MASON and MACfflDORI: POPULATIONS OF SYMPATRIC SCULPINS 



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UJ 

 CD 



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■• ALEUTICUS 



WATERLOO CREEK 



. jIIMm L .-I. . — ,j ^ 



— . J»l J ». 



■• ASPER 



2242 

 1727 

 1242 



939 



€36 



333 



121 







I J** >^  '  " "■ I  



5 6 7 8 9 10 II 



TOTAL LENGTH (cm) 



Lymn Creek contained older fish of both species 

 but C. aleuticus lived longer than did C. asper. 



Distribution of Biomass 



The autumnal distribution of biomass by 

 stream zone was derived from population esti- 

 mates and length-weight data for both species of 

 sculpin in Lymn, Waterloo, and Cabin creeks 

 (Table 4). Density of sculpin biomass (grams per 

 square meter) was lowest in the estuaries and 

 increased upstream. Cottus aleuticus showed the 

 greatest increase in biomass density with in- 

 creased distance upstream, particularly when 

 proceeding from the estuary upstream into the 

 lower stream zone. About 69-94% of sculpin 

 biomass in the estuaries was C. asper, whereas 

 about 60-100% of sculpin biomass were C. aleuti- 

 cus in the upper zones whose downstream 

 boundaries were marked by the first significant 

 streambed obstruction. Species biomass in the 



Figure 7. — Length-frequency histograms for sculpin popu- 

 lations in Chef and Waterloo creeks from collections made 

 in September and October. Sampling stations are identified 

 as distances upstream or downstream (-) from a high tide 

 mark (0) in meters. 



Table 2. — Age distributions of Cottus aleuticus in successive 5-mm intervals of total length, sexes combined. Number in parentheses 

 indicates total number of fish when not all fish in the length interval were aged. 



14.5-19.4 



19.5-244 



24.5-294 



29.5-344 



34.5-39.4 



39.5-44.4 



44.5-494 



49.5-54.4 



54.5-594 



59.5-64.4 



64.5-69.4 



69.5-74.4 



74.5-79.4 



79.5-84.4 



84.5-894 



89.5-944 



94.5-99.4 



99.5-104.4 



104.5-109.4 



109.5-114.4 



114.5-119.4 



119.5-124.4 



124.5-129.4 



129.5-134.4 



134.5-139.4 



139.5-144.4 



144.5-149.4 



(7) 

 12(83) 

 5(73) 

 3(50) 

 8(15) 

 9 



8 

 40 

 37 

 25 



6 



(4) 

 3(65) 

 6(75) 



10(80) 

 6(40) 



21 



1 



1 



2 



4 



10 



6(24) 

 10(154) 

 14(169) 



3(50) 



9 

 16 



4 



Total fish 240 116 25 16 4 5 11 288 



25 12 



6 426 



2 

 2 

 9 

 9 

 12 

 3 

 3 



(8) 

 3(137) 

 18(132) 

 9(64) 2(13) 

 3(6) 22(42) 

 39 



27 



13 



6 



5 

 10 



9 

 12 



3 



1 



2 



5 

 13 

 17 

 13 



2 



1 



1 



5 



14 



15 



15 



6 



3 



40 19 7 2 347 140 40 14 1 52 60 17 12 4 



137 



