Assessing synergistic habitat changes and interspecific relationships of small pelagic fish in the northwest Pacific Ocean

Aim: Small pelagic species constitute a critical component of fishery resources in the northwest Pacific Ocean. Understanding the interactions among interspecific relationships, environmental niches, and resource abundance is essential for developing science-based fisheries management. This study aims to investigate the differential habitat responses of small pelagic species in the Northwest Pacific to environmental factors, specifically evaluating the ecological interpretation of interspecific relationships through joint species distribution modeling. Location: The northwest Pacific Ocean Taxon: Japanese sardine; Chub mackerel; neon flying squid Methods: This study examined three economically important small pelagic species from the northwest Pacific Ocean: Japanese sardine (Sardinops melanostictus), chub mackerel (Scomber japonicus), and neon flying squid (Ommastrephes bartramii). Using a joint species distribution model (JSDM) and ecological niche theory, we integrated multiple environmental variables to analyze interspecific associations and patterns of synchronous habitat variation among these species. Results: The JSDM accurately predicted suitable habitats for all three species, revealing spatial synchrony in habitat suitability. Notably, a positive interspecific (0.9) association is observed between S. melanostictus and S. japonicus, while both exhibit negative associations (−0.84 and −0.95) with O. bartramii. The breadth of suitable ecological niches for key environmental factors and their corresponding response curves offers ecological insights into these interspecific interactions, confirming the dynamic variations in suitable habitat ranges for these species. Main Conclusions: The interspecific relationships reflected similar species responses to environmental factors and highlighted their occupation of overlapping ecological niches. This consistency in environmental responses may drive synchronized habitat shifts, potentially affecting fluctuations in small pelagic fish abundance.