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BROOKS LAKE 

 SOUTH BAY 

 BROOKS RIVER 

 NORTH ARM 

 GROSVENOR LAKE 



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 JUNE 



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Figure 7. — Length frequencies of age 0+ pygmy whitefish collected in 1962 and 1963. Vertical bar represents length 

 range ; horizontal line represents mean length of each collection. Asterisk indicates collection was made in 1963. 



20 30 40 



FORK LENGTH (MM.) 



60 



Figure 8. — Range and mean length of age 0+ round white- 

 fish and pygmy whitefish caught in the same seine haul 

 in Brooks Lake, August 10, 1962. Horizontal bar shows 

 range ; vertical bar indicates mean length of samples. 



Plant debris such as small twigs, bits of wood, 

 grass, seeds, and spruce needles occurred in nine 

 samples and accounted for 14 percent of the vol- 

 ume in both samples from Brooks River (table 8). 

 The relatively high occurrence of these items in 

 Brooks River probably represents drift items. 



The significance of fish scales in six samples 

 (table 8) is not understood. All undigested scales 

 that could be identified were from pygmy white- 

 fish. No fish remains other than scales were found 

 in any stomachs. Our observations suggest that 

 pygmy whitefish might readily ingest any small 

 bright object either in the current or from the 

 stream or lake bottom. 



PYGMY WHITEFISH OF SOUTHWEST ALASKA 



Underwater observations of pygmy whitefish 

 feeding in lower Brooks River showed that they 

 frequently picked up mouthfuls of material off 

 the bottom and passed fine silt, sand grains, and 

 bits of debris posteriorly through their gill open- 

 ings. They did not feed along the bottom in a 

 suckerlike manner, but made short distinct jabs or 

 darts, apparently at specific food items, such as 

 insect larvae, when picking up mouthfuls of bot- 

 tom material. Sand grains and other bits of de- 

 bris are undoubtedly passed into the alimentary 

 tract during such feeding behavior. Not all 

 pygmy whitefish feeding activity in Brooks River 

 was associated with the bottom. Frequently in- 

 dividual fish would rise off the bottom, as much as 

 35 to 50 cm. in water 1 m. deep and would pick 

 specific items out of the passing current. With the 

 diet of pygmy whitefish being primarily zooplank- 

 ton and insects in various parts of the Naknek 

 system and macrobenthic crustaceans in Lake Su- 

 perior (Eschmeyer and Bailey, 1955), it is obvious 

 that the species has a flexible diet and feeding 

 behavior. 



569 



