Modeling the oceanic habitats of pelagic fish using recreational fisheries data

Defining the oceanic habitats of migratory marine species is important for both single species and ecosystem-based fisheries management, particularly when the distribution of these habitats vary temporally. We developed species distribution models that describe the oceanic habitats of two pelagic fish (dolphinfish, Coryphaena hippurus and yellowtail kingfish, Seriola lalandi), using 19 years of presence-only data from a recreational angler-based catch-and-release fishing program. A Poisson point process model within a generalised additive modelling (GAMM) framework was used to determine the species distributions off the east coast of Australia as a function of several oceanographic covariates. This modelling framework uses presence-only data to determine the intensity of fish (fish km^-2), rather than a probability of fish presence. Sea surface temperature, sea level anomaly, sea surface temperature frontal index, and eddy kinetic energy were significant environmental predictors for both dolphinfish and kingfish distributions. Models for both species indicate greater fish intensity off the east Australian coast during summer and autumn in response to the regional oceanography, namely shelf incursions by the East Australian Current. This study provides a framework for using presence-only recreational fisheries data to create species distribution models that can contribute to future dynamic spatial management of pelagic fisheries. Using this model framework, we have also created a seasonal forecast of dolphinfish habitats that predict the distribution of fish abundance along the east coast of Australia. Such forecasts allow ocean user groups and management to adapt to spatial and temporal variability in fish distributions. The application of such fish forecasts to the recreational sector will be discussed.