Abstract:
Accurate identification of species is essential to understand their biology and management. Some species of fishes, such as amberjacks (genus Seriola) are difficult to identify in the field, including the four species that occur in the western North Atlantic: greater amberjack (Seriola dumerili (Risso, 1810)), lesser amberjack (Seriola fasciata (Bloch, 1793)), almaco jack (Seriola rivoliana Valenciennes, 1833), and banded rudderfish (Seriola zonata (Mitchill, 1815)). All four species are caught by standardized Spring and Fall bottom trawl surveys (BTS) from Cape Hatteras to the Gulf of Maine conducted by the National Oceanic and Atmospheric Administration's Northeast Fisheries Science Center; historical records of captures since 1963 are maintained in a database. At sea, captured fishes are assigned to taxa; specimens that are difficult to assign are retained for further study in the laboratory at Woods Hole, Massachusetts. In the laboratory, we identified 105 specimens of the four species of Seriola collected by the BTS from 2006-2019 using morphological characters and Cytochrome Oxidase subunit I genetic barcodes to understand rates of at-sea misassignments. We found that at-sea assignments were =91% correct for S. fasciata, S. rivoliana, and S. zonata, but only 24% correct for S. dumerili. We then applied our analysis of at-sea assignments to evaluate 1218 historical records of Seriola caught by the BTS from 1963–2006. We conclude that records in the database are likely valid for catches assigned at sea to S. fasciata, S. rivoliana, and S. zonata but not reliable for S. dumerili. To facilitate future at-sea assignments of the four species of Seriola, we summarize useful field characters and incorporate these into a new identification guide for banded juveniles and adult-coloration individuals. We also provide new data on diets, reproductive condition, spawning periods, sizes (including a new maximum size for S. fasciata), historical literature, and seasonal and geographic distributions for the four species of Seriola in the western North Atlantic.
