Life-history
To determine if fatty acid groups differed in size-at-age, length vs. age was modeled using the Von Bertalanffy length-age model fit to length at age-of-capture of individual fish (Quinn et al., 1999):
The length-age model describes length Lt at age-of-capture t as a function of theoretical maximum length (L = mm), instantaneous rate at whichLt approaches L (K= 1/year), theoretical age-at-zero length (t 0 = years), and multiplicative error (ε ). Model parameters,L , K , and t 0, and associated standard errors were estimated using nonlinear regression. Residual sums-of-squares were compared between a full model (separate models for each group) to a reduced model (a single model for all groups) in a likelihood-ratio test (Hosmer Jr et al., 2000). If the likelihood-ratio test was significant (P <0.05), we concluded that growth differed among groups identified by fatty acids. If the likelihood-ratio test was not significant (P> 0.05), we concluded that growth did not differ among groups. The same test was repeated for each pair of groups, with and without giant individuals (fork length ≥900 mm) included in each group, to isolate the influence of this subset in our size-at-age comparison due to the prevalence of giants in one of the groups (see Results).