120 



FISHERY BULLETIN OP THE FISH AND WILDLIFE SERVICE 



pearlsides, while the lantern, viper, and lancet 

 fishes are of different general aspect. 



Four salmons 46 occur in the Gulf of Maine, or 

 have recently, one of which, the sea trout, resorts 

 to tidal estuaries at the mouths of a few of our 

 streams; a second and a third — the humpback 

 salmon and the silver salmon — were introduced 

 from the Pacific coast, leaving the Atlantic sal- 

 mon as a characteristic inhabitant of the open 

 waters of the Gulf of Maine. 



KEY TO GULF OF MAINE SALMONS 



1. Scales so small that they are hardly visible; back with 



vermiculate markings; teeth on roof of mouth con- 

 fined to a group in front Brook trout, p. 120 



Scales large enough to be easily visible; back without 

 vermiculate markings; a row of teeth runs back along 

 the mid line of the roof of the mouth 2 



2. Anal fin with only 8-10 rays Salmon, p. 121 



Anal fin with 12 rays or more 3 



3. Back and lower half of tail fin, as well as its upper half, 



conspicuously marked with large black spots 



Humpback salmon, p. 131 



Back with very small black spots or none at all; no 



black spots on lower half of tail fin.Silver salmon, p. 133 



Brook trout Salvelinus jontinalis (Mitchill) 1815 

 Sea trout; Salter 



Jordan and Evermann, 1896-1900, p. 506. 



Description. — Although brook trout vary widely 

 in general form in different streams, they are usu- 

 ally salmon-like in shape when taken in salt water, 

 that is, about one-fourth as deep as long, tapering 

 gracefully to a small head. The nose of a trout, 



•> A specimon of one of the whitefishes (probably Coreoonus guadrilatiralis 

 Richardson) was taken In the mouth of the Sissibou River, St. Mary Bay, 

 Nova Scotia, September 1919 [Huntsman, Contr. Canad. Biol., (1921) 1922, 

 p. 59) straying down from fresh water. Whitensh have an adipose fin, like 

 the true salmons, but have a very small mouth, and are flattened sidewise, 

 and herring-like in appearance, rather than salmon-like. 



however, is blunter than that of a salmon, and its 

 head is longer in proportion, the total length of 

 the fish (not counting the caudal fin) being about 

 four and one-half times that of the head, 49 while 

 its mouth (gaping back of the eye) is relatively 

 larger. The general arrangement of the fins, in- 

 cluding the "adipose," parallels that of the salmon, 

 but the ventral fins stand under the middle of the 

 dorsal, thus farther forward in relation to the 

 latter than in its larger relative. All the fins, too, 

 are relatively larger, particularly the ventrals; 

 as a rule the anal has one less ray in the trout 

 (usually 8) than the salmon, but the number of 

 dorsal rays (about 11) is the same. The tail of 

 the sea trout is less forked than that of a young 

 salmon of equal size. 



Examination of the scales and of the teeth is the 

 most positive means of distinguishing brook trout 

 (in European terminology this is a "charr") from 

 young salmon, for the teeth on the roof of the 

 mouth of the trout are confined to a cluster near 

 the front, instead of extending backward in a row 

 along its midline as in the salmon ; and the scales 

 of the trout are so tiny as hardly to be visible 

 whereas those of the salmon are large and easily 

 seen. 



Color. — Trout living in salt water almost wholly 

 lack the yellow and red tints so conspicuous on 

 their freshwater relatives. They are steel blue or 

 bottle green on the back, with cheeks and sides 

 silvery like a salmon and with a white belly. The 

 sides above the lateral line are more or less dotted 

 with pale yellow spots, but the dark vermiculate 

 markings so characteristic of the fresh-water brook 

 trout are rarely seen on the trunk of sea run fish, 

 though evident as wavy crossbars on the dorsal 



■ Some trout are longer headed. 



Figure 53. — Brook trout (JSalvelinus fontinalis) , about 15% inches long. 



