MEPS 535:197-211 (2015)  -  DOI: https://doi.org/10.3354/meps11406

ABSTRACT: Culture of Atlantic cod Gadus morhua L. has been proposed as a means of diversifying the aquaculture industry in Canada and other countries within its native range. Lessons gleaned from aquaculture of salmonids suggest that escapes and interactions with wild fish are inevitable. Here, we studied the reproductive interactions of individual cultured and wild male cod in the presence of a cultured female using a series of spawning trios. The spawning success of cultured males, in terms of both overall proportion of eggs fertilized, and number of spawns in which they fertilized the larger proportion of eggs, did not differ from that of wild males. This equality was likely brought about, at least in part, by multiple paternity with appreciable proportions of eggs fertilized by the presumed satellite male. In a subset of spawning events for which behavioural data were available, neither wild nor cultured males were found to be behaviourally dominant during the night of spawning across all spawning events. The spawning success of the males was not influenced by their size or by their agonistic behaviour, but was influenced by their courting behaviour. The courting behaviour of the wild males had a negative influence on their success, while the courting behaviour of the cultured males was found to increase their success. To our knowledge, this is the first study to detect spawning success equality between wild and cultured male cod in competition.

KEY WORDS: Wild/farmed interactions · Mating behaviour · Genetic introgression · Fertilization success · Aquaculture escapes