We look here at the spurdog – a fish with few predators until it became of interest to commercial fishermen – and the smooth-hound which shares many of its characteristics lere was a time when many anglers dreaded meeting a shoal of spurdog, as this meant that most other fish would leave the area. There are few fish in the sea that can strip an area of fishlife like a pack of spurs! Voracious in appetite, they move inshore during the summer months to release their young and eat everything they find.
The spurdog, Squalus acanthias, is a small member of the extensive shark group, the Elasmobranchii. Identification of the species is no problem, for there are two distinct anatomical features that distinguish the spurdog from all other dogfish common to British waters. The spurdog has two extremely sharp, curved spines on the back, one in front of each dorsal fin. These spines can wound deeply if a fish turns on the angler when handled, wrapping its body around the wrist or arm.
Another characteristic of the spur-dog is the absence of the anal fin on the underside of the body, which is found between the pelvics and the tail in all spotted dogfish and smoothhounds. The spurdog is also one of the minor sharks without nictitating membranes, or third eyelids, that can be moved over the surface of the eyeball.
The fish is a dull grey-black on the upper part of the body, turning to sooty grey on the flanks, with the belly a dull white. The body if streamlined and sleek. Spurdogs are livebearers, and like all other species of shark and dogfish, copulate. The eggs are fertilized as they travel down the oviduct and a capsule forms around them that does away with the need for a placenta to nourish the embryos. The eggs then develop into embryonic fish, at which point the capsule will break, allowing the minute fish, with yolk sacs attached, to move freely within the oviducts. Generally, shark em-bryos live from the contents of their yolk sacs, but sometimes a nutrient is generated in the oviduct which is eaten by the developing young.
The female produces about 20 pups during the months of August and September. There is con-siderable evidence to show that at this time the females will separate from the male fish of the pack, travelling into shallow water to expel their young. Certainly, the sexes are rarely found in company during the middle months of the year. No doubt the separation serves to en-sure the survival of the maximum number of pups. The females themselves begin to eat the im-mature fish immediately after they are expelled, but with the males ab-sent enough pups survive to become adult and then plunder the fish of other species.
Mid-water trawling has done sea anglers a favour in reducing the numbers of spurdog. A shortage of round fish for the commercial market, together with a growth in demand for ‘boneless’ species for the fish and chip shops, have made the spurdog a target for professional fishermen. The spurdog has filled this demand admirably as it has sweet-tasting flesh and a soft, car-tilaginous skeleton.
The spurdog is not an exceptional fighter, but it can, nevertheless, cause havoc to the terminal tackle of sea anglers. Given a chance to show its ability on light gear, it can acquit itself well but, unfortunately, the spurdog is usually taken on tackle better suited to much larger fish. As a result it is hauled in, unable to put up much of a fight.
Challenge of light tackle
When a spurdog is sought deliberately on light tackle, it can really battle. Taken from the shore, as often happens when fishing a bass beach after dark, the fish will pull as hard as any bass.
The fierce attack methods of this predator and the continuous writhing of the hooked fish tend to tangle tackle. Unlike bottom-dwelling species, which suffer a decompression problem when being drawn to the surface, the spurdog has no swimbladder and will continue to thrash in its efforts to shed the hook – even after it has been brought aboard a boat. To avoid tangles, the tackle should be kept as simple as possible, with hook snoods only long enough to present the bait effectively. Long traces can only lead to massive tangles.
Importance of supple wire
The sharp teeth and rough skin of the species force the angler to use wire hook links or nylon of over-thick diameter. Wire traces need not be of over-strong breaking strain as the fish does not grow to the proportions of tope. But the wire must be as supple as possible. Stiff, single-strand wire kinks readily. If you catch even one fish it can reduce the breaking strain markedly by a twisting motion that quickly places a kink in the wire. Supple braided or twisted wire will allow repeated use. Spurdog are found close to the surface, near the bottom, and in mid-water, so paternosters or ledger rigs with a single 60 hook on 20 lb line and a light sea rod make adequate tackle. For boat fishing use rods in the 15-20 lb class. From the shore, an lift light beachcaster suits most situations. This gives the fish a chance to move, and the angler obtains the best possible transmission of the vibrations from the hooked fish’s movements.
Many baits can be used. Almost anything will be taken. Fish baits are best, however, as the predatory instinct is finely tuned to smell when a spurdog comes upon a lask of mackerel, herring or whole sprat. When a massive pack of spurdog arrives there are times when they can be caught with hardly any bait at all! They grab at anything – a flashing spoon attached to a cod paternoster rig has been known to take them continually for a whole afternoon from a stationary boat.
Extracting the hook
Handling the boated fish can present a novice angler with a few difficulties. The best method of removing the hook involves first immobilizing the fish by standing on its tail. With the trace held out tight, the fish should be grasped just at the back of its head. The hook can then be extracted with a pair of long-nosed pliers. If the spurdog is not to be thrown back, it must be killed by a sharp blow across the snout. Then you are free to remove the spurs with the pliers to prevent them embedding in either the fish bag or yourself.
Don’t take too many fish from one shoal. It becomes highly repetitive, and an enjoyable day’s angling demands a change in fishing style from time to time. And although there may be a lot of spurdog, our seas are becoming denuded of so many angling species that the sea angler should discipline himself to follow certain commonsense conservationist guidelines.
The spurdog is sometimes confused with other small sharks such as immature tope. Two species which can be mistaken for a spurdog are the smoothhound, Mustelus mustelus, and the associated but lesser-known fish Mustelus asterias. Both at first sight look like the spurdog, but lack the spines in front of the two dorsal fins. M. asterias is also known as the stellate smoothhound.
Unlike the spurdog, which is found in clean, deep, western waters, the smoothhounds are fond of shallow, estuarine areas which are likely to provide the type of food they prefer – crabs and crustaceans. Both have the kind of grinding teeth, arranged in flat rows, that are associated with members of the skate and ray families.
Neither of the smoothhound species could be called sporting fish. Commonly hooked by shore anglers, they are beached like weighty sacks. They tend to swim in with the baits, faithfully following the direction of the pull of the rod.
It is easy to identify the smooth-hounds, or rather to separate them from other dogfish. They are ungainly creatures. The fins are much larger than those found in the other species. They may have light spots along their flanks. But the most im-portant identifying feature is the mouth. The teeth and jaws of the smoothhound are intended for grin-ding hard-backed creatures; in the spurdog they are for tearing flesh.
The teeth also give a clue to the habitual environment of these two species. Smoothhounds are essen-tially bottom-feeders, spending their time cruising the mixed weed and rocky ground in search of prawns, lobsters and crabs. They come close inshore during the summer months, both to feed on the rich crustacean life and to give birth to their young, for the smoothhound is also a livebearing dogfish.
Look for the species in sand and mud estuaries. A simple ledgered trace is a suitable rig. Both worm and crab baits will lure the fish, but remember to use a short wire trace to guard against those powerful, grinding teeth. A 60 hook on 12in of cable-laid, supple wire should be joined to the reel line by a swivel. Such a rig will also be useful when fishing for rays and small conger. In fact, the style of fishing and type of bite you get is common to fishing for thornback rays and other inshore members of the skate family. An initial nod of the rod tip is followed by a few sharp twitching movements as the fish moves its body over the bait, then there is a pause before the reel rattles as the line moves out steadily off the spool.
Fishing for the smoothhound is one kind of shore angling where the rod can be left in a rest. Just put the ratchet on, with the reel left out of gear. Strike firmly to set the hook, as the fish has a tough jaw area. Do not expect a fast and furious fight – the smoothhound is not a speedy opponent – but it can be a dour fight where the fish has a strong tide to its advantage. Keep the fish out of inshore weedbeds, for it is well able to dive into shelter from which it is difficult on light shore gear, to extract it.