POPULATION CHARACTERISTICS OF THE BLACK SEA BASS CENTROPRISTIS STRIATA FROM THE SOUTHEASTERN U.S.

摘要

We examined the age structure and status of the southeastern U.S. stock of black sea bass, using recorded and estimated landings and size frequencies of fish from commercial, recreational, and headboat fisheries from 1979—1990. Annual landings in numbers at age were estimated by application of separable virtual population analysis (VPA), which was used to estimate annual, age-specific fishing mortality for different levels of natural mortality (M = 0.2, 0.3, 0.4 and 0.5 yr~(-1)). Mortality levels (F) ranged from 0.54 to 1.59 between 1979 and 1990 for fully recruited ages (4—7) (M = 0.3). Maximum spawning potential ranged from 42% to 50% based on mature female biomass, from 49% to 56% based on egg production, and from 22% to 30% based on total mature (male and female) biomass. Because black sea bass are protogynous hermaphrodites (transforming from females to males) and the effect of changes in population abundance on sex transformations is unknown, the percent reduction in males to females was estimated solely on increased mortality by fishing (ranging from 50% to 60% of the unfished proportion). Thus, the use of maximum spawning potential based on total mature biomass should also be considered for comparison to a biological reference point used in defining overfishing.