Habitat use,temporal abundance variability,and diet of blue crabs from a New Jersey estuarine system |
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| Authors: | Email author" target="_blank">C?J?MeiseEmail author L?L?Stehlik |
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| Institution: | 1.National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Northest Fisheries Science Center, James J. Howard Marine Sciences Laboratory,U. S. Department of Commerce,Highlands |
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| Abstract: | In a long-term, spatially comprehensive beam trawl survey of the Navesink River-Sandy Hook Bay estuary, the blue crabCallinectes sapidus was one of the most abundant species. Seasonal changes in abundance were evident, with low abundances in summer followed
by peak abundances in the fall, after juveniles recruited to the estuary. We saw no long-term trends in abundance during the
5 yr study. Location in the navesink River or Sandy Hook Bay explained most of the variance in abundance within any one survey.
In diet analyses, we found evidence of cannibalism in all seasons, but in the size range of crabs caught in this study (10–180
mm), we did not find a relationship between cannibalism and juvenile crab abundance. Within surveys, crabs divided into 20
mm size categories showed no sizerelated differences in location within the estuary or among 7 habitat types examined (algae
bed, amphipod bed, beach, channel, marsh edge, mid-depth, and sandbar). Channels and sandbars tended to exhibit lower crab
abundance than other habitats. Shallow habitats with and without cover were equally preferred by juvenile blue crabs, implying
that the presence of structure was not critical. Spatial models of crab abundance (<- 80 mm carapace width) to environmental
data were fit from several seasons of intensive sampling in the Navesink River-Sandy Hook Bay estuary between summer 1996
and spring 1998. These models indicated that fine-grained sediments, tmmperature, depth, and salinity were good indicators
of crab abundance in spring, summer, and fall. Using these spatial models and environmental data collected in subsequent seasons
(summer 1998−fall 1999), we were able to predict blue crab abundance in the river as evidenced by significant correlations
between predicted and observed abundances. For the size range of crabs examined here, physical conditions may be as important
as structural habitat types or cannibalism in determining habitat use in northerly estuaries. |
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