Mackerel on the Move: Cooperative Research Investigates Atlantic Mackerel Abundance Under Changing Ocean Conditions

Atlantic mackerel have long followed a predictable seasonal migration across the Northwest Atlantic. Each spring, mackerel move north from southern New England and the Mid-Atlantic-through Georges Bank and along the Scotian Shelf-toward the Gulf of St. Lawrence and Newfoundland. Then, they return south as ocean temperatures start to cool in the fall.

In recent years, that familiar pattern has become less predictable. Throughout a period of persistent warming across the Northeast U.S. shelf, several marine species were observed shifting northeast and into deeper waters. But beginning in 2024, an unusual period of cooler ocean conditions across the region drew attention from both scientists and fishermen. As scientists and fishermen documented widespread cooling, delayed migrations, and species redistributions, fishermen began reporting an apparent uptick in Atlantic mackerel-sometimes in unexpected locations.

The Atlantic Mackerel Cooperative Research Initiative is looking at which ecosystem drivers are influencing the increased mackerel population and shifting migration patterns.

Fishermen Spot Signs of Change

After decades of declining Atlantic mackerel abundance, commercial and recreational fishermen throughout the Northeast began reporting an uptick over the past few years. Fishermen have also observed other target species like white marlin, billfish, sand lance, and Illex squid in surprisingly high numbers. At the same time, Atlantic mackerel, striped bass, red drum, bluefish, and other species are appearing in unexpected places and at unusual times.

Fishermen are essential partners in helping understand shifting oceanic conditions. Their firsthand accounts are often an early indication something is changing in the ecosystem. Fishermen's reports prompted conversations between Northeast Fisheries Science Center researchers and industry members. They wondered: Are Atlantic mackerel beginning to recover, and what environmental drivers are behind the changes in the mackerel population and distribution?

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Cold-Water Events Offer New Clues

The timing of the fishermen's observations coincides with an unusual oceanographic event. Although the Northeast U.S. Shelf is one of the fastest-warming marine ecosystems in the world, something unexpected happened in 2023. A pulse of cold, fresh northern water entered the region, spreading cooler ocean temperatures throughout the northeast continental shelf and slope through 2024. Scientists had not observed oceanographic conditions like that since the 1990s.

NOAA's annual State of the Ecosystem reports help connect observations like those from the fishing community with the long-term scientific monitoring that revealed cooler-than-expected ocean temperatures. The 2025 report documented the cold, fresh pulse and highlighted fishermen's reports of abundant Atlantic mackerel and other cold-water species. Although those cooler temperatures persisted through 2025, the mechanisms that drove those conditions in 2024 were likely different from 2025.

Building on this shift in conditions, the 2026 State of the Ecosystem report introduced marine cold spells as a new ecosystem indicator. It added seasonal and decadal ocean temperature forecasts that extend through 2035. These adaptations are helping managers move beyond describing ecosystem changes and towards anticipating and planning for them.

"We haven't seen an oceanographic signal like this since the 1990s. This cold pulse could be associated with the cooler ocean temperatures in 2024 and 2025 reshaping the habitat of Atlantic mackerel during their migration" - Dr. Glen Gawarkiewicz, Physical Oceanographer and Senior Scientist at Woods Hole Oceanographic Institution

For Atlantic mackerel, these changes could matter. The latest Atlantic mackerel stock assessment found signs of improving abundance after years of rebuilding efforts. But questions remain about the role of recent ocean conditions in mackerel abundance and migration.Cooler waters have historically been associated with higher survival rates for larvae and juvenile fish, but temperature alone is unlikely to tell the whole story. Scientists suspect it may be one piece of a much larger environmental puzzle, with cooler ocean temperatures acting as a proxy for other conditions that influence recruitment and survival.

Cooperative Research to Solve the Puzzle

NOAA Fisheries is supporting multiple collaborative research programs to answer these questions-and more. We recently launched a $2.3 million cooperative research initiative that will engage more than 50 fishing vessels to improve our understanding of the Atlantic mackerel stock. Fishermen will work alongside researchers to:

• Develop new survey tools and technologies that improve estimates of stock abundance
• Quantify mackerel movement between Northeastern U.S. and Canadian waters
• Evaluate mackerel spawning seasonality
• Collect and analyze data to reduce uncertainty in future stock assessments

Another complementary project is exploring how changing ocean conditions may be influencing where Atlantic mackerel are found and when they are encountered by fishermen and scientific surveys. The NOAA-supported Quantitative Ecology and Socioeconomics Training Program will include researchers from the Cooperative Institute for the North Atlantic Region, led by Dr. Camrin Braun at the Woods Hole Oceanographic Institution. They will combine fisheries observations, scientific survey data, and ocean measurements to better understand shifts in mackerel distribution and availability. The team will specifically investigate how the recent influx of colder northern waters to the shelf ecosystem influence Atlantic mackerel availability throughout the Northeast. This will give scientists and managers better context for interpreting survey and fishery data.

"Mackerel may not always be where we expect them to be. Our goal is to understand whether recent changes reflect a real shift in the population or whether changing ocean conditions are affecting where the fish are found and how often fishermen and surveys encounter them." -Dr. Camrin Braun, Ocean Ecologist and Assistant Scientist at Woods Hole Oceanographic Institution

Together, these efforts are combining local knowledge and long-term science to improve our understanding of a changing ocean and help managers prepare for what comes next.