Silver Salmon 



Silver salmon enter the lower Trinity River to spawn* They are 

 not known to migrate above the mouth of the South Fork at the present 

 time, end there are no definite indications that they have ever migrated 

 upriver as far as Lewiston. Residents of ^yainpom on the South Fork 

 clearly describe a silver salmon migration to that area during one year 

 when unusually early fall rains occurred. Silver salmon are known 

 to be present in the Hoopa Valley during October. 



Steelhead Trout 



Steelhead trout using Trinity River spawning grounds are of little 

 importance to the California commercial fishery, but they are outstanding 

 as sports fish. Anglers seeking the thrill of catching these large gamey 

 fish contribute to a sitable tourist population along the river in the 

 fall and winter months. 



In the Trinity River, yoving steelhead start to emerge from the 

 gravel late in April and a few begin moving downstream in May and June. 

 This early movement reaches a peak in June and July (Figure 8 and Table 14) 

 and subsides rapidly with decreasing river flow and increasing water 

 temperatures. In some years, many adult steelhead utilize the main 

 Trinity River at and above Lewiston as spawning ground. Whenever such 

 spawning occurs, there is a post-hatching migration downstream of very 

 small steelhead which are apparently not migrating seaward, but are drift- 

 ing downstream to satisfactory holding areas in quiet water. Generally, 

 tributary streams are used by the steelhead, and under such oirciaBstanoes, 

 the large fyke-net catches of very young fish are materially reduced* 

 Some downstream movement continues through the summer and generally 

 increases during the fall and winter. The migration is practically 

 complete about the time fry of the next generation are starting to leave 

 their nests. 



Early, freshwater growth of the steelhead in Trinity River is 

 reflected to a certain degree by the length frequency distributions 

 of fish taken by fyke nets. Catches were grouped into 10-day periods, 

 and lengths of the fish were grouped at 3 millimeter (0.118 inch) intervals. 

 Idealized growth curves for each season have been fitted by inspection 

 on the basis of mean lengths for each period as they applied to brood 

 years (Figure 9) • Generally, no difficulty in separating the fish of 

 each brood year was experienced. Because the hatching period of the 

 steelhead in Tirinity River extends over about 5 months, from March 

 through Jtily, length frequency distributions are especially broad. 

 However, enough scales of young steelhead have been examined to sub- 

 stantiate the separations of year broods through the first 18 months 



40 



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