COBIA (Rachycentron canadum)

ecommend that precautions be taken well before water temperatures reach 13 °C in a freezescenario.48. Meyer, G.H., & Franks, J.S. (1996). Food of cobia, Rachycentron canadum from the NorthcentralGulf of Mexico. Gulf Research Reports, 9(3), 161-167.The stomach contents of 403 cobia, Rachycentron canadum, caught in the Northcentral Gulf ofMexico recreational fishery from April through October of 1987-1990 were examined. Cobiaranged from 373-1,530 mm in fork length. Of the 403 stomachs, 287 (71.2%) contained at least oneidentifiable prey taxon. Crustaceans, consisting primarily of portunid crabs, were the predominantfood. Crustaceans occurred in 79.1% of the stomachs and comprised 77.6% of the total number ofidentifiable prey. The second most important prey category was fish, which was dominated byhardhead catfish, Arius felis, and eels. Fish occurred in 58.5% of the stomachs but only accountedfor 20.3% of the total number of prey. The importance of fish as prey increased with increasing size(length) of cobia, with the largest size class of cobia (1,150-1,530 mm FL) showing the highestpercent frequency occurrence of fish prey (84.4%). There were no significant differences betweenthe diets of male and female cobia. Species composition of the diet indicated that cobia examined inthis study were generalist carnivores in their feeding habits and fed primarily on benthic/epibenthiccrustaceans and fishes. However, the occurrence of pelagic prey provided evidence of diversity inthe foraging behavior of cobia. Feeding cobia indicated their dependence upon prey availabilityrather than upon a few specific food organisms.49. Phinchongsakuldit, J., Chaipakdee, P., Collins, J.F., Jaroensutasinee, M. & Brookfield, J.F.Y.(2013) Population genetics of cobia (Rachycentron canadum) in the Gulf of Thailand and AndamanSea: fisheries management implications. Aquaculture International, 21(1), 197-217.Population genetics has been recognized as a key component of policy development for fisheriesand conservation management and aquaculture development. This study aims to evaluate thegenetic diversity and population structure of native cobia (Rachycentron canadum) in the Gulf ofThailand and Andaman Sea, establishing the existing population distributions and contributinginformation to aid in the development of policy, prior to extensive aquaculture development.Microsatellite analysis of natural cobia populations in these two ocean basins shows similar levelsof gene diversity at 0.844 and 0.837, respectively. All populations and almost all microsatellite locistudied show significant heterozygote deficiency. Genetic differentiation between local populationsis low and mostly not significant (R ST = -0.0109 to 0.0066). The population shows no markedstructure over the long geographic barrier of the Thai-Malay peninsula, either when analyzed usingpairwise genetic differences or evaluated without predefined populations using STRUCTURE.Additionally, a Mantel test shows no evidence of isolation by distance between the populationsamples. The significant heterozygote deficiency at most of the loci studied could be explained bythe possibility of null alleles. Alternatively, given the behavior of forming small spawningaggregations, seasonal migration, and hitchhiking on large marine animals, the population geneticscould be complex. The population of cobia at each location in Thai waters may be inbred, as aresult of breeding between relatives, which would reduce heterozygosity relative to Hardy-Weinberg frequencies, while some of these populations could be making long distance migrationsfollowed by admixture between resident and transient groups. This migration would causepopulation homogeneity in allele frequencies on a larger geographic scale. The results suggest thatfisheries management for this species should be considered at both national and international levels,and until the possibility of local adaptation is fully investigated, policy development should applythe precautionary principle to ensure the preservation of genetic diversity and the sustainability oflocal and regional fisheries.50. Richards C.E. (1967). Age, growth and fecundity of the Cobia, Rachycentron canadum, fromChesapeake Bay and adjacent mid-Atlantic waters. Transactions of the American Fisheries Society,96(3), 343-350.Age, growth, fecundity and distribution of cobia, Rachycentron canadum, were studied. Data werecollected primarily from lower Chesapeake Bay and adjacent mid-Atlantic waters. Age analysis byscale methods, growth estimates by use of Bertalannfy's equation, and observations of juvenilecobia indicate rapid growth. Ten age groups were represented in scale collections from 284 fish,4.2–56.4 inches in fork length. Males and females can mature at two and three years, respectively.Growth equations are: males, L t = 49(1-e −0.21(t+0.67) ), W t = 59(1-e −0.13(t-0.62) ); females, L t = 59(1-e −0.20(t+0.65) ), W t = 120(1-e −0.10(t-0.80) ). Fecundity in hundreds of thousands of eggs was evaluated as afunction of body weight where fecundity was equal to 0.98 times the weight in pounds minus 6.39.14