Understanding sex change in exploited fish populations: a review of East Coast fish stocks and assessment of selectivity and sex change in black sea bass (Centropristis striata) in New Jersey

Abstract

Fishing operations are often biased toward certain individuals in the population, resulting in fishing mortality that varies by size and age. In protogynous hermaphrodite species (female to male sex change), the sex ratio varies with size and, consequently, indirectly causes fishing gear to be sex selective. Protogyny is also associated with complex social structures and patterns of sex-specific behavior that may directly result in sex selectivity. A tagging experiment was carried out in 2011 and 2012 in south central New Jersey on black sea bass (Centroprisitis striata), an economically important protogynous hermaphrodite. Tagging data were used to measure sex selectivity curves for commercial and recreational fishing gears, and to measure sex change as a function of size, age, and season to further understand black sea bass life history. Sex selectivity curves varied by sex and gear. Male black sea bass experienced increasing selectivity with greater body size, producing an asymptotic selectivity curve. Alternatively, males experienced dome-shaped selectivity by commercial traps, indicating traps were biased toward intermediate size males. Male black sea bass also experienced greater selectivity over a wider range of body sizes compared to female selectivity for both fishing gears. Commercial traps captured a higher proportion of males at length compared to hook-and-line fishing gear, especially at small to intermediate body sizes. Sex change was found in eight females, size at sex change was 365 mm and all sex changing females were 3-4 years old. In 2011 15 females were tagged and recaptured in 2012 to verify sex change, seven of these changed sex, giving an