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American John Dory[28] Zenopsis ocellata (Storer) 1858

[Jordan and Evermann, 1896-1900, p. 1660.]

American John Dory (Zenopsis ocellata)

Figure 156.—American John Dory (Zenopsis ocellata), Provincetown. From Goode. Drawing by H. L. Todd.


The John Dory is easily distinguishable from all other Gulf of Maine fishes of similar body form by its long dorsal fin spines, bony armor, tiny tail fin, and the curious profile of its head. Like the butterfish it is very deep (only about one and three-fourths to twice as long as it is deep) and very much flattened sidewise. Its body is rounded in side view, with the dorsal profile of its head noticeably concave, its large mouth is set very obliquely, and its caudal peduncle is very slender. Its dorsal fin is in two parts, spiny and soft rayed; the former, originating over the upper corner of the gill covers, has 9 to 10 spines; the first, second, and third spines very long, the others graduated. And all the spines are filamentous toward the tip. The soft dorsal fin [page 298] (25 to 27 rays) is somewhat longer than the spiny dorsal fin, but less than half as high, and its anterior rays are only about half as high as the posterior ones. The two dorsal fins, together, occupy the entire length of the back of the fish from nape of neck to caudal peduncle.

The anal fin (24 to 26 rays preceded by 3 short stout spines) corresponds to the soft dorsal in location, height, and outline. The very small caudal fin is brush shaped, the ventral fins are very long, with the rays free at their tips, and they are situated in front of the pectorals. The pectorals are short and rounded. The skin is naked except for a series of bony bucklers, each with a hooked thorn or double thorn; two or three of them along the base of the spiny dorsal fin and four along the base of the soft dorsal; two in front of the ventral fins; one in the midline behind the ventrals, followed by six pairs along the belly to the anal fin; and five along the base of the anal fin.


Silvery all over. Specimens that we have seen up to about 10 inches long are marked on either side with about 12-24 vaguely outlined dark spots, irregularly arranged, and fish up to about 15 inches long retain some of the spots.[29] But it seems that the spots tend to fade out with growth, for larger specimens that we have at hand, 16-20 inches long, have only one vague blotch on each side, a short distance behind the gill opening.


The largest four specimens yet seen measured 18¼ and 18½ inches;[30] 19 inches, weighing [page 299] 3 pounds;[31] and 20 inches, weighing 4½ pounds and 24 inches, weighing 7 pounds.[32]


The presence of plates along the base of its first (spiny) dorsal fin, as well as along the bases of its second (soft) dorsal and anal fins, and of only three anal spines marks our fish off from its close counterpart, the European John Dory (Zeus faber), which has four stout anal spines and lacks plates along the first dorsal fin. Other structural differences are that the plates are much larger in our species than in the European, but the thorns smaller and less conspicuous;[33] that the base of each of the dorsal fin spines (except for the first and last one or two) is armed in the European species with a stout thorn (not in the American); and that the upper profile of the head is much the more deeply concave in the American species.


All that is known of the habits of our John Dory is that we found two butterfish 6 to 7 inches long and one squid in the stomach of a large one (of about 18½ in.) trawled by the Albatross III about 74 miles off Long Island, N. Y., May 12, 1950, at 72 fathoms; and that the ovaries were well developed with orange colored eggs 1.2 to 1.4 mm. in diameter, in a 20-inch female that we saw trawled between January 27 and February 2 on the outer part of the shelf off Marthas Vineyard.[34]

General range—

Outer part of the continental shelf from the latitude of Chesapeake Bay to the vicinity of Sable Island, Nova Scotia, and perhaps to the Laurentian Channel that separates the Nova Scotian Banks from the Newfoundland Banks. It reaches the inner parts of the Gulf of Maine now and then as a stray.

Occurrence in the Gulf of Maine—

Only four specimens are known to have been taken in the inner parts of the Gulf of Maine. One (the specimen from which the species was described) was found at Provincetown, at the tip of Cape Cod many years ago; one found in a herring weir at Campobello Island, New Brunswick, at the mouth of the Bay of Fundy in 1942;[35] one trawled 25 miles off Cape Ann in 75 fathoms, January 1948.[36] One also was trawled on the northeastern edge of Georges Bank in the summer of 1941,[37] and one taken in Cape Cod Bay, July 7, 1952, by the dragger Santina.

It is to be expected anywhere along the seaward slope of the offshore rim of the Gulf, for the dragger Eugene H took them in nearly every trawl haul on the southwest slope of Georges Bank, near Veatch Canyon, at about the 75-fathom contour line, in late March 1951, some hauls bringing in several hundred (estimated) specimens. Other specimens[38] have been trawled recently on the outer part of the continental shelf southeast of Cape Henry, Va., from between 28 and 50 fathoms;[39] off Long Island, New York, in 72 fathoms and from between 145 and 200 fathoms; off Marthas Vineyard in 55 to 68 fathoms; off Nantucket in 66 to 75 fathoms; on Emerald Bank off Halifax, Nova Scotia, in 70 fathoms; and west of Sable Island, Nova Scotia, at 62 fathoms.

[28] Separable from the common John Dory of Europe by having three anal spines instead of four, and by a greater development of the bony plates.

[29] This agrees with the original account of the species (Storer, Proc. Boston Soc. Nat. Hist., vol. 6, 1858, p. 386) and with a photograph of one about 3½ inches long, from Campobello, New Brunswick, sent us by Dr. A. H. Leim.

[30] Taken off Long Island, N. Y., by the Albatross III, lat. 39° 39' N., long. 72° 08' W., May 12, 1950.

[31] Caught on the northeast edge of Georges Bank in the summer of 1941 and reported in the Boston Traveler for September 9 of that year.

[32] Taken 85 miles off Marthas Vineyard by the dragger Eugene H, May 15, 1950.

[33] Double and sometimes triple in the European Z. faber.

[34] Trawled by the dragger Eugene H from between 55-68 fathoms.

[35] Reported to us, with a photograph, by Dr. A. H. Leim.

[36] This specimen, trawled by the Agatha and Patricia, is in the Museum of Comparative Zoology.

[37] Reported in the Boston Traveler for September 9, 1941.

[38] Specimens seen by us or reliably reported.

[39] Reported by Firth, Copeia, 1931, p. 162.