Multi-decadal decline in reef fish abundance and species richness in the southeast USA assessed by standardized trap catches

Abstract

Reef fish species naturally fluctuate in abundance over various temporal and spatial scales, but recent broad-scale declines in abundance have been observed worldwide and attributed to various anthropogenic influences. We used 25 years of fishery-independent trap data (N = 11,237 trap hauls) to examine the spatial and temporal variability in temperate reef fish abundance along the southeast coast of the USA, a relatively understudied region with many economically important reef fish species. Overall, 441,298 individuals from 118 species were caught in the trap survey. Number of species and total number of individuals caught in the trap survey declined over the 25 years, but when separated, nontargeted fish species declined more than fishery-targeted species. For instance, traps caught a median of 18 nontargeted individuals and a median of 2–3 nontargeted reef fish species in the early 1990s, but by the 2010s, traps caught a median of fewer than three nontargeted individuals and a median of one nontarget species. Using generalized additive models, we found that the catch of fishery-targeted and nontargeted species was positively related to bottom water temperature, while depth influenced nontargeted and fishery-targeted species in opposite ways. The substantial and consistent decline in nontargeted fish species suggests that more research and management attention should be given to these often ignored species. These results suggest that the temperate reef fish community in the southeast USA is influenced by more than just fishing, perhaps including invasive species (e.g., lionfish Pterois volitans), decadal-scale environmental variability, or climate change.