SYSTEMATIC CATALOGUE OF FISHES. 127 



continues its journey northward. This theory was at one time generally enter- 

 tained and is still cherished by some people, although there are no facts to sus- 

 tain it. Another theory which has had and still has many adherents is the so- 

 called "instinct of nativity", by virtue of which an individual shad or other 

 migratory fish, when mature, makes its way back to the particular stream in 

 which it was hatched. 



The facts seem to be that bodies of shad which are destined to enter a partic- 

 ular stream or hydrographic basin (such as Chesapeake Bay or the North Caro- 

 lina sounds) occupy sea areas off these waters, and that when the fish reach matur- 

 ity and are impelled by the spawning instinct to seek fresh water, they move 

 inshore and pass up to their spawning grounds when the temperature of the water 

 becomes favorable. In this way fish may and doubtless often do return to the 

 stream in which they were hatched, but they are just as likely to enter adjacent 

 streams. Thus, shad which were hatched in Roanoke River and went to sea 

 during their first year, when they return to North Carolina waters and pass into 

 Hatteras Inlet, might ascend Pamlico River, or, entering Albemarle Sound, 

 might go up the Pasquotank or the Chowan. To claim anything else for the 

 shad would be to ascribe to fish a higher order of intelligence than is possessed by 

 any other class of animals. 



Successive schools of shad arrive in a given stream during a period of several 

 months, resulting in a rise and fall in the catch. The fish in the early runs 

 are largely males, 90 per cent of some schools consisting of males, while later in 

 the season males are often scarce. Shad may spawn anywhere in fresh water, 

 but they prefer areas in rivers off the mouths of creeks or in sounds off the 

 mouths of rivers, where the warmer water of the stream mingles with the cooler 

 water below. While the eggs may be cast at any hour of the day or night, the 

 largest percentage are deposited about the time the water on the spawning 

 grounds reaches its highest daily temperature. This occurs about sunset, and it 

 has been found that the bulk of the eggs are extruded between 5 and 10 p.m. 

 The eggs are shot loosely in the water and quickly fall to the bottom, many 

 escaping fertilization, many being killed by mud, and many being devoured by 

 eels and other fishes. The average number of eggs produced by the shad is 

 25,000 to 30,000, although over 100,000 eggs (in one case 156,000) have been 

 taken from large fish. The hatching period varies with the water temper- 

 ature, but ordinarily is 6 to 10 days; when the water is very warm, the eggs may 

 hatch in 3 days, but so short an incubatory period is likely to result in weak fry. 



The newly-hatched shad are a little less than .4 inch long; they are very 

 active from the outset, and feed freely and grow rapidly, so that their size doubles 

 in 10 days, and by fall, when they leave the fresh waters, they are 3 to 7 inches 

 long. Under especially favorable conditions, they may attain a length of 9 

 inches in 7 months. 



Some years there is a small run of shad in fall, which naturally excites consid- 

 erable interest. Thus in 1904 a full-grown shad was caught in North River. 

 October 31, and another in Neuse River on the same date (described as " a fine 



