Nieuws - 13 september 2011

Baby sole born in breeding pond

Farmed sole that has grown up in captivity can reproduce naturally, Wageningen UR researchers noticed in Zeeland this summer.

Until now, Dutch sole farmers have used sole caught at sea, which can reproduce in the covered ponds on the fish farms. The second generation of sole (which has grown up in captivity) has hardly ever done so to date, although the researchers have experimented with light and temperature in order to imitate natural conditions as closely as possible.

Last year Wageningen UR released farmed sole into open-air ponds at the experimental farm of the Zeeland Sole Foundation at Colijnsplaat.  This summer they found very young sole weighing between 5 and 20 grams in the ponds - much smaller than any of the fish released there. 'We wondered whether the first generation of sole in captivity would be of good enough quality to reproduce', says research group leader Henk van de Mheen. 'The answer is yes. Apparently we didn't recreate natural conditions well enough in the covered ponds. For example, last winter was extremely cold - perhaps that is an important factor in the reproduction of the sole.' Wageningen Imares now wants to do further research on the decisive factors in the reproduction of the fish. Reproduction in captivity is important to sole farmers, because it would enable them to select the fastest growing sole. Without that selection, commercial farming of sole is not, or hardly, viable.