Spurdog

Spurdog by Marc Dando

Image | Marc Dando, Copywrite protected

Description

Also known as spiny dogfish, rock salmon or flake the spurdog is a small grey shark with spines at the base of each dorsal fin. They grow to a maximum size of 124 cm.


Sustainability Overview

Spurdog is a long-lived, slow-growing, and late-maturing species and therefore particularly vulnerable to fishing mortality. The North East Atlantic stock is now considered to be depleted. Targeted fisheries for the species have effectively been outlawed as there is Zero TAC for the species in 2015 and 2016. Bycatch in non-target fisheries is still thought to be a problem and must be minimised to allow the stock to rebuild. The species is assessed as Critically Endangered in the North East Atlantic by IUCN and has been recently added to the OSPAR list of threatened and/or declining species and habitats.

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When is best to eat?

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All Applicable Methods

Avoid eating Spurdog, often marketed as rock salmon, or flake, regardles of the method of capture.

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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

Spurdog is a long-lived, slow-growing, and late-maturing species and therefore particularly vulnerable to fishing mortality. The North East Atlantic stock is now considered to be depleted. Targeted fisheries for the species have effectively been outlawed as there is Zero TAC for the species in 2015 and 2016. Bycatch in non-target fisheries is still thought to be a problem and must be minimised to allow the stock to rebuild. The species is assessed as Critically Endangered in the North East Atlantic by IUCN and has been recently added to the OSPAR list of threatened and/or declining species and habitats.

Spurdog by Marc Dando

Biology

Spurdogs are a highly migratory species that is capable of moving great distances in very little time. They grow slowly and have a low rate of reproduction meaning that this species is very vulnerable to fishing. Biological vulnerability rating 69%, Cheung et al 2005. Spurdog (spiny dogfish, dogfish, rock salmon or flake) are sharks. In the North Atlantic female dogfish grow to a maximum total length of 110-124cm, males 83-100cm. In the Northwest Atlantic spurdog mature at around 60cms total length and at an age of 6 years for males and at around 75cms, at an age of 12 years for females. In the Northeast Atlantic females are reported to mature slightly larger and older at 83cm total length and 15 years. Gestation or pregnancy lasts between 18 and 22 months, one of the longest recorded for any vertebrate, and they give birth to live young. The fecundity of spurdog increases with length, and females of 100-120cm produce a higher number of pups (10-21) than those females below this length. Spurdog tend to aggregate in groups of one sex and size.

Stock Info

As the most commercially valuable shark species caught in European waters spurdogs have been fished at high levels for the last 40 years and stocks are thought  to have decreased by over 90% since the 1970’s in European waters (ICUN). The species is assessed as Critically Endangered in the North East Atlantic by IUCN and has been recently added to the OSPAR list of threatened and/or declining species and habitats.
ICES say that Spurdog stocks suffered a high fishing mortality for more than four decades, and was not managed during this time. Management measures have been restrictive only since 2007. The spawning biomass and recruitment have declined substantially since the 1960s and are now stable at a low level. Exploitation is now below MSY level which is good but stocks are not yet above safe levels.
Spurdogs  have tough skin which means that they have a higher survivability when accidentally caught and released back into the sea by fishermen, providing they haven’t drowned from lack of oxygen. 
 

Management

It is currently illegal to land spurdogs commercially, a Zero Total Allowable Catch has been set in European Waters. Since 2010 there has been a Zero TAC with a 10% by catch allowance and a maximum landing size of 100cm in EU waters. As spurdogs are patchy in their distribution when fishermen accidentally catch spurdogs they will usually catch large numbers. CFPO and NFFO are lobbying DEFRA to review the Zero TAC which they say does nothing to reduce mortality of Spurdogs and results in discarding so that less is known about the health of the stocks. Project Neptune is working to asses the scale of this problem and to provide management advice.

Capture Info

Spurdogs have been targeted in the past using nets and longlines but are now not targeted but are occasionally caught accidentally in gill nets, trawls and with longlines. Any caught currently have to be discarded as they are not allowed to be landed.  

References

ICES advice October 2014 Spurdog in the Northeast Atlantic
MMO landings data
 
Shark Trust; 2010. An Illustrated Compendium of Sharks, Skates, Rays and Chimaera. Chapter 1: The British Isles and Northeast Atlantic. Part 2: Sharks. 
OSPAR Commission 2010, Background information for spurdog or spiny dogfish, biodiversity series 2010
MB0125: Common Fisheries Policy reform implementation: aligning zero quota species and improving fisheries management – a spurdog case study. DEFRA
 
Fordham, S., Fowler, S.L., Coelho, R., Goldman, K.J. & Francis, M. 2006. Squalus acanthias. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 28 January 2015.
 

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