Red snapper demographic structure in the northern Gulf of Mexico based on spatial patterns in growth rates and morphometrics

Fishery Bulletin, Oct, 2004 by Andrew J. Fischer, M. Scott Baker, Jr., Charles A. Wilson

Demographic variation in growth rates may indicate the existence of separate management units of red snapper in the GOM. Our data indicate that the red snapper inhabiting the waters off Texas are reaching smaller maximum sizes at a faster rate, but are consistently smaller (TW) at age than those collected from Louisiana and Alabama waters.

Whether these differences are environmentally induced or result from genetic divergence remains to be determined. The more productive, nutrient-rich waters of the Mississippi River and north-central GOM off Louisiana and Alabama may be more conducive to faster growth than the less fertile waters off Texas. Fishing pressure and its effects on population size may also be leading to the observed differences in growth rates. Fishery-dependent landing data and disproportionate discard-to-landing ratios in Texas waters loosely support the concept that fewer red snapper are available for harvest in the southwest GOM. Regardless of the cause, the existence of demonstrable demographic differences argues for the delineation of multiple red snapper management units in the GOM.