The secret lives of eels

It’s 10pm and NIWA trucks are driving along Thornton beach towards the Rangitaiki river mouth, a 10 minute drive west of Whakatane.

At 10:30pm Waikato university masters student, Siobhan Nuri will drop her nets to start collecting glass eels and plans to be at the river mouth until 3.30am.

She’s helped by Eddie Bowman, an environmental monitoring technician from NIWA, her father Niwa Nuri and sister, Sinead Nuri.

The job has to be done at night because that’s when the eels enter the river mouth.

Glass eels are juvenile forms of tuna (eel) that begin life in deep ocean tranches in the sub-tropical Pacific. The eels then drift with ocean currents, eventually reaching freshwater in New Zealand.

Glass eels do not migrate to the same river or stream that their parents come from, says Eddie.

“That would be a big ask.”

If it was the case the eels would form genetically distinct groups in freshwater and there is no DNA evidence to support this.

The eels are 5.5-6.5cm long and are known as glass eels because of their transparent bodies.

Once the eels reach fresh water, they take days to adjust before moving further upstream.

One of the changes made by the eels is that they stop becoming transparent and start to turn darker as they change from a glass eel to an elver.

Siobhan is attempting to unlock some of the mysteries of the shortfin and longfin eel’s migration patterns.

“We’re trying to figure out when the length of migration is and how different environmental variables can effect migration.”

Siobhan and her team put on waders, life jackets and high-vis vests. They flick on head torches and set nets by the river bank. Waders are not only a good way to stay dry but a practical way to keep warm during the wee hours of the morning.

The team is set up for a long night. On the back of one of the NIWA utes lies a spread of coffee, tea and snacks to see the researchers through the night.

There is limited research done on glass eels and the research done has predominantly been done in the South Island. Siobhan is hoping to come up with updated information that’s relevant to the Bay of Plenty and North Island.

Siobhan says the local’s response to the research has been amazing, “every week we get a whole lot of tangata whenua helping us out”.

Siobhan has had schools come visit and she’s chatted to classrooms in the local area about the eels. Classrooms have also run projects focused on tuna inspired from the work her and NIWA have done.

Siobhan took over research started by NIWA last year. She’s been going since June and will finish up next month in December.

Next year Siobhan is hoping to pass on the project to someone else. “We’re hoping to get someone from the iwi to continue the work.”

Siobhan says tuna hold cultural significance to iwi, as well as being a valuable food source. Tuna are a taonga for Maori and have more than 100 different names for freshwater eels, to describe differences in colour and size. Many of the glass eels’ secrets hide in its ear bones (otoliths). “The ear bones are kind of like tree rings.” Glass eels grow a ring in its ear bone every day and larger, older eels, grow a ring every-year. Siobhan says the rings provide information on the length of migration and where the eels have been on their migration journey. Each month 50 longfin and 50 shortfin eels are used for the research.

Catching the eels is not always easy though. Siobhan has done the sampling in all conditions.

“We’ve sampled in heavy rain, hail, big surf, big river flow… there was a sandstorm one night so we couldn’t keep our eyes open.”

A memorable collection night was in June last year, when the first eels should have just started to enter New Zealand’s rivers.

“The literature says that we shouldn’t catch any but we caught heaps.”

The peak migration of the eels is meant to be around October, September and November.

Siobhan says the fact that lots of eels were caught in June is evidence of lack of research done in the area. Caleb Fotheringham

The glass eel collection begins. Photo: Niwa Nuri.

Sinead Nuri transfers the catch into the right bucket.

Events a plenty

The Mount Maunganui Yacht Club Summer programme has seen some outstanding sailing conditions, along with well attended social events.

The Triple Series kicked off with the White Island Race in November, with a relatively steady breeze giving boats a reasonable finish time in the early hours of Sunday morning. In collaboration with Whangamata Yacht Club, this year saw the race taking the Whangamata to Tauranga route.

The regatta started at the Sunset Bar with a briefing, a barbecue and beverages going down with sea stories new and old. Mayor Island race, the third and final event of the series, saw light conditions but sunny skies, topped off with some fine hospitality on arrival.

A number of MMYC members attended the Bay of Islands Sailing Week, experiencing some of the best sailing conditions on offer in the far north. Sandbank cricket and the Christmas Raft Up were an effervescent hit as we saw out 2020 and batted in the new year under sunny skies and a strong flotilla of boats, families and friends.

The Winter Series 2 Handed and Open Series dates are now on the website calendar. We have some new and exciting courses planned for 2021, so join in the fun. MMYC operate a Mark Foy start system, taking some of the stress out of fleet racing with your own start time.

MMYC are pleased to announce that we are working with SSANZ to host a brand new race leg with a stop-over in Tauranga for 2022. We can’t wait!

In other big announcements, we have a new website and you can now find us on Instrgram @mmyc8 and on Facebook. Follow along to keep up-to-date with the latest events and news.

Our membership base has grown substantially over the past year and we continue to welcome new members. As they say, the more the merrier. If you’re keen to join, visit: www.mmyc.org.nz

Lyndsay Hayward, Mount Maunganui Yacht Club Sandback cricket.

Whangamata 2021 start of race.

Christmas raft up.

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BOAT OF THE MONTH

Old gem

The Orinda II was built by Max Carter Boat Builders in Auckland in 1964, measuring 36’ x 12’ x 3’ draft and originally powered by an eight cylinder 285hp Grey Marine petrol engine.

Launched as a registered ship with glistening varnished coamings and flybridge, Orinda was a very much an admired vessel in her day.

She is now powered by a 240hp Ford diesel engine, cruising at 10-12 knots. She is game rigged, has a game chair, is bow thrusted and is still a good looking vessel for her age.

Orinda is currently on the market with Gulf Group Marine Brokers Ltd, Tauranga. Listing broker: Brian Worthington.

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Phone: +64 (9) 444 8212 Email: info@chainsropesandanchor.co.nz

How octopus suckers‘taste by touch’

Imagine if you could taste something simply by avoid toxic prey. But, the researchers add, many other unknown touching it. Octopus do just that with their unique natural compounds also might stimulate different responses in a similar way. ‘touch-taste’ sense, made possible by the suction- In future studies, the researchers hope to explore this touchcup-like suckers along each of their eight arms. taste sense in other cephalopods, such as squid, which have two specialised prey-catching tentacles instead of eight long arms.

Now, researchers are reporting in the This raises a series of intriguing questions. Have journal ‘Cell’ that they have new evidence chemotactile receptors evolved to support these specific as to how this sensory ability works. behaviors? Do receptors detect specific molecules The findings help to explain how based on ecological context or behavior? What octopuses, and perhaps other marine are the structural mechanisms underlying organisms, explore the seafloor by protein adaptations to mediate different tasting objects underwater with a ligand sensitivities and/or biophysical simple touch. features? How does this contribute to

Harvard University peripheral processing in the unique molecular and cellular biologist cephalopod nervous system? Nicholas and Nicholas Bellono says aquatic his team will continue exploring these and chemosensation has long been other questions. associated with distant waterborne This research was supported by the signaling via hydrophilic chemicals New York Stem Cell Foundation, the while terrestrial sensation utilises Searle Scholars Program, the Sloan detection of airborne volatile molecules Foundation, the Klingensteinthat are poorly soluble in water. Simons Fellowship, the National “Nonetheless, aquatic organisms produce and respond to a variety of hydrophobic Octopus in a cup. Institutes of Health, and the Swiss National Science Foundation. compounds, suggesting a distinct form of aquatic ‘taste’ mediated by contact-dependent chemosensation of insoluble molecules that do not readily diffuse in water.

“By identifying specific chemotactile receptors as mediators of this octopus sense, our study also provides a molecular basis for aquatic ‘taste’ of poorly soluble molecules.”

Nicholas and his colleagues first showed that the California two-spot octopus (Octopus bimaculoides) responded differently when its suckers touched a prey item versus another object. The finding confirmed that their suckers have a kind of tastetouch ability.

To learn more, the researchers looked more closely at the octopuses’ suckers to identify the sensory cells involved. They discovered the sucker did indeed include discrete populations of sensory cells.

But how do chemical signals received via those suckers work together with other physical stimuli to decide whether an octopus grabs what it touches? While there’s much more to learn, this study shows that distinct chemotactile receptors form discrete ion channel complexes that detect specific signals and send them on to the nervous system. Nicholas suggests this could serve as a signal filtering system suited to the octopus’ uniquely distributed nervous system.

“We also showed that separate and distinct chemo and mechanosensory cells express specific receptors and exhibit discrete electrical activities to encode chemical and touch information, respectively,” says Nicholas. “Our results demonstrate that the peripherally distributed octopus nervous system exhibits exceptional signal filtering properties that are mediated by highly specialized sensory receptors.”

Their findings show chemicals known as terpenoids act on octopuses’ receptors and sensory cells in their suckers to encourage different responses. They note that terpenoids are produced by many marine invertebrates as a defence or warning signal. By detecting these signals with their arms, octopuses might

Bride and pride of the 60s still turning heads

This beautiful Carl Augustin cabin boat would be the oldest trailer boat still operating out of Mercury Bay.

In fact she has never left the area after arriving from the Waikato where she was built in 1966. The Bernadine first impressed the author many years back when I was a young fisherman who spent numerous hours on the wharf fishing,watching boats being launched and listening to the tales from returning skippers of the time. My mother was not impressed with some of the vocabulary I acquired or my ability to recite all the launches and most of the skippers’ names or in many cases nicknames. She could not fathom how this information was prioritised against learning times tables in the early years.

The Bernadine was one of my favourites together with the Ngaire which was skippered by Connie Simmonds, the first female skipper of a charter launch which operated out of Whitianga for many years. Her colourful deckie was Koni and they made a most successful team with many great catches landed.

Built in 1966 by Jack Moreland and his son Andy Moreland, the Bernadine is now the pride and joy of Kim and Grant Moreland who own property and regularly visit Whitianga continuing the family

A recent shot of the launch at the Whitianga ramp.

Bride and pride of the 60s still turning heads

tradition. The launch has now had five generations fish off her.

The Bernadine was named after Pat Boone’s popular hit song of the time and some of the lyrics in the song certainly reflect opinions expressed about the launch.

“Your remarkable form is a pure delight.”

She was originally powered by a 283 Chevrolet V8 from a Corvette until 1982 when it was converted to outboard power. She is now onto her fourth outboard. The Bernadine is now powered by a 150 4 stroke Yamaha.

She was originally towed by a 1959 Ford that had the winch mounted in the boot.

She was rebuilt in 1990 with the double skinned glass hull being extended to 23 foot adding one foot to the length.

Grant and Kim proudly share memories and photos of early trips with great family trips some incredible hapuka catches evident.

They continue to be impressed with the attributes and capabilities of the design of the launch.

“The flat bottom and being so heavy enables the Bernadine to follow the waves and sit flat in a variety of seas.

“She has proved her worth and served her time.”

The Bernadine certainly is a stand out and the Morelands are regularly quizzed by visitors and locals alike as to her history with many remembering her from years gone by.

With the prolification of alloy launches witnessed on launching ramps today the “Golden Girl” of another era still attracts more than casual glances .

Age does not weary this lovely lady! Ron Morgan

The spelling of the earlier photos had Bernardine with an r.

The bottom photo shows the Bernadine on show at the Hamilton Winter Show.

Population positive

Total biomass within the Leigh Marine Reserve is five times higher than it was 40 years ago when the

Reserve was first established, a study shows.

University of Auckland’s Institute of Marine Science PhD candidate Harry Allard conducted a three-year survey of 22 fish species within the reserve, 10 of them targeted by fishers. Finishing the survey in 2018 meant it was exactly 40 years since a 1978 study, which established a baseline for future research.

Both old and new studies were similar in approach, using biomass as a measuring tool which takes into account both outright numbers and size of individual organisms. Harry counted fish at similar locations to the previous study.

However, he also surveyed 12 fished (unprotected) sites outside the reserve that weren’t done 40 years ago.

Results show snapper are on average six centimetres larger in the reserve than in fished areas outside but overall numbers have remained stable while the number of juvenile fish has decreased.

Red moki and butterfish – both favoured by spear divers – are also larger in the reserve than in fished areas but numbers had also remained stable since 1978. While red moki are similar in abundance compared to 40 years ago, total biomass of the species has increased with a greater number of legal-sized (more than 40cm) fish.

“Overall, the data shows the marine environment within the reserve is now dominated by fewer, larger fish with most of these being of prime breeding age,” says Harry. “The offspring of these fish are now seeding areas outside the reserve.”

Numbers of three target species included in the study – parore, leatherjacket and blue cod – are more abundant inside the reserve than in fished areas but showed a decline in numbers overall since 1978. This could be due to wider environmental factors or the fact sea urchin barrens – areas with a high number of kina or sea urchins – have been widely replaced by kelp forests suiting some species but not others.

“This may reflect larger-scale changes in the Hauraki Gulf rather than local effects, perhaps due to warming winter temperatures,” says Harry. “Blue cod are still larger and more numerous within the reserve than fished areas outside, which shows protection of this species may be increasingly important.”

There are fewer juvenile leatherjackets within the reserve but still more than outside, with a similar finding for parore but large-scale changes due to climate change could also be a factor, says Harry.

One of the most notable changes since 1978 is the replacement of sea urchin barrens with kelp forest and algae species, a sure sign that kina predators – such as larger snapper – are more numerous in the reserve.

Three species, hiwhiwi, spotty (a common wrasse species) and goatfish, all showed a decline in numbers within the reserve compared to fished areas outside. This might be due to a decrease in sea urchin areas or could point to increased predation by the higher number of larger fish within the reserve.

Overall, six out of 10 species targeted by fishers showed positive growth in either weight or abundance in the reserve during the last 40 years – but Harry says further research is needed to investigate longer term changes in the wider marine environment such as those caused by climate change.

However, the research does undermine reports from the public there are fewer fish in the reeserve than there used to be.

“The fish are still there but they don’t come into shore anymore for a feeding frenzy of peas and bread now that feeding is banned,” says Harry. “But it’s amazing how long a snapper’s memory can be, some of the older fish still follow people around expecting food.”

During research dives Harry regularly saw the reserve’s most famous resident – ‘Monkey Face’, the giant snapper – estimated to be at least 40 years old. However, the last time he saw him was 2018 and he’s heard that other divers haven’t seen him for some time. “It may be he’s finally gone to that big marine reserve in the sky.”

PhD candidate Harry Allard