Table of Contents
The silver hakes; and the cods are so closely allied that many European ichthyoloigsts group them in a single family. American practice, however, is to separate them because of certain differences in the structure of the skull and ribs. They are soft-finned fishes, lacking true spines at any stage in development (though in one local species, the silver hake, the basal parts of the dorsal and anal fin rays are so stiff as to feel like spines to the touch), but they are distinguishable from all other soft-rayed Gulf of Maine fishes by the fact that their large ventral fins are situated under the pectorals or in front of them, and not behind them, as they are in the herrings and salmons. They and their relatives, the grenadiers (p. 243), are separated from most of the typical spiny-rayed fishes by the structure of the skull.[21]
| Key To Gulf Of Maine Hakes, Cods, And Other Species | |||
|---|---|---|---|
| 1. | There are three separate dorsal fins and two anal fins | 2 | |
| There are two separate and well developed dorsal fins | 5 | ||
| There is only one well developed dorsal fin | 11 | ||
| 2. | The lateral line is black; there is a black blotch on each shoulder | — | Haddock, p. 199 |
| The lateral line is pale; there is no shoulder blotch | 3 | ||
| 3. | The lower jaw projects beyond the upper; the chin barbel is very small, if there is one | — | Pollock, p. 213 |
| The upper jaw projects beyond the lower; the chin barbel is large | 4 | ||
| 4. | The ventral fins are narrow, and prolonged as filamentous feelers that are as long as the rest of the fin; the eyes are small | — | Tomcod, p. 196 |
| The ventral fins are broad, and their filamentous tips are less than one-third as long as the remainder of the fin; the eyes are large | — | Cod, p. 182 | |
| 5. | The anal fin originates considerably in front of the point of origin of the second dorsal fin | — | Hakeling, p. 233 |
| The anal fin originates under the point of origin of the second dorsal fin or behind it | 6 | ||
| 6. | The ventral fins are short and of ordinary form | — | Silver hake, p. 173 |
| The ventral fins are very long and feeler-like | 7 | ||
| 7. | The first dorsal fin is hardly higher than the second dorsal, and none of its rays are prolonged or filamentous | — | Spotted hake, p. 230 |
| The first dorsal fin is much higher than the second dorsal, with one or two long filamentous rays | 8 | ||
| 8. | The ventral fins reach nearly or quite as far back as the rear end of the anal fin | — | Long-finned hake, p. 232 |
| The ventral fins do not reach back to the middle of the anal fin | 9 | ||
| 9. | The anal fin is so deeply notched about midway of its length as to suggest two separate fins | — | Blue hake, p. 233 |
| The anal fin is of about equal height from end to end | 10 | ||
| 10. | There are about 140 rows of scales along the lateral line from gill opening to base of caudal fin; the upper jaw bone reaches back to below the rear edge of the eye | — | White hake, p. 221 |
| There are only about 110 rows of scales along the lateral line; the upper jaw bone reaches back only as far as the rear edge of the pupil | — | Squirrel hake, p. 223 | |
| 11. | There are no isolated rays in front of the dorsal fin, nor barbels on the top of the snout | — | Cusk, p. 238 |
| The dorsal fin is preceded by a fringe of short rays and one long ray; the top of the snout bears barbels as well as the chin | 12 | ||
| 12. | There are three barbels on the top of the nose | — | Four-bearded rockling, p. 234 |
| There are only two barbels on the top of the nose | — | Three-bearded rockling, p. 237 | |