John Dory

Zeus faber

John Dory

Image | Illustration by Sarah McCartney Copywrite Cornwall Wildlife Trust

Description

A strange looking, but delicious fish that is common around the Cornish coast. A John Dory's bizarre shape and long fins make it look from another planet.  It has a large mouth which is used to suck in very large prey items such as fish and shrimps. It has a black spot on each side of the body which is said to be the thumb print of St Peter. It has a fantastic scientific name being named after Zeus, king of the Greek Gods.


Sustainability Overview

John dory is a relatively abundant species in Cornish waters that is caught as a valuable by-catch in trawl and net fisheries. Little is known about stocks of john dory but there is no evidence that numbers are decreasing, however they are a species which has a relatively high vulnerability to fishing. Due to their strange shape young John Dory are easily caught in fishing gear and they can't easily escape thorugh mesh or escape gaps. Avoid eating small John Dory smaller than 29cm that haven't had the opportunity to spawn yet.

Updated October 2017

Find local fish

When is best to eat?

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Beam Trawling

Cornish vessels landing to Cornish ports

Beam trawls are nets attached to 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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Gill Netting

Cornish vessels landing to Cornish ports

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

Cornish vessels landing to Cornish ports

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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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

John dory is a relatively abundant species in Cornish waters that is caught as a valuable by-catch in trawl and net fisheries. Little is known about stocks of john dory but there is no evidence that numbers are decreasing, however they are a species which has a relatively high vulnerability to fishing. Due to their strange shape young John Dory are easily caught in fishing gear and they can't easily escape thorugh mesh or escape gaps. Avoid eating small John Dory smaller than 29cm that haven't had the opportunity to spawn yet.

Updated October 2017

John Dory

Biology

John Dory is an ambush predator that relies on its thin front profile to creep up on smaller fish. Once close it launches an attack by rapidly opening its huge mouth, creating a vacuum that sucks in its unsuspecting prey. John Dories usually live a solitary life but are occasionally found in small schools in inshore waters. They become sexually mature at an age of around 4 years and at a length of 29-35cm. 
Reproduction takes place at the end of winter and at the start of spring in the north eastern Atlantic, (ICES WGNEW report 2010). Vulnerability to fishing is relatively high 68% (Cheung et al 2005).
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Stock Info

Landings of John Dory have fluctuated at around 100 tonnes per year to Cornish ports (MMO data).
Little is known on the stock status of this species which is poorly studied and not considered economically important enough. John dory is vulnerable to fishing as a slow growing species which is difficult to avoid catching due to its unusual shape. 

Management

John Dory catches are not limited by quota. There is also no Minimum Landing size. 
According to Project inshore, there is a disincentive for the IFCA to take management action within the 6 mile limit and similarly for MMO to take management action outside of 0-6nm as this would only apply to local or UK vessels, not foreign vessels, therefore would be seen as unfair. 
 

Capture Info

John dory are caught in Cornish waters by gill nets and in demersal and beam trawls.

References

Seafish Responsible Sourcing Guide John Dory January 2014 v3
MMO landings data Cornwall
ICES WGNEW report 2010
Identifying underutilised species - Tom Catchpole, Cefas, January 2011
Cheung, W.W.L., T.J. Pitcher and D. Pauly, 2005. A fuzzy logic expert system to estimate intrinsic extinction vulnerabilities of marine fishes to fishing. Biol. Conserv. 124:97-111
 

Recipes for John Dory

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