GRAYLING OF GREBE LAKE 



347 



fishes. By way of illustration, during the evening 

 grayling and trout rose to the surface within a few 

 feet of one another with no gross evidence of 

 strife in a common feeding ground. Apparently, 

 there was sufficient food in Grebe Lake for both 

 species, judging from the gorged condition of the 

 digestive tracts and plumpness of the fish. The 

 only exception was on the spawning grounds 

 where many fish were crowded into the small 

 streams; a relatively large number of the stomachs 

 collected were empty. 



HARVEST OF GREBE LAKE FISHES BY ANGLING 



Despite the recognized limitations of a volun- 

 tary creel census it was necessary to employ such a 

 method to obtain information on the magnitude 

 of the sport fishery. The data gave a measure 

 of the effect of angling on the fish population. 

 Also, the reports made it possible to adjust the 

 procedures of the mark-and-recapture population 

 estimate that was in progress. A creel census form 

 was employed to obtain records of the amount of 

 time anglers spent in fishing, the kinds, numbers, 

 and sizes of the fishes caught, whether or not there 

 were identifying marks on the fish, and the types 

 of lures used. 



These creel census forms were placed in a box 

 near the parking area, from which all fishermen 

 had to walk the 3.5 miles to Grebe Lake. The 

 importance of completing the creel-census records 

 was stressed by personal contacts with the anglers. 



The completeness of the voluntary returns was 

 checked by counts of all fishing parties. In 1953, 

 65 of 98 groups (66 percent) filled out creel census 

 blanks during the time of the population estimate. 

 In 1954, the response improved slightly; 93 of 

 132 counted parties (70 percent) completed the 

 forms. For the rest of the seasons in both years 

 it was estimated that only about 50 percent of 

 the fishermen responded. 



Adjustment of the creel records on the foregoing 

 basis enabled an approximation of the total catch 

 each year. In the 1953 season, 780 fishermen 

 removed 2,148 fish. Anglers increased to 818 in 

 1954 and caught 2,863 fish. This represented a 

 harvest of the estimated populations that approxi- 

 mated 7.1 percent in 1953 and 9.9 percent in 1954. 



The average size of 81 of the grayling measured 

 from anglers' creels was 11.4 inches. Since this 

 figure was not too different from the 11.0-inch 

 average size of the grayling captured during the 



population study, I assumed the size distribution 

 of the anglers' catch to approximate that of the 

 trap nets during the respective years. Under 

 these conditions the total weight of fish removed 

 by the fishermen was 903.8 pounds in 1953 and 

 1,191.3 pounds in 1954. 



Although grayling are approximately 10 times 

 as numerous as trout in Grebe Lake, they com- 

 prised only 67 percent of the catch in 1953 and 

 75 percent of the total captures in 1954. Thus in 

 the catch, the grayling-to-trout ratio of 3.1 to 1 

 in 1954 was higher than in 1953 (1.9 to 1). Per- 

 sonal contact with anglers indicated that most 

 preferred to catch the hybrid trout, and that 

 they fished primarily for it. 



Results of creel-census information tabulated 

 by monthly intervals showed a decreasing trend 

 in fish per fisherman between July and September, 

 1953, but an increase during the same interval in 

 1954 (table 29). Fishing effort also declined 

 rapidly after August 29 (fig. 30) However, the 

 efficiency of the late season anglers, as reflected 

 by the fish-per-hour rate, increased in September 

 of both years. 



Table 29. — Monthly summary of fishing pressure and yield 

 for Grebe Lake, based on 138 creel census returns in 1953, 

 and HO in 1954 



The average number of fish per fisherman 

 (3.1 in 1953, 3.5 in 1954) was good considering 

 that the limit imposed by the National Park 

 Service on Grebe Lake was five per angler. Some 

 fishermen who reported limit catches often caught 

 two or three limits and released all but five fish; 

 others released all fish. Only trout and grayling 

 actually removed from the lake were included in 

 the foregoing analysis of yield. Therefore, fishing 

 in Grebe Lake was probably better than the 

 figures indicate. However, there was a compen- 



