Postcapture survival and future reproductive potential of ovigerous blue crabs Callinectes sapidus caught in the Central North Carolina pot fishery
Harvest restrictions by sex or reproductive status are used to protect many spawning stocks. In most U.S. states, fishery regulations for blue crabs Callinectes sapidus require release of ovigerous crabs. Ovigerous crabs caught in pots become stressed by capture and physically damage the egg mass and remove eggs. We conducted a survey to assess the extent of egg mass damage in pot-caught crabs as well as crabs caught by hand and not subjected to pot stress. Egg mass damage was more prevalent in pot-caught crabs (>45% during all months) than in crabs caught by hand (<6% during all months). We investigated the postcapture survival, reproductive output, and larval viability of crabs with varying amounts of egg mass damage by collecting ovigerous crabs from the pot fishery and confining them in the field for the duration of their lifetimes. Over 80% of the crabs survived to release the clutch present at capture, and crabs produced up to six clutches of eggs. Of 156 clutches produced in confinement, only 1 was damaged. Crabs confined individually and fed do not experience the stress that causes egg mass damage in pots. The lipid content of early-stage eggs (77.0 ± 1.3% [mean ± SE]), larval carapace width (269.0 ± 3.34 μm), and larval survival time without food (3.0 ± 0.11 d) were similar for all clutches and levels of egg mass damage. Clutch volume decreased by approximately 20% with each subsequent clutch, and the percentage of embryos developing normally decreased from 97 ± 0.6% for clutch 1 to 79 ± 10.8% for clutch 5. Immediate release of ovigerous crabs could be a viable management strategy, but it would have severe economic consequences for fishermen in high-salinity areas. Area closures, combined with subsidies for crabbers during critical times, may be the most viable management strategy until crab populations recover from current diminished levels. © by the American Fisheries Society 2010.
Zachary Darnell, M; Darnell, KM; Mcdowell, RE; Rittschof, D
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