466 U. S. BUREAU OF FISHERIES 



species. In the rivers striped bass, white perch, black bass, and other 

 predacious fishes devour the young, and when they reach salt water 

 sharks, horse mackeral, kingfish, etc., undoubtedly destroy many 

 adults. It has been observed by North Carolina porpoise fishermen 

 that as the shad swim close along the shore the porpoises follow and 

 feed on them until they pass into fresh water, in the rivers the 

 adult shad is comparatively free from enemies. 



FOOD 



After entering the rivers the shad takes but little, if any, food 

 previous to spawning but after casting its eggs it bites at flies or any 

 small shining object and has been known to take the artificial fly. 

 The mouth of the adult is practically toothless, and its throat con- 

 tains no functionally active teeth. The water that passes through 

 the branchial filter — the gill rakers — is deprived of the small animals 

 that are too large to pass through its meshes. It is a common re- 

 mark mth fisherman and others that food is rarely found in the 

 stomach of the adult shad in fresh water, but examinations have 

 shown that the shad does, in some instances, eat small Crustacea, 

 insects, etc. The only substance commonly found in its stomach in 

 fresh water has the appearance of black mud. It is held by some 

 that the shad swims with its mouth open and may imintentionally 

 swallow the small organisms found in its stomach under such circum- 

 stances, but as far as observation of fish in aquaria and experiences 

 of net fishermen go the shad does not swim with its mouth open. 



SPAWNING 



Shad in spawning condition may be found anywhere above brack- 

 ish water, and under favorable temperature conditions spawn where- 

 ever they happen to be, but in some river basins they exhibit a 

 well-defined choice of spa"s\Tiing places, preferring localities below the 

 mouths of creeks, where the warmer water of creeks mingles with the 

 colder channel water. The shad lays its eggs during the highest 

 daily average temperature, a condition realized about sunset, when 

 the warmer shoal water commingles with the colder channel water, 

 establishing^ a balance. The principal spawning occurs from 5 to 

 10 p. m. Observations on the Potomac River show that of the eggs 

 from shad caught in a seine only 1 1 per cent were taken between 

 midnight and noon, the percentage in the morning being 14 one 

 year and 8 another. 



The eggs in the ovaries remain in a compact mass until they ripen, 

 at first occupying but a small space but gradually increasing until 

 they distend the whole abdomen, the average weight of the ovaries 

 being about 13 ounces. Close examination at the approach of the 

 spawning time will disclose large maturing eggs of rather uniform 

 size and others smaller a.nd of variable size. Whether the latter are 

 the forming eggs for the next year, for two or three succeeding years, 

 or for the lifetime of the fish, has not been determined, nor is it 

 knowm whether shad spawn every yeai\ The small and shrunken 

 ovaries of a spent fish are found still full of these eo;gs of different 

 sizes. Shortly before spawning, transparent eggs of large size, con- 

 trasting strongly with the opaque golden hue of less mature ones, 

 will be found scattered through the still compact ovarian mass, grad- 



