Embarking on a new project – farmed perch

by Thomas Jensen

Pärnu Laht’s recirculation system was designed and built by a Lithuanian company with experience in the production of systems for pike-perch fry, as Danish, Norwegian and Latvian offers were too expensive.

Estonian independence in 1991 led to the creation of a number of private companies in the fisheries sector. Among them was Pärnu Laht which started its operations processing the freshwater fish perch and pike-perch and selling the fillets to Western Europe. Since then the company has faced a number of ups and downs and today is working on the farmed production of perch.

After a long period of fluctuating supplies Ott Sool, chairman of Pärnu Latt decided to switch from trading perch to farming it. We felt we had to solve the raw material problem ourselves, says Mr Sool, as supplies from the wild are so unstable, both in terms of availability and price, but also with respect to size and quality. There is now a fry system, an incubation system, and two broodstock systems in place. The two broodstock systems will ensure that the market can be supplied with raw material for 9 months. To deliver all 12 months of the year will call for a third broodstock system, on which the company has already working. The first batch of eggs has already hatched resulting in some half a million fry. These are now being on-grown at a former eel farm, a solution that is less than ideal since the farm is not designed for perch. However, on-growing the first batch has led to an understanding of some of the problems, and changes have been made to improve things for the next batch. As Ott Sool says, there is little point in investing in a new on-growing facility unless there is an assured supply of fingerlings. Since importing fingerlings is not possible as the suppliers are located too far away, the company will rely on its own broodstock.

Multiple batches of eggs to be hatched this year

This year three batches of eggs will be produced, one from each of the two brood stocks and one to be taken from the wild. Each batch should result in about 600,000 fingerlings, a quantity that should enable a full year’s production. In parallel the company has plans to collect a broodstock of pike-perch, because pike-perch farms are being established across Europe, according to Mr Sool, and they will need a supply of fingerlings if they do not have their own hatcheries. Perch is a rapidly-growing fish that requires just six months to grow from a 2 g fingerling to a 100-150 g fish, which is the size needed to produce a decent fillet. Already some Swiss buyers have shown an interest in the product, but Mr Sool is not ready to sign any contracts as he cannot yet guarantee an uninterrupted supply of fillets. Over the next 18 months he hopes to have a production of between 50 and 70 tonnes of fish. In the meanwhile, a new filleting facility is being designed. Potential buyers of the fillets are also demanding a factory that will be at least IFS certified. The new plant will be smaller than the old one and will be built in one of the rooms that was used as a coldstore in the past. It will be designed to accommodate a maximum of 15 workers including 12 filleting personnel and should be completed by the end of 2015.

Farming perch is a new activity for Pärnu Laht and has meant a steep learning curve says Ott Sool, Chairman of the Board.

Perch require water at a temperature of 23 degrees to grow optimally and therefore farming them effectively can only be done in a closed recirculation system. In the hatchery the water is recycled three times in the space of an hour and the system has a capacity of 1.5m fry per cycle. The perch need to be sorted from the time they are 3 g in size to prevent cannibalism. If a basin has a mix of big and small fish the big ones will feed off their siblings, so it is important to grade them early and frequently to prevent this from becoming a problem. Grading is also necessary to ensure that when the fish reach market size and are being harvested they are more or less the same size as this will ensure consistent fillet sizes too. On the Swiss market the preferred sizes are 15-20 g and 20-30 g and getting satisfactory volumes of just these sizes is difficult to obtain with wild fish, which tend to vary in size more than farmed fish. On other markets, such as those in Sweden and Finland, however, there is a preference for bigger fillets. Here, the company is looking to sell frozen fillets in the sizes 40-60 g, 60-80 g and 80+ g.

Experimenting with feeds for the highest yields

Farming perch is a completely new activity for Pärnu Laht and has meant a steep learning curve. Feed for the larvae, for example, during the first 8-10 days after hatching is artemia, which is gradually replaced with dry feed. However, the type of dry feed that gives the best growth has been a question of trial and error as there are no feeds developed specifically for perch. The company has therefore tried feeds designed for pike-perch, trout, and sturgeon finally deciding on a type that gave a yield of 43% when the fish was filleted. We expect to maintain that yield throughout the year, says Mr Sool, something that is not possible with wild fish, where the yield swings between 25% and 40% depending on the season. Getting the broodstock to eat pelleted feed was also difficult. As a wild carnivorous fish perch are used to eating live prey and the broodstock showed no interest in the pellets that were showered on them. Finally live prey were introduced into the tanks and the fish started feeding. Now the fish have acclimatised themselves to captivity and today they even feed on chopped Baltic herring.

Cooperation between scientists and industry would have mutual benefits

The recirculation system that Pärnu Laht uses was designed and built by a Lithuanian company with experience in the production of systems for pike-perch fry. Offers from Norway, Denmark, even Latvia were too expensive, says Mr Sool, who is happy with the way the system has functioned to date. If something goes wrong a
nywhere in the system, it is wired to send a signal to a mobile phone, so that immediate action can be taken. The consequences of not receiving timely intimation of a problem can be disastrous, so these safeguards are vital. Although the water in the system is cleaned and recirculated, regular infusions of fresh water are needed which the company gets from the municipal supply. The volume of fresh water pumped into the system varies from 3 to 5 cubic m a day depending on the amount of fish there is in the system. The company would like to collaborate more closely with university scientists so that both the researchers and the company can gain a better understanding of the fish and the system in which they are growing. One issue in particular concerns the broodstock which must be renewed regularly to maintain the quality of the eggs and the larvae. Fish to renew existing broodstock can be taken from the wild and go through the long process of acclimatisation, or they can be bred from the fish that are grown in the tanks. The advantages and disadvantages of these and other farming processes can best be investigated by scientists and industry working together.

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