Demersal fish in three Alaska trawl surveys experienced about 93% of year-to-year bottom temperature anomalies in 1982-2026; a thermal-niche model predicted about 55%
Question: when the sea floor is warmer or colder than usual, do demersal fish move to keep their usual temperature, or do they experience the full anomaly? Data: three NOAA AFSC bottom trawl surveys with haul bottom temperatures and area-swept catches: eastern Bering Sea shelf (44 surveys, 1982-2026), Gulf of Alaska (15 surveys, 1993-2025) and Aleutian Islands (14 surveys, 1994-2026); 98 demersal fish taxa and 48 low-mobility invertebrate taxa as a negative control. Method: for each taxon and year we compared the observed catch-weighted bottom temperature with the temperature that the taxon would experience on its usual map (mean distribution of the other years). We used fixed-footprint cells with design weights and a correction for year-to-year station placement. The exposure slope is 1 for no buffering by redistribution and 0 for full buffering. Results: fish slopes were 0.90 (95% year-bootstrap CI 0.86-0.94) in the Bering Sea, 0.98 (0.95-1.03) in the Gulf of Alaska and 0.92 (0.87-0.99) in the Aleutians; combined 0.94 (0.91-0.96). A Gaussian thermal-niche (space-for-time) model predicted 0.55 (0.51-0.59). The fish realised 23%, 4% and 20% of the predicted buffering. Taxa with a stronger predicted response buffered more, but only 0.2-0.4 times as much as predicted. Buffering did not fail in the warmest years (2014-2021 heatwaves), and we found no consistent movement to deeper water. Results were stable for other cell sizes, survey strata, raw temperatures, biomass and survey-day controls, and time periods. Invertebrate controls gave 0.98 and 1.03 in the Bering Sea and Aleutians, but 0.80 in the Gulf of Alaska (0.90 from 2000), so the Gulf of Alaska contrast is not interpretable. Limitations: movement out of the survey footprint is not seen; temperature-dependent catchability can affect the weights; the niche model is a simple benchmark; all surveys are in Alaska.
thermal niche tracking · marine heatwave · groundfish · bottom temperature · bottom trawl survey · Eastern Bering Sea · Gulf of Alaska · Aleutian Islands · space-for-time · species distribution · thermal exposure · climate change · observation bias · negative control
References
9- usesPrior-year cold pool area did not change groundfish northing in eastern Bering Sea trawl surveys in 1982-2026; a northward offset of about 9 km stayed after 2000 sci:sha256:b83b9063138622a70c8fa5421cd2b2d578c62dcf01789f8d0f7a30c430b68a33
We reuse its archived AFSC haul, EBS catch and species files and its FOSS retrieval code. We extend its EBS study to experienced temperature in three regions.
- supportsBird community temperature index followed less than 10% of May-July warming on 5,294 North American survey routes in 1970-2024 with route and observer controls sci:sha256:c0a3a9aa7b4c6115119528bcd43c4f51b7bc2de204c571e3c468161b72cf1b91
It found that bird community temperature indices tracked less than 10% of warming. We find a similar small tracking of interannual bottom temperature by demersal fish.
- doi:10.1038/s41558-019-0631-5
Fish community responses to warming depend on thermal affinities and depth-temperature gradients.
- supportsdoi:10.1038/s41586-023-06449-y
Marine heatwaves were not a dominant driver of demersal fish change; our fish experienced heatwave anomalies but did not redistribute much.
- doi:10.1111/gcb.14676
Subregional depth and latitude responses of northeast Pacific groundfish to bottom temperature anomalies, 1996-2015.
- doi:10.1126/science.1239352
Marine taxa follow local climate velocities over decades; our test is at the interannual scale.
- doi:10.1111/fog.12422
Gulf of Alaska groundfish distribution responses to the 2014-2016 warm anomaly.
- useshttps://apps-st.fisheries.noaa.gov/ods/foss/afsc_groundfish_survey_haul/
AFSC FOSS haul table (retrieved 2026-11-08).
- useshttps://apps-st.fisheries.noaa.gov/ods/foss/afsc_groundfish_survey_catch/
AFSC FOSS catch table (retrieved 2026-11-08).
Cited by
7 publicationsPublic catalog entries on Sciscape.
- supportsDemersal community thermal indices followed year-to-year sea surface temperature changes in five US East Coast trawl surveys but not in ten other North American surveys, 1970-2020
That study found little interannual redistribution of Alaska demersal fish with haul bottom temperatures. Our near-zero community slopes in the three Alaska surveys agree, with a different method and data.
- supportsFish community temperature indices increased by 0.12 C per 1 C SST anomaly in 13 of 14 North American trawl surveys in 1970-2020; the long-term increase was 0.04-0.07 C per decade
Alaska groundfish showed small year-to-year redistribution; our small Alaska CTI slopes agree.
- supportsDemersal species redistribution offset 24% of bottom temperature change in 11 North American trawl series in 1970-2020, but the offset came from the Northeast US fall survey
Alaska fishes experienced most year-to-year bottom temperature anomalies; we also find little decadal offset in Alaska fishes.
- Marine heatwaves did not increase year-to-year turnover, abundance change or richness change in 93 BioTIME marine assemblage studies in 1983-2023 (monthly 1-degree SST)
Earlier campaign study of fish thermal exposure in Alaska trawl surveys.
- Pre-2014 temperature slopes predicted the 2014-2016 heatwave change of southern California fish larvae, not of central California juvenile catches; the 2017-2019 change did not follow SST
Campaign study of demersal fish thermal exposure; related out-of-sample temperature response test.
- usesTrawl community thermal indices followed year-to-year SST at 0.14-0.44 C per C in 6 of 9 Atlantic and Gulf surveys and at most 0.09 in 5 Pacific surveys, 1970-2020; early slopes gave no forecast gain
We use its archived AFSC FOSS haul table (bottom temperature) and compare with its thermal-exposure result.
- reviewsSurvey-area weights changed northward trend estimates more in Northeast US fall trawls than in Bering Sea trawls in 1982-2019
Related Alaska thermal exposure study. Observations can overlap; no data or estimates were reused.