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Author (up) Émond, K.; Sainte-Marie, B.; Galbraith, P.S.; Bêty, J. url  openurl
  Title Top-down vs. bottom-up drivers of recruitment in a key marine invertebrate: Investigating early life stages of snow crab Type Journal Article
  Year 2015 Publication Abbreviated Journal ICES Journal of Marine Science  
  Volume 72 Issue 5 Pages 1336-1348  
  Keywords cannibalism; climate; groundfish predation; larval production; population dynamics; recruitment; snow crab  
  Abstract Many snow crab fisheries have fluctuated widely over time in a quasi-cyclic way due to highly variable recruitment. The causes of this variability are still debated. Bottom-up processes related to climate variability may strongly affect growth and survival during early life, whereas top-down predator effects may be a major source of juvenile mortality. Moreover, intrinsic density-dependent processes, which have received much less attention, are hypothetically responsible for the cycles in recruitment. This study explored how climate, larval production, intercohort cannibalism and groundfish predation may have affected recruitment of early juvenile snow crab in the northwest Gulf of St Lawrence (eastern Canada) over a period of 23 years. Abundance of early juvenile snow crabs (2.5-22.9 mm in carapace width), representing the first 3 years of benthic life, came from an annual trawl survey and was used to determine cohort strength. Analyses revealed a cyclic pattern in abundance of 0+ crabs that may arise from cohort resonant effects. This pattern consisted of three recruitment pulses but was reduced to two pulses by age 2+, while the interannual variability of cohort strength was dampened. This reconfiguration of the earliest recruitment pattern was dictated primarily by bottom water temperature and cannibalism, which progressively overruled the pre-settlement factors of larval production and surface water temperature that best explained abundance of 0+ crabs. The results strongly suggest that bottom-up and density-dependent processes prevail over top-down control in setting the long-term trends and higher-frequency oscillations of snow crab early recruitment patterns. © 2015 International Council for the Exploration of the Sea 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.  
  Address Department of Fisheries and Oceans, Maurice Lamontagne Institute, 850 Route de la Mer, Mont-Joli, QC, Canada  
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  Notes Export Date: 17 March 2016 Approved no  
  Call Number McgGll @ elizabethburgess @ Serial 42532  
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