The latest round of updates to the Marine Conservation Society‘s Good Fish Guide – a downloadable guide that gives consumers and businesses access to seafood sustainability advice – highlights the recent decline in mackerel populations around the UK due to overfishing. 

Twice a year, the UK’s ocean membership charity updates the Guide in line with the latest scientific advice and this spring’s update sees 17 ratings change, with 8 moving down the sustainability scale.

One of the most noticeable changes is that ratings for mackerel have dropped further down the sustainability scale.

According to the UK charity, Northeast Atlantic mackerel has been overfished by an average of 23% over the last four years. It now therefore recommends against businesses sourcing the species caught by midwater trawl.

Prior to April 2023, all mackerel ratings had been on the charities green list, but at that time Northeast Atlantic mackerel caught by midwater trawl moved to category 3 or amber due to a steady decline in population.

Alice Moore, Good Fish Guide Manager at the Marine Conservation Society, said: “It’s deeply concerning to see a source of seafood that was once a sustainable choice in such decline. Mackerel is under immense pressure from fishing activities across multiple nations, and the stock will soon be no longer able to sustain itself.

“We’re witnessing a steady decline in numbers, and they are nearing a breaking point. Immediate action must be taken by the UK Government to work with other nations to align catch limits with scientific advice.” 

The Marine Conservation Society’s Good Fish Guide is the charity’s flagship tool for identifying sustainable seafood, using a traffic light system for consumers, and a 1 to 5 scale for businesses. The system colour-codes each rating depending on where and how a species is caught or farmed.

‘Best Choice’ options get the green or 1 or 2 ratings, seafood options that need improvements in their conservation receive an amber rating (3 or 4), and ‘Fish to Avoid’ are listed as red (rating 5). The Marine Conservation Society recommends businesses, including restaurants and supermarkets, to only stock seafood that is rated 1 to 3.

This spring’s update to the Good Fish Guide sees Northeast Atlantic mackerel caught by midwater trawl move from a 3 to a 4, recommending that businesses do not source it. Mackerel caught in this way in the Northeast Atlantic makes up most of what supermarkets and restaurants sell. Mackerel caught in the Northeast Atlantic by hook and line, moves from a 2 to a 3.

Although some management measures are in place for Northeast Atlantic mackerel, enforcement remains insufficient. Countries like Norway, Iceland, the Faroe Islands, and the UK, all fish this stock but there is no unified management plan to prevent overfishing across the entire fishery.

Catch limits (Total Allowable Catches or TACs) set by all parties have consistently exceeded scientifically recommended levels by between 5% and 80% since 2009. In recent years (2020 – 2024) TACs were, on average, 39% higher than scientific advice. Although actual catches have typically fallen below these TACs, they still exceeded recommended levels by an average of 23% (188,410 tonnes).

While there is agreement between countries that catches should match scientific advice, there is no agreement on how to share quotas between the countries. All parties must work together to develop an appropriate strategy that leads to a recovery of this stock.

As a more sustainable alternative to mackerel, the charity recommends herring from the North Sea and eastern English Channel, or sardines from Cornwall certified by the Marine Stewardship Council (MSC).

Other notable movements on the Good Fish Guide see monkfish caught in the North Sea move from amber to green and blue marlin move off the red list, from a 5 to 4, due to a slight improvement in fishing pressure.

Farmed ratings reviewed remained the same, with certified responsibly produced basa and tilapia remaining green rated, and farmed bluefin tuna remaining red rated.

The charity updates a proportion of ratings on the Good Fish Guide twice a year, depending on the latest scientific advice. The next update is due to be in October.

Visit the charity’s website for more information on the Marine Conservation Society’s Good Fish Guide and how the ratings work.

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