Reproductive styles of shallow-water groupers (Pisces: Serranidae) in the eastern Gulf of Mexico and the consequences of fishing spawning aggregations

Abstract

Seasonal and spatial aspects of spawning for three commercially important grouper species in the northeastern Gulf of Mexico are detailed. These species — all of which are protogynous hermaphrodites - spawn in deep water (> 25 m for red grouper,> 40 m for gag and scamp), making it difficult to observe spawning behaviors without ROV or submersible support. They respond to intense fishing pressure in ways that are directly related to their respective reproductive styles. Species that aggregate appear to be more susceptible to such pressures than those that do not, as evidenced by marked skewing of sex ratios in favor of females. Gag, Mycteroperca microlepis, have suffered a drop in the proportion of males from 17% to 1% in the last 20 years; scamp, Mycteroperca phenax, have dropped from 36% to 18%; and red grouper, Epinephelus morio, which do not aggregate, have shown little change in the sex ratio over the past 25–30 years.