Examining depredation of reef fish on descender devices across the Gulf of Mexico

Abstract

Abstract Objective We partnered with the charter-for-hire fishing fleet to document depredation rates of fish on ­descender devices across the U.S. Gulf of Mexico and identify the species responsible for depredation. Methods Two types of data were collected: (1) underwater video footage of fish descents on fish descender devices called SeaQualizers and (2) information about fishing sites and fish that were descended. All resulting video footage was then analyzed. Each recorded fish descent was assigned water clarity and vision field scores. The presence and, if applicable, the identity of the predators were logged. The fate of each descended fish was assigned. Results From March 2022 to March 2024, 987 fish descents were successfully recorded off Texas, Louisiana, Alabama, and Florida. Most of the descended fish—representing 20 species in total—were Red Snapper Lutjanus campechanus or Red Grouper Epinephelus morio. Based on all video footage recorded during the study, only three fish on descender devices were depredated, and all three were Red Snapper. Conclusions Our study suggests that depredation, though a significant occurrence among ascending fish (i.e., fish being caught), does not frequently impact reef fish on descender devices. The video footage indicated that depredation of fish returning to depth on descender devices is exceedingly rare. The overall depredation rate of fish on descender devices was 0.3%, and the depredation rate of fish on descender devices at sites where fish were depredated on ascent was 1.3%.