To test the utility of otolith chemical composition as a tool for determining the natal stream of origin for salmon, we examined water chemistry and otoliths of juvenile and adult Chum Salmon Oncorhynchus keta and Coho Salmon O. kisutch from three watersheds (five rivers) in the Norton Sound region of...
We evaluated the impact of predation on juvenile steelhead Oncorhynchus mykiss and yearling and subyearling Chinook Salmon O. tshawytscha by piscivorous waterbirds from 11 different breeding colonies in the Columbia River basin during 2012 and 2014. Fish were tagged with both acoustic tags and PIT tags and were tracked via...
To describe the life histories and demography of a fluvial population of Bull Trout Salvelinus confluentus, we PIT-tagged and radio-tagged Bull Trout captured in Mill Creek, a tributary of the Walla Walla River (Washington–Oregon), during 1998–2009. Adult abundance declined 63% during 2006–2010, driven primarily by a 10-fold reduction in subadult-to-adult...
Structured estuarine habitats, such as salt marshes, seagrass beds, and oyster reefs, are recognized as critical nurseries for juvenile fish and crustaceans. Estuarine habitat usage by fish, including juvenile Pacific salmon Oncorhynchus spp., was characterized by sampling with a modified tow net in Willapa Bay, Washington, where 20% of the...
Spring Chinook Salmon Oncorhynchus tshawytscha are transported above dams in the Willamette River to provide access to blocked spawning habitat. However, 30–95% of these transplants may die before spawning in some years. To varying degrees, salmon in other tributaries—both blocked and unblocked—have similar prespawn mortality (PSM) rates. Our study determined...
Accurate assessment of specific mortality factors is vital to prioritize recovery actions for threatened and endangered species. For decades, tag recovery methods have been used to estimate fish mortality due to avian predation. Predation probabilities derived from fish tag recoveries on piscivorous waterbird colonies typically reflect minimum estimates of predation...
Fish scales have long been used to reconstruct fine-scale habitat transitions such as the movement of juvenile fish from freshwater, estuary, and ocean environments. Despite the importance of life history information to fisheries management and conservation, few studies have validated that scale morphology accurately describes fish movement between these habitats....
Addressing the ongoing decline of Pacific Lamprey Entosphenus tridentatus across its range along the west coast
of North America requires an understanding of all life history phases. Currently, spawning surveys (redd counts)
are a common tool used to monitor returning adult salmonids, but the methods are in their infancy for...
Chinook Salmon Oncorhynchus tshawytscha returns to the Yukon River basin have declined dramatically since
the late 1990s, and detailed information on the spawning distribution, stock structure, and stock timing is needed to
better manage the run and facilitate conservation efforts. A total of 2,860 fish were radio-tagged in the lower...
Understanding how individual characteristics are associated with survival is important to programs aimed at recovering
fish populations of conservation concern. To evaluate whether individual fish characteristics observed during
the juvenile life stage were associated with the probability of returning as an adult, juvenile steelhead Oncorhynchus
mykiss from two distinct population...