| October 13, 2011

Today we look at the Spurdog in the third of our Species Fishing and ID guides.

If you have a picture of yourself with a Spurdog and want to show it off on this page please send it to contact@ssacn.org or post it on the Scottish Shark Tagging Programme’s Facebook page! Remember to keep checking www.tagsharks.com to make sure you don’t miss your chance to show off your PB shark, skate or ray!

#3 Spurdog



Other Names: Squalus acanthias, Spiny Dogfish

Description: Dark grey/brown dorsal surface often with small white spots and a pale grey to white ventral surface. Spurdog have a large sharp spine in front of the first and second dorsal fins. Spurdog Map

Maximum Size: 160cm

Habitat: Found over a wide range of habitats. Often found in deep water over soft muddy sea beds. Although Spurdog are generally considered a bottom dweller they are occasionally found mid-water when feeding on small fish.

Depth: Shallows to 900m.

Distribution: Found along the south west, west and north coast of Scotland, often in deep sea lochs. Spurdog are considered a migratory species and generally move offshore to deeper water during the winter, however anecdotal evidence and tagging data suggests that resident populations may exist in some of the deep water lochs on the west coast of Scotland.

Feeding: Spurdog are opportunistic feeders though their diet consists mainly of small fish and squid. Other prey species include crabs, prawns, shrimps and sea cucumbers.

Biology: Males mature at 11 years old at around 60-70cm (1.8-2.7lb); females mature at 18-21 years old at around 75-90cm (3.8-6.9lb). Spurdog length (cm) can be easily converted to weight (lb) using the SSTP calculator. Spurdog have a gestation period of 22-24 months (the longest of any vertebrate) and are ovoviviparous, this means that eggs hatch and develop inside the female fish. Every 2 years, females give birth to 1-20 fully developed pups around 20cm long. Spurdog may live for up to 70 years.

Caution: Spurdog have sharp spines in front of both dorsal fins that secrete a mild poison, sharp teeth and abrasive skin.

Current Fishery: Cannot be landed in Europe. Recreational fishing for Spurdog in Scotland must be on a catch and release basis. More information on safely handling sharks is available here.

Conservation Status: Critically endangered. Spurdog populations have been depleted by around 95% and are considered locally extinct in many areas.

GFAC Size: Release of Spurdog is required by law in Scotland.

Tagging: The minimum SSTP tagging size for Spurdog is 90cm (6.4lb). For advice on tagging sharks please refer to the SSTP tagging guide here. If you are interested in tagging the fish you catch please send an email to contact@ssacn.org. For more information check out SSACN’s downloadable Spurdog Fact File!

Targeting Spurdog in Scotland

Tackle: From the boat a 6-12lb class rod and suitable reel loaded with 30lb braid is sufficient, braid will aid bite detection and allow the use of smaller lead weights in deep water. From the shore a 5-6oz beach rod paired with a strong multiplier or fixed spool reel loaded with 15-20lb monofilament is generally suitable though some people prefer to use a larger reel with 30-35lb monofilament to resist abrasion over rough ground.

End Tackle: Spurdog have sharp teeth and so require a heavy monofilament or wire hook length: an 80-150lb mono or 60-100lb wire hook length attached to a single size 3/0 to 6/0 bronze barbless hook is recommended. From the boat two hook flowing traces are often used; from the shore pulley rigs and clipped down fixed paternoster rigs are popular particularly when a long cast is required.

Bait: Fish and squid baits are most effective. Large cocktails of mackerel, sandeel, bluey, whiting and squid are extremely effective. Spurdog are active predators and will readily take live baits. In many areas small whiting make excellent live baits for big Spurdog.

Tactics: In the deep water of some Scottish sea lochs Spurdog can be caught during the day, however many shallow marks are considerably more productive in darkness. Spurdog are an inquisitive shark and can be attracted to bait using luminous beads, muppets or hokkais positioned above hooks: luminous attractors should be charged up using a torch before each cast. Baits will often be taken up by small Spurdog, whiting and lesser spotted dogfish: if this is the case using a small whiting as live bait can help pick out the larger Spurdog.

Category: ID Guide

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