Relationship of Blue Crab Abundance to River Discharge and Salinity

The relationships between 2 environmental factors (river discharge, salinity) and blue crab (Callinectes sapidus) abundance, as measured by juvenile recruitment and commercial landings, were evaluated. Correlation coefficients were calculated between a blue crab recruitment index (Jan-Feb catch-per-unit effort of individuals <40 mm carapace width) or commercial harvest and lagged or concurrent salinity and river discharge. The recruitment index was correlated with monthly means of lagged late summer/early fall Mississippi River discharge (positively) and salinity (negatively) whereas commercial harvest were significantly correlated with unlagged Mississippi River discharge (positively) and salinity (negatively). The effects of Mississippi River discharge and salinity on blue crab recruitment and abundance were probably manifested indirectly through biotic mechanisms such as predation.

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