In 1866, Norwegian marine biologist G.O. Sars made groundbreaking advances in aquaculture science with the first artificial hatching of cod. Yet cod remains one of the hardest fish species to farm. Norwegian scientists at Nofima have found new ways to produce more robust cod and lift the financial potential for fish farmers.
Norway first began fish farming using the species rainbow trout. These days, the production of Norwegian farmed salmon dominates its aquaculture industry and outpaces rainbow trout by nearly ten-fold. In 2008, Norwegian farms produced 742,976 tonnes round weight of farmed salmon compared to 75,406 tonnes of rainbow trout, according to Statistics Norway.
Cod ranks third in farmed production at about 11,000 tonnes and still has a long way to go before it can reach salmon and rainbow trout. Part of the problem with farming cod is that – like most marine species – it has immature larvae with no stomach. Cod hatch very small fish that start feed on live feed organisms and before being weaned onto formulated feed. Salmon and trout, by comparison, are hatched in fresh water and much bigger and feed on formulated feed from the start.
||Atlantic cod juveniles.
© Nofima Marin
One way to increase the growth rate in the farming stage is to reduce malformations at the hatchery stage. New research published in November 2009 by the Norwegian Institute of Food, Fisheries and Aquaculture Research (Nofima), shows great promise of reducing the rate of malformation in farmed cod and other species and could improve the welfare of these fish and aquaculture profits.
“It costs the same to feed a fish with malformations, but the slaughter weight will be about half a kilo lower,” said Synnøve Helland, a Nofima Marin scientist who worked with the project. “Fish without malformations provide better earnings for the industry, while it is also of great significance for the welfare of the fish.”
The study found that the majority of defects occur in the first six months of the cod’s life, also known as the fry or hatchery stage. The scientists tested 80 different cod families. The study found malformations in just 3% of the fish after six months, well below the average of 20–70%.
The most common find of malformation in cod is an axis break in the neck. These are referred to as stargazers because the head is protruding upwards. Other types are lordosis (an inward curvature of the spine) and vertebrate fusion. One of the most important ways to avoid malformations was by optimising the temperature and speed of the water that flows through the tanks.
“The optimal temperature for normal development may be lower than the temperatures that give the greatest growth,” said Helland. “Our recipe allows the cod to grow slower in the first couple of months, which gives a more robust growth. Since it is so flawless, it will compensate with growth later in life.”
These and other recommendations are included in a manual on control of malformations in fish aquaculture, equivalent to a step-by-step guide for the industry, as part of the EU-financed Collective research project Fine Fish. Eight research institutions and 10 fish farms from around Europe participated in the project, which was co-ordinated by the Federation of European Aquaculture Producers (FEAP). Nofima Marin was responsible for the scientific activity.
||Broodstock of Atlantic Cod.
© Nofima Marin
Profunda, a west coast Norwegian hatchery producing Atlantic cod juveniles, participated in the FineFish project to find how the company could reduce the prevalence of malformations in their production and to understand more about what causes malformations in farmed fish. Its participation resulted in a new and wider focus on the effects of tank environment on protocols for cod productions, in particular the need to control water current, according to Aquamedia, an information resource about aquaculture provided by the Federation of European Aquaculture Producers. This development came as a result of realization that the knowledge generated from sea bass and sea bream production was also applicable to cod.
“You have to have slow-moving tank rearing water, otherwise you induce lordosis, as it has been shown for sea bass,” said Helland.
Profunda focused during the project period on water circulation and aeration of incoming water to create a calmer environment in the larval and juvenile tanks. The company made significant investments to its hatcheries towards this purpose and as a result managed to lower the incidence of lordosis considerably, resulting in much lower percentages of malformed juveniles, said Aquamedia.
One of the leading Norwegian cod farming companies in this relatively new industry is Atlantic Cod Farms. Based in Stadlandet, it is an integrated aquaculture company that has ambitions to become a world leader in cod farming. It is in the process of securing a licensing volume for fish production of over 21,000 tons and aims to be among the players in Norway with the greatest volume licensing. Another company is Cod Farmers, which was the first cod farming company listed on the Oslo Stock Exchange on 19 October 2006 under the ticker code COD.
Norway exported NOK 275.5 million of farmed Norwegian cod in 2009, up 28% from the previous year, according to the Norwegian Seafood Export Council. The biggest market is France, which received more than 40% of total exports. Exports of fresh whole farmed Norwegian cod rose from NOK 16.6 million to NOK 207.2 million. Denmark and Sweden were the biggest markets, each with a 30% share of the total exports.