FAMILY CLUPEIDAE 91 



River by Surber in 1913-14 at Homer, Minnesota, but since then few- 

 have been reported. It might truthfully be said that the skipjack is the 

 only strictly migratory fish occurring in the upper river. For several 

 weeks after the waste gates at the Keokuk Dam were first closed during 

 the spring of 1913 the skipjacks literally swarmed in the swift current 

 below the powerhouse in a fruitless effort to reach the waters above. 



The skipjack is a very active fish. Often it jumps clear of the water 

 in play or in pursuit of its prey, for its favorite food is smaller fishes. 

 Frequenting by preference the swiftest waters, it is more often found 

 about the ends of the wing dams than elsewhere. The angler in pursuit 

 of sport alone will find it a savage fighter on light tackle. It readily 

 takes a small spoon hook and live minnows and occasionally takes flies 

 (see Forest and Stream, November 1, 1913) . Unfortunately it has no 

 value as food, for it is excessively bony. 



In accordance with the old rule that nothing exists in nature without 

 a specific purpose, this fish performs at least one valuable function in 

 the general scheme of nature. It was discovered in August 191*2 (Surber, 

 1913) that this species was the only specific host of the niggerhead 

 mussel, which supplied a shell valuable in the button industry. With 

 the passing of -the skipjack from the upper river the niggerhead mussel 

 has become extinct and along with it part of the livelihood of a con- 

 siderable number of people. At present the skipjack is very rare if not 

 extinct above the Keokuk Dam. 



GENUS Doroso?na Rafinesque 



This genus contains four species, one of which ranges from Minne- 

 sota to New York and southward to Mexico and lives also in brackish 

 water of the Gulf of Mexico and the Atlantic. 



GIZZARD SHAD (Hickory Shad, Mud Shad, Hairy Back. 

 Norwegian Herring) 



Dorosama cepedianum (LeSueur) 



The gizzard shad (Figure 8) is silvery in color, with a bluish back. 

 The young fish have a spot just posterior to the pectoral fin. The belly 

 is sharply serrated, or keeled. This species is easily distinguished by the 

 last ray of the dorsal fin, which is very long. Teeth are absent in the 

 adult, though present in the young. The stomach is very muscular or 

 gizzardlike, and the intestine is long and coiled. The gill-rakers are long 

 and extremely fine. They reach a length of over 15 inches. 



Gizzard shad frequent large rivers and muddy lakes. They are com- 

 mon in the St. Croix and Minnesota rivers and in the Mississippi River 

 below St. Paul. They seldom reach a length of over 12 inches, though 

 lengths of 18 inches have been reported. In quiet, muddy stretches of 



