134 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 

 DISTRIBUTION AND ABUNDANCE. 



The shad is distributed along the entire east coast of the United 

 States, and northward and eastward to the Gulf of St. Lawrence. It 

 has gradually spread from the Sacramento Eiver, California, where it 

 was introduced by the California Fish Commission, and is now taken 

 from southern California (Los Angeles County) to southeast Alaska. 

 In the early history of the country its abundance excited unbounded 

 astonishment. Nearly every river on the Atlantic coast was invaded in 

 the spring by immense schools, which, in their upward course, furnished 

 an ample supply of good food. Notwithstanding greatly increased fish- 

 ing operations and the curtailment of the spawning-grounds, the supply 

 in recent years has not only been generally maintained, but owing to 

 fish-cultural efforts has been largely augmented in certain streams, 

 notably in the Kennebec, Hudson, Delaware, Susquehanna, Choptank, 

 Potomac, Nanticoke, Eappahannock, York, James, Chowan, Eoanoke, 

 Neuse, and St. Johns rivers, and in Chesapeake Bay, Albemarle Sound, 

 Croatan Sound, and Pamlico Sound, and the Sacramento and Columbia 

 rivers. 



SHAD IN THE OCEAN. 



The shad passes most of its existence at sea, and little is known of 

 its habits and movements when out of the rivers. The ocean areas to 

 which it resorts are unknown, and what its salt-water food consists 

 of has not been determined. In the Gulf of Maine it is known to 

 associate in large numbers with mackerel and herring during the 

 months of June, September, and October, being most numerous in June. 

 It has been taken at North Truro, Massachusetts, in the fall, Av-hen the 

 ocean temperature was from 43° to 49°. In the month of November, 

 one year after another, it has been found on the west side of Sakonnet 

 Eiver, Ehode Island. In May and June it has been captured with 

 mackerel a few miles northeast of Cape Cod Light. Some instances 

 of capture indicate that under certain conditions the adults may 

 remain in the fresh-water rivers a whole year. In November, 1890, 600 

 were taken in the Chesapeake Bay. It has been found in the Potomac 

 in considerable abundance in August and September, and even during 

 the last week in December. Its movements are largely controlled by 

 the water temperature. It is believed that it aims to occupy a hydro- 

 thermal area of certain temperature; that its migrations are determined 

 by the shifting of this area, and that this temperature is between 00° 

 and 70O. 



SHAD IN THE RIVERS. 



The annual migration of the shad from the ocean to the rivers is 

 for the sole purpose of reproduction. It ascends to suitable spawning- 

 grounds, which are invariably in fresh water, occupying several weeks 

 in depositing and fertilizing its eggs in any given stream. 



Its migrations from the sea are in quite a regular succession of 

 time with relation to latitude. It first appears in the St. Johns Eiver, 



