Apparent habitat extensions of dolphinfish (Coryphaena hippurus) in response to climate transients in the California Current

Abstract

Dolphinfish, Coryphaena hippurus, a globally distributed, fast growing, predatory species has extended its habitat poleward off the west coast of North America in response to atmosphere-ocean climate transients that can be measured throughout the Pacific Ocean basin. Poleward habitat extension is measured by the availability of dolphinfish to southern California Commercial Passenger Fishing Vessel (CPFV) anglers. Before 1972 the annual CPFV dolphinfish catch during the July-October fishing season seldom exceeded a few hundred fish. Thereafter, more than 103 dolphinfish were taken in 23 of the next 25 seasons. The next shift was in 1990 when catch exceeded 3.0 x 104 fish. More than 2.0 x 104 fish were reported in three of the next seven seasons. The apparent habitat extension coincides with increased ocean temperatures, forced by increases in North Pacific cyclogenesis and increases in downwelling coastal-trapped long wave transmission from the equatorial ocean. Interannual analysis shows that habitat expansion is associated with a decrease in upwelling off northern Mexico, which may be locally or remotely forced. Dolphinfish habitat shifts poleward in response to Pacific climate transients, reflecting global environmental trends. If subtropical ocean surface layers continue to warm throughout the world, as observed off southern California and northern Mexico, a global increase in the dolphinfish habitat is expected.