Evidence for declining numbers of large Dolphinfish in the western North Atlantic

Objective Our objective was to use annual data on recreational fishing effort and the number of large Dolphinfish Coryphaena hippurus caught in North Carolina to determine if their abundance has changed over recent decades. Methods We gathered data on citation-sized Dolphinfish (≥15.9 kg) and Wahoo Acanthocybium solandri (≥18.1 kg) from the North Carolina Division of Marine Fisheries and fishing effort data from the National Marine Fisheries Services’s Marine Recreational Information Program. We generated species-specific annual values for trips per citation caught. Linear models were fit to these data by regressing them against year. Results An analysis of covariance model with a separate regression slope for each species provided the best fit to the data for trips per citation caught. Our data set from 2000 to 2023 revealed a meaningful and roughly fourfold increase in the effort required to catch a citation-sized Dolphinfish, while no trend was observed for Wahoo. Conclusions A substantial increase in effort required to catch a citation-sized Dolphinfish suggests that the abundance of large individuals of this species has declined. In the context of no such trend for Wahoo, possible confounding causes (e.g., changing social norms) are unlikely to explain our finding. Causes of the decline for Dolphinfish are likely related to increased exploitation of the stock.