The angler fish lies on the seabed, perfectly camouflaged, and attracts its prey to within striking distance by waving a lure around—but is itself caught mainly by accident.
The angler fish (Lophius pisca-torius), also known as the Frogfish, is widely distributed in European seas, while a closely related species, known as the goosefish, is found along the Atlantic coast of the United States and Canada.
In British seas the angler fish is especially common on the coasts which face the open sea, and as a result is least common on the East Anglian coast and in the eastern Channel. It is, nevertheless, caught in small numbers on these coasts. Indeed, the current British shore-caught record fish was taken from the shore of Canvey Island in the Thames Estuary, by H G T Legerton in 1967. It would be difficult to imagine a less likely haunt for the species than this, although other large specimens have been caught in the mouth of the Thames over the years. The current shore-caught record stands at 68lb 2oz, and it is a sobering thought for the paddlers and bathers at Southend-on-Sea and other nearby resorts that such a large and formidably toothed fish could be caught so close inshore!
Boat-caught record fish have come from the area normally associated with the angler fish—the western Channel. The current record went to K Ponsford for an 82lb 12oz fish caught off Mevagissey, Cornwall, on 14 April 1977, which toppled the previous record of 7412lb, established southwest of Eddystone by J J McVicar in 1972. These areas are far more typical of the habitat of the species than the shallow, muddied waters of the North Sea.
Functional but ugly
Although the angler fish is often described as ugly because of its huge mouth, broad head and large teeth, such judgements only reflect pre-judices of the observer. The species is, in fact, beautifully adapted to its own life-style.
Primarily demersel, or bottom-living, the angler fish has a head and body flattened on top, helping it to blend almost imperceptibly into the seabed. The small stump-like pelvic fins are hidden beneath its nearly spherical body and most of the time they lie pressed against the belly. However, when the fish needs to make small movements, these fins can be angled forward to lift the body off the bottom. At such times, the curiously elbow-like joints of the pectoral fins take the weight of the body, permitting a little motion.
The life of the angler fish is essentially one of lying still and not being seen. The match between the colour of its back and the sand or gravel on which it lies is near perfect. As in other bottom-living fishes, the eyes can detect the tone of its background and to some extent the col-our, causing the colour cells in the skin to expand or contract automatically until the overall colour is very similar. The roughness of the back is caused by blunt spines hidden under the rather loose skin, while the skin itself is liberally supplied with small flaps and papillae, which conceal the fish’s outline. These are most developed along the edge of the body and tail, where they form a distinct row of uneven lappets, or flaps.
Angler settles in the swim On board a boat these flaps look like just another example of the ugliness of the creature, but actually provide it with a subtle means of blending into the seabed more effectively. An angler fish taking up its position swims along the bottom, settles, often shuffles around on its pectoral and pelvic fins and then, before finally settling, raises itself up on its pelvics and drops suddenly. The water expelled from underneath the body fans out the skin flaps around the outline of the fish, disturbing the sand. As this settles again it falls partly over the edges of the body, giving the fish perfect concealment. Underwater, a settled angler fish can only be picked out by the luckiest of chances. In general, they are fairly safe from predators, possibly because of their size but also because of their camouflage, although in Icelandic waters they have been found in the stomachs of sperm whales on numerous occasions. Undoubtedly, the main reason for their near-perfect camouflage is connected with their feeding habits, which, incidentally, give rise to the name angler fish.
The lure on the snout
On the snout, nearly midway between the mouth and the eyes, there is a slender, flexible ray, which is in effect a modified dorsal fin ray. A fleshy flap of uneven shape at the tip of this ray can be vibrated or moved to act as a lure to smaller fishes. The angler fish’s eyes, which can scan the seabed all around as well as look upwards, give early warning of the approach of prey, whereupon the lure is moved to entice the prey closer. The striking position is when the prey is anywhere above the snout or up to a halflength in front.
The reason for the huge jaws becomes apparent when the angler fish’s strike is considered, for it does not move bodily, but flings its mouth open, rearing up its head and swinging open its gill covers. The prey is swept into the angler fish’s mouth on the rush of water generated in this way. As the mouth closes the water escapes through the gill openings and the partly closed mouth, but the massive teeth which line the jaw and gill arches prevent the prey escaping.
The list of prey species found in the stomachs of angler fish is very long, but the most frequent food eaten off the coast of South-West England seems to be the pouting. Codling, pollack and saithe also appear here and on other coasts, and the list continues with spurdog, rays, flatfish, sandeels, and other lesser fish. Other animal food is taken also, including squids, crabs, and occasional lobsters. It seems from this, and from the fish that are eaten once in a while that the angler is an opportunist feeder, ready to snap up any edible item that comes within range of its efficient jaws.
This is probably the explanation for the occasional capture of this fish by fishermen whose bait happens to fall or drift within striking range, for the usual feeding behaviour of the fish is unlikely to lead it to search out an angler’s bait.
Although the angler fish does not appear to be built for extensive swimming, there is evidence that it makes seasonal migrations of a modest kind, these differing in proportion to the size of the fish. Young fish of up to 12in are found from the shore down to a depth of about 600ft in spring and summer, but by autumn an inshore migration is taking place and they are found in less than 500ft of water, and by winter they are mostly no deeper than 400ft. Larger fish tend to be in deep water—of over 400ft—in spring and summer and to move closer inshore in autumn and winter to depths of around 220-400ft. These findings are based on catches by trawlers outside the depths at which anglers can fish, but the figures do demonstrate that at least part of the angler fish population in our waters migrates during the year.
The tendency for adult angler fish to move into deeper water in spring and summer is almost certainly due to their breeding habits. The species spawns between March and June in deep water on the lower continental slope at around 6,000ft. The eggs float to the surface but are embedded in a mass of jelly which forms a ribbon, the egg mass. This looks remarkably like a strip of fine gauze, lft wide and perhaps as long as 36ft. As a result of the need for deep water for spawning, most observations have been made on the western and northern coasts. This requirement is possibly the reason why the angler fish is rare on the shallower eastern and south-eastern coasts. It is possible that the exceptional fish in the southern North Sea are the survivors of the larvae which drift away from the deep water and get swept up the Channel from the west, or get caught in the great anti- clockwise current system of the North Sea and are carried from northern waters down towards the English coast. The larvae and post-larvae live in sea between 100 and 500ft deep, near the surface, where the planktonic stage is prolonged. The young angler fish may be nine months old before it starts to live on the sea-bed.
A second species
Until 1974 it had been assumed that there was only one species of angler fish in British waters, but in that year it was announced that a second species, Lophius budegassa, had been discovered in the western Channel, in the Bristol Channel and off the Argyllshire coast, as well as in the deep commercial fishing grounds to the south-west of Britain and Ireland.
The two species are clearly distinct but for many years been confused. Lophius piscatorius has dark edged or dusky pelvic fins, bet- ween 11 and 12 rays in the second dorsal fin, although these are extremely hard to find in the soft fin tissue, and a creamy or white skin lining the inside of the body cavity. Lophius budegassa has creamy coloured pelvic fins—dusky in only the largest spcimens—between 8 and 9 rays in the second dorsal fin, and dark skin lining the inside of the body. This dark skin shows through the belly skin on all but the largest specimens and suggested the common name proposed for the species—black-bellied angler.
Since this discovery was published, the black-bellied angler has been caught on a number of occasions on the western Irish coast, and there seems no reason why its range should not eventually be found to extend as far north as southern Norway. It has not yet been found in the eastern Channel or the North Sea.
Although its life-style is believed to be similar to that of other angler fish it has been studied relatively little. In general, it seems to prefer to live in deep water, even the young ones being more common in 250ft or more, and the adults mainly inhabiting water around 600ft deep. It is, however, caught in shallow water at times, as for example on the Rame Mud, Looe Grounds, and in Barnstaple Bay. So far as is known, it has never been caught on rod and line, so there is no British record fish, but as scientists failed to recognize it before 1974 in our seas it is not surprising that anglers or boatmen have never reported its capture. It is quite possible that several specimens are caught each year but are never looked at twice. It is generally reported to be a smaller species than the common angler fish, the majority growing to a length of up to 20in and Lophius piscatorius regularly exceeding this. This discrepancy in maximum length between the two species is echoed in their growth rate, the black-bellied species growing more slowly than its more common counterpart. At the end of the first year they are 4V£in and 6in respectively, at the end of the second, 5!4 in and 7in, while by the end of the eighth year the gap has widened to 14in and 20in respectively. The maximum age to which the common angler fish lives is not known for certain, but the larger specimens can rarely be less than 20 years old.
Angler’s tasty tail
While the angler fish hardly enter the stakes for the best fighter award, a big specimen will put up a dour and heavyweight struggle. It seems impossible to set out to catch these fish deliberately, because of their specialized feeding habits, but some grounds are well-known haunts, possibly because of the abundance of suitable prey fishes.
The sport angler is in competition with commercial fishermen, for angler fish fetch a good price today, although they were at one time regarded as rubbish. Even so, only the tail is saved and marketed. The meat is white and fibrous—some would say a little chewy—and reminiscent of lobster or white crab meat, and there are dark tales current that low-priced restaurant scampi might sometimes have started life as an angler fish!