Nursery habitats, growth rates, and seasonality of age-0 red snapper, Lutjanus campechanus, in the northeast Gulf of Mexico

We sampled inner shelf habitat in the northeast Gulf of Mexico, for age-0 r ed snapper, Lutjanus campechanus, to estimate growth rates and seasonality, as well as to identify nursery habitats. We collected 7507 age-0 red snapp er in 1994 and 1995, from 536 10-min trawl tows. Red snapper first settled to benthic habitat in June after reaching 17.4 mm standard length (age=26 d ). In both years, catch per unit of effort (CPUE=number/10-min tow) peaked July through September, then declined in the fall as fish were leaving the habitat before winter. Most fish (80-81%) were caught at one location, 13 k m south of Mobile Bay, Alabama. At this location in 1995, the August CPUE+/ -SE (712+/-243) far exceeded all previous estimates. Based on otolith micro increments, hatching-date frequencies showed distinct cohorts in June and J uly 1994 and May and June 1995. Growth rates for the June (0.77 mm/d) and J uly (0.71 mm/d) cohorts in 1994 were significantly faster compared with gro wth rates for May (0.51 mm/d) and June (0.67 mm/d) cohorts in 1995. Density -dependent mechanisms may be operating with faster growth rates and lower C PUEs in 1994, compared with slower growth rates and higher CPUEs in 1995. H owever, environmental constraints may also be operating, as indicated by th e slow growth rate of the May 1995 cohort that probably resulted from colde r temperatures. Newly settled red snapper were aggregated on the inner shel f, at a particular location and time period. These concentrations indicated an important nursery habitat just south of Mobile Bay,Alabama, From July t hrough September.