Juvenile red snapper density, diet, and growth among four nursery habitats in the northcentral Gulf of Mexico

The overfished status of Gulf of Mexico red snapper has been estimated to be primarily due to bycatch of juveniles in the shrimp trawl fishery, although fishing mortality rates in the directed commercial and recreational fisheries also are substantial. Bycatch reduction devices required in trawls since 1998 do not effectively reduce juvenile red snapper mortality. Therefore, identifying juvenile red snapper essential fish habitat may provide useful information to fishery managers considering shrimp trawl time/area closures. This study utilized side-scan sonar to map areas that historically supported high, median and low juvenile red snapper catches in the National Marine Fisheries Service's Fall Ground Fish Survey. Juvenile red snapper growth, density and diet then was estimated in summer and fall 2001 and 2002 within mud, sand, low shell rubble and high shell rubble habitats. Sand and low shell habitats produced highest growth and density, but mud habitats were more utilized by newly settled individuals. Diet shifted ontogenetically but no difference was detected among habitats. Overall, results suggest greater structural complexity is required as juveniles increase in size and age.