Growth and recruitment rates of juvenile blue crabs ( Callinectes sapidus) in Chesapeake Bay

Abstract

Recent marked declines of the commercially and ecologically important blue crab in Chesapeake Bay have prompted requests for improved scientific information on blue crab population dynamics. I evaluated recruitment rates to blue crab fisheries using three independent approaches: direct observations, length-frequency analysis, and lipofuscin-based ageing. Three cohorts of known-age pond-reared blue crabs were sampled monthly, growth rates were modeled and compared to estimates from length-frequency analysis of field-collected crabs. Mean growth rates for juvenile pond-reared and field-collected cohorts ranged from 0.4 to 1.4 mm/day. A temperature-dependent growth model back-calculated settlement dates and predicted partial recruitments of juvenile winter size distributions. Predictions coincided with observations for wild blue crabs. Lipofuscin accumulated exponentially with age. The high growth rates, rapid recruitment rates, and lipofuscin-based age designations suggest that peeler/soft crab fisheries in the summer and hard crab fisheries in the fall/winter are predominately dependent on recruits less than 18 months of age.