Evidence for distinct stocks of king mackerel, Scomberomorus cavalla, in the Gulf of Mexico

Evidence supporting a two stock hypothesis for king mackerel, Scomberomorus cavalla, in the Gulf of Mexico was developed principally from the results of electrophoretic patterns of one polymorphic dipeptidase locus and supporting evidence from mark-recapture, charterboat catch, and spawning studies. There are two identifiable stocks of king mackerel in the Gulf of Mexico: a western stock and an eastern stock. The western stock migrates northward along the Mexico-Texas coast during the spring and early summer from its winter grounds in Mexico (Yucatan Peninsula). This stock has a high frequency of the dipeptidase PEPA-2*a allele. The eastern stock migrates at the same time northward along the eastern coast of the Gulf of Mexico from its winter grounds in south Florida (Gulf of Mexico and Atlantic coast). This stock has a high frequency of the dipeptidase PEPA-2*b allele. Both stocks migrate simultaneously into the northern Gulf of Mexico and mix at varying degrees in the northern summering grounds (Texas to northwest Florida).