WEISEL, HANZEL, and NEWELL: PYGMY WHITEFISH IN MONTANA 



Table 1 1 . — Production of eggs of pygmy whitefish. 



Time and Locality of Spawning 



No fully mature pygmy whitefish has been 

 found in Bull Lake in November, but ripe fish 

 were readily collected from Ross Creek, the 

 inlet, on 26 December and 12 January 1952, 

 10 December 1955, and 20 December 1967. 

 Also, fisherman were observed catching ripe 

 fish from the mouth of Stanley Creek, a tribu- 

 tary at the opposite end of the lake, on 3 January 

 1952 (Weisel and Dillon, 1954). Although milt 

 and roe were easily stripped, the appearance 

 of the gonads indicated that most of the fish 

 had not spawned. The spawning period in Bull 

 Lake must extend from mid-December well 

 into January. All evidence indicates pygmy 

 whitefish spawn in streams rather than in the 

 lake. As previously stated, mature fish were 

 congregated at the mouths of the two major 

 inlets of Flathead Lake in late November and 

 December. 



The species spawns in Alaska apparently 

 between mid-November and mid-December in 

 rivers and at the mouths of rivers during the 

 night. In Lake Superior, Glacier National Park, 

 and British Columbia the fish is believed to 

 spawn in November or December in shallow 

 water. 



DISCUSSION 



The pygmy whitefish is typified by low 

 meristic counts. In gill raker counts the popu- 

 lations from Flathead and Bull Lakes are 

 intermediate compared to Alaskan popula- 

 tions. This does not support McCart's (1970) 

 contention that the low-rakered form persisted 

 in the Columbia River Basin during Pleistocene 

 glaciation. Vertebral counts range widely even 

 within individual populations. Most of the 



vertebral variation is in the caudal rather than 

 in the precaudal vertebrae. 



The pygmy whitefish is flexible in diet and 

 feeding behavior. Depending on the season and 

 locality, the species may feed primarily on 

 insects and zooplankton or on macrobenthic 

 crustaceans. In any one habitat, however, the 

 diet is either highly selective or restricted 

 compared to many other species of fishes. 



The pygmy whitefish must be important in 

 the trophic system of Flathead Lake. They are 

 a small, abundant primary carnivore and con- 

 sequently must be an important food source 

 for the secondary carnivores such as lake trout 

 and Dolly Varden which frequent the deeper 

 water. Its primary food competitor is un- 

 doubtedly the lake whitefish. The lake whitefish 

 feeds extensively on molluscs but also includes 

 chironomids and copepods as main dietary 

 items in Flathead Lake (Brunson and Newman, 

 1951). 



The species is short-lived. In the Montana 

 populations no male was found older than age 

 III and no female beyond age IV. In growth 

 rate and fecundity the Montana populations 

 are similar to those from Alaska and Lake 

 Superior. 



The pygmy whitefish exists successfully with 

 sympatric salmonoids in spite of its small size 

 and relatively low egg production. The moun- 

 tain whitefish in Montana, its closest rival in 

 respect to reproduction, produces an average 

 of 4,400 eggs; the largest pygmy whitefish 

 produces a quarter of this number. However 

 the pygmy whitefish produces more eggs per 

 pound of fish — 10,000 eggs for Bull Lake speci- 

 mens compared with 5,340 for mountain white- 

 fish (Brown, 1952). This production is made 

 possible by the reduced size of the eggs of the 

 pygmy whitefish, which are 2.4 to 2.6 mm in 

 diameter when water hardened compared with 



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