20 REPORT OF THE COMMISSIONER OF FISHERIES. 



has revealed the cause of death in many cases, and remedial measures 

 have been suggested to the superintendents of trout stations. 



Efforts to find a satisfactory food for J'oung salmonoid fishes at a 

 lower price than the expensive meat products in general use have 

 been continued. Canned herring milt has been found to have some 

 value when used in combination with meat, but used alone it has not 

 yielded good results, as it appears to lack some important require- 

 ment of a full meat diet. 



Climatic conditions during the 1921 nesting season of the basses 

 ■were very unfavorable for a large output of fish. A period of 

 unseasonable warmth in March unduly advanced the spawning 

 season. This was followed b}- a cold spell in April and variable 

 weather in May, such conditions appearing to prevail all over the 

 country. A sudden fall in water temperature invariably causes 

 spawning bass to desert their nests, with a subsequent loss of the eggs 

 deposited. The bass output was therefore curtailed at practically 

 all stations, and at some of them it was a complete failure. 



In cooperation with the fishery authorities of Minnesota, investi- 

 gations were made with the view, of determining the feasibility of 

 making collections of pike-perch eggs in the Rainy Lake region of 

 that State. OiDcrations were conducted at two sites, and eggs to the 

 number of 13,G80,000 were obtained as the Bureau's share of the 

 returns. 



On the Atchafalaya RiA^er, in Louisiana, 9G.440,000 eggs of the 

 buffalofish were taken between February 27 and March 25, 1921, the 

 collections being materially reduced below those of the preceding 

 year by the short spawning season and the small numbers of fish 

 available. These unfavorable conditions are attributed to the late 

 rise in the river, which, occurring in Januaiy, acted as an incentive 

 to the fish to pass by their usual spawning grounds and seek more 

 inaccessible spots in the denser portion of the flooded swamps. The 

 catch of fish along the river was reported by local fishermen to be the 

 smallest since 1913. 



Taking advantage of an opportunity to save eggs of buffalofish 

 and carp on the Mississippi River at Bellevue, Iowa, and Lynxville, 

 Wis., during the spring of 1921, the Bureau collected 68,267,000 eggs 

 of the former and 42,712,000 of tlie latter species, all of them being 

 secured from fish caught for the market by commercial fishermen. 

 The eggs were fertilized and immediately planted on the spawning 

 grounds in the river. 



HATCmXG OF MARINE FISHES. 



Operations in this branch were conducted at the usual points in 

 Maine and Massachusetts and were addressed to the cod, pollock, 

 haddock, winter flounder, and pole flounder. The weather through- 

 out the spawning season of the various species Avas favorable, result- 

 ing in the taking of eggs of better than average quality at a lowered 

 cost of production. There was a reduction in the number of cod and 

 pollock eggs taken as compared with the previous year. A rather 

 sharp decline in the price of pollock deprived the local fishermen of 

 an incentive to pursue the fishery, and the catch at Gloucester fell 

 off about 70 per cent. The collection of eggs for hatching purposes 



