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Common Sole

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General

Flatfish

Flatfish belong to the order Pleuronectoformes. There are more than 500 species of flatfish. Flatfish live on and partly in the seabed, only the halibut swims higher up in the water column. Flatfish have an oblong, flat shape and their eyes on one side. The upper-side, the eye-side, of the flatfish has a camouflage colour and the underside is white. It may seem like flatfish swim on their belly, however, in fact, they are laying on their side. Flatfish larvae have a regular fish shape, with eyes on each side and a vertical swimming mode. After 6 weeks, one of the eyes migrates upwards, over the head to the other side. From now own, the flatfish swims with their eyes up and their blind side facing the seabed.

The best known flatfish species in the Netherlands are sole and plaice. Other flatfish species that occur in the North Sea are the common dab, halibut, turbot, brill, European flounder and lemon sole. Flatfish are caught with beam trawls, pulse trawls or demersal otter trawls.

 

Common Sole

Common sole is one of the most important species for Dutch fishermen. It is a relativily long and narrow flatfish, with eyes on the right side. They reach spawning maturity at 3-5 years at a length of 25-35 cm. The smallest size of sole that is commercially traded is in dutch called a ‘sliptong’. This size class has not reached the spawning age. The largest size is called ‘zeetong’. Soles can reach up to 70 cm and weigh up to 3 kg. The maximum age is around 26 years, but those are not found anymore in the North Sea. Spawning season is from april till june in the southern Northsea. It has a preference for relatively shallow water with sand or mud covering the bottom.

Common Sole

Solea solea
Origin

North Sea, Skagerrak and Kattegat (FAO 27)

Farming- / Catch method

Scottish seining/flyshoot, Beam trawl, Demersal longlines

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Explanation assessment

In 2019 several Danish and Dutch fisheries on common sole (solea solea) were MSC certified within the ‘Joint Demersal Fishery‘. These fisheries fish in Skagerrak, Kattegat and the North Sea. They use miscellaneous gear to fish for sole, otter trawls, Scottish and Danish seines, longlines and the controversial beam trawl.

Please note: Good Fish does not recommend the MSC beam trawl sole

Fisheries that target sole and plaice use several types of bottom trawls, with varying impact on the seafloor and different ranges of CO2 emissions. The least sustainable gear is the beam trawl. Good Fish is critical towards the certification of the beam trawl. The recommendation for sole and plaice, caught with the beam trawl, has a RED rating on our seafood guide. We advice supermarkets and consumers to avoid this fish.

Common Sole

Solea solea
Origin

Atlantic Ocean, northeast (FAO 27)

Farming- / Catch method

Anchored gillnets

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Fish stocks and fishing pressure
Ecosystem effects
Fishery management
Final assessment
Explanation assessment

The common sole stock in the North Sea has grown in the past years and is since 2011 within biological safe limits again. The fishing pressure is almost at the level that is determined in the long-term management plan for sole.

Set gillnet fishery is quite selective with little bycatch of undersized fish or other species. Sometimes dab, flounder or plaice are bycatch. These bycatches are generally landed. There is incidental bycatch of porpoises and sea birds. The porpoise population is under pressure. Aggregate bycatches in (set gillnet) fisheries contribute to this.

This fishery has no significant bottom impact.

The management of this fishery is done at EU-level and a long-term management plan for sole has been accepted. This plan is positive for sole.

 

Common Sole

Solea solea
Origin

Atlantic Ocean, northeast (FAO 27)

Farming- / Catch method

Electric pulse fishing

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Fish stocks and fishing pressure
Ecosystem effects
Fishery management
Final assessment
Explanation assessment

The common sole stock in the North Sea has grown in the past years and is since 2011 within biological safe limits again. The fishing pressure is almost at the level that is determined in the long-term management plan for sole.

A pulse trawl is a more selective method to catch flatfish than the traditional beam trawl, but there is still a lot of bycatch and a lot of discards. The survivability of these discards are low. A pulse trawl has a less heavy impact on the seabad than a beam trawl. The effects of the electric pulses on vulnerable species, like rays, are not fully known.

The management of this fishery is done at EU-level and a long-term management plan for sole has been accepted. This plan is positive for sole. However, measures are needed to limit the bycatch and environmental impacts.

 

Common Sole

Solea solea
Origin

Atlantic Ocean, northeast (FAO 27)
Deelgebieden: Skagerrak and Kattegat

Farming- / Catch method

Beam trawl

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Fish stocks and fishing pressure
Ecosystem effects
Fishery management
Final assessment
Explanation assessment

The common sole stock in the North Sea has grown in the past years and is since 2011 within biological safe limits again. The fishing pressure is almost at the level that is determined in the long-term management plan for sole.

The minimum mesh size of 80mm in the beam trawl fishery on sole in the southern North Sea leads to considerable bycatch of undersized young fish, mainly young plaice. Undersized fish needs to be discarded back in the sea. Beam trawl fisheries discard about half of the total catch. The main part of these discards doesn’t survive. Fishing with bottom trawls touch the seabed and there is a direct disruption of the bottom life. Intensive fishing with a beam trawl leads on the long-term to a change in species composition in sea.

The management of this fishery is done at EU-level and a long-term management plan for sole has been accepted. This plan is positive for sole. However, measures are needed to limit the bycatch and environmental impacts.

 

ASC label

Fish with the ASC label is farmed in a sustainable manner.

MSC label

Fish with the MSC label is caught sustainably.

Good fish

This fish is not being overfished or is being responsibly farmed, with minimal impact on the environment.

Second choice

This fish is a second choice. There are still some improvements to be made in this fishery or fish farm.

Avoid

Do not buy this fish. It's being overfished or the way it's farmed or caught has a negative impact on the environment.

Welfare

There is fish available of this species that is farmed or caught using high welfare standards.

GlobalG.A.P.

GlobalG.A.P. certified farms are doing a step in the right direction in terms of sustainability. A few species with this label are getting a better score on the VISwijzer.

Organic

Organic standards are the strictest when it comes to fish feed. They also require certain measures for animal well-being.