By Colin Shea, Tiffanie Cross, and Bev Sauls
Florida’s recreational fishery in the Gulf of Mexico is characterized by over one million participants dispersed over a broad geographic area. For a recreational fishery of this size, the most feasible method for monitoring effort (number of angler trips) and catch (landings in pounds) is through off-site sampling. Florida’s Gulf Reef Fish Survey (GRFS) employs an off-site mail survey of registered anglers, in addition to dockside intercept surveys conducted in the field, to estimate annual recreational fishing effort and catch for several reef fish species, including red snapper. Although off-site sampling methods such as the GRFS mail survey enable monitoring of large-scale fisheries at a reasonable cost, estimates derived from these methods are typically not available until after the recreational fishing season has ended. This delay presents a challenge, as management of recreational fisheries under annual catch limits (ACLs) requires the ability to accurately predict when an ACL will be reached. Managers of recreational fisheries would therefore benefit from the availability of in-season estimates of effort and catch.
Using the 2019 Gulf of Mexico recreational red snapper fishery in Florida as a case study, Fisheries Dependent Monitoring collaborated with the Center for Biostatistics and Modeling to explore the utility of a model-based approach to estimating in-season effort and catch. This approach used an in-season index of fishing effort, derived from interviews conducted at fish landing sites throughout the region, to estimate recreational fishing effort prior to the availability of GRFS mail survey estimates. We then derived mean catch rates (pounds harvested per trip) to estimate total catch (landings in pounds) for the 2019 red snapper recreational fishing season. Ultimately, our goal was to compare the model-based estimates of effort and catch to those derived from the GRFS after the close of the 2019 season. Our case study indicated that a model-based approach provided in-season estimates of effort and catch that were comparable to those derived from the GRFS. The model-based prediction of total red snapper catch in June and July 2019 averaged 1,141,127 pounds, or 67% of the ACL, whereas the GRFS estimate for the same time period was 1,175,920 pounds, or 69% of the ACL.
Reliable in-season estimates of effort and catch are useful to managers because they can help to inform decisions about extending or shortening the recreational fishing season. Indeed, our efforts contributed, in part, to the decision to extend the 2019 red snapper season by six days in October and November. Importantly, the Gulf Reef Fish Survey was credited by officials for contributing to the effective management of Florida’s recreational red snapper fishery in the Gulf of Mexico. As a group, the Center for Biostatistics and Modeling is excited to continue our collaborative effort with Fisheries Dependent Monitoring, and we hope to refine our approach and explore new avenues as we move into the 2020 recreational fishing season and beyond.