Genetic Breakthroughs Drive West of Scotland Herring Quota Changes

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Genetic analysis splits West of Scotland herring stocks. Quotas will rise temporarily before falling to 1,557 tonnes in 2026

Genetic Advances Separate Herring Stocks

The management of herring fisheries in the West of Scotland has undergone significant changes following breakthroughs in genetic analysis.

For decades, herring in the northern area (6.aN) and the southern area (6.aS) were often assessed jointly due to difficulties in distinguishing the populations.

However, a project completed in 2020 successfully developed genetic profiles that can differentiate between the northern autumn spawning stock and the southern winter spawning stock even when they mix.

This scientific advancement allowed the International Council for the Exploration of the Sea (ICES) to split the combined assessment back into component stocks during a benchmark meeting in February 2022.

From Zero Catch to New Limits

The fishery has faced strict limitations in recent years. Due to low stock levels, the herring fishery in this region operated under a zero catch advice with a monitoring Total Allowable Catch (TAC) from 2016 to 2022.

This monitoring allowance was primarily intended to maintain sampling levels for scientific assessment. Following the separation of the stocks, the fishery transitioned back to a standard TAC in 2023.

While the quota is scheduled to increase in 2024 and 2025, current advice indicates a reduction in 2026 to 1,557 tonnes. This figure remains significantly lower than the 2015 TAC, which stood at 22,690 tonnes.

Ecosystem Impact and Biological Tracking

Herring play a critical role in the marine ecosystem off the West of Scotland. They serve as a vital food source for predators including grey seals, whose numbers have increased in the region, as well as cetaceans and seabirds.

To track the age of these fish, scientists use a specific terminology known as rings rather than years. This method helps researchers account for the differences between autumn and spring spawning components, ensuring that a fish is correctly classified based on its spawning season.

Current assessments indicate that the stock productivity has declined since the 1970s and is currently fluctuating at low levels.

Read the "Stock Annex: Herring (Clupea harengus) in division 6.aN (West of Scotland" by clicking here

Source: ICES