FISHES OF THE GULF OF MAINE 



103 



of streams, running indifferently up rivers as large 

 as the St. John, Merrimac and Potomac, or 

 streams so small that one can almost leap across, 

 and only a few inches deep. In large rivers they 

 run far upstream — how far they may do so we 

 do not know— or their journey may be one of 

 only a few yards, as it is in the artificial cuts that 

 are kept open through barrier beaches to allow 

 the fish access to fresh water ponds behind the 

 latter. 



The alewife spawns in ponds, including those 

 back of barrier beaches (if there are openings to 

 the sea, natural or artificial) and in sluggish 

 stretches of streams, never in swift water, each 

 female depositing from 60,000 to 100,000 eggs or 

 more, according to her size. 68 Spawning lasts 

 only a few days for each group of fish. 



The spent fish run down stream again so soon 

 after spawning that many of them pass others 

 coming up, as we have often seen; fish on their 

 return journey to salt water are familiar sights in 

 every alewife stream. 



The adults, when entering streams to spawn, 

 make the change from salt water to fresh within 

 a short time without damage; this is equally true 

 of the spent fish on their return to the estuaries. 

 But Dr. Huntsman informs us that they appear 

 unable to endure repeated changes between salt 

 water and fresh, and that great numbers are 

 killed in this way in the estuaries under certain 

 conditions of tide. The strain of spawning leaves 

 them very thin, but they recover rapidly after 

 they reach salt water. We have seen spent 

 alewives that had already put on considerable 

 fat, taken from a trap at Provincetown as early 

 in the season as July 16 (in 1915). 



Spawning ordinarily takes place at tempera- 

 tures of about 55 to 60°. The eggs are about 

 0.05 inches in diameter, pink like those of the sea 

 herring, and they stick to brush, stones, or any- 

 thing else they may settle upon. 89 Incubation 

 occupies about 6 days at 60°. The young 

 alewives, which are about 5 mm. long when 

 hatched, growing to 15 mm. when a month old, 

 soon begin to work their way downstream. They 

 have been seen descending as early as June 15 in 

 the more southerly of Gulf of Maine streams; 



«* The average number of eggs in 644 females taken In the Potomac was 

 102.800 (Smith, N. C. Qeol. and Eeon. Survey, vol. 2, 1907. p. 123). 



• The development of the eggs, larval stages, and young fry are described 

 by Ryder (Report, U. S. Comm. of Fish. (1885), 1887, p. 505) and by 

 Prince Contr. Canad. Diol. (1002-1005), 1907, p. 95). 



successive companies of fry move out of the pond 

 and down with the current throughout the 

 summer; and by autumn the young alewives have 

 all found their way down to salt water when 2 to 

 4 inches long. We have seined young alewives 

 as long as 4 to 4K inches (102-115 mm.) in salt 

 water near Seguin Island, Maine, at the end of 

 July, but others, only 3 to 3% inches long (78-92 

 mm.), near Mt. Desert Island as late as the first 

 of October. Thenceforth the alewife lives in 

 salt water until sexual maturity. 



Hildebrand and Schroeder 70 found that little 

 alewives in Chesapeake Bay had grown to about 

 4K to 5 inches long by the time they were 1 year 

 old. 



The rate of growth of the older alewives, in salt 

 water, has not been traced. But experiments in 

 planting adult alewives in ponds in which there 

 were none before, led, long ago, to the conclusion 

 that they became sexually mature at 3 or 4 3 r ears 

 of age, for none of their progeny returned until 

 3 or 4 years after the original plant. Specific 

 instances, cited by Belding 71 are: 



(1) Three years after a large number of alewives 

 were hatched in Keene's Pond, Maine, tributary 

 to the Calais River, from a "plant" of mature fish, 

 a run of adult fish entered Keene's Pond stream 

 where none had ever been seen before ; this case was 

 reported by the U. S. Bureau of Fisheries. (2) 

 The establishment of a fishery, in the same way at 

 Plymouth, Mass., in 4 years after restocking in 

 1865; and (3) G. M. Besse obtained results in 

 3 years in ponds in Wareham, Mass. 



The fact that alewives have been known to 

 return, for spawning, to streams in which their 

 parents had been planted, lends support to the 

 "parent stream" theory; i. e., that alewives, like 

 shad, tend to spawn in the stream system in 

 which they were hatched. But a much more 

 intensive study is needed of this interesting 

 question before any categorical statement can be 

 made, as to how generally this is true; and to 

 what extent their return depends on their never 

 having wandered far afield. 



Food. — The alewife is chiefly a plankton feeder 

 like the herring; copepods, amphipods, shrimps, 

 and appendicularians were the chief diet of speci- 

 mens examined by Vinal Edwards and by Linton 



•• Bull. U. S. Bur. Fish., vol. 43, 1928, p. 91. 



" Rept. Alewife Fish. Mass., Mass. Dept. Conservation, Div. Fish, and 

 Game, 1921, p. 18. 



