What the Science Says About Alaska Pollock Trawling, Seafloor Habitat, and Bycatch

Understanding the differences between global trawling and Alaska’s pollock fishery

Trawling is not a single fishing practice with uniform environmental effects. Gear design, fishing location, seabed composition, target species, management requirements and monitoring systems all influence how a fishery operates and its potential impacts.

That distinction matters when evaluating the U.S. Alaska pollock fishery, one of the largest fisheries in the world and a major source of high-quality protein for millions of American consumers. The fishery operates in the Bering Sea and Gulf of Alaska under a science-based management system, with strict limits on the catch of both target and non-target species, habitat protections and extensive independent monitoring.

As with any commercial fishery, the Alaska pollock fishery is not without environmental impacts. Salmon and other prohibited species are caught incidentally, and fishing gear can interact with the seafloor. These impacts deserve serious scrutiny, transparent reporting and continued efforts to improve fishing practices. This is exactly what occurs in the U.S. fisheries management process.

Evaluating those impacts requires examining the gear actually used, the specific conditions where fishing occurs, and the best available scientific evidence. Findings about bottom trawling in one part of the world cannot automatically be applied to every trawl fishery, and estimates of global environmental impacts should not be presented as measurements of the Alaska pollock fishery.

The following explains what the science tells us about Alaska pollock fishing, seafloor habitat, carbon emissions, bycatch and fisheries management.

Key facts about Alaska pollock trawling

Gear. Alaska pollock is caught with pelagic (midwater) trawl nets that target schools of fish in the water column. NOAA Fisheries says this gear, although it sometimes contacts the bottom, has “minimal impact on habitat.”

Seafloor. NOAA’s Fishing Effects Model estimates that about 94.8% of the eastern Bering Sea continental shelf is undisturbed by fishing across all gear types, according to the agency’s 2022 Evaluation of Fishing Effects on Essential Fish Habitat.

Bycatch. NOAA Fisheries describes the Alaska pollock fishery as “one of the cleanest in terms of incidental catch of other species.” Most of what the fishery catches incidentally is other managed groundfish, jellyfish, squid and herring.

Salmon. NOAA’s adult-equivalent (AEQ) analyses estimate that pollock fishery bycatch has reduced coastal western Alaska Chinook salmon returns by an average of 1.9% since 2011, and Upper Yukon River Chinook returns by 0.6%. The estimated impact on coastal western Alaska chum salmon returns averages 1.75%.

Yukon River Chinook declines. A 2026 NOAA Fisheries study linked recent Yukon River Chinook declines to poor early-life survival and a rise in natural mortality tied to Bering Sea marine heatwaves, and found no evidence that bycatch was a significant factor in population-level declines.

Crab and halibut. Pelagic trawl bycatch of Bristol Bay red king crab has averaged 13 animals per year since 2013, and the pollock fishery accounted for 0.52% of fishery-related halibut mortality in the Alaska Region in 2025. 

Carbon. A 2024 NOAA Fisheries field experiment in the eastern Bering Sea found no detectable effect of bottom trawling on seabed organic carbon at a previously untrawled site.

Management. The fishery is managed by NOAA Fisheries and the North Pacific Fishery Management Council under the Magnuson-Stevens Act, and has been certified sustainable by the Marine Stewardship Council (MSC) since 2005.

1. Is Alaska pollock trawling the same as bottom trawling?

Short answer: No. Alaska pollock is caught with pelagic (midwater) trawl nets designed to fish schools of pollock in the water column, while bottom trawls are designed to be towed along the seafloor. Pelagic gear can touch the bottom, but NOAA Fisheries describes its habitat impact as “minimal.”

The distinction: Trawl fisheries use different types of gear, and the differences matter when assessing environmental impacts.

What the science and fishery practices show: Alaska pollock is primarily harvested using pelagic, or midwater, trawl gear. These nets are designed to capture schools of Alaska pollock anywhere in the water column they are found rather than drag along the seabed to catch bottom-dwelling species.

Bottom trawls, by contrast, are designed to operate along the seafloor. Depending on their design and the environment in which they operate, they can interact with and disturb seabed sediments, corals, sponges and other marine organisms, if present.

Pelagic trawl gear, despite its name, is not exclusively deployed in the mid-water or pelagic zone. Alaska pollock are semi-demersal species and adults often aggregate close to the seafloor, and seafloor contact – primarily from the chain footrope and clump weights - can occur. That is why the fishery's actual gear interactions, fishing footprint and potential habitat effects must be evaluated using fishery-specific evidence.

Research measuring the habitat impacts of bottom trawling cannot automatically be treated as a direct measurement of the habitat impacts of Alaska pollock fishing in the Bering Sea or Gulf of Alaska.

Why it matters: Broad statements about the impacts of trawling worldwide do not, on their own, establish the magnitude of habitat impacts associated with Alaska pollock fishing. Those conclusions require evidence specific to the fishery, its gear and its operating environment.

2. Does Alaska pollock trawling damage the seafloor?

Short answer: Federal science indicates the impact is limited. NOAA’s Fishing Effects Model estimates that about 94.8% of the eastern Bering Sea continental shelf is undisturbed by fishing across all gear types, and a 2014 NOAA field study found that storms had a greater effect on seafloor life than bottom trawling at the study site.

The claim: Trawl fishing can devastate seafloor habitat.

What the evidence shows:
Mobile bottom contact fishing gear can affect seabed habitats. The extent and duration of those effects depend on the gear used, the frequency of contact, sediment characteristics, natural disturbance and the sensitivity of the organisms living in the area.

In Alaska, scientists use the NOAA Fishing Effects Model to estimate habitat disturbance from fishing activity across the North Pacific. The model tracks habitat transitions between disturbed and undisturbed states and provides a quantitative framework for evaluating fishing impacts across different gear types.

Results from NOAA’s 2022 Evaluation of Fishing Effects on Essential Fish Habitat indicate that approximately 94.8% of the area remains undisturbed by fishing gear, across all gear types, under the model's defined habitat-disturbance framework. This is important context when evaluating claims about the scale of fishing-related habitat impacts in the region.

It is also important to understand what this figure does and does not mean. It is a model-based estimate of habitat condition, not a claim that fishing never affects the seafloor or that every habitat is equally resilient.

Alaska's management system also includes area closures and restrictions designed to protect sensitive habitats and marine species. These measures reflect differences in gear, location and the risks associated with particular fishing practices.

Research conducted in the Eastern Bering Sea provides additional context.

A 2014 study by NOAA Fisheries scientists Robert McConnaughey and Stephen Syrjala in the Eastern Bering Sea and a 2025 study by Bradley Harris et al. on Georges Bank both confirmed that natural and fishing disturbances can be almost indistinguishable in areas where benthic shear stress forces are strong and sufficient enough to regularly mobilize seabed sediments.

In particular, the 2014 Eastern Bering Sea NOAA study highlights: The effect of trawling on invertebrate biomass after one year was not statistically significant for any of the taxonomic groups (p ≥ 0.23), indicating no evidence of a delayed response to the commercial-trawl disturbance. Further analysis suggests that storms have an overall greater effect on the benthos than do bottom trawls at this location. Both the numbers of taxa significantly affected by trawling and the storm (3 vs. 12), as well as the median sizes of these effects (−14.2% vs. −22.0%), were greater for the storm event.

These studies are not evidence that bottom trawling has no effects everywhere. Rather, they demonstrate why local environmental conditions and direct measurements matter when assessing the effects of fishing.

Why it matters: The appropriate question is not whether trawling can affect habitat. It can. The question is what effects occur in a particular fishery, where they occur, how significant they are and how effectively they can be managed. Alaska's scientific assessment and management framework is designed to address those questions.

3. Does trawling in Alaska release carbon stored in the seabed?

Short answer: Field research in the eastern Bering Sea has not found it. A 2024 NOAA Fisheries experiment found no detectable effect of bottom trawling on seabed organic carbon at a previously untrawled site. The most widely cited global estimate of trawling emissions (Sala et al., 2021) has been challenged in Nature for potentially overstating carbon release by several orders of magnitude.

The claim: Trawling releases substantial quantities of carbon stored in the seabed, contributing to climate change.

What the evidence shows:
This is an issue that requires a thorough analysis that considers the type of trawl gear used and the characteristics of the ocean floor that is disturbed.  Recent concerns that commercial bottom trawling can contribute to the release of sequestered marine seabed carbon and contribute to increased carbon dioxide emissions highlight a need for additional research in this area. The scientific questions proposed are complex, as estimating the scale of carbon emissions requires assumptions about sediment composition, carbon reactivity, the fate of disturbed carbon and the environmental conditions in which fishing occurs.

A widely discussed 2021 study by Sala et al. estimated global carbon emissions associated with bottom trawling. Subsequent peer-reviewed research refuted the findings of this study and challenged important assumptions in that analysis.

In a 2023 contribution published in Nature, Hiddink and colleagues argued that Sala’s estimate of the carbon impacts of bottom trawling substantially overstated carbon release because it applied carbon-decomposition rates derived from highly reactive organic matter to bulk seabed sediments, which contain carbon with differing levels of reactivity. Their analysis concluded that this approach could overestimate the impact on global carbon mineralization by several orders of magnitude.

Other researchers have continued to investigate and debate these estimates. The broader scientific literature therefore should not be reduced to a single global number presented as a settled measurement of emissions from all trawl fisheries.

Research in the Eastern Bering Sea is particularly relevant to understanding local conditions. A 2024 study by NOAA Fisheries scientists J. Drew Stephens and Robert A. McConnaughey sought to examine the potential for stored seabed carbon release following bottom trawl events at a previously untrawled Eastern Bering Sea site. Using a before-and-after experimental design with control areas, the researchers found no detectable trawling effect on measured total organic carbon, total nitrogen, carbon and nitrogen isotope ratios, or sediment-size classes.

In other words, there was no observed release of stored carbon from the seabed. This was likely due to the site's high sand content, low carbon content and exposure to natural storm disturbance which may have limited the effects observed. It did not establish that carbon-related effects are impossible in other locations or under other conditions, rather the authors emphasized once again the importance of site-specific research when investigating complex scientific questions.

Most importantly, the study examined bottom trawling effects, not the environmental effects of the Alaska pollock fishery's pelagic gear as a whole. The frequency and magnitude of contact for pelagic trawl gear are far lower than that of bottom trawl gear.

Why it matters: Global models and local field experiments answer different questions. Estimates of carbon emissions associated with bottom trawling worldwide cannot be presented as measured carbon emissions from Alaska pollock fishing without fishery-specific evidence establishing that connection.

Responsible discussion of this issue should distinguish between modeled global estimates using extremely broad assumptions across model parameters, and results from controlled experiments using direct measurements of impacts attributable to a particular fishery.

4. How much bycatch is there in the Alaska pollock fishery, and what is it?

Short answer: Incidental catch makes up about 2% of the eastern Bering Sea pollock catch, and NOAA Fisheries describes the fishery as “one of the cleanest in terms of incidental catch of other species.” Most of that bycatch is other managed groundfish, jellyfish, squid and herring. Widely cited totals for “Alaska trawl fisheries,” such as 96 million pounds of discards in 2025, combine the pollock fishery with separate bottom trawl fisheries for flatfish and Atka mackerel.

The claim: Large amounts of discarded catch demonstrate the environmental impact of Alaska pollock fishing.

What the evidence shows:
Bycatch is an important fisheries management issue. However, the term covers many different species, and the environmental implications of incidental catch depend on which species are caught, the quantities involved, their survival, and the effectiveness of measures designed to avoid or reduce those catches.

Figures covering all Alaska trawl fisheries should not be attributed to the Alaska pollock fishery alone. Likewise, a total weight of discarded catch does not reveal its species composition or establish the impact on a particular population.

In the Eastern Bering Sea Alaska pollock fishery, the bycatch of other species is divided into the following three categories: 1) Species that are managed under NOAA’s Groundfish Fishery Management Plan; 2) Species that fall outside of that Fishery Management Plan; and 3) Prohibited Species such as salmon, halibut, herring and crab that cannot be retained except for those that can be retained and donated to U.S. food bank programs.  For those species in the first category, fishermen are allowed to retain those up to specified limits and convert them into commercial products and they represent 1.1% of the total catch in the Alaska pollock fishery. The catch of those species in the second category represents 0.9% of the catch in the Alaska pollock fishery and 98 percent of this catch is either jellyfish or squid. Finally, the catch of prohibited species in the third category make up 0.25% of the total catch and 75% of that is herring.

In the most recent AKFIN data reporting of the 2025 Eastern Bering Sea pollock fishery, approximately 84% of the reported bycatch returned to the sea consists of jellyfish, herring and squid, according to the industry's analysis of the relevant catch data. This figure includes both the species that are required to be discarded (PSC) as well as those in the ecosystem component but does not include the composition of bycatch across all Alaska trawl fisheries.

Salmon, halibut, crab and herring are subject to specific management measures because of their ecological, commercial and cultural importance. Their incidental catch warrants separate consideration rather than being obscured within a single aggregate weight.

The Alaska pollock fishery uses catch monitoring, avoidance measures, area restrictions and salmon excluder devices to reduce incidental catch. Catch is recorded through independent observer coverage, electronic monitoring where applicable and shoreside monitoring.

These systems allow managers to track catches, assess performance against applicable limits and adapt management measures as conditions change.

Why it matters: A meaningful assessment of bycatch should identify the fishery involved, break down the catch by species and explain the relevant biological and management context, particularly the volume of directed harvest. Trawl fisheries in Alaska account for 80% of the total landings, and the pollock fishery in the Eastern Bering Sea is one of the largest wild capture fisheries in the world. A headline comparison involving the total weight of discarded catch cannot substitute for that analysis and context.

5. Is pollock fishery bycatch causing Western Alaska salmon declines?

Short answer: Federal science does not support that conclusion. NOAA’s adult-equivalent (AEQ) analyses estimate that pollock fishery bycatch has reduced coastal western Alaska Chinook salmon returns by an average of 1.9% since 2011 (0.6% for the Upper Yukon River stock), and 2026 peer-reviewed NOAA research identifies poor early-life survival and Bering Sea marine heatwaves as key drivers of Yukon River Chinook declines.

The claim: Salmon caught in the Bering Sea pollock fishery are driving the decline of Western Alaska salmon populations.

What the evidence shows:
Salmon declines across Western Alaska are a serious concern for subsistence users, commercial fishermen and communities whose cultural and economic lives are connected to these fish. The impact of salmon bycatch in the Alaska pollock fishery must be analyzed within the context of other issues driving the salmon declines. Demonstrating that salmon are caught incidentally is not the same as establishing that the Alaska pollock fishery is driving the decline of a particular river's salmon population.

Salmon bycatch varies between years, and the number of salmon caught does not, by itself, establish the impact on the number of adult salmon that would otherwise return to a river. That requires analysis of where those salmon originated, and the relationship between fishery removals and eventual returns. NOAA Fisheries genetic testing has identified the origins of salmon caught in the fishery and it shows that the vast majority of non-Chinook salmon and the majority of Chinook salmon taken as bycatch in the Alaska pollock fishery would not have returned to Alaskan rivers. Most of the non-Chinook salmon are from Asian hatcheries that compete with wild salmon from Alaska in the ocean environment. Adult-equivalent (AEQ) analyses account for this by factoring in natural mortality, because many salmon caught as bycatch would have died from predation or other natural causes before returning to spawn.

In 2026, NOAA Fisheries published new peer-reviewed research examining the causes of Yukon River Chinook salmon declines and it provides important context for evaluating environmental and other factors affecting these populations. This research clearly shows changing environmental conditions, specifically higher ocean and river temperatures are the primary cause of these declines.

NOAA’s Alaska Fisheries Science Center uses AEQ modeling to estimate how pollock fishery bycatch affects adult salmon returns. Since 2011, the estimated impact on Chinook returns has averaged 1.9% for coastal western Alaska stocks and 0.6% for the Upper Yukon River stock. The estimated impact on chum returns has averaged 1.75% for coastal western Alaska stocks and 1% for the Middle/Upper Yukon River stock. These estimates should be considered alongside other available evidence, rather than replaced by conclusions drawn solely from the number of salmon caught. 

Historical bycatch figures also require context. For example, 2021 was an unusually high year for chum salmon bycatch. Data collected by independent observers on board Alaska pollock fishing vessels show that average non-Chinook salmon bycatch in the Bering Sea pollock fishery over the following three years was approximately 18% of the 2021 level. Year-to-year variation matters when evaluating long-term impacts.

None of this diminishes the importance of Western Alaska salmon or the need to reduce bycatch. It underscores the importance of identifying the actual drivers of salmon declines while continuing to improve avoidance measures and monitor the fishery's effects.

Why it matters: The scientific question is not simply how many salmon were caught, but how those removals affect specific populations and how they compare with the other factors influencing salmon survival and returns.

6. How is the Alaska pollock fishery managed?

Short answer: The fishery is managed by NOAA Fisheries and the North Pacific Fishery Management Council under the Magnuson-Stevens Fishery Conservation and Management Act, with science-based annual catch limits, bycatch caps, habitat closures and independent observer monitoring. NOAA describes the Bering Sea fishery as often considered one of the best-managed fisheries in the world, and it has been certified sustainable by the Marine Stewardship Council since 2005.

The claim: Large-scale trawl fisheries are inherently poorly managed or lack adequate accountability.

What the evidence shows:
Alaska pollock is managed under a federal fisheries management system involving NOAA Fisheries and the North Pacific Fishery Management Council. Scientific assessments, annual catch limits, ecosystem information and precautionary management measures inform decisions about harvest levels and fishing practices.

The Council provides a public process through which scientists, fishery managers, fishermen, communities and other stakeholders are given the opportunity to contribute information and comment on proposed management actions.

The fishery has been recognized for its management practices by organizations beyond the commercial fishing industry. NOAA Fisheries describes the Bering Sea fishery as one of the first U.S. fisheries managed with catch shares and notes that it is often considered one of the best-managed fisheries in the world.

Independent certification assessments have also examined the fishery's management framework, monitoring and environmental performance. The eastern Bering Sea pollock fishery has been certified as sustainable by the Marine Stewardship Council (MSC) since 2005.

Recognition as a well-managed fishery does not mean that every environmental concern has been resolved. It means that management measures, scientific review and accountability mechanisms are in place to assess and address those concerns.

Why it matters: The existence of environmental impacts does not establish that a fishery is unmanaged. A fair evaluation must consider the rules, monitoring, scientific assessments and corrective measures governing its operations.

7. Why Alaska-specific evidence matters

Determinations of the environmental impacts of any form of commercial fishing deserve careful, evidence-based scrutiny. Meaningful comparisons require more than grouping fisheries together because they use nets or share the label “trawling.”

Bottom trawling and pelagic trawling involve different gear designs and operating conditions. Seabed habitats differ in their composition, sensitivity and exposure to natural disturbance. Bycatch varies by species and location. Carbon estimates depend on the methods and assumptions used to produce them.

Alaska's pollock fishery is subject to scientific assessment, extensive catch monitoring, bycatch controls and habitat protections. Its environmental performance should be evaluated through those fishery-specific facts and the best available scientific evidence.

The industry recognizes that responsible fishing requires ongoing scrutiny and improvement. Research into gear design, seabed interactions and bycatch reduction is an important part of that work.

The goal should be an accurate understanding of both the fishery's impacts and the measures used to manage them. That requires transparent data, independent scientific evaluation and a willingness to distinguish established findings from assumptions, estimates and unresolved questions.

Alaska pollock is an important source of seafood and supports fishermen, processors, coastal communities and businesses throughout Alaska. Those interests deserve reporting that is as precise about the science as it is about the challenges facing the fishery.

Summary of the evidence on Alaska pollock trawling

The environmental impacts of commercial fishing deserve serious scrutiny. Alaska pollock fishing is no exception. Bycatch must be reduced, habitat impacts must be understood, and fishing practices must continue to evolve as science and technology advance.

But those discussions must be grounded in accurate information and evidence specific to the fishery being evaluated.

Pelagic trawling is not the same as bottom trawling. Estimates of global environmental impacts from bottom trawling are not measurements that can, or should, be applied to Alaska pollock fishing. Total bycatch weights do not tell the full story without identifying the species involved and the number of salmon caught does not, by itself, establish the effect on salmon populations or explain why those populations are declining.

Alaska's pollock fishery operates under a rigorous management system built on scientific assessment, catch limits, independent monitoring and ongoing research. That does not mean every question has been answered or every impact eliminated. It means those questions can and should be evaluated using the best available evidence, with a clear understanding of what the science establishes and where uncertainty remains.

The fishermen, processors and coastal communities connected to this fishery have a direct stake in its long-term sustainability. They also have a stake in ensuring that public discussion reflects the realities of how the fishery operates, what its impacts are, and what is being done to address them.

Good environmental reporting requires more than identifying a potential problem. It requires examining the evidence, distinguishing between different fishing practices, and presenting the context necessary for the public to understand the issue.

The Alaska pollock fishery deserves that type of scrutiny. So do the people and communities whose livelihoods depend on it.