Tuna and billfish larval distributions in a warming ocean

Abstract

Tuna and billfish are charismatic pelagic fishes attracting considerable scientific attention due to their ecophysiological and socioeconomic importance. However, the knowledge of their basin-wide spawning and larval habitats, especially in a warming ocean, is limited. This knowledge gap undermines effective fishery management by introducing recruitment uncertainty, which makes population dynamics unpredictable. We fill the gap with a parsimonious geostatistical species-distribution model trained on the largest available dataset on tuna and billfish larvae in the Pacific Ocean. The model reveals (i) the basin-wide seasonal larval distributions over the reference period 1960-85, (ii) the expected impact of ongoing ocean warming on these distributions, and (iii) the biogeochemical factors, such as pH, phosphate concentration, and sea-surface height, that shape the larval habitat. Our findings make a quantum leap in understanding the ecophysiology of tuna and billfish, providing valuable information for future conservation efforts.