TABLE 3 Summary oi Merwin Trap Catch at Lyons Ferry in the Snake River, 

 January to August, 1974 



Species 



Jan. 30 



to 

 Apr. 4 



Apr. S 



to 

 May 28 



May 29 

 to 



lune 26 



June 27 



to 

 July 24 



July 30 



to 

 Aug. 12 



Totals 



Chinook, Oncorhynchus tschawytscha 



Coho, Oncorhynchus kisutch 



Sockeye, Oncorhynchus nerka 



Steelhead, Sa/mo gairdneri 



Shad, Alosa sapidissima 



Squawfish, Ptychocheilus oregonensis 



Whitefish, Prosopium williamsoni 



Yellow bullhead, Ictalurus natalis 



Sucker, Catostomus macrocheilus 



Crappie, Pomoxis annularis 



Yellow perch, Perca flavescens 



Sunfish, Lepomis sp. 



Shiner, Notropis sp. 



Madlom, Noturus gyrinus 



Bluegill, Lepomis sp. 



Chiselmouth, Acrocheilus alutaceus 



Carp, Cyprinus sp. 



Channel catfish, Ictalurus punctatus 



Dolly varden, Salvelinus malma 



Chub, Hybopsis sp. 



Bass L.M., Micropterus salmonides 



Bass S.M., Micropterus dolomieui 



Lamprey, Entosphenus tridentatus 



Sturgeon, Acipenser sp. 



Peamouth, Mylocheilus caurinus 



Sucker, Unident., Catostomus sp. 



Total fish 



80060 



avoided during transience, but whether the squaw- 

 fish were able to detect and avoid this area is 

 unknown. The depth they normally inhabit may be 

 sufficient to adequately compensate for the levels 

 of supersaturation which occurred. 



Length frequencies of those taken in the trap 

 were different from those captured in the purse 

 seine. In Fig. 5 a bimodal frequency is shown for 

 fish sampled at Little Goose Dam in July and August 

 with the lesser mode which is similar to the length 

 frequency of fish sampled at the trap (Fig. 6). In the 

 upper mode a group of squawfish, between 300 and 

 460 mm, had not been encountered before, suggest- 

 ing that they may represent an entirely different 

 population. One population may be reservoir 

 spawners and the other tributary spawners. We 

 have had tags turned in from the Palouse and 

 Tucannon Rivers, the mouth of the Snake River and 

 the Columbia River at Kennewick, Washington. 



Purse Seine - Feeding 



Purse seine catch at Little Goose Dam is shown 

 in Table 4. When dissolved gas saturation was high, 

 176 squawfish were taken; five showed evidence of 

 feeding. The numbers of squawfish taken per purse 



seine set were 11.7, indicating that there were few 

 available. When dissolved gas saturation returned 



200 



240 



280 



320 360 



LENGTH (mm) 



400 



440 



480 



FIG. 5 Bimodal length frequency of squawfish taken by purse 

 seine in the tailrace at Little Goose Dam from July 31st to 

 August 8, 1974. 



Effects on Squawfish 45 



