338 Memoir Sears Foundation for Marine Research 



It has long been known that anadromous fishes, as a rule, feed sparingly or not 

 at all while ascending streams, and Graybacks are no exception to this rule. However, 

 the spent fish feed ravenously on shrimp on entering brackish water along the coast, 

 where anglers often hook them on an artificial fly (x6). 



Enemies. The young are undoubtedly preyed upon by various predatory fishes, 

 turtles, snakes, and birds while they live in fresh water. When they begin to school and 

 migrate out to sea, marine fishes and numerous other sea inhabitants very probably 

 destroy many. When they re-enter shallow shore water as adults in great schools, large 

 marine fishes of many kinds, finback whales, birds, and turtles, take a further toll. 

 Upon arriving inshore and in the rivers, man — who captures great quantities for food 

 — must be their chief enemy. 



Parasites. The following have been listed by Sumner, et al. {12 j: 742): Acanthoce- 

 phala (Echinorhynchus acus) ; cestodes {Rhynchobothrium imparispine) ; trematodes (Distomum 

 appendiculatum, D. bothryophoron^ D. vitellosum, and Monostomum sp.); and copepods {Ar- 

 gulus alosae., Caligus rapax, and Lepeophtheirus edwardsi). 



Variations. Specimens from various localities within the range of this species 

 along the coast {Study Material., p. 332) show a tendency toward a more slender body 

 and a proportionately larger head toward the northern part of the range; and a limited 

 number of specimens from fresh water, Cayuga Lake and Lake Ontario (proportions 

 not used in Description)., show this tendency to be even more pronounced there. In 

 general, the fish from the northern part of the range (especially from Casco Bay, Maine), 

 and more particularly those from fresh water, have the appearance of being more or 

 less emaciated. However, insufficient specimens have been studied to determine the 

 significance of the apparent diff"erences mentioned. These differences may be of sub- 

 specific value, but more likely they are of only racial importance. The decrease in 

 body depth in northern specimens makes their separation from P. aestivalis more 

 difficult than identification of specimens from the southern part of the range. 



Abundance and Commercial Importance. The relative abundance of pseudoharengus 

 and aestivalis is discussed in the account of the latter (p. 330). It has been claimed 

 by various writers that Graybacks are far less numerous now than during colonial days, 

 or even a half century ago. The matter was summed up for the Gulf of Maine by 

 Bigelow and Welsh {16: 108) in these words: 



During the past two centuries ... its numbers have declined, and its range has been restricted, both by 



actual extirpation from certain streams by overfishing, by the pollution of river waters by manufacturing wastes, 

 and by the erection of dams that it cannot pass. However, the alewife is still a familiar fish all along our coast, 

 and yields an abundant catch in many of our streams. 



These remarks also apply in a measure to fish in the more southern part of the range, 

 though the decline apparently has been less pronounced southward. 



The following statistics give the catches of Graybacks and bluebacks combined, 

 under the name "Alewlves." These records show in part the decline in their abundance 

 during the past 50 years or so, but they also show that these fish are still abundant 

 and of great economic importance. There has been no compensation tor any variations 



