110 BULLETIN OF THE BUREAU OF FISHEHIES 



the bottom like the latter, for Huntsman (1922a, p. 10) reports its young at 

 Campobello Island, Bay of Fundy, in December and March. 



The rate of growth of the alew'ife during its sojourn in the sea has not been 

 studied, but experiments in stocking ponds with alewives long ago led to the con- 

 clusion that they attain sexual maturity at 3 or 4 years of age. This has been 

 confirmed on many occasions in recent years, for it has proved easy to restock 

 suitable streams with alewives by planting adult spawners at the proper season in 

 the ponds which they drain, as has been done in many localities in Massachusetts. 

 In the third year after the "plant," and not until then, tlie progeny appear in the 

 stream. The success of such restocldng operations, moreover, has demonstrated 

 that the "parent stream" theory — that is, that alewiyes, like shad, return to spaA\Ti 

 in the stream in which they were hatched — is correct. We have no record in historic 

 times of their having spontaneously adopted a stream previously barren of them. 



Alewives retiu-n to the sea immediately after spawning (the old 'belief that 

 they spawn but once and then die has no foundation), the spent fish on their return 

 jom-ney to salt water being familiar sights in every alewife stream. After spaA\Ti- 

 ing they are thin, but we have seen spent alewives that had already put on con- 

 siderable fat taken from a trap at ProvincetowTi as early in the season as July 16 

 in 1915. 



Food. — The alewife, like the herring, is chiefly a plankton feeder, copepods, 

 amphipods, shrimps, and appendicularians being the chief diet of specimens exam- 

 ined b}' Vinal Edwards and Linton at Woods Hole. However, they also take 

 small fish, such as herring, eels, launce, cunners, and their own species, as well as 

 fish eggs. Unlike the herring, alewives often contain diatoms even when adult. 

 Alewives fast when they are running upstream to sjjawn, but when the spent fish 

 reach brackish water on their return they feed ravenously on the shrimp that abound 

 in the tidal estuaries and which they can be seen pursuing. 



Commercial imporUince. — Alewives are excellent food fish, preferred by many 

 to the sea herring, and a favorite bait for cod, haddock, and pollock. They are of 

 considerable commei'cial importance among the minor fisheries.'' 



42. Blueback {Pomolobus aestivalis MitchiU) 

 Alewife; Glut herring; Summer herring; Blackbellt; Kyack 



Jordan and Evennann, 1896-1900, p. 426. 



Description. — Bluebacks and alewives are often confused; even experienced 

 fishermen who recognize the existence of the two separate fish can not always tell 

 them apart, so closely do they resemble one another in general appearance. There 

 is one infalhble mark, however, that distinguishes the "blackbelly" not only from 

 the alewife but from the liickory shad and herring as well, and that is that the lining 

 of its belly is black, or at least black-spotted, instead of smoky gray as in its relatives. 

 Apart from this we need state only that it is a slightly more slender fish than the 



13 For a brief period during the war alewife scales commauded a high price for use in the maufacturo of artificial pearls. 



