Feeding Ecology of Juvenile Goliath Grouper (Epinephelus itajara) in Southwest Florida Using Fecal Metabarcoding

The Atlantic goliath grouper (Epinephelus itajara) experienced a severe population decline in the latter half of the 20th century, leading to a U.S. harvest moratorium in 1990. Despite uncertainty surrounding the recovery of the species, some fishers claim that goliath grouper are negatively impacting commercial and recreational fisheries, with many advocating for the reopening of the fishery. To assess these claims, this study used environmental DNA (eDNA) metabarcoding to investigate the feeding ecology of juvenile goliath grouper in southwest Florida. Fecal samples from 31 juvenile goliath grouper were sequenced, identifying 18 prey taxa across three classes, eight orders, and 15 families. Notably, three prey taxa are considered commercially valuable—Atlantic blue crab (Callinectes sapidus), southern pink shrimp (Farfantepenaeus notialis), and Florida stone crab (Menippe mercenaria)—with the Florida stone crab being the most frequently consumed (detected in 12 of 31 samples; 38.7%). Additionally, the sandy sea cucumber (Holothuria inornata), a previously unreported prey item, was detected in three samples (9.7%). These findings show that fecal metabarcoding can be an effective alternative to traditional methods and highlight the need for further research on the potential impacts of goliath grouper on the West Florida stone crab fishery.