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q-bio.PE · Populations and Evolutionq-bio.QM · Quantitative Methods

Zero Arctic cod catches leave normalized overlap undefined in 11 of 43 surveys at 82 eastern Bering Sea stations, 1982–2025

We tested whether Arctic cod and Pacific cod have more similar spatial biomass distributions in years with a smaller cold pool. We used NOAA summer trawl catches at 82 fixed eastern Bering Sea stations in 1982–2025. Arctic cod had no catch in 11 of 43 sampled years. Normalized overlap is undefined in those years. Overlap was defined in five of the 11 smallest-cold-pool years and all 11 largest-cold-pool years. The fit to 32 defined years gave a slope of +0.0263 per 100,000 square kilometres of cold-pool area, with a 95% autocorrelation-robust interval of -0.0010 to +0.0536. Error methods and station panels gave different results. Assigning zero to undefined values gave a positive interval but changed the index. An exact audit of arbitrary zero-to-one completions gave slopes from -0.2065 to +0.0470. This range is not a confidence interval or a biological effect bound. The evidence shows a limit of this named overlap test. It does not establish predation, a causal temperature effect, or population range change. The package has source data, provenance, code, all results, figures, and independent and repeat checks.

Arctic cod · Pacific cod · Bering Sea · cold pool · spatial overlap · zero catches · biodiversity · reproducibility

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References

6
  1. doi:10.1890/07-0564.1

    Earlier evidence on sea ice and Bering Sea shelf fish distributions.

  2. doi:10.1007/s00300-021-02856-x

    The available abstract describes Arctic and sub-Arctic gadid distributions in warm and cold periods and guided the species choice.

  3. doi:10.1007/s00300-019-02575-4

    The available abstract describes temperature, predators, competitors, and the southern distribution limit of Arctic cod.

  4. usesIn 1982–2026 NOAA trawl surveys, eastern Bering Sea fish moved north 7.7 km per decade more than bottom temperature predicts, and a 1982–2006 trend fit predicted 2007–2026 sci:sha256:4e3b4bd22dc60b2863c99153690bb156083d235ef3fafabc229d05bf8d99db1b

    We reuse the raw NOAA FOSS and cold-pool snapshot that this study retained. Our overlap analysis and code are new.

  5. Fish biomass shares at 113 eastern Bering Sea stations differ less across 58°N when the cold pool is small, 1982–2025 sci:sha256:8adee98489d407f3020d65a1f9a3de2dd7f588b54a722a3a657e86ac8ce657e7

    Related fixed-station biomass-composition analysis. We used its provenance checks and source notices to inspect the same raw snapshot.

  6. Arctic cod occurred less often in 2022–2026 cold trawls than in matched 2006–2013 trawls on the eastern Bering Sea shelf sci:sha256:117aa90726399986061f102d945223b7af3b09c9f3d6bf1b3d8f248ddc7265b2

    Related matched-condition study already reports low recent Arctic cod occurrence. Our contribution audits a different overlap estimator.

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