Bering Science

Spring 2023

The Bering Sea is experiencing many changes. Here, we share observations and research that is happening in and around the region. This year’s report focuses on five topics identified by our Community Advisory Panel.

The Alaska Ocean Observing System (AOOS) and IARC compiled the information from many sources, with funding from National Oceanic and Atmospheric Administration (NOAA).

The Bering Region Ocean Update project began in spring 2020 to help increase regional data sharing among federal, state, community and private sector partners. Read previous updates and learn how information is gathered and reviewed.

We provide a resource to state, federal, community and university partners to share recent observations with community members and other scientists and management agencies.

Get in touch

If you gather data or have observations of changes in the Aleutians, Bering Sea or southern Chukchi Sea, please contact us for possible inclusion in a future Bering Science report.

Your opinion is valuable to us and can help guide future reports. Please provide feedback by filling out an online survey.

Read past reports

When sockeye salmon first return to a river from their years at sea,
their backs are a bright blue-green and their bellies flash pure silver. Credit: Lisa Hupp / US Fish and Wildlife Service
When sockeye salmon first return to a river from their years at sea, their backs are a bright blue-green and their bellies flash pure silver. Credit: Lisa Hupp / US Fish and Wildlife Service

Who are we?

This report is part of the Alaska’s Changing Environment series. It was compiled by AOOS and IARC, with collaboration from NOAA.

We thank our Community Advisory Board for providing direction and feedback. 

  • Shayla Shaishnikoff, Qawalangin Tribe of Unalaska
  • Jennifer Hooper, Association of Village Council Presidents
  • Lauren Divine and Chris Tran, Aleut Community of St. Paul Island
  • Mellissa Maktuayaq Johnson, Arctic-Yukon-Kuskokwim Tribal Consortium
  • Craig Chythlook & Connie Melovidov, University of Alaska Fairbanks (UAF)

We also thank our reviewers who provided valuable input on this publication.

Suggested citation

Bailey, A., C. Rosner, and H.R. McFarland, editors. Bering Science: Spring 2023 Bering Region Ocean Update, Issue 6 [newsletter]. Alaska Ocean Observing System, Anchorage, Alaska.

Disclaimer:  We have done our best to provide balanced, synthesized and easy to understand current perspectives on crab, HABs, seabirds, weather & climate, and salmon in the Bering Sea Region. We provide a “sampler” of research happening on each topic, though much more work is being done than can be covered here. Although state and federal management agencies, Tribal and science organizations generously contributed research information to this report, Bering Science is primarily meant for science outreach and is not part of any official management process. It is not comprehensive and does not take the place of official documents like the NOAA Ecosystem Status Reports.



Closures of two iconic Bering Sea crab fisheries have had a devastating impact on harvesters, industry and communities. In 2022, the Bering Sea snow crab fishery closed for the first time ever after a population-wide collapse the previous year. The Bristol Bay red king crab fishery closed for a second season in a row after more than a decade of gradual decline. In the northern Bering Sea, Norton Sound red king crab abundance increased enough to support a commercial fishery.

What happened to the snow crab?

Between 2018 and 2021, snow crab populations dropped. Annual trawl surveys by NOAA Fisheries reported a record high in 2018. In 2019 the abundance of larger crab increased, while smaller crabs dramatically declined. No survey took place in 2020 because of the pandemic. In 2021, the male population estimate was the lowest ever recorded. Legal size crabs continued to decline in 2022, causing the closure of the 2022/23 fishery, but the numbers of small crab increased from 2021.

Researchers and managers agree that the crabs did not move elsewhere, because there was not a population increase in other areas. The peak of the snow crab population occurred during the marine heatwave of 2018–2019, when bottom temperatures rose significantly in the Eastern Bering Sea. The warm water likely stressed the crabs and increased their metabolic needs. Crabs were forced to gather in small areas of cool water at a time when they needed extra food. Scientists hypothesize that they died from starvation.

Graphic showing snow crab collapse

Surveys by NOAA Fisheries recorded more male snow crabs than ever before in 2018. But between 2018 and 2021, the population of male snow crabs plummeted from almost 6,000 million to approximately 300 million. The 2022 survey observed new recruitment of small crab. Source: Ben Daly / Alaska Department of Fish and Game (ADFG)

Snow crab lesson plans

Students can explore snow crab biology and climate change in the Bering Sea with new lesson plans from NOAA Fisheries. The curriculum is for 7th grade students but may be adapted for younger or older classrooms.

In 2023, NOAA Fisheries will expand the curriculum for mixed-grade classrooms in rural Alaska. Download the materials or request a copy by mail from Erin Fedewa,

Male snow crab movement

Scientists are piloting the use of satellite tags to learn more about where mature male snow crabs go during the year. In 2022, 30 crabs were tagged during the spring commercial fishing season and tracked until July. These crabs moved north to the area surveyed by NOAA Fisheries each year. During that survey, 18 crabs were tagged and tracked for five months and generally moved in a southwesterly direction. The study showed that tagged crabs traveled between three and 80 miles, and that satellite tags may be a good way to investigate their movement and distribution.

Who is doing this research? University of Alaska Fairbanks (UAF), NOAA Fisheries and ADFG. Additional funders include the Bering Sea Fisheries Research Foundation and the Central Bering Sea Fishermen’s Association.

Crab fishery disaster declarations

ADFG is responding to fisheries disaster requests and developing spending plans for disaster relief funds from NOAA Fisheries.

  • Disasters have been declared and funds have been announced for 2019 Norton Sound red king crab ($1,433,137) and 2019/2020 Eastern Bering Sea tanner crab ($12,935,199).
  • Disasters have been declared for 2020–2021 Norton Sound red king crab, and for 2021–2022 & 2022–2023 Bering Sea crab.

Tracking Bristol Bay female red king crab to learn about their early lives

The Bristol Bay red king crab decline is likely related to low survival in early life. To understand where females release larvae in spring, scientists tagged 225 female crabs in fall 2021. Crabs were tracked for six months, moving eastward about a quarter of a mile each day. Tags popped off in April–May, when they typically molt and release larvae. Tagged crabs reached nearshore areas along the Alaska Peninsula and central Bristol Bay. They were mostly within management areas that protect them from trawling. This research will help future studies determine whether larvae reach good habitat to grow into juveniles.

Who is doing this research? ADFG, NOAA Fisheries and Bering Sea Fisheries Research Foundation.

Source: Andrew Nault / ADFG

Warmer water is stressing Bering Sea crabs

Warm water stresses crabs and makes them more vulnerable to disease. Scientists are analyzing crab blood samples to see if bitter crab disease increased in the Bering Sea before and during the snow crab collapse.

Bitter crab disease can be fatal to crabs. It causes cooked meat to taste bitter (like aspirin) and have a chalky texture. The meat is not toxic to humans, but crabs with the disease cannot be eaten or sold commercially.

Researchers at NOAA Fisheries have been monitoring bitter crab disease in the Bering Sea since 1988. They found the disease in almost 40% of the snow crab samples collected in 2017, which was 25% more than the prior year. Over half of the juveniles sampled near St. Matthew’s Island nurseries were infected in 2017, suggesting that the disease may have negatively impacted survival of juvenile snow crab in recent years.

This summer, scientists will process blood samples collected during 2018 and 2019. In the laboratory, they will monitor snow crabs infected with the disease to see how increased temperatures affect survival.

Norton Sound red king crab are doing well

In Norton Sound, crab large enough to legally harvest returned to support a commercial fishery in 2022. Trawl surveys found few such crabs beginning in 2018, leading to a low commercial harvest in 2019 and almost no commercial harvest in 2020 and 2021. However, the survey also showed a record number of small crabs in 2018. These crabs have now grown and should support a commercial fishery for the next three years.

Why are Norton Sound crab doing okay, while other crab species are not? The most likely explanation is that Norton Sound is geographically isolated from the southern Bering Sea, so factors causing declining abundances of other crab fisheries are not affecting the Norton Sound population.

chart of king crab sizes

King crab sizes over time. Surveys found many king crab in 2018–2020, but most were too small—carapace lengths <105 mm—to legally harvest. 2021 was the first year that crabs would be large enough to legally harvest in 2022. Source: Jenefer Bell / ADFG

Thanks to crab research contributors

  • Jenefer Bell, ADFG,
  • Erin Fedewa, NOAA Fisheries,
  • Connie Melovidov, UAF,
  • Miranda Westphal, ADFG,
  • Leah Zacher, NOAA Fisheries,
Harmful Algal Blooms
Weather & Climate