PROPAGATIOX AND DISTRIBUTION OF FOOD FISHES, 19 38 481 



returned to the natural spawning grounds, while the flounder eggs 

 were hatched with a loss of only about 10 percent. The number of 

 eggs taken from adult flounders averaged approximately 243,000 per 

 fish, but, due to the development of slime on the spawidng grounds and 

 the disappearance of eelgrass, the station was unable to collect as 

 many spawners as heretofore. In cooperation with the Department 

 of Sea and Shore Fisheries of Maine, lobster culture was continued. 

 On account of the low water temperature, coupled with the canni- 

 balistic tendencies of this crustacean, it has been a difficult task to 

 hold the fry until they have reached the fourth stage. However, 

 experiments are being conducted in the heating of the hatchery water. 

 While it is too early to reach any definite conclusions it appears that 

 by heating the water 12 to 15 degrees, lobsters can be reared to the 

 fourth stage in 11 to 13 days with a loss of only about 50 percent, while 

 about only 15 to 20 percent would reach this stage under natural 

 water temperatures. 



GREAT LAKES SPECIES 



Except at the Put-in-Bay, Ohio, station, the propagation of com- 

 mercial species of the Great Lakes contmued on a restricted basis. 

 As the closed season on lake trout was set ahead to October 1, the 

 Duluth, Minn., station was miable to secure any eggs of this species 

 from the early runs of fish. After the closed season some lake- trout 

 eggs were received from the commercial fishermen, and the State of 

 Michigan, but, due to the scarcity of fertile males at this time of the 

 year, the percentage of hatch from these eggs was very low. There 

 were 7,870,000 whitefish eggs handled during the season and 5,000,000 

 of this number were allotted by the State of Mmnesota. More than 

 1,000,000 lake-herring fry were planted in the inland lakes of the 

 Superior National Forest. The output of pike perch from the 

 Duluth station was greatly increased over that of 1937. The propa- 

 gation of this species was carried on in cooperation with the Minne- 

 sota Conservation Department, fish being liberated in the waters of 

 that State. Of the 61,500,000 eggs handled, 50,000,000 were cofiected 

 by the State. In addition to the propagation of the above commercial 

 species, the station hatched Loch Leven, brook, and rainbow trout for 

 the supplying of rearing stations in the national forests. 



The collection of pike-perch eggs at the Fut-in-Bay, Ohio, station 

 was considerably below that of last season, as weather and water con- 

 ditions were unfavorable during the entire spawning period. How- 

 ever, approximately 256,000,000 eggs were collected from the various 

 fields. In addition to the pike-perch work, more than 120,000,000 

 whitefish eggs were handled. The propagation of both species was 

 conducted on a joint basis with the State of Ohio. 



The output of commercial species from the Cape Vincent, New 

 York, hatchery was relatively insignificant. All whitefish and lake- 

 trout eggs handled were received from local and Canadian fishermen 

 witli the exception of 500,000 lake- trout eggs received from the 

 Province of Ontario in exchange for brook- trout eggs from the York 

 Pond hatchery. There was no active work at the Swanton, Vt., 

 substation which had previously handled pike perch and yellow perch. 



To supplement the Cape Vincent output, rainbow, brook, and 

 Loch Leven trout and smallmouth black bass were propagated. The 



