Table of Contents
The true herrings (Clupeidae) are soft-finned fishes wholly lacking spines, with one short dorsal fin, deeply forked tails, ventral fins situated on the abdomen far behind the pectorals, teeth small or lacking in adults, deep bodies flattened sidewise, and large scales that slip off at a touch. They are, perhaps, the most familiar of northern sea fishes and certainly are the most abundant in number of individuals. Seven species of herring occur in the Gulf of Maine— the hickory shad (not very common), the sea herring, the alewife, the blueback, and the shad (regular and plentiful), thread herring (scarce), and the menhaden (irregular in its occurrence). The shad, menhaden, sea herring, and thread herring are easily named; but the alewife and the blueback resemble one another so closely that they are often confused, even by the fishermen who handle them constantly. The round herrings (Family Dussumieriidae) differ from the true herrings chiefly in their rounded bellies and less deep bodies. The members of the Tarpon Tribe (Family Elopidae) are very closely allied to the true herrings (Clupeidae), from which they differ in having a bony plate on the throat between the branches of the lower jaw. There are only about five species, all of them tropical. Two are known from the Gulf, as strays.
| KEY TO GULF OF MAINE HERRINGS AND TARPONS | |||
|---|---|---|---|
| 1. | Last dorsal fin ray prolonged | 2 | |
| Last dorsal ray not prolonged | 3 | ||
| 2. | Dorsal fin originates in advance of the ventrals; scales only moderately large | — | Thread herring, p. 112 |
| Dorsal fin originates behind the ventrals; scales very large | — | Tarpon, p. 87 | |
| 3. | Belly rounded | 4 | |
| Belly sharp edged | 5 | ||
| 4. | Scales very small; mouth very large with upper jaw-bone extending considerably beyond the rear edge of the eye; point of origin of dorsal fin about over that of the ventral fins | — | Ten pounder, p. 86 |
| Scales large; mouth small, with upper jaw-bone extending rearward only about as far as the front edge of the eye; point of origin of dorsal fin well in advance of that of the ventral fin | — | Round Herring, p. 87 | |
| 5. | Head (tip of snout to edge of gill cover) very large, occupying about one-third the total length of the body to base of the central rays of the caudal fin; free edges of scales fluted, not rounded | — | Menhaden, p. 113 |
| Head about one-fourth the total length of the body; free edges of the scales rounded | 6 | ||
| 6. | Distance from point of origin of dorsal fin to tip of lower jaw (mouth closed) about as long as from origin of dorsal fin to base of central rays of caudal fin; edge of belly hardly saw-toothed, though sharp; general form comparatively shallow; there is a cluster of teeth on the roof of the mouth | — | Sea herring, p. 88 |
| Distance from point of origin of dorsal fin to tip of lower jaw (mouth closed) considerably shorter than from point of origin of dorsal fin to origin of central rays of caudal fin; edge of belly more or less strongly saw-toothed, especially in space between the ventral and anal fins; general form deep; there are no teeth on the roof of the mouth | 7 | ||
| 7. | The tip of the lower jaw extends noticeably beyond the upper when mouth is closed | — | Hickory shad, p. 100 |
| The tip of the jaw does not extend appreciably beyond the upper when mouth is closed | 8 | ||
| 8. | The upper outline of the forward part of the lower jaw (visible if mouth is opened) is nearly straight, and does not show a pronounced angle; the upper jaw extends back about level with the rear edge of the eye | — | Shad, p. 108 |
| The upper outline of the forward part of the lower jaw is concave with a pronounced angle; the upper jaw reaches back only about to the level of the center of the eye | 9 | ||
| 9. | Breadth of eye is greater than distance from front of eye to tip of snout; back distinctly grey green; lining of belly cavity pale grey | — | Alewife, p. 101 |
| Breadth of eye is only about as great as distance from front of eye to tip of snout; back distinctly blue green; lining of belly cavity sooty or black | — | Blue back, p. 106 | |