Near Real-time Temperatures from the 2026 Aleutian Islands Bottom Trawl Survey

Survey Progress and Bottom Temperatures

Every other year, NOAA’s Alaska Fisheries Science Center conducts the Aleutian Islands Bottom Trawl Survey. We are mandated by the Magnuson-Stevens Act to collect distribution and abundance data for fish, crab, and other bottom-dwelling species in the Aleutian Islands region. These data inform stock assessments and ecosystem status reports for the North Pacific Fisheries Management Council.

Temperature is one of many factors that influences species’ ranges and population sizes. For instance, we see many species moving farther north as ocean temperatures warm. To understand what's going on around the Aleutian Islands, we recorded ocean bottom and surface temperatures at each sample station on the survey. These data help understand how variations in temperature over time relate to the fish and crab we find—or don’t find—at the same station. 

We have conducted this standardized survey in most even-numbered years since 1991, culminating in 15 surveys over three decades of sampling. Learn more about this year’s survey, view temperature maps from previous years, and see examples of how these temperature data are collected and used in this story from 2023.

All data collected on these surveys are and will be publicly accessible from:

• Fisheries One Stop Shop public data portal
• Distribution Mapping and Analysis Portal
• Alaska Fisheries Information Network

View the daily maps of our progress and bottom temperatures throughout the survey. The last page includes a regional map of the Aleutian Islands bottom trawl survey and the Western Aleutians, Central Aleutians, Eastern Aleutians, and Southern Bering Sea districts.

Survey Dates

The 2026 Aleutian Islands bottom trawl survey ran from early June to early August aboard the F/V Ocean Explorer and the F/V Alaska Provider. This year, we staggered the start for the two vessels conducting the surveys. The F/V Ocean Explorer departed Dutch Harbor on June 2 and the F/V Alaska Provider departed Dutch Harbor on June 3. Throughout the survey, the vessels were scheduled to be in port on the following dates:

• Depart Dutch Harbor June 2 or 3 to start the survey
• Dutch Harbor on June 21 between legs 1 and 2
• Adak on July 15 between legs 2 and 3
• Dutch Harbor on August 8 at the end of the final third leg

After leg 3, both vessels returned to port for demobilization. Our survey scientists returned to Seattle and Alaska to finalize the data collected.

Watch for preliminary results from the survey in the September Joint Groundfish Plan Team presentation.

Survey Location

The Aleutian Islands bottom trawl survey began in Unimak Pass. From there we swept westward along the north side of the Aleutian archipelago to Samalga Pass.

In Samalga Pass and at the Islands of Four Mountains (Chuginadak), we sampled on both the north and south sides of the archipelago and continued to sweep westward along the Aleutian Islands chain. Crew changes occurred twice during the summer—in late June in Dutch Harbor and in mid-July at Adak Island.

We ultimately sailed past Attu Island (the last U.S. island in the Aleutian chain) and steamed to Stalemate Bank to collect the last of our samples in early August. Both vessels then returned to Dutch Harbor.

Pictures from the Field

What does survey life and research look like? Check out the 2026 photo gallery. These photos show the incredible places that NOAA scientists go and showcase our mission in ways that words cannot.