Cod

Gadus morhua

Cod by Sarah McCartney

Image | Sarah McCartney, Copyright Cornwall Wildlife Trust

Description

Hugely popular in England as the main fish used in fish and chips. White, flakey flesh with few bones make this a perennial favourite. Sadly Cod stocks are not doing so well in Cornish waters due to some warm winters, fortunately there are lots of other Cornish species that taste just as good in batter! 

 


Sustainability Overview

Cod has been over fished in many areas of the Atlantic but due to good managment many stocks are now far healthier than they were 10 years ago. In the southwest of England cod stocks fluctuate. Cod do well in cold years and not so well when the winters are mild. Recent mild winters have resulted in poor survival rates of young cod and the stocks are now considered below optimum levels, with fishing effort still too high. In Cornwall cod stocks have benefitted since the introduction of the cod box, a seasonally closed area off Cornwall’s North Coast brought in under pressure from local fishermen that protects breeding cod during the early spring breeding season. 
 
 

 

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When is best to eat?

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Handlining

Cornwall, areas VIIe-h

A low impact, selective method of fishing using hook and line.

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Gill Netting

Cornwall areas VIIe-h

Gill nets are lightweight nets made of nylon (monofilament) fishing line that are anchored to the seabed and are used to catch fish by entangling the gills.

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Demersal Trawl

Cornwall, areas VIIe-h

Demersal trawls are large nets that are pulled through the water with the bottom edge of the net touching the seabed. At each edge the net is pulled open by metal ‘trawl doors’. Sometimes referred to as Otter trawling.

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Beam Trawling

Cornwall, areas VIIe-h

Beam trawls are nets with a steel beam that holds the net open. The belly of the net is made of chains and the upper surface of the net is mesh. Beam trawlers pull two nets along the seabed simultaneously.

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How we rate fish

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Cornwall Good Seafood Guide rates fish on sustainability using a scale of 1 to 5.

1, 2 and 3 are recommended, Fish to avoid are rated 5.

We use the system devised by the Marine Conservation Society (MCS) so our scores are comparable with the scores produced by MCS for the UK and fisheries from all around the world. For more information on scoring click here.

Sustainability Overview

Cod has been over fished in many areas of the Atlantic but due to good managment many stocks are now far healthier than they were 10 years ago. In the southwest of England cod stocks fluctuate. Cod do well in cold years and not so well when the winters are mild. Recent mild winters have resulted in poor survival rates of young cod and the stocks are now considered below optimum levels, with fishing effort still too high. In Cornwall cod stocks have benefitted since the introduction of the cod box, a seasonally closed area off Cornwall’s North Coast brought in under pressure from local fishermen that protects breeding cod during the early spring breeding season. 
 
 

 

Cod by Sarah McCartney

Biology

Cod are large predatory fish that hunt small fish and animals that are found on and near the seabed. They are greedy and powerful fish. Cod prefer cool waters and are in the same family as several other whitefish such as whiting, haddock, pollack, pouting and ling.  Their depth range is 0 - 600 m, but they are more usually found between 150 and 200 m. They have a common length of 100 cm and can grow up to a massive two meters in length. Maximum published weight 96 kg and a maximum reported age of 25 years. In the North Sea cod mature at 4-5 years at a length of about 50 cm. They spawn in winter and the beginning of spring from February to April. Fecundity ranges from 2.5 million eggs in a 5 kg female to a record of 9 million eggs in a 34 kg female. The fish has a protruding upper jaw, a conspicuous barbel on the lower jaw (used to look for food), and a light lateral line, curved above the pectoral fins. Cod are widely distributed in a variety of habitats, from the shoreline down to the continental shelf. Juveniles prefer shallow (less than 10-30 m depth) sublittoral waters with complex habitats, areas with gravel, rocks, or boulder, which provide protection from predators. Adults are usually found in deeper, colder waters. During the day, cod form schools and swim about 30-80 m above the bottom, dispersing at night to feed. The Trevose bank off the north coast of Cornwall is one of the most important cod spawning areas in Europe and adult cod congregate there in early spring to spawn in huge shoals.  These aggregations are now better protected from fishermen thanks to the cod box. 

Stock Info

According to ICES scientists cod populations are below maximum sustainable yeild and fishing efforts are too high in our areas. As cod is a cool water species warm years result in poorer survival of young fish. This is known as poor recruitement. Conversely when we have cold winters cod does better. Sadly we are now in a position where cod stocks are not as healthy in our waters as warm, mild winters have resulted in poor recruitments to the stock. Spikes in cod populations are typical in this area and can lead to problems in years when it results in accidental by catch of young fish. 

Management

Cod stocks are carefully managed through the EU Common fisheries Policy which sets quotas that control the amount of fishing. The minimum landing size for cod  is 35cm in Cornish waters. The aim of the EU Common Fisheries Policy is to work towards recovery of all commercial fish species and cod across European waters are recovering but in our waters warm conditions have meant that they are not doing so well. The industry led closure of the Trevose cod box was set up in 2006 to protect spawning cod in one of Europes most important spawning areas. Prior to this closure fishing vessels were targetting spawning aggregations of cod at a really vulnerable and important stage of life. The closure has had a  positive impact on cod stocks and has also helped many other species who spawn in this area at the same time of year. 

Capture Info

Cod are caught by Cornish fishermen in gill nets, handlines and trawls. Handlining is the most sustainable method of fishing for cod but the quanties landed are low. 

References

 
 
Project inshore pre assessment data base- Project Inshore 
Project inshore Species Profiles stage 1 November 2012 Food certification international for Seafish
Marine conservation Society Good Fish Guide and Fishonline 
PICES Gear selectivity; www,pisces-rfr.org
 
 

Recipes for Cod

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