Several aspects of kokanee (Onchorhynchus nerka) ecology were studied in the fluctuating, 80ha Porcupine Reservoir, Utah in order to determine optimum management strategies. In 1981, escapement was enumerated and estimates of egg deposition were made . An estimate of the resulting fry recruitment was also attempted and was successful up to the arrival of spring runoff. In 1982, escapement was enumerated and estimates of egg deposition were made, with subsequent estimates of egg deposition and percent survival to the advanced eyed stage. Age and growth rates were determined and survival rates estimated. Escapement for 1981 and 1982 was 5,463 and 7,113 kokanee, respectively, depositing an estimated 1,843,955 and 2,393,757 eggs, respectively._ The estimated fry recruitment to the reservoir for the 1981 spawning run was 57,000 fish up to the arrival of spring runoff and appeared to be only a fraction of the total number of fry in the river. From the 1982 spawning run, an estimated 2,265,507 eggs were actually deposited, of these an estimated 64.2% or 1,457,599 eggs were fertilized and survived to the advanced eyed stage. Kokanee growth rates were good. Fish mature and spawn at 34 months of age at an average total length of 364mm. Twelve month old kokanee average 124mm and 24 month old fish 257mm. The kokanee population continues to grow but at a decreasing rate and survival rates are declining. For every kokanee that estimated 8.2 progeny survived to spawn spawned in 1972, an in 1975 and for every spawning kokanee in 1979 an estimated 3.0 progeny survived to spawn in 1982. The kokanee is presently underharvested and appears to be at or near the carrying capacity of the reservoir. In order to acheive an optimum sustainable yield the spawning population should be reduced and maintained at approximately 2,000 fish ( 1,000 redds).

Different strains of rainbow trout (Salmo gairdneri), Ten Sleep, Sand Creek, Beitey, Shepherd-of-the-Hills, New Zealand, Fish Lake- Desmet, Desmet, were compared for survival to the creel, growth and catchability after being stocked in a fluctuating 80 ha Utah reservoir . Fish were stocked in the spring and fall as fingerlings and monitored by creel censusing, gill netting and electrofishing. Fish were tagged with coded wire snout tags prior to stocking . An angler opinion survey was conducted to determine angler satisfaction with numbers and size of fish caught. Regardless of strain, spring stocking was superior to fall stocking in survival to the creel. In the spring 78 stocking the Ten Sleep strain had the highest survival to the creel (33.7 percent), followed in order by Shepherd-of-the-Hills (11.0 percent), Beitey (5.5 percent), Sand Creek (5.4 percent), New Zealand (4.1 percent), and Fish Lake-Desmet (2 .9 percent). In the spring 79 stocking the Shepherd-of-the- Hills strain had the highest survival to the creel (7 .6 percent), followed in order by the Sand Creek (7.3 percent) and the Ten Sleep (6.5 percent). Similar trends in survival were found in gill netting and electrofishing samples. Migration out of the reservoir was negligible for each strain. There were no strain differences in catchability by different methods (shore, boat) or gear (bait, artificial lure). Differences in growth between the fastest growing strains (Ten Sleep, Sand Creek) and the slowest growing strains (New Zealand, Fish Lake-Desmet) averaged as great as 16 mm in length and 43 g in weight. Differences in growth and survival among strains were great enough to span the range of angler satisfaction with numbers caught and size of fish caught from satisfactory to unsatisfactory. Therefore, strain selection can be a useful tool to improve fingerling stocking programs and manipulate the number of anglers who are satisfied with the angling experience.