Trans-Pacific multidecadal changes of habitat patterns of two squid species

Abstract

Trans-Pacific changes in the habitat patterns of neon flying squid (Ommastrephes bartramii) in the Northwest Pacific Ocean and jumbo flying squid (Dosidicus gigas) in the Southeast Pacific Ocean during 1950–2015 were examined on a decadal scale using a habitat suitability index (HSI) model. The HSI model involved two environmental drivers for the occurrence of O. bartramii and D. gigas: sea surface temperature (SST) and sea surface height anomaly (SSHA). Significant seesaw-like patterns of environmental variability and habitat changes, consistent with the regime shift of positive and negative Pacific Decadal Oscillation (PDO), were observed for the two squid species. In a negative PDO phase, SST anomaly and SSHA increased on the fishing grounds of O. bartramii. The areas of suitable habitat of O. bartramii contracted markedly due to the decrease in suitable SST and SSHA. In contrast, cooling SST and decreasing SSHA on the fishing grounds of D. gigas during a negative PDO phase led to the formation of more suitable SST and SSHA, yielding expansive suitable habitats for D. gigas. Moreover, the most favorable SST for O. bartramii and D. gigas moved northward in the negative PDO regime, and the suitable habitat for both squids shifted into the northern regions as well. When the climate regime shifted into a positive PDO phase, the responses of the two squids were opposite to those in the negative PDO phase. Our findings indicate that interannual-to-decadal variability in habitat patterns of O. bartramii and D. gigas can be detected from climate regime shifts in the Pacific Ocean.