Comparison of fisheries yield and oceanographic features at the southern boundaries of the western and eastern Subarctic Pacific Ocean

The ecological characteristics of fish communities were compared at the southern boundaries of the eastern and western Subarctic Pacific, based on oceanography, fishery information, and ecological features. Sea surface temperature (SST) was higher in the western North Pacific (NP) than in the eastern NP, and changes in SST showed regional and temporal alternating patterns. Cool and warm SST regimes were observed in the western NP during the early 1980s and the early 2000s, respectively, compared with warm and cool regimes in the eastern NP. Increasing SSTs were more conspicuous in the western than in the eastern NP. Catches from commercial fisheries were higher in the western NP than in the eastern NP. Small pelagic fish were dominant in the western NP, whereas demersal behaviour was common for fish populations in the eastern NP. Changes in species composition also showed contrasting characteristics between the two regions. In the western NP during the early 1980s, landings were dominated (35.8%) by sardine. After two decades, however, landings consisted of a more diverse species group. In the eastern NP, five species appeared in similar percentages (similar to 10% each) during the early 1980s, but hake alone made up 36.3% of the landings in the early 2000s.