Fred R. Monzyk

Migration Characteristics of Hatchery and Natural Spring Chinook Salmon Smolts from the Grande Ronde River Basin, Oregon, to Lower Granite Dam on the Snake River

Abstract Smolts of spring Chinook salmon Oncorhynchus tshawytscha experience substantial mortality while migrating through free-flowing reaches of the Snake River basin before reaching Lower Granite Dam, the first dam encountered in the Columbia-Snake river hydrosystem. We investigated the patterns of travel time and survival of hatchery and natural smolts fitted with passive integrated transponder (PIT) tags through specific reaches of the migration corridor during the 2000-2006 migration years for two populations originating in the Grande Ronde River basin (Lostine River and Catherine Creek). For both populations, median travel times for natural smolts were significantly longer in the upper reaches of the migration corridor but shorter in the lower reaches than for their hatchery counterparts. Also, among both hatchery and natural smolts, smaller individuals spent more time in the upper reaches, presumably feeding to attain a larger size before continuing their migration. Within populations, both hatche...

Adfluvial Life History in Spring Chinook Salmon from Quartzville Creek, Oregon

AbstractThrough spawning ground and snorkel surveys, we confirmed the presence of adfluvial spring Chinook Salmon Oncorhynchus tshawytscha in a tributary upstream from a high-head dam in the upper Willamette River in northwest Oregon. Spring Chinook Salmon previously had been extirpated above the dam but juvenile hatchery fish were released in the reservoir in subsequent years. In 2012, we recovered six carcasses of adfluvial Chinook Salmon adults, identified nine live adults, and recorded nine redds. Analyses of scales from carcasses revealed those fish were ages 5–6. Otolith microchemistry from an unmarked adult female Chinook Salmon did not indicate ocean residence, and no hatchery thermal marks were observed, suggesting this fish was the progeny of adfluvial adults. In 2013, we observed one live, unclipped adult and three juvenile Chinook Salmon. We conclude that adfluvial spring Chinook Salmon exist in Green Peter Reservoir and successfully reproduce. This is the first documentation of adfluvial Chin...

Infection of Juvenile Salmonids by Salmincola californiensis (Copepoda: Lernaeopodidae) in Reservoirs and Streams of the Willamette River Basin, Oregon

AbstractWe assessed infection prevalence and intensity by the ectoparasitic copepod Salmincola californiensis among salmonid species rearing in reservoirs and streams upstream of reservoirs in the Willamette River basin, Oregon, during 2012 and 2013. Infection levels of juvenile Chinook Salmon Oncorhynchus tshawytscha, Rainbow Trout O. mykiss, and Cutthroat Trout O. clarkii were greater in reservoirs than in streams and increased with the age and size of fish. Copepods were more likely to be attached within the brachial cavity of reservoir fish (79%), whereas fins were the most common attachment site on stream fish (71%). Chinook Salmon in reservoirs were more vulnerable to infection than other species. Age-0 Chinook Salmon in reservoirs showed increasing infection prevalence throughout the year, reaching 84% by fall (compared with 11% in streams). Infection intensity was greater for age-0 Chinook Salmon in reservoirs than for those in streams. Infection prevalence for reservoir-rearing Rainbow Trout was ...