Fecundity of Atlantic cod (Gadus morhua) farmed for stock enhancement in Newfoundland bays

In response to the historically low spawning biomass of Atlantic cod (Gadus morhua) off eastern Newfoundland and Labrador, Canada, we are investigatin g the feasibility of enhancing recruitment through the release of wild-prod uced, captively-grown broodstock into bays with resident, inshore spawning populations. Large numbers of small cod can be trapped, their growth and fe cundity increased by feeding in captivity, and then released back into the bay where captured. The released cod would augment the wild spawning popula tion. To estimate the potential contribution of released fish to population fecundity, we determined the fecundity of wild cod held in sea cages for s everal years and fed a naturally available diet. Cod captured in Placentia Bay on the south coast of Newfoundland were fed capelin or herring at 2-3% of their body weight every second or third day for three growth seasons. Th ese farmed fish exhibited potential fecundities twice that of foe-living Pl acentia Bay cod of the same weight or length. Cod captured in Trinity Bay o n Newfoundland's eastern shore were fed capelin, herring, or squid to near satiation over four growth seasons. These fish exhibited potential fecundit ies 2-4 times that of wild Trinity Bay cod of similar size. Greater vitello genic oocyte production per unit somatic weight in these farmed fish appare ntly is related to good nutrition provided early in the annual reproductive cycle. Spawning potential represented by the weight of farmed fish release d into Newfoundland bays for stock enhancement would be underestimated if f ecundity-weight relationships based on data from free-living cod were used. (C) 1999 Elsevier Science B.V. All rights reserved.