Nearshore settlement and localized populations of age 0 Atlantic cod ( Gadus morhua ) in shallow coastal waters of Newfoundland
Mark-recapture experiments and seasonal sampling were carried out to examine the nearshore movements, abundance, and behaviour patterns of age 0 Atlantic cod (Gadus morhua) in eelgrass (Zostera marina) and no-eelgrass habitat in Trinity Bay, Newfoundland, during 1994 and 1995. Cod remained localized...
Published in: | Canadian Journal of Fisheries and Aquatic Sciences |
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Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Canadian Science Publishing
1998
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Subjects: | |
Online Access: | http://dx.doi.org/10.1139/f97-310 http://www.nrcresearchpress.com/doi/pdf/10.1139/f97-310 |
Summary: | Mark-recapture experiments and seasonal sampling were carried out to examine the nearshore movements, abundance, and behaviour patterns of age 0 Atlantic cod (Gadus morhua) in eelgrass (Zostera marina) and no-eelgrass habitat in Trinity Bay, Newfoundland, during 1994 and 1995. Cod remained localized, not moving further than a few hundred metres in eelgrass and no-eelgrass habitats for several weeks after settling from a pelagic habit, and may remain localized during their first winter. Observations from this study of bulk movements of marked and unmarked cod, high within-site variation in catch rates during the day, and significant day-night differences in the mean and variance of catch data, combined with results from related studies, provide indirect evidence that age 0 cod shoal during the day and disperse at night within the study area. Behaviour patterns exhibited by age 0 cod (restricted nearshore movements, diurnal shoaling, and preference for structurally complex habitat) are mechanisms for predator avoidance, suggesting that predation risk is high in coastal Newfoundland. A significant increase in abundance of age 0 cod in less suitable habitat (no-eelgrass cover) when settlement strength was high is consistent with the hypothesis of density-dependent habitat selection. |
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