REPORT OF COMMISSIONER OF FISH AND FISHERIES. CXXXIX 



waters all summer, with practically no downward migration. At this 

 season, also, near the surface in the open water of the river, they seem 

 to be present in moderate numbers and are perhaps abundant, but the 

 means available for collecting in the offshore waters have not been 

 satisfactory. With the approach of cold weather the young shad do 

 not descend the river along the shores in order to reach warmer water, 

 but withdraw to the river channel. When the temperature of the water 

 falls to a point between 46° and 56°. which happens in November, 

 they leave the places they have frequented during the summer. This 

 movement is perfectly well marked throughout the section above brack- 

 ish water. Observations in winter and spring indicate that there is 

 some downward movement after the fish leave ttie shores, and this 

 must necessarily take place in the deeper water. Seining in the Lower 

 Potomac and along the western shore of Chesapeake Bay in the latter 

 half of February showed that no young shad were there, but about the 

 end of March numbers were noticed in the pound nets set along the 

 shores of the Lower Chesapeake near Old Point Comfort and the Vir- 

 ginia capes. These were the previous spring's hatch, and such fish 

 have also been noted in the Lower Potomac. Shad of apparently two 

 years' growth have been taken in both the bay and lower river, but 

 the young do not reappear on the shores in spring in the fresh water 

 of the river. 



It seems probable that at least some of the young shad of a particu- 

 lar season's spawning do not reach the ocean during the ensuing year, 

 and it is possible that .some reach maturity (in three or four years) 

 without visiting the ocean. Deep-water collecting in Chesapeake Bay 

 in midwinter will do much to fill the present hiatus in our knowledge 

 of the shad during that season. 



Insects and entomostracans are the most important food of the young- 

 shad in fresh water. Of entomostracans, the genera Daphnia, Cyclops, 

 Cijpris, and Bosmina are largely represented in the stomach contents. 

 Ehizopods, nematodes, amphipods and gastropods are eaten; vege- 

 table food is rarely taken. In a few cases small fish had been ingested 

 and shad fry have been found in the stomach, but this is unusual. 



When 2 months old, shad are about 2 inches long; having attained 

 this size, they add about an inch to their length in from 2£ to 3i months, 

 so that when they leave the fresh water in the fall they are from 3J to 

 4 inches long. They grow slower in the river than in ponds (such as 

 the Government fish-ponds at Washington). Pish from the upper part 

 of the river are distinctly smaller than those from the lower, having 

 been hatched later. 



FISHES AND FISHING-GROUNDS OFF SAN DIEGO COUNTY, CALIFORNIA. 

 In March and April, 1898, Messrs. C. Putter and F. M. Chamberlain 

 were assigned to an examination of the fishery resources and fishing- 

 grounds of the southern California coast. The steamer A Ibatross, which 

 was then lying off San Diego, was made the headquarters of these 

 assistants while working in the vicinity. It was the intention to have 



