Age and growth analysis of spotted seatrout from Galveston Bay, Texas.

Abstract

Age and growth were estimated from sectioned otoliths for 426 spotted seatrout Cynoscion nebulosus collected from Galveston Bay, Texas, between October 1981 and September 1982. Marginal increment measurements showed that a single annulus formed on the otoliths during March and April. Annulus counts made by two independent readers agreed completely, suggesting that age interpretation from sectioned otoliths was precise. After age 1, back- calculated length-at-age estimates were much greater for females than males. Spotted seatrout from Galveston Bay generally grew faster than fish collected from other areas in the Gulf of Mexico. Gonadosomatic index values (gonad weight: body weight ratios) reflected a prolonged 6-month spawning period, which may have accounted for a four-fold difference in back-calculated lengths at age 1. The length advantage was gained by larger individuals at age 1 as they grew older.