A Preliminary Study of Predation on Blue Crabs by Three Fish Predators in a Seagrass Bed

Abstract

This report serves as a preliminary assessment of potential feeding impacts on blue crab prey inhabiting a seagrass bed in the York River by three species of recreationally and commercially important fish (striped bass, croaker, and red drum). We also provide an historic perspective indicating possible changes in relative abundance of these predatory fish between the period 1978-1980 and 1998. In no way do we intend for this report to reflect an accurate, bay-wide assessment of these relationships; the extremely limited temporal and spatial scope of this effort precludes such conclusions. However, this report supports the contention that habitat-specific predation impacts on juvenile crabs inhabiting seagrass beds that serve as nurseries for blue crabs may be important to consider when examining sources of natural crab mortality. Definitive conclusions regarding such impacts await more comprehensive research efforts targeting these relationships at the appropriate bay-wide scale. Finally, it is important to recognize that mortality impacts on blue crab populations stem from a combination of causes. Natural mortality via predation (which is difficult to control) apparently impacts crabs less than 75 mm (3 inches) in carapace width (Moody, 1994; Smith, 1995), whereas those individuals larger than 75 mm likely experience heaviest mortality from commercial and recreational fisheries (which can be controlled through effective management policy)

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