Spatio-temporal variations in the potential habitat of a pelagic commercial squid

Abstract

An integrated habitat suitability index (HSI) model was developed for a pelagic commercial squid Ommastrephes bartramii in the Northwest Pacific Ocean based on three crucial environmental variables: sea surface temperature (SST), chlorophyll-a concentration (Chla) and sea surface height (SSH). The model was established by data from 2006 to 2014 and validated by data in 2015 on the basis of fishing effort and CPUE (catch-per-unit-effort). Results suggested that the HSI model had good capacity to predict habitat suitability for O. bartramii . Squid habitat quality showed significant monthly variation, the ranges of suitable habitats in July and August were much larger than those in September. Besides, the latitudinal location of suitable habitats gradually moved northward from July to September. Further, the spatial extents of potential habitat of O. bartramii across months were strongly regulated by favorable environmental conditions. The variability trends of monthly CPUE and LATG (latitudinal distribution of fishing efforts) were closely associated and consistent with spatio-temporal habitat variations during 2006–2015. Moreover, climate variability strongly affected habitat variations and squid stocks. Relative to the El Niño event in 2015, the La Niña event in 2007 yielded expanded suitable habitat from July to September, consequently, the CPUE was much higher. And the potential high-quality habitats in 2007 mainly located in northern regions except July comparing to 2015, leading to the higher latitudinal distribution of LATG in August and September 2007. Our findings indicated that O. bartramii habitats obviously varied from month to month and were largely affected by environmental changes. • Habitat patterns of Ommastrephes bartramii was examined by habitat modeling approach. • Spatio-temporal variations of O. bartramii habitats showed monthly patterns. • Climatic and environmental variability strongly affected O. bartramii habitats.