Who stays, who leaves? Recreational fishing responses to harmful algal blooms in Lake Erie

Harmful algal blooms dominated by cyanobacteria (HABs) have been increasing in extent and intensity in aquatic ecosystems worldwide. As they degrade water quality, threaten human health, and alter ecosystem services, behavioral responses by people who recreate in affected waterways remain incompletely understood. This study uses directly observed fishing counts and causal identification to examine behavioral and temporal heterogeneity in recreational fishing responses to HABs, addressing the questions of who avoids blooms, when, and what the potential benefits of HAB mitigation might be. We combine spatiotemporally varying measures of cyanobacteria intensity with on-site counts of three distinct recreation types—private boats, charter boats, and shore anglers—across 36 Ohio Lake Erie harbors during 2011–2018. Using Poisson pseudo-maximum likelihood with a Control Function approach, we identify pronounced heterogeneity across multiple dimensions. Behaviorally, charter boats demonstrate the strongest response magnitude, followed by shore anglers and private boats. Temporally, shore anglers and private boats show stronger HAB avoidance on weekdays than weekends, while charter boats respond consistently across day types. We further simulate potential impacts under HAB reduction and increase scenarios ranging from 10% to 50%, finding that reductions could increase fishing trips by 2% to 27% and increases could reduce them by 2% to 16%, depending on recreation type and scenario. Collectively, our findings provide new empirical evidence of heterogeneity in angler responses to HABs based on observed behavior and causal estimation, offering critical insights for fisheries managers seeking to protect Lake Erie's multibillion-dollar recreational fishing economy.