Marine Research Institute, Klaipeda University: Optimising recirculation systems for aquaculture

Farming saltwater species on land

Researchers at the Marine Research Institute of Klaipeda University consider recirculation aquaculture systems an innovative way to establish a marine water farming industry in a country that has a 100 km coastline.

EU imports of frozen warmwater shrimps amounted to close to 285,000 tonnes with a value of just under EUR2bn in 2019 according to the EU Fish Market report from EUMOFA. Th e species imported are the Pacifi c white leg and the giant black tiger. Shrimp that is frozen and shipped from Asia or Latin America is quite a diff erent product from fresh shrimp grown locally. Th e challenge is that Europe does not have the climatic conditions to grow fresh shrimp the way they are grown in tropical parts of the world. Th e popularity of warmwater shrimp in Europe and the high price it commands combined with the evolution of farming technology has inspired several attempts to produce shrimp in recirculation aquaculture systems. Th ese endeavours are made by research institutions interested to customise the technology and develop the protocols for this production, as well as by entrepreneurs who sense an opportunity.

Experimenting with warmwater shrimp production

In Lithuania, at the Marine Research Institute of Klaipeda University (KU), Nerijus Nika and Gintautas Narvilas are studying the biological implications of shrimp production and the technology that enables it, respectively. Th e researchers have partnered with Klaipeda Science and Technology Park (KSTP), a business support agency with

Klaipeda University Marine Research Institute

The time it takes to reach a 22 g shrimp has been decreasing as the scientists identify and solve issues that stress the crustaceans.

extensive facilities including a recirculation aquaculture system (RAS), to investigate the best way to produce under local conditions warmwater shrimp which require water at a temperature of about 30 degrees C. Th ey also seek to make this technology most eff ective and attractive to potential investors. To produce shrimp on land using RAS, beside heat, artifi cial marine water is an important issue. In western Lithuania, where Klaipeda is located geothermal resources are extensive, but also shallowly located and therefore relatively easy to access. Th e area is the site of the country’s only geothermal power plant and since it was trying to diversify its activities, feasibility studies were conducted to fi nd out whether this resource could be used for aquaculture production. Th eir conclusions suggested that shrimp would be one of the most suitable species to farm.

Th e research is being conducted as an activity of the Aquaculture Competence Centre, a joint venture between KU and KSTP established in 2018, the goal of which is to acquire shrimp cultivation knowledge, to optimise growth technology for local conditions and to comercialise this knowhow. Over the last three years of running the trials diff erent issues have cropped up in the production which the researchers have tried to overcome and thereby improve the system. Th e goal is not to produce commercially themselves, Dr Nika emphasises, but to develop reliable production technologies and knowhow that can then be off ered to potential investors interested in shrimp production. Th e RAS being used is designed by German experts

At the Marine Research Institute experiments are conducted with rainbow trout with a view to growing them in saltwater recirculation aquaculture systems.

who were also consulting Lithuanian researchers. Using a RAS in northern Europe to produce fresh shrimp compensates for environmental impacts associated with some shrimp production in Asia as well as for emissions attributable to the freezing and shipping of the product to Europe. But while recirculation aquaculture has been used for many years to produce fi sh, shrimp production is still a new activity and needs a lot of development. Even in countries like Poland with a long history and large volume of farmed fi sh production, a pilot RAS for shrimp was only recently established at Gdansk University as part of an EU-funded project (InnoAquaTech).

Challenges abound when producing shrimp in recirculation systems

White leg shrimp is naturally found on the Pacifi c coast of Central and South America, from where it was brought to the US, where the technology to produce it was developed. Today, most of the production has shifted to Asia. Everywhere in the world, the shrimp aquaculture sector is dependent on a sustainable supply of post-larvae (PL), imports of which to Europe are not allowed from Asia. Some of the biggest suppliers of specifi c pathogen free (SPF) shrimp larvae are based in America, from where Europe sources its requirements. As interest in Europe to produce shrimp increases, there is likely to be a ready market for post-larvae produced within the EU. But fi rst, the challenges associated with production need to be solved. Growth, for example, tends to be uneven across a batch leading to large individuals and small ones in the same tank which increases the risk of cannibalism. Understanding what stresses the shrimp and how to prevent it is another subject that the researchers want to concentrate on. Th ey have already established that there are periods when the shrimp seem to be more stressed than at others, so interventions at these times are reduced to the minimum. Also, other stressors, like fl uctuations in water quality, light regime, animal density, food availability are being better managed to minimise stress. Th ese adjustments have led to a decrease in mortality and a faster growth rate.

Th e post-larvae are 10-15 days old (PL10, PL12, PL15, where the number refers to the days) and the target size 22 g on average. In the fi rst production cycle the average size was 25 g after fi ve months, but by the third cycle this was achieved in four months as a result of making minor adaptions to the system, among others, to eliminate cannibalism. If this growth rate can be maintained, Dr Nika expects it to be possible to manage three production cycles in a year with an output of 100-200 kg