Calculations for most units were based on the assumption that the 

 mean of the sampled days in each biweekly period would be representative 

 of all days in that period. Accurate figures on the rowboats and party 

 guideboats and the number of anglers using these facilities were obtained 

 from the boat concessionaire,, the Yellowstone Park Companyo Thus the cal= 

 culated means for each biweekly period could be applied to the biweekly 

 totals furnished by the Yellowstone Park Company for deriving the biweekly 

 estimates o 



As each unit of the Yellowstone Lake fishery has problems which are 

 unique, and to simplify the presentation of the census results., the indi= 

 vidual units have been treated and analysed separatelyo 



FISHING BRIDGE DOCK 



Fishing Bridge dock is located on the Yellowstone River immediately 

 downstream from Fishing Bridge (figo l)o This is the largest and most 

 popular of the docks providing rental boatso The duration of each of the 

 rowboat and guideboat trips is recorded to the nearest tenth of an hour 

 by a recording clock o The Yellowstone Park Company also keeps a record 

 of the number of persons occupying each rented boato These data have 

 proven to be of great value^, for an accurate record of the length of each 

 boat trip and the number of persons making the trip is thus recorded for 

 each d^ of the season, 



Rowboat Fishery? 



The Fish and Wildlife Service observer at Fishing Bridge dock recorded 

 the total trip hours for each boat coming into the dock, the number of per= 

 sons actually engaged in fishing from the boat, and the total number of 

 fish taken by the fishing party. It was assumed that the trip hours approx= 

 imated the actual fishing hoursj for fishable water is encountered immed- 

 iately after leaving the dock. The area of the lake in which fishing was 

 done was also recorded. The observer was on duty at the dock from 8 a.m, 

 to 5 Pom, Another observer reported to the dock at 6 p,m. and remained 

 until all rental boats had been returned^ usually by 8 pom. In many 

 instances the data from boats which returned between 5 and 6 pom, were 

 recorded by the dock workers. 



During the 19^0 season. Fishing Bridge dock was censused every other 

 dsy„ or seven times during each 2=week period. Because of limited person= 

 nel and an expanding research program, it was essential to reduce the nuj7i-= 

 ber of censuses during the 1951 season without materially reducing the ac- 

 curacy of our estimate. Setting up the hypothesis that there was no dif= 

 ference between the number of parties and persons interviewed on odd and 

 even census days when numbered consecutively from the first census day of 

 the season., an adjusted Chi=square test was made using one=half of the 

 season's total as the expected number. The results of this test are shown 

 in table 2, 



