Moving the region boundary from 58 to 58.5 degrees N raised mean fish catch correlation for six taxa at 113 Bering Sea stations, 1982–2025

We tested whether annual fish catch changes north and south of 58 degrees N agreed more for the same taxon than for different taxa. We used open NOAA data, 113 fixed eastern Bering Sea stations, six fish taxa selected by early biomass, and 41 annual changes in 1982–2025. At 58 degrees N, mean same-taxon correlation was 0.038 and mean different-taxon correlation was 0.063. Their difference was -0.025, with a nominal 95% common-year block interval of -0.139 to +0.110. A planned check at 58.5 degrees N gave mean same-taxon correlation of 0.174 and extra correlation of 0.126. Moving 19 stations between groups raised extra correlation by 0.151. A paired block interval was 0.065 to 0.230. A check over all three pairs of three planned boundaries gave an approximate family interval of 0.041 to 0.246 for this change. Count data and broader panels gave increases in the same direction. The emphasis on boundary dependence followed the initial null result. The evidence shows that regional grouping changed this catch index. It does not identify fish movement, true stock synchrony or a climate cause. The package has unchanged source data, provenance, code, all results, figures and independent checks.

Bering Sea · fish · spatial synchrony · bottom trawl · regional aggregation · reproducible research