FISHERY BULLETIN: VOL. 71, NO. 2 



Because of the small size and abundance of 

 the pygmy whitefish, it must be important as 

 a primary carnivore available to species next 

 in the food chain. The only extensive detailed 

 publications on pygmy whitefish, however, are 

 those of Eschmeyer and Bailey (1955) dealing 

 with Lake Superior populations and of Heard 

 and Hartman (1966) and McCart (1970) with 

 Alaskan populations. Our work is concerned 

 with populations from Flathead Lake and Bull 

 Lake in the upper Columbia River drainage 

 but involves comparisons where applicable to 

 the Lake Superior and Alaskan forms. Some 

 comparisons are also made with the mountain 

 whitefish, Prosopium ivilliaynsoni, a closely 

 related sympatric species. 



whitefish are lake whitefish, lake trout, and 

 Dolly Varden. 



Bull Lake is comparatively small and shallow 

 and is somewhat eutrophic. The total surface 

 is 1,250 acres and the maximum depth is 

 64 ft. Ross Creek, where the pygmy whitefish 

 were captured during their spawning runs, is 

 the largest tributary. 



No thorough studies have been made of the 

 fish species in Bull Lake but, besides pygmy 

 whitefish, it is known to contain rainbow trout, 

 cutthroat trout, brook trout, Dolly Varden, 

 kokanee, mountain whitefish, redside shiner, 

 northern squawfish, peamouth, longnose sucker, 

 largescale sucker, largemouth bass, and a 

 sculpin. 



ASSOCIATED FISHES AND 

 DESCRIPTION OF THE LAKES 



Flathead Lake is a large oligotrophic lake 

 covering 126,000 surface acres and reaching a 

 depth of 365 ft. Its major tributaries are the 

 Flathead and Swan Rivers. Its outlet, the 

 Flathead River, joins the Clark Fork River of 

 the Columbia River. 



Like many glacial lakes, Flathead Lake is 

 depauperate in native fishes. Indigenous fishes 

 in the lake are cutthroat trout {Sol mo clarki), 

 Dolly Varden, pygmy whitefish, mountain white- 

 fish, longnose sucker {Catostomus catostomus), 

 largescale sucker (C macrocheilus), peamouth, 

 redside shiner (Richardso}iius balteatus), north- 

 ern squawfish, and slimy sculpin (Cottus cog- 

 natus). 



Around the turn of the century a number 

 of other species were introduced. The exotic 

 forms presently in the lake are rainbow trout 

 {Salmo gaircbieri), lake trout (Salvelinus iiamay- 

 cush), brook trout (S. fonti)(alis), kokanee, lake 

 whitefish, black bullhead {Ictalurus melas), 

 yellow perch, pumpkinseed (Lepomis gibbosiis), 

 and largemouth bass (Micropterus salmoides). 

 Plants of other exotics, including a 1969 plant 

 of coho salmon, Oiicorhy)ichns kisutch, were 

 not successful. The northern pike, E.so.r Incius, 

 thrives in Flathead River below the hydro- 

 electric dam at the lake's outlet but is not 

 reported from the lake. Fish species most often 

 taken in the same net settings with pygmy 



MATERIALS AND METHODS 



Pygmy whitefish were collected from Flat- 

 head Lake during an investigation on fish 

 populations by the Montana Fish and Game 

 Department. A 35-ft former commercial fishing 

 boat modified to handle specialized fishing gear 

 and provided with a recording sonar was used 

 to set and pull nets from 11 sample areas 

 during 4 seasons from November 1967 through 

 August 1971. Six hundred feet of gill netting 

 ranging from %-inch to 4-inch stretched mesh 

 were laid in 165 settings. Except for spawning 

 populations practically all pygmy whitefish 

 were caught in the %-inch and lV4-inch mesh 

 portion and were taken within 3 ft of the bottom. 

 The largest collections were taken during the 

 late summer at depths of 60 to 270 ft. Un- 

 fortunately, too few pygmy whitefish were 

 taken to interpret an overall distributional 

 pattern. 



The Bull Lake collections were taken with 

 seines from spawning aggregations in the lake's 

 inlet during December of 1952, 1955, and 1967. 



Counts on scales, gill rakers, and vertebrae 

 followed the methods outlined by Hubbs and 

 Lagler (1964). Gill raker counts included rudi- 

 mentary rakers and sutures in the hypural 

 complex were regarded as separating vertebrae. 

 Specimens used for vertebral counts were 

 eviscerated, filleted, cleared in KOH, and stained 

 in alizarine red S according to the procedure 

 of Evans (1948). 



} 



588 



