| dc.description.abstract | By estimating probabilistic reaction norms for age and size at maturation, we show that maturation schedules
of Atlantic cod (Gadus morhua) off Labrador and Newfoundland shifted toward earlier ages and smaller sizes during
the late 1980s and early 1990s, when these populations underwent a severe collapse in biomass and subsequently were
closed for directed commercial fishing. We also demonstrate that this trend towards maturation at younger ages and
smaller sizes is halted and even shows signs of reversal during the closure of the fisheries. In addition, our analysis
reveals that males tend to mature earlier and at a smaller size than females and that maturation age and size decrease
with increasing latitude. Importantly, the maturation reaction norms presented here are robust to variation in survival
and growth (through phenotypic plasticity) and are thus strongly indicative of rapid evolutionary changes in cod maturation
as well as of spatial and sex-specific genetic variation. We therefore suggest that maturation reaction norms can
provide helpful reference points for managing harvested populations with evolving life histories. | en |
