Rough headed grenadier Macrourus berglax Lacépède 1802 [6]
RAT-TAIL; ONION-EYE
[Jordan and Evermann, 1896-1900, p. 2583.]
Description—
This species resembles the common grenadier (p. 243) so closely in general appearance that we need only indicate the points of difference. Most obvious of these are that its snout is shorter and blunter, with more highly arched dorsal profile; that it has 4, 5, or 6 distinct ridges on the top of its head; that its head is relatively larger (about one-fourth to one-fifth the length of the fish, only one-sixth to one-seventh in the common grenadier); that its trunk is relatively stouter (about six times as long as it is deep); that its vent is close to the point of origin of the anal fin with the skin scaly around it, and no darker colored than on the back; and that the serrations on the large spine in the first dorsal fin are so fine that they are hardly visible.
Furthermore, there are fewer (about 124) rays in the second dorsal fin, but more rays (about 148) in the anal than in the common grenadier, and its first dorsal fin is of rather different outline. The second dorsal fin, too, is relatively higher than in the common grenadier and with its membrane more developed (compare fig. 120 with fig. 119), while the filamentous prolongation of the outer ray of the ventral fins is not so long in berglax as it is in bairdii. The structure of the scales, too (visible to the naked eye), is diagnostic, for those on the head and shoulders of berglax are armed with either one longitudinal row of spines (10-12 rows of spines on each scale), or with up to 3 or 4 radiating ridges of spines while those farther back each have a single row of spines, which together form conspicuous longitudinal ridges along each side of the rear part of the body.
Color—
The only newly caught specimens we have seen were ash gray below as well as above; with the chest a little darker; with the rear edges of the scales on the rear part of the body still darker; with the anal fin narrowly dark edged; with the first dorsal fin and the pectoral fins sooty; and with the ventral fins sooty, except that the outermost rays are white after preservation in alcohol.
Size—
This fish is larger than the other grenadiers (p. 243). It is credited with a maximum [page 246] length of 3 feet and a weight of 4 or 5 pounds but the largest we have seen is only 29 inches long.
General range—
This is a deep-water fish like its relative, but is more northerly in its distribution, being known off northern Norway, Spitzbergen, Iceland, southern Greenland, in Davis Strait, and southward along the continental slope of North America as far as Georges Bank. One has even been found floating dead on the surface, off New York Harbor, but it may have been thrown overboard from a fishing boat returning from the offshore banks.
Occurrence in the Gulf of Maine—
Three quarters of a century ago, when halibut were more plentiful in the Gulf of Maine than they are today, and when vessels, long-lining from Gloucester, still resorted regularly to the deep channel between Georges Bank and Browns Bank as well as to the deep gullies that interrupt the Nova Scotian banks, large grenadiers were often hooked. Fishermen described them as common enough to be a nuisance, for they stole the baits meant for other fish and were of no commercial value themselves. It was on the strength of such reports that Goode[7] characterized them as "exceedingly abundant on all of our offshore banks." A few were brought in "from off the coast of New England."[8] And our re-examination of three specimens, one taken on the outer edge of either La Have Bank or Banquereau in 1878 a second taken "off New England" in 1880, the third (probably from the Grand Banks) obtained in Boston Market by Prof. G. H. Parker in 1903[9] has proved that earlier identifications of them as berglax were correct.
We have not heard of one, either from Nova Scotian waters or from the Eastern Channel since 1903;[10] not because they have vanished thence, but simply because very little long-line fishing is now done deep enough off our coasts. And there is always the chance that some vessel, fishing down the slopes of Sable Island Bank, La Have Bank, or southeastern Georges, may pick a few rough headed grenadiers at any time when least expected.
One hundred fathoms may be set as about their upper limit; most of those caught have been from 100 to 300 fathoms on both sides of the Atlantic; and they have been taken as deep as 677 fathoms by the Albatross off the southeast slope of Georges Bank. They are supposed to feed on small fish and on Crustacea but we find no definite record of the contents of their stomachs. Females with the roe nearly ripe have been taken off northern Norway in May, suggesting that this is a spring spawner, but nothing definite is known of its breeding habits.
[6] Authorities disagree as to the correct scientific name of this grenadier, for while it has usually been referred to as berglax Lacépède, 1802, Jensen (Spolia Zool., Mus. Hauniensis, Copenhagen, vol. 9, 1948, p. 178) prefers the speciesname fabricii that was applied to it more recently by Sundevall, 1840, on the ground that the grenadier to which Lacépède gave the name berglax was another fish, Coryphaenoides rupestris Gunnerus, 1765, which is commonly termed "berglax" on the west coast of Norway.
[7] Fish. Ind. U. S., Sect. 1, 1884, p. 244.
[8] Bean, Proc. U. S. Nat. Mus., vol. 3, 1881, p. 80.
[9] These three specimens, the largest 29 inches long, are in the Museum of Comparative Zoology.
[10] The most recent record with which we are acquainted is of one 16 inches long that we trawled on the southeastern slope of Georges Bank, at 500 fathoms, June 1949, on Caryn of the Woods Hole Oceanographic Institution.