Growth of wild and domesticated Atlantic cod Gadus morhua reared under semi-commercial conditions

Abstract

Genetic interactions between farmed escapees and wild fish represent a challenge to environmentally sustainable aquaculture. Breeding programs for Atlantic cod Gadus morhuahave been initiated; however, the genetic response to selection, and therefore the degree ofdomestication, has not been evaluated. We compared growth of 2 wild and 2 partly domesticatedstrains that had been under selection for 2 generations. Offspring of 54 synchronously producedfamilies were reared in 2 common-garden experiments, each consisting of Phase I: parallelrearing in mesocosms and tanks 0−8 mo post-hatch, and Phase II: rearing in tanks or sea-cages8−18 and 8−34 mo post-hatch, respectively. One of the domesticated strains displayed significantlyhigher growth compared to the wild Northeast Arctic cod population (48−67% higherweight), while the other domesticated strain had a similar growth rate to the Northeast Arctic codpopulation. The wild population from southern Norway displayed a significantly higher growthrate compared to the wild Northeast Arctic cod population. These results represent the first experimentalestimation of domestication-driven changes in farmed cod, and demonstrate that the firstbreeding programs for this species have been partially successful, resulting in improved growthrates of cod in 2 generations