Abstract

A review of available scientific information on the age, growth, and reproduction of cobia, Rachycentron canadum, from United States waters of the Gulf of Mexico and Atlantic Ocean is provided. Periodicity of annulus formation on sectioned sagittae has been partially validated by marginal-increment analysis, and age in years is estimated as the number of observed opaque bands. Growth in length for both sexes is rapid through age 2. Females grow faster and live longer than males and dominate all age groups. Gulf males reached age 9 and 1,390 mm FL; females reached age 11 and 1,651 mm FL. Atlantic males reached age 14 and 1,360 mm FL; females reached age 13 and 1,420 mm FL. Estimates of the von Bertalanffy growth parameters (L8, K, and to) within studies showed significant differences in L8 and K for the sexes, whereas estimates for to were not always significantly different. Ages 2 - 5 dominated the age structure of Gulf and Atlantic samples. Cobia were fully recruited to the northeastern Gulf recreational fishery at age 4, and the instantaneous rate of total mortality (Z) estimated for fully recruited cobia ages 4 - 8 was 0.75. Cobia have an extended spawning season throughout their range in United States waters, averaging five months (mid-April-August) in the Atlantic Ocean and six months (April-September) in the Gulf of Mexico. Some Gulf females appear to cease spawning by july. Female cobia can obtain sexual maturity as small as 700 mm FL. Histological analysis shows cobia are a multiple spawning species; females are estimated to spawn once every five days throughout most of the U.S. region. Batch fecundity increases significantly with FL and ovary-free body weight (OFBW); mean relative batch fecundity is 53.1 ± 9.4 eggs/g OFBW. While the testis of males contain sperm year-round, spermatogenesis only takes place from February - August, and spermatogonial proliferation is observed during nonspawning months

PDF Preview