"They Caught Our Billfish": Implications of shared resources between artisanal and recreational billfish fisheries in the Western Indian Ocean

Several user groups catch billfish; they are caught as bycatch in tuna longline and purse seine fishing fleets, and as a target species in recreational and artisanal fishing sectors. Despite their importance, most fisheries... [ view full abstract ]

Several user groups catch billfish; they are caught as bycatch in tuna longline and purse seine fishing fleets, and as a target species in recreational and artisanal fishing sectors. Despite their importance, most fisheries management actions for billfish are usually dependent on factors such as time series catch rates, fishing intensity, and spatial and temporal dynamics associated with large industrial fishing operation, but little consideration for artisanal and recreational fisheries. Differences in the mean weight of billfish caught could be caused by factors such as seasonality, type of fishery or fishing techniques, and distance travelled for fishing. Here, we examined the relationship between the mean weight of billfish and several predictor variables (seasonality, distanced fished, boat size and the type of fishery).

We used Generalized Linear Models fitted to aggregate average weight data from artisanal and recreational fisheries. The model that combined seasonality and fishery type best explained the observations. The mean weight of billfish in artisanal fisheries increased during periods of low fishing activity. The interaction between fisheries and season particularly for recreational fisheries had the strongest effect. Other factors such as boat size and distanced fished were not significant which indicated an overlap and interaction between these fisheries. This study demonstrates the need to evaluate competing interests and the perception that a species belongs to one group: “They Caught Our Billfish” particularly in a shared fishery resource. This is also critical for local and regional management of billfish, given their highly migratory nature.