Metazoan endoparasites of King Mackerel as possible biological tags for stock differentiation

Objective The King Mackerel Scomberomorus cavalla is a coastal pelagic marine teleost found in tropical and subtropical waters in the western North Atlantic Ocean, including the Gulf of Mexico and Caribbean Sea. The species is important for commercial and recreational fisheries in the southeastern United States, with two populations currently recognized for management purposes (Atlantic and gulf). King Mackerel are also hosts for a diverse parasite assemblage. The goal of this study was to assess any differences between the parasite component communities of these two populations and assess the potential use of parasites as biological tags. Methods A total of 168 specimens were donated from nine fishing tournaments in Florida, Alabama, and South Carolina, spanning both the Atlantic and gulf to reflect the current fisheries management plan. The sampling area was divided into four regions, based on the geographic distance from the mixing zone. Mean abundance and prevalence were calculated for each of the parasite taxa recovered, as well as parasite species richness at both the infracommunity and component community levels. Results A total of 22 parasite taxa were identified, 7 of which had not been previously described from this host species. Compositional differences were observed in the parasite component communities of King Mackerel from the Atlantic and gulf populations, as well as differences in relative abundance of several parasite taxa. Each of the four regions in this study showed significant differences in parasite community structure with each of the others. The average dissimilarity between each of the different regions ranged from 57% to 60%, with four taxa (Hysterothylacium sp., Brachyphallus parvus, Prosorhynchoides scomberomorus, and an unidentified taxon within the order Tetraphyllidia) driving the dissimilarity. Conclusions We found significant differences between the endoparasite communities of King Mackerel in the Atlantic and gulf. Multiple parasite taxa found in the Atlantic were not found in the gulf, but even among parasites found in both regions, there were still significant differences between the parasite community composition of the regions. The observed differences suggest that parasite relative abundance and community composition might be useful biological tags in this management unit.