18 



proaches and retreats covering a period of many hours, one 

 fish, more bold than the rest, dared to enter the outlet, and 

 after it trailed the entire school. Several days are consumed in 

 passing down stream, the exact period of time depending upon 

 the length of the river. 



Parent Stream Theory. — From observations in handling local 

 alewife fisheries the "parent stream theory" has been evolved. 

 Briefly, the theory is that the young alewives descending from 

 a particular pond and stream return as adult fish to the same 

 stream for spawning, thus establishing a continuous chain. 

 There are good reasons to consider this theory favorably. Prac- 

 tical demonstration has shown that fisheries have been created 

 in streams which had no alewives by the simple expedient of 

 placing spawning alewives in the headwaters. The offspring 

 returned as adult fish to the same spawning grounds, thus 

 establishing a fishery. Similarly, depleted fisheries have been 

 re-established. Experience has likewise shown that a poor year, 

 when but few alewives reach the spawming grounds, is followed 

 at a stated interval by a corresponding lean year. From such 

 observations we can accept the "parent stream theory" as the 

 best working hypothesis available. 



Among the specific illustrations of the return of alewives to 

 the parent stream may be mentioned the following : — 



(1) According to the United States Bureau of Fisheries, sev- 

 eral hundred spawning alewives were placed in Keene's Pond 

 which had an outlet into Calais River, Maine. The young 

 were noted in large numbers in the pond, and on the fourth 

 year large numbers of adult fish returned for spawning to the 

 Keene's Pond stream, where no alewives had even been seen 

 before. 



(2) Lyman (3) reports the establishment of a fishery in four 

 years in a similar manner at Plymouth. 



C\) Mr. George M. Besse of Wareham obtained results in 

 three years in Little Mill Pond and in Five Mile Pond, and a 

 remarkable increase in the fishery was obtained in Mattapoisett 

 River in L920 by allowing all fish to reach the spawning grounds 

 in L917. 



This theory has been accepted as the basis of our future work 

 in the development of the alewife fishery, and we can confi- 



