Michelle Jones1
1Simon Fraser University
January 05, 2016 9:00 (PST): FSH 203
Maturing estimates of maturity – probabilistic maturation reaction norms for British Columbia sablefish (Anoplopoma fimbria)
Predicting the size and age at which fish will mature is a key factor in estimating stock productivity. In fisheries stock assessment, this relationship is usually defined by estimating maturity ogives, which describe the proportion of the stock mature at a given age or length. However, length is a function of growth. Thus, differences in growth rates among years may cause apparent changes in maturation rates. While consistent spatial variation is expected in maturity ogives, in the case of sablefish (Anoplopoma fimbria), significant temporal variation in maturity ogives is unexpected and is large enough to cause substantial concern to stock assessment modeling. Here, we examine Probabilistic Maturation Reaction Norms (PMRNs) as an alternative for estimating sablefish maturity schedules. PMRNs condition the probability an individual will mature over a set time interval given its age, size, and survival, which may reduce confounding among each of these parameters, providing a temporally-stable model. If PMRNs can provide a stable relationship to estimate sablefish maturity schedules, then uncertainty in stock assessment models may be significantly reduced.