Assessing changes in age and size at maturation in collapsing populations of Atlantic cod (Gadus morhua)

Olsen EM, Lilly GR, Heino M, Morgan MJ, Brattey J, & Dieckmann U (2005). Assessing changes in age and size at maturation in collapsing populations of Atlantic cod (Gadus morhua). Canadian Journal of Fisheries and Aquatic Sciences 62 (4): 811-823. DOI:10.1139/f05-065.

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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 decreases with increasing latitude. Importantly, the maturation reaction norms presented here are robust to variation in survival and growth (through phenotypic pasticity), 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.

Item Type: Article
Research Programs: Adaptive Dynamics Network (ADN)
Bibliographic Reference: Canadian Journal of Fisheries and Aquatic Sciences; 62(4):811-823 (April 2005)
Depositing User: IIASA Import
Date Deposited: 15 Jan 2016 02:17
Last Modified: 19 Feb 2016 13:28
URI: http://pure.iiasa.ac.at/7510

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