374 U.S. BUREAU OF FISHERIES 



sion of Fish Culture of the Bureau also made possible a study of 

 Bear Lake, Utah. 



Fish Lake. — Inasmuch as this is probably the most productive trout 

 lake for its size in the countr}^, the privile<2je of making a limnological 

 study here was welcomed not only as an opportunity to assist the 

 State in its planting policies there, but also to seek to determine the 

 reason for its phenomenal productivity. Since accurate information 

 as to what constitutes a good trout lake is scarce, additional infor- 

 mation is of great value in judging the carrying capacity of other 

 waters and in seeking means to improve them. 



The usual procedure for the study of lakes was followed except 

 that more complete data were taken than is usually possible during 

 a preliminary survey. One hundred forty soundings were made as 

 a basis for the construction of a reasonalDly accurate contour map. 

 Temperatures were taken at frequent intervals from surface to bot- 

 tom in various parts of the lake. Chemical analyses for dissolved 

 oxygen, free carbon dioxide, carbonates, bicarbonates and pH were 

 made at a number of stations and on the principal tributaries. 

 Transparency was measured by the Secchi disk. Numerous samples 

 of plankton and bottom foods in the benthic and littoral zones were 

 secured. The type of bottom and areas of vegetation were recorded 

 on the large scale map. Three 1-hour gill net sets were made and 

 a number of fish taken by anglers were secured for scale samples, 

 weight-length data, and stomach analysis. The tributary streams 

 were also examined in order to determine their relation to the lake's 

 productivity. A record of the planting and fishing history is being 

 compiled by a member of the State Department. When the study 

 of the data is comi^lete. a joint paper will be prepared covering this 

 investigation. It is believed that valuable information will result 

 from this study. 



Sfrawhe?v'}/ Reservoir. — A marked decline in the fishing in this 

 lake resulted in the request for a study to determine the cause and 

 possible remedies. This investigation was begun in May, just before 

 the break-up of the ice. At that time it was impossible to study 

 conditions except at one point. Samples of the bottom water indi- 

 cated a marked deficiency in oxygen which, if typical of the lake, 

 might account for reported winter losses. Plans are made to obtain 

 sufficient samples in February 1935 to determine the severity and 

 extent of this deficiency. 



Sets with the graded size gill net, the approximate efficiency of 

 which has been determined, indicated an extreme scarcity of trout 

 in June of this year. This, together with the small run of spawning 

 jBsh, led to an order by the State Fish and Game Commission clos- 

 ing the reservoir and its tributaries to fishing in order to conserve 

 the remaining stock of native cutthroat trout. 



Samples of the plankton and bottom organisms in June and in 

 August indicated a great abundance of both of these foods but a 

 scarcity of shore forms, the latter being caused by severe fluctuation 

 in water level. Stomach examination of trout and chubs (Tigoma) 

 showed them to be direct competitors. The studies of June and 

 August showed an abundance of oxygen to be }3resent everywhere 

 in the bottom waters. Apparently no summer deficiency occurs here, 

 probably because of shallow water, exposed location and frequent 



