Geographical Distribution Variations of Humboldt Squid Habitat in the Eastern Pacific Ocean

Abstract

The Humboldt squid Dosidicus gigas is a pelagic cephalopod species extensively distributed in the Eastern Pacific Ocean. Geographically separated habitat patterns of D. gigas show large spatiotemporal variations due to the distinct different regional environmental conditions. This study explored geographical variation in seasonal habitat of D. gigas off Peru and the Eastern Pacific Equator using maximum entropy (Maxent) model, with fishing occurrence data and environmental variables including sea surface temperature (SST), sea surface salinity, net primary production (NPP), photosynthetically active radiation (PAR), chlorophyll a concentration, eddy kinetic energy, and sea level anomaly. Results indicated that all the environmental variables exhibited conspicuous seasonal and geographical differences off Peru and the Eastern Pacific Equator. On the basis of the percent contribution from the Maxent model, seasonal and spatial extents of habitat were largely explained by SST, NPP, PAR, and eddy kinetic energy in the Eastern Pacific Equator and SST, sea surface salinity, NPP, and PAR off Peru. Suitable ranges of each environmental variable differed between regions and were controlled by the seasonal variability. Furthermore, movement patterns of longitudinal and latitudinal gravity centers of fishing effort of D. gigas were consistent with spatial and temporal distribution of suitable habitats but showed dramatically geographical variations off Peru and the Eastern Pacific Equator. Our findings highlighted Maxent mode’s ability in exploring Humboldt squid habitat hotspots in the Eastern Pacific Ocean and suggested that constructing the habitat model for D. gigas should consider the geographical differences under environmental conditions.