW, Australia 2446 Phone 02 6586 4933 Fax 02 6586 4944 aquaculture@aquasonic.com.au Web Site www.aquasonic.com.au

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The only equipment supplier to be allied with Future Fisheries Veterinary Service Dr Matt Landos Mobile: 0437 492 863 matty.landos@gmail.com

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