abundance, or there is a similar bias op- 

 erating at all traps. The latter is unlikely, 

 considering the wide variety of trapping sites 

 and conditions under which traps were fished. 



only 2 years at sea) late in migration, the 

 result is an apparent decline in the numbers 

 of fish taken in the gill nets relative to the 

 trap catch. 



Comparison of Experimental Gill 

 Net and Fyke Trap Catches 



Test fishing with gill nets adjacent to fyke 

 trap sites in 1957 showed the same timing and 

 duration of the migration that the trap catches 

 did. The gill net catches were small (one 50- 

 foot net was used), but the effort was constant 

 each day, and as shown in figure 12, the gill 

 net catches fluctuated with the fyke trap 

 catches, except in the late part of the migra- 

 tion. One possible explanation of the poor 

 correlation then is that the gill nets selected 

 somewhat larger fish than the fyke traps 

 (fig, 13). Also, during the latter part of the 

 migration the numbers of fish present were 

 probably so few that the catches in the gill 

 nets were not significant. When the effect of 

 gill net selectivity is combined with the 

 presence of smaller fish (fish that had spent 



Selectivity of Fyke Traps for Size 



Hallock, Fry, and LaFaunce (1957; see foot- 

 note 3) found that fyke traps did not capture 

 king salmon as effectively as they caught steel- 

 head trout. In experiments on the Sacramento 

 River, traps captured from 10 to 20 percent 

 of the steelhead trout run each year, but only 

 about 1 percent of the king salmon run. Their 

 studies revealed that traps were selective for 

 small king salmon. King salmon measured on 

 the spawning grounds and at counting stations 

 were larger than those taken in traps. 



Only a little information was gained in the 

 Kenai River work about the selectivity of fyke 

 traps in extremely turbid water. The results 

 for king salmon are inconclusive, since rela- 

 tively few king salmon ascend the river. In 

 1957 and 1959 traps did not appear to be 



2 70 



Figure 12.--Daily catch of red salmon in index fyke traps and experimental gill nets 



in the Kenai River in 1957. 



15 



