A product for discerning clients

Julia Lynne Overton, hatchery manager at AquaPri

AquaPri is one of the few companies in Europe to successfully farm pike-perch in a closed recirculation system. While other attempts to rear this species both in Denmark and abroad have floundered for one reason or another, the company is currently completing a large new facility to replace its existing on-growing tanks for the fish.

Danish aquaculture production is dominated by trout, raised both in freshwater and saltwater, and salmon. Of the 43,000 tonnes of farmed fish that were produced in 2013 41,000 tonnes (95%) were trout and salmon. The other main cultured species are eel with a production of 1,000 tonnes and mussels with a volume of 560 tonnes in 2013. The Danish aquaculture industry, in common with the sector in the rest of Europe, has shown little if any growth for more than a decade. Since 2000 aquaculture production in the EU has stagnated at 1.3 million tonnes, while almost doubling in Asia and America, and almost tripling in Africa, over the same period. The lack of growth in the European aquaculture sector is all the more striking as demand for fish in Europe has been increasing steadily. Since domestic capture fisheries do not meet European requirements for fish the result has been that today 65% of Europe’s requirement for fish and seafood is met through imports.

More support available for fish farming

The lack of growth in the European aquaculture sector can be attributed to a number of factors. These include a shortage of suitable sites, cumbersome bureaucracy, competition with other users of marine areas and inland water courses, and strict environmental protection laws. Recently, however, policy makers have woken up to the potential of the sector as a source of economic growth, particularly in rural regions with few other opportunities, as well its importance for the supply of fish in Europe. The Common Fisheries Policy and the European Maritime and Fisheries Fund both reflect this emphasis on aquaculture, and include several measures to support its sustainable development. Among these is the introduction of new species as well as the use of recirculation systems. In Denmark one of the outcomes of the environmental legislation has been the development of recirculation systems that are largely isolated from their surroundings. These systems have been used to grow rainbow trout, salmon, and eel, but also some less well-known species such as pike-perch (Sander lucioperca).

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AquaPri, a family-owned company, is Denmark’s biggest producer of pike-perch. The firm has a history in the fisheries business that goes back to the early 1900s and today is an important producer of trout (both freshwater and marine), trout roe, and also has an interest in salmon produced on land. However, while salmon and trout are long-domesticated species, cultivating pike-perch is pioneering work with all the perils and joys that go with it. Though we have had our successes the path this far has been anything but smooth, says Julia Lynne Overton, the hatchery manager, partly because pike-perch is still a wild species. This means that the fish has traits that, while beneficial in the wild, need to be bred out in the farmed fish. The company started its pike-perch farming activities around 2007 in Egtved using a converted eel farm with a recirculation system that was gradually adapted to the requirements of the new species. Initially the entire production cycle was at this site but a few years ago the company invested in another site in Holstebro, which was used as an additional grow-out facility for the fingerlings. The Holstebro site is now to be replaced with the bigger, purpose-built grow-out facility that is currently under construction in the Vejen municipality.

Recirculation is expensive and technically demanding

Recirculation systems, as the name suggests, repeatedly recycle the water in the system after cleaning and reprocessing it. Very little fresh water is added to the system. Mechanical filters remove the larger particulate impurities, faecal matter and uneaten food, while biofilters strip from the water the very fine particles and dissolved substances converting them into harmless products. Biofilters are made of microorganisms often settled on a substrate. It is the metabolic activity of these microorganisms that renders harmless the toxic substances secreted by the fish or generated by the breakdown of proteins from the fish faeces or the uneaten feed. Recirculation systems have the advantages that they have little impact on the environment, all the parameters, temperature, oxygen levels, acidity etc. can be controlled, the risk of diseases brought by the water is very low, and they can be used for a number of species. On the other hand these systems are expensive and technically complex requiring trained personnel to run and maintain them. The biofilter is the heart of the system and like any sensitive living creature needs to be treated carefully so that it performs optimally. At AquaPri farming pike-perch in a closed recirculation system was a process of learning both about the fish and about the system. Because it is a new species to be farmed in these systems there was little help to draw on from others’ experience. Many of the other producers in the Netherlands, Germany, or France have either given up or have gone under, says Ms Overton, so we had to experience everything first hand.

As a wild fish pike-perch are particularly prone to stress, sensitive to the bacterial loading of the water, and intolerant of high densities. And if something goes wrong, it can happen with little warning and needs to be corrected immediately. Among the
problems that have surfaced is cannibalism among the young fish. Larvae that are slightly bigger than the others can start to feed on their smaller siblings. This is in fact a survival strategy for the fish in the wild as there the eggs hatch in a staggered fashion so that in environments, where food is scarce, the newly hatched larvae will function as feed for the older fish thus ensuring their survival, explains Ms Overton. AquaPri has also learned that cannibalism is something that the fish learn from each other. If there are five cannibals one day there will be 50 the next and 500 the day after, so rapidly containing the problem is vital. Fortunately this has become less of an issue with each succeeding generation, as fish with these or other undesirable impulses, such as territorialism, are isolated and not bred further. The broodstock that the company is using originates from a local lake, but it has also started collecting populations from different parts of Europe to start a breeding programme. This will entail crossing fish from different populations with desirable characteristics and then isolating candidate fish from the next generation that show the most promise and breeding those eventually to obtain the individuals that can be used as broodstock. In the hatchery music is constantly played in the background. It is to get the fish accustomed to sounds, explains Julia Overton, because initially the wild fish would react very badly to any noise, but they gradually get more used to sounds.

Potential markets in Eastern Europe

By controlling the temperature and light the fish can be made to spawn four times a year in the recirculation system in contrast to the wild where once a year is the norm. Although a freshwater fish the eggs in size and number are akin to those of marine fish. At AquaPri the eggs and the milt are stripped from the fish rather than allowing the fish to spawn. Stripping the fish enables accurate data about numbers of eggs, fertilisation and survival rates. Samples from different groups of eggs are monitored and if a sample is not developing as it should the group can be discarded without wasting resources on it. While this approach is more labour intensive it is cost-efficient in the long run. The larvae although tiny when the eggs hatch grow rapidly once they are introduced to pelleted feed. It takes 15-18 months to reach a market sized fish of 800 g to 1.2 kg, says Henning Priess, the managing director and co-owner of the company. The main product at the moment is whole round fish, but the company is also looking at producing fillets, and here the size of the fish plays a role. At about 1 kg it is possible to get a good fillet, he says, but we are looking for a market for slightly smaller fillets as growth is very rapid up to about 800 g, but then flattens dramatically making it disproportionately expensive to produce a larger fish. The market for pike-perch is also affected by the wild catch, with prices fluctuating depending on whether the catch is good or poor. Pike-perch is still a niche product, relatively unknown in many markets. Today the company is selling the fish in Switzerland, Germany, France, and a little in Denmark. It is easier to sell in markets that know the fish, says Mr Priess, for example Spain, though a big consumer of fish, is unfamiliar with pike-perch and breaking into that market is difficult. On the other hand the Baltic States and countries in central Europe like Hungary and the Czech Republic that produce the fish themselves are more promising. The new grow-out facility is expected to be ready in March or April 2015. While the company has learned much about the production of pike-perch in closed recirculation, how the fish will react to the new system will be studied with great interest in Denmark and outside. For if sustainable farmed fish production is to increase in the EU, these systems will have an increasingly important role to play.