In 1945, the first group of steelhead migrating up the Trinity 

 River reached Lewis ton on June 10» This run continued until July 12 

 and totaled 41 fish (Table 15). A similar migration started on June 30, 

 1946, and continued until July 25, totaling 21 fish. These counts of 

 migrating fish are minimal. Many smaller steelhead in the migration 

 were able to pass through the pickets on the weir and were not counted* 

 No counts were made early in 1944, but upstream migrant steelhead were 

 caught by sportsmen during the first part of July. Adult steelhead 

 are common in the deep holes along the river below North Fork in summer* 

 These fish start moving upstream along with fresh run steelhead during 

 October. Counts of steelhead through the Lewlston weir in the first 3 daya 

 of November 1944 amounted to 456 fish. The weir was removed November 4* 

 In 1945, a run of 170 steelhead was counted in the period October 1 to 

 29. The counting weir was removed from the river on the latter date. 

 Steelhead continue their spawning migration up the Tlrinity until sometime 

 in March. Attempts to cotint the migrants have failed as they move during 

 storm periods when it is usually necessary to remove the oovinting weir. 



Steelhead trout enter the larger tributaries such as North Fork, 

 Browns Creek, and Stuart Fork following the first fall rain. Smaller 

 tributaries are entered during the first rain in February after which 

 these streams maintain a flow sufficient to insure adequate spawning 

 conditions. Spawning begins in the upper IS-inity River drainage during 

 the last part of February and reaches a peak in the last two weeks of 

 March and the first two weeks of April. Some scattered spawning con- 

 tinues until the first week of June. All observations of spawning 

 activity were made in tributary streams where steelhead were confined 

 to small areas and could be easily seen. Host nests in tributary streams 

 are located in gravel pockets between large boulders. However, the few 

 larger riffle areas available were so heavily utilised that individual 

 nests could not be distinguished. Considerable spawTiing takes place 

 in the main Trinity during the spring run-off period when silt-laden 

 water obscures their activities. This main river spawning has never 

 been observed directly. It is evidenced by the many nests which are 

 exposed as waters recede following the run-off period. The idenity 

 of these nests was proven through recovery of dead steelhead eggs from 

 one nest exposed in shallow water. Usually, fry have hatched and escaped 

 from the gravel before such examinations can be made. Steelhead nests 

 in the main ri-yrer are most cosBionly found in gravel areas along the 

 edge of the stream and in long, comparatively shallow pools with flat 

 bottoms. Some of these nests are possibly those of the lamprey, whioh 

 spawns during the same period and under similar conditions. 



Directly following spawning, adult steelhead start a return 

 migration to the ocean. Thia downstream movement irtiich probably starts 

 sometime in March continues to pass Lewlston throughout the month of 

 Jtme and into July. From June 6 through July 6, 1945, 195 of these 

 migrants were counted throvigh the gates of the Lewlston weir (ifcible 16). 

 The weir was not in operation in 1946 during the corresponding period, 

 thus only seven migrants were coxinted between June 20 and July 22, 1946* 



46 



