Hidden in the Haul: What New Bycatch Data Means for Atlantic Salmon

A new report from Wildlife and Countryside Link, Hidden in the Haul: The true scale of bycatch (June 2026), brings together UK bycatch data across species for the first time. The picture it paints for fish — and for the endangered Atlantic salmon in particular — is stark.

What is bycatch, and why does it matter for fish?

Bycatch is the incidental capture of wildlife that fishing boats are not targeting. Modern gear often cannot discriminate between the target catch and everything else in the water. Towed nets sweep up whatever is too large to pass through the mesh, static nets hang like curtains that snag passing fish and longlines of baited hooks catch indiscriminately. For protected and sensitive fish species, this means animals are caught and killed even though it is illegal to target them commercially.

The report’s headline estimates include over 10,000 seabirds, over 1,000 cetaceans, around 500 seals, over 120 tonnes of protected sharks, skates and rays and over 1,000 endangered Atlantic salmon caught every year in UK waters. The authors stress that these are almost certainly underestimates: government monitoring covers only a tiny fraction of fishing activity — as little as 2.4% of days at sea for midwater trawling and 1.2% for static nets — and self-reporting has proven wholly unreliable. Since marine mammal bycatch reporting became a legal requirement in 2021, fishers reported just nine marine mammals over five years, against estimates running into the thousands.

The impact on Atlantic salmon

Atlantic salmon is a celebrated British fish, famous for its migration from river to sea and back. But its populations have collapsed. In the latest IUCN Red List assessment, the species was reclassified from Least Concern to Endangered in Great Britain, following a 30–50% decline in British populations since 2006. Commercial fishing to eat wild salmon is no longer permitted — yet salmon are still caught and killed as bycatch, because they migrate through the same sea areas as commercially targeted fish.

Salmon are caught mainly in pelagic (midwater) trawls and static nets, but also by bottom trawls, bottom longlines and purse-seines. Significant fishing activity has been recorded in salmon migration regions in every month studied, pointing to a high and persistent bycatch risk.

Two strands of evidence underpin the report’s estimates:

Static nets. The Salmonid Management Round the Channel (SAMARCH) project found bycatch by static nets in inshore South-West England of around one salmon per 1.25km of net. Large boats may deploy several tiers of gillnets, reaching lengths of almost 20km for a single vessel — implying substantial cumulative bycatch that current data cannot precisely quantify.

The mackerel fishery. Estimates of salmon bycatch rates vary widely: from 0.0002 to 5.93 fish per tonne of mackerel in the Norwegian Sea, 4.8 to 7.0 salmon per 1,000 tonnes off Iceland, and up to 37 salmon per 1,000 tonnes in the Faroese fishery. Applying a central Icelandic rate of 5.4 salmon per 1,000 tonnes to the 233,000 tonnes of mackerel UK boats landed in 2024, the report estimates that over 1,000 salmon are likely caught in the UK mackerel fishery each year.Even this is likely a significant underestimate, as it excludes fish that are damaged but escape the nets, and conservation tags that screening equipment fails to detect.

The salmon bycatch problem sits within a wider fisheries-management failure. Mackerel catch limits have repeatedly been set above scientific advice, contributing to a 75% decline in Northeast Atlantic mackerel populations since 2015 — ecosystem damage that runs alongside the protected-species bycatch.

A monitoring gap that is only just beginning to close

Despite being listed as Endangered and protected in the UK and internationally, Atlantic salmon were not included in the work of the ICES Working Group on Bycatch of Protected Species (WGBYC) until 2025. That listing should begin to produce better estimates of salmon bycatch across the North Atlantic from May 2026 — a starting point, but no substitute for direct quantification.

What the report calls for

The report sets out a clear path for fish and for salmon specifically:

• A dedicated Atlantic Salmon Bycatch Mitigation Action Plan with tangible, measurable and time-bound targets.
• Recognising Atlantic salmon and other migratory diadromous fish as sea-fish, so they are included in UK marine research and monitoring programmes.
• Sampling of pelagic vessels operating in young salmon migration highways and adult feeding areas to determine protected-fish bycatch.
• Treating protected-fish bycatch as a material consideration in Fisheries Management Plans for bass, mackerel, herring and sprat, and within the Marine Wildlife Bycatch Mitigation Initiative.
• Rolling out remote electronic monitoring (REM) across the fleet, including under-10m boats, to reveal the true scale of bycatch.
• Phasing out high-bycatch static nets in favour of lower-impact gear in the long term.
• Exploring eDNA as a novel means to detect and quantify salmon bycatch.

The bottom line

Bycatch is avoidable. The evidence shows that an endangered, much-loved British fish is being lost in numbers we are only beginning to measure — and that the real figure is almost certainly higher than the 1,000-plus salmon a year these estimates capture. With better monitoring and a clear, time-bound plan, those deaths can be prevented and salmon populations given a chance to recover.

The Institutes View

“This report should be a wake-up call. Atlantic salmon are now classed as Endangered in Great Britain, with populations down by up to half since 2006 — and yet every year more than a thousand are being killed, unseen and unrecorded, as bycatch in UK fisheries. The true figure is almost certainly far higher, because we are monitoring only a tiny fraction of what our fishing fleet catches. We cannot manage what we refuse to measure. The Institute of Fisheries Management urges the UK Government to recognise salmon as a sea-fish, roll out remote electronic monitoring across the fleet, and deliver a properly funded Atlantic Salmon Bycatch Mitigation Action Plan before this iconic species slips further toward the brink.”

— [Marcus McAuley, Director of Policy], Institute of Fisheries Management

Read the report here