Red Snapper: Ecology and Fisheries in the U.S. Gulf of Mexico

Abstract

<em>Abstract.</em>—Red snapper <em>Lutjanus campechanus </em>larval occurrence and abundance during Southeast Area Monitoring and Assessment Program (SEAMAP) Summer Shrimp/Bottomfish (1982–2003) and Fall Plankton (1986–2003) surveys were examined to identify the time series of ichthyoplankton data that might best reflect trends in the red snapper spawning population in the U.S. Gulf of Mexico (GOM). Since bongo nets were more effective than neuston nets at capturing red snapper larvae only catches from bongo nets were used to estimate annual occurrence and abundance, i.e. the SEAMAP larval red snapper index. The summer survey was conducted during the peak of red snapper spawning in June and July, but limited and inconsistent coverage during this survey did not permit development of a reliable Gulfwide (U.S. continental shelf) index of larval abundance. In contrast, the fall survey conducted near the end of the spawning season in September yielded a 16 year time series over which to examine trends in red snapper abundance throughout the GOM. Although occurrence and abundance of red snapper larvae were lower during September than in June and July, estimates from both summer and fall surveys showed the same inter-annual patterns and were highly correlated. Larvae were eight times more abundant and occurred in five times as many samples in the western than in the eastern GOM. Separate standardized indices of relative abundance were generated for the western and eastern GOM. The standardization procedure accounted for the effects of year, time of day, depth and subregion in the western GOM, but only for subregion in the eastern GOM. Larval indices of red snapper abundance suggest an increased spawning stock in both the western and eastern GOM after 1995.