MANUAL OP FISH-CULTURE. 187 



water rivers is wholly for the purpose of spawning". The time of their 

 arrival in a given place is quite constant from year to year. The 

 branch alewife precedes the summer alewife by three or four weeks, 

 and also arrives several weeks before the shad. The run of the glut 

 herring occurs during the middle of the shad season. The branch 

 herring ascends the small streams to spawn, often entering branches 

 only 10 feet wide and not more than G inches deep. After spawning, 

 very little is known of the habits of the fish or of the departure from 

 the rivers; nor has their winter abode been ascertained. 



The eggs resemble those of the sea herring rather than of the shad, 

 being glutinous and adhering to brush, stones, piling, and other 

 objects under water. The netting, roj)es, and stakes of traps in which 

 the fish are caught are often covered with the fertilized eggs 5 the ale- 

 wives thus have a great advantage over the shad, and to this fact 

 must largely be attributed the continuance of the supply in the face of 

 very extensive fishing not counteracted by artificial propagation. The 

 eggs are about gV inch in diameter. 



There has been no eflbrt to regularly hatch the eggs of alewives 

 artificially. The undiminished abundance of these fish in the regions 

 of the most extensive fisheries has made their artificial propagation 

 unnecessary. In the New England States, where the alewife is an 

 important fish in many of the smaller towns, the supply has been 

 maintained by constructing fishways which permit the fish to reach 

 their spawning- grounds. In this way comparatively small streams have 

 annually yielded very large quantities of fish, and many streams, in 

 which the alewife run had been entirely inhibited by obstructions, have 

 been reopened and very successfully restocked. 



As early as 1871 the eggs of the alewife were artificially fertilized 

 and hatched, and those of the branch herring were similarly treated in 

 1877. Their cultivation presents no special difficulties, and can be 

 prosecuted on a large scale whenever it becomes necessary. The milt 

 is first taken in a pan, and then, while one jjerson keeps the pan in 

 motion, another expresses the eggs; this prevents the eggs from mat- 

 ting together and facilitates the contact of all with the milt. Eggs 

 adhering to the side of the pan may be removed with a stream of water. 



The automatic shad jar is the proper apparatus in which to hatch the 

 eggs, which are treated precisely like those of the shad. Sufficient 

 water is supplied to keep them moving freely and to overcome adhesion. 



The alewives are much more prolific than either the shad or the sea 

 herring. On one occasion, in the Potomac Eiver, 04:1 female branch 

 herring yielded 6G,20G,000 eggs, an average of 102,800 per fish. Prob- 

 ably 100,000 may be taken as a fair average. The eggs hatch quite 

 quickly under normal conditions. The period of incubation, in water 

 having a mean temperature of G0<^ P., is G days. The fry are very 

 minute. They are planted at the same time and in the same manner 

 as shad fry. Those in the rivers and lakes attain a length of 2 to 3 

 inches by the time they move toward salt water in the fall. 



