Estimation of stock reproductive potential: History and challenges for Canadian Atlantic gadoid stock assessments

Abstract

The knowledge and scientific history of maternal and paternal aspects of reproduction dates back several decades, though only recently are fishery scientists and managers giving this subject area greater attention in the provision of management advice. This paper outlines and summarizes several recent advances made in understanding the importance of variation in gadoid reproductive output as a function of spawner age, size, maturation, condition and reproductive history. An assembled score-card applied to 45 Canadian Atlantic gadoid stock assessments conducted from 1985 to 1998 portrays the evolution and current degree to which this scientific knowledge has been incorporated into fishery advice in eastern Canada. For future research, recommendations are made which promote the integration of basic reproductive biology into groundfish stock assessments. These emerging policies encourage managers worldwide to initiate relevant sampling programs which will lead to improved stock conservation reference points. A new term referred to as stock reproductive potential (SRP) is introduced. Compared to spawning stock biomass and population fecundity, SRP more accurately represents the annual variation in a stock's ability to produce viable eggs and larvae that may eventually recruit to the adult population or fishery. SRP is a term (concept) which will likely evolve in such a manner as to provide a more accurate measure of a stock's reproductive potential.