PROGRESS IN BIOLOGICAL INQUIRIES, 1931 505 



the transfer the eyes of fish already affected continued to de<^enerate, 

 but no new cases of tlie disease could be found. 



Parasifefi of Great Lakes -fishes.— Dxwm^y^ October and November, 

 1931. Dr. Frederic F. Fish made a preliminary survey of the extent 

 of infestation Avith the larval sta<ie of the cestode Triaetiophoi'us 

 rohustus amono- fishes of the Great Lakes. This parasite was found 

 to present a serious problem in the tullibees and whitefish of Lake 

 of the Woods, the lake herrincr and whitefish of Rainy Lake, the lake 

 herrino- of Avestern Lake Superior, and the lake herring and chubs 

 of the Green Bay reoion of Lake Michigan. The parasite was found 

 to a lesser extent in the lake herring taken at Cheboygan, Saginaw 

 Bay, and Marquette, Mich. Other fish, including the pike-perch, 

 pike, pickerel, yellow perch, sauger, black sucker, redhorse sucker, 

 bullhead, carp, crappie, and cisco, were examined in several locali- 

 ties and were found to be uniformly negative. 



Lake Erie was found to be free from the parasite. Lake Ontario 

 was not visited, but there isi no reason to suppose that the parasite 

 occurs there. 



CALIFORNIA TROUT INVESTIGATIONS 



Early in the j^ear arrangements were made with the California 

 Division of Fish and Game for a cooperative trout study in that 

 State. In March a meeting of the members of the bureau's staff who 

 are working on trout propagation was held in Washington, and an 

 outline was made of those lines of investigation which promised to 

 be of most help in maintaining the western game fishes under the 

 constant increase in angling which has followed the extension of 

 roads and the development of the automobile. 



Three major lines of investigation were proposed : 



(1) A study of the development of a domestic brood stock as a 

 source of eggs. 



(2) Investigation of the problems involved in raising larger fish 

 for planting. 



(3) The development of a stocking policy through stream surveys. 

 Active work on this program was started in May. This prelimi- 

 nary work has included a survey of certain streams with a view to 

 selecting those which are suitable for experimental work. In the 

 course of this work streams have been studied in the four geographi- 

 cal groups into which the streams of the State may be divided, viz, 

 the streams of the eastern slope of the Sierras, of the western slope of 

 the Sierras, of southern California, and of the Coast Range from 

 Monterey north to the Oregon line. 



Data have been gathered also regarding the development of 

 selected brood stock as a source of eggs. This has included a study of 

 the present brood stock in the State and the characteristics of the 

 wild stock from which eggs are now derived. 



It was not possible to start selected brood stocks during the present 

 season, as no sites were availa])le for holding such fish, but plans 

 have now been formulated which will make it possible to carry on this 

 work during the coming year. There is a particularly pressing need 

 for the development of a source of brown-trout eggs in southern Cali- 

 fornia, and it is now planned to use for this work certain storage 

 reservoirs which are not subject to great fluctuations in level. 



