126 BULLETIN OF THE BUREAU OF FISHERIES 



may be expected most often in the Gulf in midsummer since it appears from May to 



October in southern New England waters. Sandy beaches and the mouths of 



rivers are its chief resorts. 



Habits. — An accoimt of its embryology and larval development is given by 



Kuntz." 



THE SALMONS. FAMILY SALMONID.E 



The salmons are soft^rayed fishes with no spines in any of the fins, with the 

 ventrals situated on the abdomen far behind the pectorals, and with a fleshy rayless 

 "adipose" fin on the back behind the rayed dorsal fin, the presence of this adipose 

 fin and its location separating them from all other Gulf of Maine fishes except the 

 smelt family, the pearlsides (p. 151), and the viper and lancet fishes (p. 155).^^ The 

 rounded noses, stout bodies, and nearly square tails of the salmons mark them at a 

 glance from the sharp-nosed, slender, forked-tailed smelts; the absence of phos- 

 phorescent organs distinguishes them from the pearlsides, while the viper and lancet 

 fishes are of quite different general aspect. At the present time three salmons ^^ 

 occur in the Gulf of Maine, one of which — the sea trout — resorts to tidal estuaries 

 at the mouths of a few of our streams, while a second — the humpback salmon — has 

 recently been introduced from the Pacific coast (the success of the experiment is 

 still in doubt), leaving the Atlantic salmon alone as a characteristic inhabitant of 

 the open waters of the Gulf of Maine. 



KEY TO GULF OF MAINE SALMONS 



1. Anal fin long, with 14 to 17 rays Humpback salmon, p. 126 



Anal fin short, with less than 13 rays 2 



2. Scales so small as to be hardly visible; back with vermiculate markings; teeth on roof 



of mouth confined to a group in front Sea trout, p. 138 



Scales large enough to be easily visible; back without vermiculate markings; a row of 

 teeth runs back along the midline of the roof of the mouth Salmon, p. 130 



46. Humpback salmon iOncorhynchus gorhuscha Walbaum) 



Jordan and Evermann, 1896-1900, p. 47S. 



Description. — The humpback is of the familiar salmon outline while living in the 

 sea, the body being deeper than thick but with rounded belly. (See fig. 52, p. 129.) 

 The head is naked but the body is covered with scales large enough to be seen easily. 

 Its dorsal fin stands about midway of the body above the ventrals, and the flaplike 

 adipose fin is over the rear end of the anal. In all this it agrees so closely with the 

 Atlantic salmon that the two might easily be confused were it not that the anal fin 

 of the humpback invariably has 14 or more rays while that of the Atlantic sahnon 

 has only about 9 . The male humpback, Uke all the Pacific salmons and to a lesser degree 

 the Atlantic salmon, undergoes a very noticeable change in form in the spawning season , 

 when the body deepens and develops a prominent hump in front of the dorsal fin, 

 while the jaws elongate and become hooked at the tip and the teeth increase in size. 



" Bulletin, U. S. Bureau of Fisheries, Vol. XXXIII. 1913 (1915), p. 13. 



" Sundry other deep-sea fishes have adipose fins. 



" A specimen of one of the whiteflshes (probably Coregonun quadrilateral^ Richardson) was taken in the mouth of the Sissibou 

 River, St. Mary Bay, September, 1919 (Uuntsman, 1922a, p. U), straying down from fresh water. Whiteflsh are recognizable 

 by the presence of an adipose fin, a."! in the true salmons, but a very small mouth and compressed, herringlike rather than salmon- 

 like body. 



