Environmental Niche Models: Distribution and Seasonal Movements of the Ocean Sunfishes

The ocean sunfishes (family Molidae) have often been described as rare, inactive drifters. However, recent studies have revealed many high density aggregations in coastal seas, with potential interchange through long-distance migrations. Anecdotally, the Molidae are believed to have a pan-global distribution within temperate and tropical latitudes, although limited sightings records and inherent difficulties in species identification have led to an incomplete picture of their range and seasonal movements. There is a pressing need to address this gap in our knowledge as current fishing pressures (both targeted and bycatch) remove 100,000’s of sunfishes each year, leading the IUCN to evaluate the four species as “vulnerable” or “data deficient” globally.

Here we present a primary range map of the family Molidae which suggests that ocean sunfishes are not randomly distributed, but significantly clustered globally. We used Random Forest species distribution models to assess the annual movement of sunfishes, which suggests that the total suitable area available changes in size and shifts latitudinally with the seasons. It is hoped that such efforts will identify areas with high seasonal pulses of sunfish, which can inform fisheries management to minimise accidental bycatch.