Virginia Institute of Marine Science
The effect of different fishing mortality (F) and natural mortality (M), and age at first capture (t(c)) on yield-per-recruit of Atlantic croaker, Micropogonias undulatus, in the lower Chesapeake Bay and North Carolina were evaluated with the Beverton-Holt model. Independent of the level of M (0.20-0.35) or F (0.01-2.0) used in simulations, yield-per-recruit values for Chesapeake Bay were consistently higher at t(c) = 1 and decreased continuously with increases in t(c) (2-5). Although maximum yield per-recruit always occurred at the maximum level off (F=2.0), marginal increases in yield beyond F = 0.50-0.75 were negligible. Current F (F-CUR) is estimated to be below the level that produces maximum potential yield-per-recruit (F-MAX)and at or below the level of F-0.1 if M greater than or equal to 0.25. Although modeling results indicated yield-per-recruit could be maximized by reducing the current level of t(c) (t(c)=2), the resultant gains were small and did not appear to justify such management measures. Instead, it is suggested that regulatory measures be directed at maintaining the current level of t(c) in the lower Chesapeake Bay. Simulation results for North Carolina showed a pattern opposite to that shown for Chesapeake Bay, with yield-per-recruit curves increasing consistently with increases in t(c). Estimates of F-CUR for t(2) = 1 were consistently higher than F-0.1 as well as F-MAX, indicating that during the period 1979-81 Atlantic croaker were being growth-overfished in North Carolina. However, differences between Chesapeake Bay and North Carolina seem to reflect temporal rather than spatial differences in Atlantic croaker population dynamics, because data for North Carolina came from a period coinciding with the occurrence of unusually large Atlantic croaker along the east coast of the United States.
Population-Dynamics; Cynoscion-Nebulosus; Chesapeake Bay; Growth; Mortality; Waters; Age
Barbieri, Luiz R.; Chittenden, Mark E.; and Jones, Cynthia M., Yield-Per-Recruit Analysis And Management Strategies For Atlantic Croaker, Micropogonias Undulatus, In The Middle Atlantic Bight (1997). Fishery Bulletin, 95(4), 637-645.