Performance of cultivated northwest Atlantic cod (Gadus morhua) families: Initiation of a selective breeding program in eastern Canada

Declining wild populations of cod worldwide has resulted in a renewed interest in farming this renowned species, and was the impetus for the creation of the Atlantic cod genomics and broodstock development program (www.codgene.ca and www.genomecanada.ca). One of the aims of this program is to evaluate the potential for improvement of commercially important traits through selective breeding using family-based selection programs established in New Brunswick and Newfoundland. Wild broodstock were obtained from three locations in Canada (Bay of Fundy, Cape Sable Island, and Eastern Newfoundland) and one in the United States (New Hampshire coast). The broodfish were either artificially strip-spawned or pair-mated to establish full and half sibling families using the Berg and Henryon breeding design. In total, 429 crosses and 215 families have been generated at three marine fish hatcheries over the first two years of the four year project. Hormonal implants were used to facilitate timing and collection of gametes. Extended gamete contact time in seawater and optimal sperm:egg ratios were explored as methods to maximize fertilization rates. Each of these families was reared in individual tanks to PIT tagging at approximately 15 g. At hatch, individual families were reared in separate tanks and/or combined with other families and co-reared in larger tanks. Families were reared to PIT tagging at approximately 15 g, transferred to sea cages for grow out and a pre-harvest performance evaluation made ~ 1 yr post-stocking. Heritability estimates were high for body length and weight (h2 ~ 0.45 to 0.55) at juvenile and pre-harvest stages