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- Comparative Demography of Skates: Life-History Correlates of Productivity and Implications for Management
- Age-structured demographic models were constructed based on empirical estimates of longevity and maturity for five deepwater Bering Sea skates to investigate how observed differences in life history parameters affect population growth rates. Monte Carlo simulations were used to incorporate parameter uncertainty. Estimated population growth rates ranged from 1.045 to 1.129 yr-1 and were lower than those reported for other Alaskan skates and most chondrichthyans. Population growth rates of these and other high-latitude skates increased with relative reproductive lifespan, but displayed no significant relationship with body size or depth distribution, suggesting that assemblage shifts may be difficult to predict for data-poor taxa. Elasticity analyses indicated that juvenile and adult survival had greater per-unit effects on population growth rates than did egg-case survival or fecundity. Population growth rate was affected more by uncertainty in age at maturity than maximum age. The results of this study indicate that if skates are deemed to be a management concern, gear modifications or depth-specific effort controls may be effective. © 2013 Barnett et al., Fish and Fisheries, Art. No.: e65000
- Barnett, Winton, Ainsley, Cailliet, Ebert
- Life history of Bathyraja trachura from the eastern Bering Sea, with evidence of latitudinal variation in a deep-sea skate species
- Although many skates possess life history characteristics that may make them vulnerable to exploitation, the detailed biological information needed to enact effective management schemes is lacking for most species. The objectives of this study were to provide age, growth, and maturity estimates for the roughtail skate, Bathyraja trachura, from the eastern Bering Sea. Maximum age was estimated at 36 yr based on band pair counts in vertebral centra. Of the four growth models applied, the logistic model provided the best description of growth (asymptotic total length = 911 mm; growth coefficient = 0.131 yr-1). There was no evidence of difference in growth between males and females. Females attained maturity at larger sizes and older ages than males. The median size-at-maturity was estimated at 741 mm total length (TL) for males and 796 mm TL for females; median age-at-maturity was estimated at 21.1 yr and 24.7 yr for males and females, respectively. The results of this study may indicate a latitudinal pattern in size and growth, with individuals from the eastern Bering Sea growing more slowly and reaching higher maximum ages than previously reported for specimens collected off the western coast of the continental United States. Copyright © Marine Biological Association of the United Kingdom 2013., Fish and Fisheries, Downloaded from: http://journals.cambridge.org/action/displayFulltext?type=1&fid=9155760&jid=MBI&volumeId=94&issueId=02&aid=9155757 (9 June 2014).
- Winton, Natanson, Kneebone, Cailliet, Ebert