Changes in life history patterns of vermilion snapper and red porgy in the Gulf of Mexico

Peter B. Hood
Gulf of Mexico Fishery Management Council, 3018 US Hwy 301, Suite 1000, Tampa, FL 33619, (ph. 813-2282815, fax 813-225-7015, email peter.hood@gulfcouncil.org

Andrea Johnson
North Carolina State University, Department of Zoology, Box 7617, Raleigh, NC 27695-7617

Recent studies of reef fish populations have shown that life history traits such as growth and reproduction have changed over time. These changes (e.g. lower mean lengths at age, changes in sex ratio, and decreased lengths and ages at maturity) have been associated with increasing fishing pressure. Vermilion snapper and red porgy are important components to the Gulf of Mexico (GOM) reef fish fishery. Fishing pressure for both species has increased from the late 1970s, and a recent stock assessment of GOM vermilion snapper has indicated that this stock is currently overfished. From October 1995 to September 1996, we had the opportunity to sample both species from the hook-and-line GOM commercial and recreational fisheries for life history analyses. We used sectioned otoliths to age the fish and used histologically prepared gonads to assess reproductive state. We found that mean length at age and estimated length and age of maturity were lower than estimates from studies conducted in the GOM in the early 1980s. The magnitude of differences observed in the GOM was similar to those reported for these species in the South Atlantic over the same time period. While these changes in life history patterns of GOM stocks may be a response to increased fishing pressure, other factors such as the use of different aging structures and differences in sampling locality between GOM studies could also account for the observed changes. Because fishing gear and fishing depth were similar between studies, these factors were considered less likely to explain differences in length at age and length and age of maturity.