Distribution, Maturity, Age and Growth of Gray Snapper (Lutjanus griseus) in the Northwestern Gulf of Mexico

Abstract

Recent population expansion of Gray Snapper, Lutjanus griseus, in the northern Gulf of Mexico is driving increasing catch in the recreational fishery in Texas. We assessed long—term trends in distribution and abundance of Gray Snapper in Texas using fishery—dependent and fishery—independent data collected by the Texas Parks and Wildlife Department in the years 1980 — 2019. Boosted regression trees (BRT) were used to evaluate factors (water quality, season, depth, bay and inlet distance) driving Gray Snapper presence in fishery—independent samples of juveniles (seines) and subadults (gill nets) found in estuaries. Estuarine Gray Snapper were subsequently sampled from gill nets, and otolith age and gonad development were evaluated microscopically to assess patterns of age, growth, and maturity. Increasing Gray Snapper abundance in Texas was coupled with expansion of the population age structure in comparisons before and after 1993. Gray Snapper juveniles and subadults encountered in Texas estuaries are generally associated with lower bays and offshore passes, and are more common in the late summer/early fall. Comparison of size (total length in mm) of recreational catch inshore versus offshore suggests that mature adults recruit to offshore habitats around 409 mm TL, or around 3 years old, which is approximately coincident with the onset of sexual maturity. Increasing abundance coupled with an expanding age structure of Gray Snapper in Texas have co—occurred with increasing winter temperatures over time. Population expansion could be facilitated by management measures that improve overwinter survival of juveniles and subadults in estuaries prior to offshore recruitment.