FISHES OF THE GULF OF MAINE 



173 



THE SILVER HAKE AND COD FAMILIES— FAMILIES MERLUCCIIDAE AND GADIDAE 



The silver hakes and the cods are so closely 

 allied that many European ichthyoloigsts group 

 them in a single family. American practice, how- 

 ever, is to separate them because of certain dif- 

 ferences 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 



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 



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 



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 



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 



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 



8, 



10. 



11 



12. 



Silver hake Merluccius bilinearis (Mitchill) 1814 

 Whiting; New England hake 



Jordan and Evermann, 1896-1900, p. 2530. 



Description. — The presence of two separate and 

 well developed dorsal fins, both of them soft-rayed, 

 the second much longer than the first, combined 

 with the location of the ventrals on the chest, is 

 sufficient field mark to distinguish the silver hake 

 from all other Gulf of Maine fishes except for the 



true hakes (genus Urophycis, p. 221). And there 

 is no danger of confusing it with any of the latter, 

 for it lacks the chin barbels so characteristic of 

 them, and its ventrals are of the ordinary finlike 

 form, whereas those of the true hakes are altered 

 into long feelers. It is a rather slender fish, about 

 five to six times as long as it is deep, its body 

 rounded in front of the vent but flattened sidewise 

 behind it, with large flat-topped head occupying 



»> The hypercoracoid bone lacks an aperture (technically a "foramen"). 



