The spiny spurdog

The spiny spurdog

In recent seasons spurdog numbers have dropped as a result of commercial overfishing. Vast numbers, taken in nets and on longlines, are skinned, then sold with other dogfish as rock salmon or flake. The spurdog’s habit of shoaling in huge numbers, along with its fighting qualities have made it popular with anglers. But now the days of big catches on rod and line appear to be numbered.

Well-named shark

Easily distinguished, the spurdog is the only common shark to have a spine at the front of both dorsal fins. These spines, fairly long, are extremely sharp and can inflict a large wound which takes a long time to heal. It pays to take great care when you are handling a spurdog.

The spurdog is dark grey on the upper half of its slender body, with scattered white spots over the back and sides. The belly is lighter in colour. The snout is pointed and the shark has large eyes and five medium sized gill slits.

The species grows to a maximum length of 1.2m (4ft), but it is more common to find specimens lm (3ft) long. Females grow larger than males, with a maximum weight of over 20 lb (9kg). Good specimen targets to aim for are 10-12 lb (4.5-5.4kg) from a boat and 6-8 lb (2.7-3.6kg) from the shore.

Follow the feeding

The spurdog is generally found on or near the sea bed – especially where the terrain is sandy or muddy – at depths of 10-100m (33-330ft). But it has been contacted by trawls at depths of 950m (over 3000ft) and also right at the surface.

It is thought to approach the surface at night to feed. Schooling fish such as whiting, herring, sprat, pilchard, sandeel and even garfish are the mainstay of the spur-dog’s diet. However, it doesn’t appear to be too fussy in its eating habits, and consumes various bottom-living species such as flatfish, dragonets and cod. It also takes crabs and squid.

Growing up in the sea

This species of shark bears its young live. Litters range from three to eleven pups. The eggs have large yolks and are enclosed in a thin membrane which breaks down as the pups grow. The pups vary in size from 20-33cm (8-13in) long at birth. Both the number of the pups carried and their length at birth depend on the size of the mother.

Females mature at 75-80cm (30-32in) long, but males mature much smaller, at 55-60cm (22-24in). The large size the female must reach before breeding, and the long gestation, greatly affect numbers.

Population controls

Early this century the spurdog was sought after for its large oil-bearing liver. It was also considered a pest by many because huge foraging packs damaged nets, while others caught large quantities of fish.

However, recent levels of exploitation have taken their toll and careful regulation is now needed if stocks are to be maintained at reasonable levels.

Fishing tackle

Since the spurdog favours sandy/muddy sea beds, your tackle should be light to medium so you can enjoy the fish’s fighting qualities. Uptiding, for example, is a sporting method which can produce good numbers; a 15-30 lb (6.8-13.6kg) downtide set-up also works well. Squid seem to account for many of the specimens landed.

Fewer spurdogs are caught from the shore, but standard beachcasting outfits should deal with any you encounter.