A guide to eating fish

Overfishing is widely acknowledged as the greatest single threat to marine wildlife and habitats. Many fish stocks are widely reported to be in a state of serious decline.

Fishermen are also moving into deeper waters in search of new fishing opportunities, resulting in the destruction of unique habitat and the overfishing of species we know nothing or very little about.

In addition to pressures from overfishing, fish stocks are also affected by climate change and pollution.

Consumers can play a crucial part by knowing which fish to avoid, and substituting these with fish from sustainably managed stocks that are caught or farmed in ways that cause minimum damage to the marine environment.

Supermarkets are making it easier for consumers choose fish with better labelling of where and how fish have been caught. Make sure you look out for the Marine Conservation Society (MCS) blue logo which certifies the fish international standard for sustainable and well-managed fisheries.

The MCS has also ranked supermarkets in a league table of supermarket fish-buying policy. Marks and Spencer topped the table with only one fish on its shelves from the MCS fish to avoid list (plaice from the North Sea). Bottom of the list was Lidl, which provided no information on where and how its fish had been caught.

To help you out, here is a pictured list of UK and European fish that should never pass your lips, and what you can choose instead.

Fish to avoid eating

These are the fish that the MCS believes are most vulnerable to over-fishing and/or are fished using methods which cause damage to the environment or and other species. They have a red, or five-star rating.

Atlantic and North Sea cod

Cod belong to a family of fish known as gadoids. They are a cold-temperate, bottom-dwelling species.

All north-east Atlantic cod stocks are assessed as being overfished, however stocks in the North Sea, Irish Sea, West of Scotland, eastern Channel, eastern Baltic, Greenland, Skaggerak, Kattegat and Norwegian coast are the most heavily depleted.

North-east Arctic (Barents and Norwegian Sea), Icelandic and Faroese cod stocks are healthier, but scientists still recommend that fishing pressure on these stocks also be reduced. Avoid eating cod from stocks which are depleted and where fishing levels are unsustainable. To help reduce the impact of fishing on other marine species choose line-caught cod where available, and try and ask for fish caught using "seabird-friendly" methods as longline fishing can result in seabird by-catch.

Atlantic halibut

Atlantic halibut, the largest of all flat fishes, is a thick-set, flat fish with both eyes on the right-hand side of the body. It lives in deep, cold waters and is slow-growing.

Atlantic halibut is overfished, which means it is caught in such high numbers that a sustainable fishery cannot be maintained by the current population size. It is also assessed by the IUCN - World Conservation Union as endangered.

Dogfish

Spiny dogfish, spurdog, rock salmon or flake are all species of dogfish, which belong to the same family as sharks and rays and give birth to live young.

Spurdogs are long-lived, slow growing and have a high age of maturity. These characteristics make them particularly vulnerable to high levels of fishing mortality. The north-east Atlantic stock is now considered to be depleted and may be in danger of collapse. Species also assessed as critically endangered by the IUCN.

European eel

Eels spawn in the sea and return to freshwater streams to grow. The European eel breeds in the mid-Atlantic Sargasso Sea.

Larvae are carried by the Gulf Stream to the continental shelf of Europe where they turn into colourless elvers or glass eels. Elvers then start to move upriver and as they mature, they change into silver eels, males between 6-12 years old and females between 10-30 years old.

As they mature sexually, they come down the river or migrate to the sea. If silver eels are prevented from returning to the sea, they start to feed again and can live up to 50 years. It is thought that they use the Earth's magnetic field to find their way to the Sargasso Sea to spawn.

There is one single European eel stock. This is severely depleted and at a historical minimum which continues to decline. Eels are exploited in all life stages and those that are fished do not have the chance to breed. Eels spawn only once in their lifetime and it is almost certain they die after spawning. Eels are also farmed but rely on juveniles from wild stocks.

European hake

Hake belongs to a group of fish known collectively as Merluccidae. There is only one species found in European seas. It is a late maturing fish, spawning from February to July in northern waters. As they approach maturity, hake move into deeper off-shore waters.

There are two main stocks for European hake - a northern and southern stock. The northern stock is below the minimum biomass level recommended by marine scientists but harvested sustainably, and the southern stock depleted. Avoid eating hake from depleted stocks and immature fish below about 50cms and during their breeding season, which is February to July.

Porbeagle

Porbeagle is part of a group of sharks known collectively as mackerel sharks, belonging to the family Lamnidae. Porbeagles live for between 30 and 40 years. Maturity for a male is gained at about seven years and for a female at 12-14 years. Porbeagles are found in the surface layers of the open ocean, they also occur in coastal waters. They can grow to a length of 350cm.

Sharks are vulnerable to exploitation because they are slow-growing, long-lived, and have low reproductive capacity. Porbeagle is assessed as critically endangered by IUCN. Avoid eating any species of shark.

Plaice

Plaice is a bottom-dwelling flatfish that sometimes makes long spawning migrations.

Plaice is a long-lived species and subject to high fishing pressure. Stocks in the Celtic Sea, western Channel, south-west Ireland and the west of Ireland are in decline and substantial reductions in fishing efforts are required to achieve sustainable stock levels.

Large numbers of undersized plaice are discarded in particular in beam trawl fisheries for flatfish (sole and plaice) in the southern North Sea. The Irish Sea stock is currently the only stock classified as healthy and harvested sustainably. Avoid eating immature plaice below 30cm and during their breeding season, from January to March.

Seabass

Seabass belongs to a family of spiny-finned fish called Moronidae, which are closely related to groupers. Bass breed from March to mid-June, mostly in April, in British coastal and offshore waters. It is a long-lived species, which may exceed 25 years of age, and can achieve a length of up to 1m with a weight of 12kg. Once mature, bass may migrate within UK coastal waters and occasionally further offshore.

Avoid eating seabass captured by nets that trawl the bottom of the sea. Trawl fisheries target spawning and pre-spawning fish, are responsible for high levels of dolphin by-catch, and deplete stocks available for inshore and recreational fisheries. Choose line or net-caught fish. Ensure nets are 'dolphin friendly'.

Line-caught seabass is a more sustainable choice than fish caught by either trawl or fixed nets. Choose fish which has been sustainably caught by handlining methods in the South West of England. Fish is identified by a tag in its gill. For more information see www.linecaught.org.uk

Skate

Common, long-nose, black and white skate are all endangered. They belong to the Rajidae family which includes skates and rays. Females can reach lengths of about 280cm and males about 200cm. The species can live for 50 years.

The common skate belies its name as it is becoming very rare in UK shallow seas and in European waters. Common skate is assessed as critically endangered by the IUCN.

Sole

Sole is a flatfish with its eyes on the right-hand side of the body, and belongs to the family of flatfishes known as Soleidae. It spawns in spring and early summer in shallow coastal water: from April to June in the southern North Sea; from May-June off the coast of Ireland and southern England; and as early as February in the Mediterranean.

North Sea Dover or common sole stock is classified as healthy and harvested sustainably. Stocks in areas Skaggerak and Kattegat, Eastern Channel and Celtic Sea are also healthy but level of fishing pressure is too high or unknown. Stocks in the Western Channel and Biscay are below the minimum level recommended by scientists and harvested unsustainably.

Avoid eating fish caught in these areas, as well as south-west Ireland, where the state of the stock is unknown and catches the lowest on record. Dover sole from the Hastings Fleet trammel net fishery in the Eastern Channel is certified as an environmentally responsible fishery by the Marine Stewardship Council. Avoid eating immature sole (less than 28cm) fresh (not previously frozen) fish caught during the breeding season (April-June).

Whitebait

Whitebait are the fry (young) of herring and sprat. As with any fishery's future, sustainability relies on young fish being allowed to mature and reproduce to maintain the population. Taking juveniles before they have a chance to spawn undermines future sustainability.

Fish to eat instead

The following is a list of fish available to the UK and European consumer which have been given a green rating of one or two and which the MCS believes are fished within sustainable levels using methods which do not cause unacceptable damage to the environment or other marine species.

Black bream

A member of a group of fish known as Sparidae, the Black bream is one of two species commonly found in northern European seas.

Choose line-caught fish where available, or fish taken in fixed nets where measures to deter marine mammals have been adopted. Avoid eating immature fish (less than 23cm) caught prior to and during their spawning season (April and May in UK inshore waters ), and give them the chance to spawn or reproduce. Choose fish from Cornwall or north-western and north Wales where available.

Gurnard (grey and red)

Gurnards belong to a group of fish known collectively as Trigliadae, or sea robins. They have a strong seasonal migration throughout the North Sea. Although an offshore species, grey gurnard is occasionally found in shallow water. Gurnards are able to grunt or growl by use of muscles associated with the swim bladder, and this is believed to help keep the schools of fish together.

Grey gurnard are taken as by-catch in trawl fisheries in deeper offshore waters and they, along with yellow or tub, are under less pressure than red gurnard. Avoid eating immature fish (less than 24cm) and fresh (not previously frozen) fish caught during the spawning season (April-August).

Lemon sole

The fishery for lemon sole is largely unregulated. Taken as by-catch in trawl fisheries. Only stocks in Norwegian and North Seas are subject to mixed quota restrictions. Choose otter-trawled fish landed in Cornwall where a minimum landing size (25 cms) above the size at which it matures is enforced. Avoid eating immature fish (below 25 cm) and during its breeding period April-August.

Mackerel

Mackerel is a fast-swimming species belonging to a group of fish known as the scombrid family, which are related to the tuna.

You can increase the sustainability of the fish you eat by choosing line- or net-caught fish from fisheries certified by the MSC. In terms of selectivity, mackerel taken by handline is an even better choice as this method only targets mackerel.

Megrim and witch

A common flatfish found in shelf seas throughout the north-east Atlantic, megrim spawns in spring in deep water off Iceland, and between January and April along the edge of the continental shelf to the south-west and west of the British Isles.

Choose megrim otter-trawled from waters (where the mouth of the net remains open) in the west of Ireland and the Western Channel where stock is classified as healthy. Avoid eating immature fish (less than 25cms) and during their spawning season (January to April).

Pollack

Distributed throughout the north-east Atlantic, pollack is a warm, temperate species belonging to the cod family.

The best choice to make, in terms of selectivity and sustainability, is line-caught pollack. Avoid eating immature fish (below 50cm) and during its breeding season (January to April).

Whiting

Whiting are a low value species and often discarded in large quantities. The English Channel stock is currently the only stock assessed by ICES as having full reproductive capacity or healthy. Avoid eating immature fish (less than 30 cms), and fresh (not previously frozen) fish caught during the spawning season (March-April).