Environmental Relationships And Predator-Prey Interactions Within The Snapper-Grouper Complex In The Southeastern U.S. Atlantic – Implications For Fisheries Management

Stock assessments indicate many valuable fish species are declining, or are considered overfished and/or are undergoing overfishing. Fisheries scientists and managers in the southeastern U.S. typically have utilized a single-species approach, and relied on catch per unit effort data derived from fishery-independent surveys to determine indices of abundance for economically important reef fish. However, catchability for these surveys vary for many reasons including environmental and predator-prey relationships. This research was developed to elucidate environmental influences on reef fish assemblages and distribution of reef-associated marine predators, and examine predator-prey dynamics that may influence relative abundance of large predators based on chevron traps and video data from the southeastern U.S. Atlantic. The first part of this study focused on fish assemblage structure association with different environmental gradients such as distance to shelf edge, depth, substrate vertical relief, substrate size, biotic class and % biotic cover. The second part of the study further detailed the association of Scamp, Gag, Yellowmouth Grouper, Red Grouper, Snowy Grouper and Red Snapper with month, latitude, depth, temperature, surface geologic class, biotic class, and percent biotic cover and revealed Red Snapper had a wider niche breadth than the groupers, while alternatively, groupers exhibited greater habitat specificity. The final part of the study determined Gag, Red Grouper and Red Snapper showed a preference toward Tomtate and small Black Sea Bass when predation occurred within traps. However, statistical analyses determined selected prey species were not important drivers in the presence of the focal predator species within the traps or video observations. Based on observations during this study, predator-prey interactions may have more implications for indices based on video outside the traps for these focal predator species. Given environmental relationships and species interactions have implications for fisheries management, this study provides details that describe assemblage patterns across environmental gradients, determines habitat associations for economically and environmentally important groupers and Red Snapper, and determines the importance of predation regarding chevron traps. This information will be used to inform stock assessments and conservation management decisions to enhance fisheries sustainability