118 BULLETIN OF THE BXJEEAU OF FISHERIES 



Atkins they begin feeding before reaching salt water and recover a good deal of fat 

 before moving out to sea. 



The eggs are transparent, pale pink or amber, and being semibuoyant and 

 not sticky like those of other river herrings they roU about on the bottom with 

 the current. The period of incubation is from 5 to 10 days in the temperatures 

 prevailing in June in the Kennebec and St. John Rivers, having been found by 

 experiment to be as follows: 



Water temperature Period of incubation 



74° F. (23.3° C.) 70 hours, or about 3 days. 



64° F. (17.8° C.) . 109 hours, or about 4H days. 



57° F. (13.9° C.) 148 hours, or about 6 days. 



54° F. (12.2° C.) 408 hours, or about 17 days. 



The larvfe are about 9.5 mm. long at the time of hatching, growing to 15.5 

 mm. by the ninth day with disappearance of the yolk sac. At 21 to 28 days the 

 fins are fully developed and the fry have attained a length of about 20 mm. Shad 

 larvae much resemble herring, being extremely slender with the vent almost as far 

 back as the base of the tail. 



The young shad remain in the rivers until fall when, at a length of 1}4 to 

 43^ inches and resembling their parents in appearance, they move down to salt 

 water. The length attained by the shad during its first autumn depends on the 

 date of hatching. In the rivers of Maine the fry may be as long as 5 to 7 inches 

 by the first week in November; even larger (6 to 8 inches) in New York streams. 



Nothing definite is known of the rate of growth of the shad after it leaves its 

 parent river; presumably, however, it grows little during the first winter but is about 

 a foot long by the second autumn. It is supposed to mature at about the same age 

 as the alewife^S or 4 years 



44. Menhaden (Brevoortia tyrannus Latrobe) 



POGY 



Jordan and Evermann, 1896-1900, p. 433. 



DescHption, — This fish is universally called "pogy" in the Gulf of Maine but 

 no less than 30 common names are in use south of Cape Cod. Like all our other 

 herrings it is flattened laterally, has a sharp-edged belly, and is as deep propor- 

 tionally as the shad (body three times as deep as long), though when the fish are 

 fat the general form is altered. The very large scaleless head, which occupies 

 nearly one-third of the total length of the body, gives the menhaden an appear- 

 ance so distinctive that it is not apt to be mistaken for any other Gulf of Maine 

 fish. It is likewise distinguishable from all its local relatives by the fact that the 

 rear margins of the scales are vertical — not rounded as in the more typical herrings — 

 and edged with long comblike teeth instead of being smooth. The dorsal fin, 

 furthermore, originates slightly behind the ventrals and is thus posterior to the 

 latter for the whole length, whereas in herring, alewives, and shad it stands directly 

 over the ventrals. We need only point out further that the pogy is toothless, its 



