Snow Crab Spatial Distributions: Examination of Density-Dependent and Independent Processes

Snow Crab Spatial Distributions: Examination of Density-Dependent and Independent Processes

J.T. Murphy, A.B. Hollowed, and J.J. Anderson

Snow Crab Spatial Distributions: Examination of Density-Dependent and Independent ProcessesThis is part of Biology and Management of Exploited Crab Populations under Climate Change
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Description

The spatiotemporal distributions of the benthic stages of eastern Bering Sea snow crab (Chionoecetes opilio) have been considered previously, but principally in qualitative and non-statistical frameworks. Using spatial indices, tests of habitat associations, correlation analyses, and regression modeling, the spatiotemporal distributions of snow crab from 1982-2008 by ontogenetic stage and sex are analyzed to consider the role of density-dependent, density-independent, and ontogenetic factors as mechanisms for the observed distributions. Males and females have different spatial dynamics, with males becoming increasingly dispersed as they age while females become increasingly aggregated. Female spatial distributions can be broadly categorized into immature–newly mature distributions and older mature distributions. Male distributions differ across life stages but not as distinctly as with females. Regression models indicate that temperature is a more important explanatory variable for younger than older crabs and spatial autocorrelation is an important factor in general for all ontogenetic categories of each sex. Regression models of spatial abundances explain less variation for older crabs than younger crabs, potentially indicating differential influences of environmental factors in structuring spatial distributions across life stages. Correlation and regression models reveal that abundance levels explain much more variation in area occupied than temperature.

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