Age, growth, and reproduction of the littlehead porgy, <I>Calamus proridens,</I> from the eastern Gulf of Mexico

Abstract

The present study is the first comprehensive examination of the life-history of Calamus proridens Jordan and Gilbert, 1884, the littlehead porgy, in the eastern Gulf of Mexico. In total, 1814 C. proridens, ranging in fork length from 76 to 361 mm, were collected along the gulf coast of Florida from 2000 through 2007. Length, sex, age, and reproductive state were determined. Length classes included the range of ontogenetic development for both sexes and transitional individuals. Overall sex ratios and sex ratios grouped by length class and age were significantly different from the 1:1 ratio characteristic of gonochoristic species. Females ranged in age from 0 to 6 yrs, while males ranged from 1 to 10 yrs. The von Bertalanffy growth model fitted to all observed data was L(t) = 306 × (1 - e -0.254 (t + 1.69)). Spatially explicit von Bertalanffy growth models (from trawl data only) indicated that fish captured in the central region grew larger than those in the southern region. Calamus proridens mature at a young age; 50% of the females collected during the spawning season were mature within their first year (132 mm FL). Histological analysis revealed that C. proridens are protogynous hermaphrodites with delimited gonads. Estimates indicated that at age 4 (231 mm FL), approximately 50% of females in the population had transitioned into males. The present study has utility for improving the accuracy of stock assessments of C. proridens in the Gulf of Mexico and also has relevance in ecosystem modeling.