Evaluating the effectiveness of management regulations under uncertainty in a recreational Spot Prawn fishery

Different regulations are best applied depending on what uncertainties are prominent in a fisheries management area. Input regulations (e.g., limits on fishing effort) will favor areas with predictable fishing effort, whereas output regulations (e.g., limits on what can be harvested) will favor areas with low and predictable release mortality. Spot prawn (Pandalus platyceros) is a significant species for both commercial and recreational fisheries in coastal British Columbia. However, while commercial fisheries have clear management rules for season length and harvest large amounts of spot prawn, the recreational fisheries are managed using a combination of input management regulations (open unless abundance is perceived below a threshold) and output regulations like bag limits and size limits. Additionally, there are some aspects of fisheries that are completely uncertain, like release mortality and recreational fisher effort redistribution (how flexible fishers are regarding when they go fishing). Recreational fisheries also must balance the conservation of the spot prawn population against fisher access and satisfaction; finding this balance adds complexity and nuance to management decisions. To address this issue, I use a stage structured population model for spot prawn to evaluate different combinations of management regulations for the recreational fishery under different assumptions of release mortality and effort redistribution. Each distinct combination is evaluated using two fishery objectives, an ecological health indicator (overfishing probability index) to indicate ecological health, and a fisher satisfaction indicator (number of days open). Results show that although management combinations do not significantly impact risk within an area, the management areas themselves have different sources of inherent risk. Due to these differences in risk between areas, the commercial and recreational fisheries may not be able to coexist as they are, with over half of the assessed study areas suggesting a closure for the recreational fishery. Additionally, results show that reducing uncertainty about release mortality and fisher effort redistribution have no significant value for managers. Results also show that if release mortality is low, output controls may be effective for these same areas, suggesting value in further investigating the release mortality for spot prawns. Carefully understanding the tradeoffs among regulation options and context improves management outcomes in recreational fisheries.