Aspects of the reporductive cycle of Atlantic cod, Gadus morhua L., from inshore Newfoundland

Data on maturity, condition and gonad histology were collected to give insight into the reproductive biology of Atlantic cod, Gadus morhua L., in Placentia and Trinity Bay, Newfoundland. Female cod in Placentia Bay spawned between April and August, with some spawning probably occurring later in the fall. Oocytes began to ripen for the next season 1--2 months after spawning with cortical alveoli appearing as early as July and exogenous vitellogenesis starting as early as August. Oocyte development continued throughout the winter. Spawning was usually determinate but the ability to boost fecundity by recruitment of oocytes into vitellogenesis during spawning was noted. Atresia of previtellogenic and vitellogenic oocytes existed as a mechanism to downgrade fecundity.; The testes of Placentia Bay cod were filled with spermatozoa between January and August and spermiation was likely possible over most of this period. Spermatogenesis was completed prior to the winter reduction in feeding intensity.; Seasonal changes in condition indices differed slightly for female and male cod from Placentia Bay.; The existence of non-reproductive cod suggests that spawning is not always annual for some individuals. (Abstract shortened by UMI.)...