The contribution of estuary‐resident life histories to the return of adult Oncorhynchus kisutch

Abstract

This study evaluated estuarine habitat use, life-history composition, growth and survival of four successive broods of coho salmon Oncoryhnchus kisutch in Salmon River, Oregon, U.S.A. Subyearling and yearling O. kisutch used restored and natural estuarine wetlands, particularly in the spring and winter. Stream-reared yearling smolts spent an average of 2 weeks in the estuary growing rapidly before entering the ocean. Emergent fry also entered the estuary in the spring, and some resided in a tidal marsh throughout the summer, even as salinities increased to >20. A significant portion of the summer stream-resident population of juvenile O. kisutch migrated out of the catchment in the autumn and winter and used estuary wetlands and adjacent streams as alternative winter-rearing habitats until the spring when they entered the ocean as yearling smolts. Passive integrated transponder (PIT) tag returns and juvenile life-history reconstructions from otoliths of returning adults revealed that four juvenile life-history types contributed to the adult population. Estuarine-associated life-history strategies accounted for 20-35% of the adults returning to spawn in the four brood years, indicating that a sizable proportion of the total O. kisutch production is ignored by conventional estimates based on stream habitat capacity. Juvenile O. kisutch responses to the reconnection of previously unavailable estuarine habitats have led to greater life-history diversity in the population and reflect greater phenotypic plasticity of the species in the U.S. Pacific Northwest than previously recognized.

Wildfire may increase habitat quality for spring Chinook salmon in the Wenatchee River subbasin, WA, USA

“…The mosaic of riparian habitats created by fires, floods, forest diseases, and other disturbances provides opportunities for fish and community diversity in plants and animals (Reeves et al, 1995). Further, complex and diverse habitats are necessary for expression of a variety of life histories and phenotypes in native salmonids (e.g., Gresswell et al, 1994;Jones et al, 2014). Attempts to manage disturbance-prone ecosystems as steady states have generally been unsuccessful, resulting in unintended consequences when new disturbances alter successional trajectories and favored life histories (Holling, 1973).…”

Food Shortage Causes Differential Effects on Body Composition and Tissue-Specific Gene Expression in Salmon Modified for Increased Growth Hormone Production

“…In addition to its importance in the marketplace, coho salmon provides a conservation and evolutionary model for study among the salmonids. This species of salmon is strictly anadromous and semelparous, with a shorter generation time and a simpler life history than most other salmonids (Kodama et al 2012), although population dynamics are still actively being examined (Jones et al 2014). We are interested in the increased growth hormone production of the GH + coho salmon strain (Devlin et al 2001) as a model along with its potential differences from wild-types under natural and/or aquaculture stressors.…”

Aquatic biodiversity in forests: a weak link in ecosystem services resilience

“…However, alterations in disturbance regimes as a result of human management may simplify aquatic habitats, reduce system capacity to absorb change, and reduce biodiversity, such as in the form of life-history expression, particularly in salmonids (Fig. 1, moving past a 'tipping point'; Jones et al 2014).…”