Unsustainable fishing practices could be putting pressure on the UK’s crab and lobster populations, conservationists have warned.

The Marine Conservation Society (MCS) said they could be flagship species for sustainable fishing in the UK.

However, several brown crab and European lobster fisheries saw a dent in their ratings in the charity’s Good Fish Guide.

It comes after the charity recently updated 146 ratings in the guide, which helps consumers to buy more sustainably by categorising fisheries using a simple traffic light system based on the latest scientific advice.

MCS said 29 fisheries moved down the sustainability scale, 93 stayed the same and just 10 moved up.

It also reviewed all its ratings for crab and lobster caught in England and Wales – 26 for brown crab and 28 for European lobster.

Only one crab fishery is currently green-rated, based in Shetland, and one lobster fishery, based in Jersey – both of which are well managed and pave the way for what sustainable practices could look like across the UK, MCS said.

Crab fisheries in Northumberland, Kent and Essex, Southern, Isles of Scilly and Devon and Severn Inshore Fisheries Conservation Authority (IFCA) districts all remained amber-rated, but received a lower score due to decreased population numbers.

Shellfish such as crab and lobster are typically caught in pots, traps and creels, lured in by bait which attracts the animals to crawl inside.

As fishers can choose which crab or lobster they take back to land, this way of fishing can be very selective, protecting young and breeding individuals.

But boats can carry and set anything from dozens to hundreds of pots at a time, with no current statutory limit on how many can be used or how many crabs and lobsters can be caught.

This has led to concerns among environmental campaigners about the impact overfishing could be having on populations.

While some areas have a pot limit in place, it is not known if this is enough to improve the stock, MCS said.

Kenneth Bodles, MCS head of innovative conservation, said: “We are really concerned about the picture of crab and lobster across the UK.

“Crab and lobster fisheries are doing well in some areas, and we need the UK Government to adopt similar management measures across the UK.”

It comes after the UK Government published a Fisheries Management Plan (FMP) for crab and lobster in December 2023, which is meant to assess the status of stocks and set out policies to restore them or maintain them at sustainable levels.

MCS said that while the FMP for crab and lobster has a “long-term vision” to achieve sustainable management of fisheries, it is not yet clear how the measures set out will achieve this or to what timescale they will be working.

Alice Moore, MCS Food Fish Guide manager, said: “The Fisheries Management Plan set out by the UK Government is welcome, but it doesn’t currently go far enough in specifying the measures and timescales needed to effectively restore populations of crab and lobster.

“The examples of the crab fishery in Shetland and lobster in Jersey provide evidence that better management can achieve sustainable fishing and still allow populations to thrive.”

MCS is calling for regular stock assessments across the UK, taking place at least every two years to better monitor populations.

It is also calling for controls for crab and lobster fisheries management measures that are responsive to changes in stock status and capture methods that minimise habitat damage and the impact on vulnerable species.

An Environment Department (Defra) spokesman said: “This Government will always back our UK fishing industry, while making sure stocks are healthy and sustainable.

“We continue to work closely with industry to ensure we have the most productive and sustainable sector possible.”