11. Develop methods of identifying stocks of salmon 

 in the ocean. Knowledge of contributions made by 

 each stock (Sacramento, Klamath, Eel, etc., and tribu- 

 taries) is essential in assessing production. 



INLAND RIVER STUDIES 



The federal aid Sacramento-San Joaquin River 

 salmon and steelhead project made good progress 

 toward attaining its two principal goals. 



The first is an evaluation of salmon and steelhead 

 losses in the multitude of irrigation diversions, leading 

 from streams utilized by these species as migration 

 routes to and from the sea. There are more than 900 

 irrigation and industrial diversions above the Sacra- 

 mento-San Joaquin River Delta, very few of which 

 are screened to prevent fish losses. This part of the 

 study was nearly completed during the biennium, 

 with an overall picture of the diversion fish loss prob- 

 lem having been obtained. These data will lead to a 

 more adequate screening program. 



The second goal is to determine the effectiveness of 

 supplementing natural steelhead production in the 

 Sacramento River system with hatchery-reared fish. 

 Facts obtained will form the basis for a sound manage- 

 ment plan for Sacramento River steelhead. A major 

 part of this phase of the study was also completed dur- 

 ing the biennium. 



Aside from the two principal goals, this project 

 initiated the introduction of silver salmon into the Sac- 

 ramento River system to provide more and better 

 fishing. This phase of the program was completed 

 during the biennium when the third and final annual 

 plant of yearling silvers was made in Mill Creek dur- 

 ing April 1958. 



Fish Losses Evaluated 



During the previous two bienniums, studies were 

 conducted in typical diversions along the Sacramento 

 and San Joaquin Rivers and in the Sacramento-San 

 Joaquin River Delta. It was demonstrated on the Sac- 

 ramento River that during years of normal runoif the 

 bulk of the young fish migrate out of the upper river 

 and into the Delta before the irrigation commences, 

 thus accounting for a much smaller loss than might be 

 expected. However, it was also shown that if pumps 

 are operating when fish are migrating, the un:icreened 

 diversions do take fish— even when near-flood condi- 

 tions are prevailing in the river. A change in agricul- 

 tural practices, resulting in an earlier irrigation season, 

 or installation of year-round diversion canals for 

 transporting water to other areas of the state, could 

 prove disastrous to salmon and steelhead resources 

 unless adequate screens are provided. 



This situation was found to be somewhat reversed 

 on the San Joaquin River, where the diversions were 

 found to be taking water near the peak of the seaward 



I 1 H,M 



Photo indicates trout fishing quality available in the Sacramento River 



during summer months. Most trout are probably young steelhead who 



have not yet been to sea. 



— Fish and Game Photo by Dick Hallock 



juvenile salmon migration and accounted for a much 

 more serious loss of young fish. 



Evaluation of Steelhead Planting 



With the increasing popularity of the Sacramento 

 River as a steelhead stream, it is necessary to determine 

 whether or not present angling regulations are ade- 

 quate to assure continued excellent fishing, as well as 

 whether or not it is economically feasible to maintain 

 or even improve the fishing by planting yearling 

 hatchery-reared steelhead. 



To answer these questions, marked yearling hatch- 

 ery-reared steelhead have been planted in the Sacra- 

 mento River during each of the past six years. To 

 evaluate the returns of marked fish from the sea, the 

 planting is supplemented by an adult steelhead trap- 

 ping and tagging program in the lower river near 

 Knights Landing each fall and winter. Adult fish are 

 also examined upstream from Knights Landing at the 

 project's counting station on iMill Creek, at the U. S. 

 Fish and Wildlife Service's Coleman Fisheries Station 

 traps on Battle Creek, and while doing creel census 

 work along the upper Sacramento River and tribu- 

 taries. 



During the biennium, 6,091 adult steelhead were 

 trapped and examined for marks and tags near 

 Knights Landing. Of the total trapped, 5,244 were 

 tagged before being released. As during the previous 

 biennium, the excellent return of tags by sportsmen 

 has shown that anglers have continued to land an 

 average of 30 percent of the total Sacramento River 

 steelhead run during the past two seasons. 



The steelhead planting program is being carried out 

 in co-operation with the U. S. Fish and Wildlife Serv- 

 ice and two sportsmen's organizations — California 



