Lumpfish Cyclopterus lumpus Linnaeus 1758

LUMP; LUMP SUCKER

Description—

The lumpfish is about twice as long (counting its caudal fin) as it is deep, with a short head, and the dorsal profile of its trunk is much more arched than the ventral. There are 7 longitudinal ridges on its body. One of these ridges runs along the back as a cartilaginous flap that incloses the first dorsal fin in adults and that continues rearward as 2 ridges from the first dorsal fin to the second dorsal fin. There also are 3 ridges along each side, one of them over the eye, one close above the level of the pectoral fin, and one marking the line of transition between side and belly. Each of these ridges is marked by a line of large pointed tubercles, and the entire skin between the ridges is thickly studded with small knobs. The presence of these ridges makes the trunk of the lumpfish roughly triangular in end view, with flat belly (except when swollen by milt or roe) and sharp back, but the caudal peduncle is rounded. The profile of the head is characteristic, being concave above, convex below, with mouth at the tip of the snout. The teeth are small and the eyes and gill openings of moderate size.

The first dorsal fin (visible only on very small specimens) is of 6 to 8 spines. The second dorsal fin and the anal fin below it are alike in outline, both of them of 9 to 11 rays. The caudal is broad [page 460] based and square tipped or slightly convex; the pectorals are large, rounded, and so broad based that they nearly meet on the throat, and they are larger on males than on females. The ventral fins are not visible as such, being altered into 6 pairs of fleshy knobs, surrounded by a roughly circular flap of skin. The entire disk, so formed, (sucking disk) is about as wide as the width of the head, and is situated close behind the throat.

Color—

Descriptions of this fish credit it with a great variety of tints, which we can corroborate. On adults the ground tint may be bluish gray, olive, brownish or yellow green, chocolate or kelp brown, or slaty blue, the belly usually being of a paler or more yellowish cast of the same hue, but sometimes whitish. On some specimens the back and sides are marked with dark blotches and more or less dotted with black. Others, however, are plain colored or nearly so, except that the tubercles are usually dark tipped. Young lumpfish (and it is with such that we are most familiar) often match their surroundings very closely in color, usually being mottled olive green and ochre yellow with silvery dots and stripings. Males, when mature, are more vividly colored than females, and their bellies turn red (brightest near the sucking disk) during the breeding season.

Size—

The longest lumpfish so far recorded from the American coast measured 23 inches, and weighed 13¼ pounds; the heaviest weighed 20 pounds but measured only 21½ inches (both from Orient, N. Y.), and the proportion of weight to length varies similarly in smaller fish. Few are longer than 14 to 16 inches, or heavier than 3 to 6 pounds while the largest we ourselves have seen was about 15 inches long.^[29] Females average larger than males. Fulton, for example,^[3O] writes that 39 females taken in the Bay of Nigg (Scotland) averaged about 16 inches and 6 pounds, 30 males only 11 inches and a little less than 2 pounds.

Habits—

Although the lumpfish is ungainly, it can swim more rapidly for a short distance by vigorous tail strokes than its shape might suggest, and its young pelagic fry are very active. The adult lump is primarily a bottom fish, but is also made semipelagic by its habit of hiding in floating masses of rockweed. In European seas it ranges from tide mark down to 150-200 fathoms, but we have never heard of one taken in more than a few fathoms in the Gulf of Maine. Perhaps it is the nature of the bottom that restricts them there for the soft sticky mud that floors the deeper basins, at least in the western side,^[31] can hardly be a favorable environment for them. Large lumpfish are often found hiding among rockweed or holding fast by the sucker to stones or other [page 461] objects. About Massachusetts Bay, lobster pots are favorite resorts for them when set on stony bottom. For instance, W. F. Clapp tells us that one pot in every 8 or 10 will yield a lumpfish on the broken ground off the entrance to Duxbury Harbor, and they often hold to the lower sides of lobster cars, probably for shade. Occasionally one is found clinging to one of the poles of a trap or weir, though this is a much less common event in the Gulf of Maine than it is in Scottish waters, where they are frequently caught in salmon nets set along shore. Welsh notes one entangled in a gill net set off Great Boars Head in April 1913; they have (rarely) been found clinging to floating logs or inside a floating box or barrel; sometimes they strand on the beach; and there is at least one record of a lumpfish clinging to a mackerel.

So far as known the only regular migrations carried out by the lumpfish are the involuntary drifts of its young fry at the surface, and a general movement of the adults into shoal water at spawning time followed by an offshore movement afterward.

The young fry swim at the surface, and we have taken them so often in our tow nets that we have learned to expect them wherever there are floating masses of rockweed (a refuge in which all but the smallest regularly hide, or to the fronds of which they cling).

Most of the lumpfish taken in tow nets or dipped up are less than 2 inches long, but large adults are sometimes seen at the surface; more often, perhaps, in the Bay of Fundy than elsewhere in the Gulf, their presence at the surface being determined less by the age of the individual fish than by the presence or absence of floating seaweed. However, most of the young lumpfish have left the surface by winter; indeed very few have been taken at any depth in the Gulf of Maine during the cold months,^[32] but we picked up one on the surface off Lurcher Shoal on April 12, 1920, and another off Yarmouth, Nova Scotia, on January 4, 1921.

Food—

We have no first-hand information to offer as to the diet of the lumpfish. In British waters this has been found to consist chiefly of isopods, amphipods, and other small crustaceans, with various other invertebrates, including worms and soft-bodied mollusks. And its diet is much the same in the Gulf of Maine for Cox and Anderson^[33] report euphausiid shrimps (Meganyctiphanes), fragments of jellyfish (Aurelia), amphipod crustaceans (Hyperia), caprellid crustaceans, with the remains of small fish in the stomachs of lumps from Passamaquoddy Bay. And large numbers of young clupeids have occasionally been found in their stomachs. This, too, is one of the few fish that regularly feed on ctenophores and on Medusae. Thus 25 specimens examined at Woods Hole by Vinal Edwards contained nothing but ctenophores. But lumps, like most other fishes, cease feeding during the spawning season. The lumpfish, in its turn, is said to be a favorite food of seals. Certainly it is so weak a swimmer that it would fall an easy prey to them.

In Scottish waters, where many observations have been made on the life of the lumpfish^[34] spawning (and the corresponding inshore migration) takes place from February until near the end of May. And the evidence afforded by our tow nettings suggests an equally protracted spawning season in the Gulf of Maine, for while we have taken larvae 27 mm. long as early as May 10, we have taken newly hatched larvae (6 to 7 mm.) as late as June 19 in the inner parts of the Gulf and as late as July 23 on the northeast part of Georges Bank, with one only 10.5 mm. long on August 22 off Seguin Island. In the Gulf of St. Lawrence, however, where vernal warming is later than in the Gulf of Maine, lumpfish probably do not commence spawning until the middle of April, for Cox and Anderson found no larvae there until late in June, with their observations pointing to late May as the height of the breeding season and to mid-June as about its termination.^[35] Presumably its period of incubation is about as long with us as it is in European waters of like temperature, i. e., 6 weeks to 2 months.

On the other side of the Atlantic the lumpfish spawns in very shallow water, chiefly close to low-tide mark. But the fact that the egg masses (more or less familiar objects on European shores) [page 462] seem never to have been reported along the coast of the Gulf of Maine, although the local presence of larvae is proof that lumpfish breed all around its coast line, suggests that the eggs are deposited at least a fathom or two down with us. And our capture of recently hatched larvae over Georges Bank is evidence that the latter also serves as a spawning ground in 15 to 25 fathoms or deeper. But the lower depth limit to spawning is yet to be determined.

Large females of 18 inches may produce up to 136,000 eggs which sink and stick together in large spongy masses through which the water circulates freely. Off the coasts of northern Europe these egg masses are often found adhering to rocks or other objects, or in crannies near low-water mark, and watch should be kept for them along the rocky coast line of the Gulf of Maine.

The male lumpfish guards the eggs until they hatch; his courage and devotion has often been described.^[36] Throughout the period of guardianship, which he performs fasting, he fans the egg mass constantly, keeping it free of silt and bathed in flowing water, never leaving it except to drive off some intruder. But his vigil ends as soon as the eggs are hatched, leaving him thin and exhausted. The females take no part in guarding the eggs, but are said to move out into deeper water once they have finished spawning.

The eggs are 2.2 to 2.6 mm. in diameter, pink when first laid but soon change to pale green or yellow, and deepen in tint as development progresses. The larvae are about 4 to 7.4 mm. long at hatching, shaped like a tadpole with a large head and slender tail, swimming actively, and soon able to cling to any bit of weed. At 34 mm. the tubercles begin to appear, and the fry then show most of the characters of the adult, except for the large first dorsal fin and slender form.

Lumpfish larvae and fry of all sizes are to be taken throughout the summer; the smaller ones undoubtedly are from that season's hatch, but the larger ones may be either those hatched earliest that spring, or late in the preceding summer, for the varying stage of development reached by different individuals at various sizes proves that the rate of growth varies widely. Thus Cox and Anderson describe one Cape Breton specimen that was only 33 mm. long in July, but that was so mature in outline and in its dermal armature that it must have been at least a year old, whereas they found that in the Bay of Fundy the fry of the year grow to 40 or 50 mm. by December with the yearlings averaging about 58 mm. in July and August. As they remark, the rate of growth is apparently about the same in the Bay of Fundy (probably in the Gulf of Maine as a whole) as it is in Scottish waters, while Gulf of St. Lawrence lumpfish correspond to those about Helgoland, in their slower growth.

Presumably all Gulf of Maine lumpfish upward of 2½ inches long are in their second year. According to Cox and Anderson lumpfish 3¾ to 4¼ inches long are in their third year, those of about 10 inches in their fifth year.^[37] But lumpfish grow much faster if fed to capacity than on the rations ordinarily available to them; one kept in the aquarium at St. Andrews increased in length from about 3.8 inches to about 12 inches in a little more than 12 months, which is as much as is to expected in 2 or 3 years under natural conditions.^[38] Probably maturity is attained in the third year.

General range—

Both sides of the North Atlantic; White Sea, northern Norway and Iceland to the Bay of Biscay and occasionally to Portugal in the east (including the Baltic); northward in the west to the Gulf of St. Lawrence, Newfoundland, outer coast of Labrador, Hudson Bay, Davis Strait, and Disko (latitude about 70° N.) [page 463] in west Greenland; southward to New Jersey, and to Chesapeake Bay as a stray.

Occurrence in the Gulf of Maine—

The lumpfish is common along the outer coast of Nova Scotia and is to be found all around the shores of the Gulf of Maine. It has been reported at Yarmouth and in St. Mary Bay on the Nova Scotian side, and is abundant in all stages at various localities in the Bay of Fundy. There are many records for it along the Maine coast, including Eastport, Penobscot Bay, vicinity of Boothbay, the offing of Seguin Island, and Casco Bay; also in Massachusetts waters where it has been reported repeatedly, as at Nahant, Swampscott, Cohasset, Plymouth, Truro, along Cape Cod, and at Monomoy while we once picked up a lumpfish in the deep bowl between Jeffreys Ledge and the coast, probably as the trawl neared the surface.^[39] It even enters river mouths, but it is never found where the water is appreciably brackish, so far as we can learn. According to fishermen large lumpfish are seldom seen on the offshore banks.

Importance—

The lumpfish is never eaten in the United States, but it sometimes finds its way to market as a curiosity. At one time a few were consumed locally in parts of the British Isles, and may still be.