Table l5 indicates that if the 1950 and 195l seasons are comparable, 

 which is suspected by the closeness of the results of other boat fishing 

 activities, the assumption of an average of tbjree days on the lake foi' 

 each boat in 1950 was fairly close to the calculated 2o86 days in 195lo 

 The assumption of one limit of five fish per day per boat was greatly 

 divergent from the calculated twelve fish per day of 1951 <> 



Tb.e road block data showed that only 78 percent of the boats 

 stopped were used on Yellowstone lake, the others being used on Lewis 

 and Shoshons Lakes, with a few just passing through the Parke It 

 could, -cherefore, be assumed that 78 percent of the total number of 

 boats to which permits were issued were used on Yellowstone Lake, and 

 this number be used as the basis for calculating the catch estimateo 

 Revising the assumptions made for the original 1950 estimate, it could 

 now be more logically assumed that the two seasons were comparable and 

 e.'Stim.ates calculated accordingly (table l6)o 



Table 16 



Estimates of total catch by 

 private trailer-type boats for 1950 and 1951 



Permits Boats used Ave, days Ave. catch 



Year issued on lake of fishing per boat day Estimate 



1950 1,888 l,li73 2c85* 12* 50,377 



1951 2,056 1,601 2o85 12 5ii,857 



(■«• Kates assumed to be the same for 195l«) 



There are several reasons to believe that the above estimates are 

 very conservativeo Road block census results show that roughly ^0 per- 

 cent of the trailer-boats are brought into the Park from the states of 

 Utah and Wyoming, Many of these boats are brought in for use on Yellow- 

 stone Lake from one to many times each season. As the one boat permit 

 issued on the first visit is valid for the entire season, there is no 

 co'unt of the num.ber of actual boat trips, but only of the member of per- 

 mits issuedo Interviews with boat ovjners at road blocks also showed 

 that a considerable number of boats were without permits o Boat owners 

 were often requested to obtain their permits from the Lake Ranger 

 Station, and in many instances this was not donee It is thus impossible 

 to estimate the number of boats without permits used on the lakeo The 

 number, however, is believed to be highly significant in making the true 

 estim.ate of catcho In view of these limitations, the estimates are con- 

 sidered very conservative, an.d plans for futiire study wi].l include col- 

 lection of sufficient data for more accurate estimates of this uniji of 

 the Yellowstone Lake fishery o 



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