Tli« spent steelhead passing Lewlston during June and July in 

 their seaward migration are generally in very poor condition* Host 

 individuals are badly spotted with fungus growth and heavily infested 

 with nematode parasites* Many badly fungused individuals died and drifted 

 downstream against the Lewiston weir* Approximately 80 percent of these 

 dead steelhead were males, which indicates that they suffer the highest 

 mortality in spawning* A few of the spent steelhead enter the sports 

 fishery during May, the first month of the fishing season* Most of these 

 fish are taken in the Trinity Center area near the upper end of the drainage 

 where the flow is generally low enough to permit fishing in the main river 

 during the first part of the season* 



Pacific Lamprey 



Least Important of the anadromous fishes of the Trinity River 

 as a commercial or game species is the Paoifio or three ^toothed lamprey* 

 Hoopa Indians trap the lampreys for. food (Snyder, 1924, p. 164), but 

 otherwise they have no apparent economic importance* 



The adult lampreys migrate up the Trinity River In small numbers 

 throughout the sunnier* Ocoasional migrations took place during July, 

 August, and September in 1944 and 1945* Migrations occurred at night 

 and were infrequent, lasting only one or two nights with Intervals of 

 several weeks between movements* Lamprey migrants were not ntxmerous emd 

 seldom could more than one be seen at a time* The upstream movement 

 seemed to be very deliberate, and there appeared to be no tendency to 

 pause, veer off, or delay as the migrants passed between picket openings 

 of the Lewiston weir and through the illuminated section of water above 

 the weir* Larger upstream migrations undoubtedly take place during the 

 winter months* 



Spawning lampreys are seen In the tributaries of the Trinity 

 River during April and May* Lampreys presumably spawn in the main river 

 during these months, but their activity is obscured by rolled waters 

 of the spring run-off* Some lampreys are observed in nesting areas of 

 the main river during June, and receding water during the same month 

 exposes many other nests completed earlier* Lamprey nests are located 

 in gravel along the river bottom where the current is not excessively 

 swift* In tributaries, nests are most frequently located in gravel 

 above riffles or in riffle areas with moderate current* 



Following spawning, the lampreys drift downstream and die* 

 Many spent lampreys were taken dtiring May and Jtine in fyke nets used 

 to capture seaward migrant salmon. In June and July of 1945 and 1946, 

 dead lampreys lodged against the pickets of the Lewiston weir eoid other 

 live individuals were observed feebly working their way tiirough the 

 pickets* 



48 



