FISHES OF THE GULF OF MAINE 



107 



Color. — Dark blue or bluish gray above, the 

 sides and belly silvery, with coppery reflections at 

 least in some waters; lining of the belly sooty or 

 blackish. 



Size. — The blueback attains about the same 

 size as the alewife, i. e., 15 inches; the adults 

 average about 11 inches in length and about 7 

 ounces in weight. 



Habits. — The blueback, like the alewife, makes 

 its growth in salt water, but runs up into fresh 

 water to spawn. And its breeding habits do not 

 differ in any important particular from those of the 

 alewife, except that it "runs" later in the season, 

 does not run up as far above tidewater, and does 

 not spawn until the water is much warmer, 70° to 

 75° instead of 55° to 60°. w The eggs, about 1 mm. 

 in diameter, sink like those of the alewife, and 

 stick to anything they may chance to touch. 

 Incubation occupies only about 50 hours at a 

 temperature of 72°. The young are 30 to 50 mm. 

 long within a month and already show most of the 

 diagnostic characters of the adult. Evidently 

 they soon find their way down to the sea, for blue- 

 backs of 50 mm. have been seined in abundance in 

 Rhode Island waters late in July. 91 Nothing 

 whatever is known of their later rate of growth. 

 The spent fish, return to sea shortly after spawning 

 as do alewives. Practically nothing is known of 

 their movements in the sea, except that they are 

 schooling fishes. The fact, however, that 7 were 

 trawled by the Albatross II on March 5, 1931 about 

 100 miles off Cape May, N. J., suggests that the 

 blueback moves out from land and passes the cold 

 season near the bottom. 



We need only note further that the blueback is 

 as gregarious as the herring or alewife; that it is 

 equally a plankton feeder, subsisting chiefly on 

 copepods and pelagic shrimp, as well as on young 

 launce and, no doubt, on other small fish fry. 



Qeneral range. — -This is a more southern fish than 

 the alewife, occurring along the American coast as 

 far south as northern Florida; as far north as 

 southern New England in abundance, perhaps less 

 regularly in the Gulf of Maine though widespread 



H The early development and larval stages of the blueback are described 

 by Kuntz and Radclifle (Boll. U. S. Bur. Fish., vol. 35, 1918, pp. 87-134). 



" In Chesapeake Bay, Hildebrand and Schroeder (Bull. U. S. Bur. Fish., 

 vol. 43, 1928, p. 88) found that while most of the young bluebacks pass out to 

 sea during the summer and fall, some remain in the deeper holes over the win- 

 ter. By the following March when about a year old these are about 3^ to 

 4 Inches long; those In the sea may grow faster than this. 



there, and known definitely as far north as Cape 

 Breton, Nova Scotia: M it spends most of its life in 

 salt water but runs up into fresh water to spawn. 



Occurrence in the Gulf of Maine. — Although 

 fishermen have recognized the existence of two 

 distinct species of alewives at least since 1816, it 

 is difficult to arrive at a just idea of the status 

 and migrations of this fish in our Gulf, because 

 fish reported as "bluebacks" at sea sometimes 

 turn out to be alewives, while the late runs of 

 alewives are often referred to as "bluebacks." 

 It seems, however, that schools of bluebacks are 

 to be expected anywhere between Cape Sable and 

 Cape Cod. Thus we have seen "gaspereau" fresh 

 caught at Yarmouth, Nova Scotia, that appeared 

 to be bluebacks. 83 Huntsman had specimens from 

 St. John Harbor and Shubenacadie River; they 

 are reported, at least by name, from the St. Croix 

 River; from Dennys River, Eastport; Bucksport; 

 Casco Bay; Small Point; Freeport; and sundry 

 other localities along the coast of Maine, as well 

 as from the shores of Massachusetts Bay, including 

 Cape Cod. 



L. W. Scattergood of the U. S. Fish and Wildlife 

 Service has sent us about 40 typical bluebacks, 

 about 3% to bVt inches (92-124 mm.) long taken 

 at Hodgdon Island, Sheepscot River, Maine, June 

 14, 1951 ; and we once saw thousands of fish taken 

 from a trap near Gloucester, most of which we 

 judged to be bluebacks from their color. 94 A few 

 fish were reported as "bluebacks" from Georges 

 Bank during the investigation of 1913, and while 

 there is no way, now, of checking whether these 

 actually were bluebacks or alewives, the fact that 

 we saw 10 bluebacks about 1 foot long, trawled 

 by Albatross III at the 45 fathom line off southern 

 New England, in mid-May, 1950, 95 shows that they 

 may spread as far offshore as alewives. 



No definite information is at hand as to how 

 regularly alewives run into our Gulf of Maine 

 streams, for spawning; or what streams they enter 

 at all. 



No distinction is made, commercially, on our 

 coast between the blueback and the more abundant 

 alewife; it is equally useful for bait and for food. 



« Dr. A. H. Leim has sent us four typical bluebacki about 12 lnchss long , 

 taken at Cape Breton, Nova Scotia, in 1950. 

 " We had no chance to examine them critically. 



•< We did not then appreciate the desirability of positive identification. 

 " Lat. 40° 06'; long. 71° 38' W. 



