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dently state that any stream with available spawning grounds 

 may be given a commercial fishery by removing all obstructions 

 to the free passage of alewives, and by placing a sufficient 

 number of mature fish in the headwaters. 



Influence of Natural Conditions. — The life history and habits 

 of the alewife are markedly influenced by environment, espe- 

 cially during migration and spawning. Wind and tide affect 

 their entrance and progress up streams, by shifting the sandy 

 openings to the brackish water ponds near the coast, and 

 changing the mouths of the streams. As a rule, alewives fol- 

 low the greatest flow, — an important fact to take into con- 

 sideration in the location of fishways. 



Judging from the fact that fresh water evidently attracts 

 anadromous fish in the spawning season, apparently the mineral 

 content of the water has an important influence upon the 

 migration of fish. If such is the case, chemical pollution from 

 manufacturing plants may be a more serious problem than 

 is commonly considered. Alewives ordinarily show a tendency 

 to avoid the dark, but on the Agawam River they pass for 

 50 feet through an unlighted fishway. However, it is advisable 

 whenever possible to have open fishways. Temperature and 

 food supply also are important factors governing the movements 

 of old and young. 



THE FISHERY. 



Commercially the alewife is valuable both for food and for 

 bait. Its abundance and comparative cheapness renders it of 

 the utmost importance to the Massachusetts shore towns. 

 Smith (4) states that in 1896 nearly 150,000,000 were sold in 

 fourteen States, in addition to large quantities given away at 

 the shore, and that over 2,500 persons were engaged in the ale- 

 wife fisheries, besides many thousands of people who operated 

 apparatus in which alewives constituted an important part of 

 the catch. At that time Maryland, North Carolina and Vir- 

 ginia were the leading alewife States, although important fish- 

 eries also existed in Maine, Rhode Island, Connecticut, Massa- 

 chusetts, New York and New Jersey. 



In Massachusetts there are two types of alewife fisheries, the 

 natural and the artificial, both of which have been developed 

 under town control. 



