Using expressed behaviour of coho salmon (Oncorhynchus kisutch) to evaluate the vulnerability of upriver migrants under future hydrological regimes: Management implications and conservation planning

Abstract

Globally, river systems have been extensively modified through alterations in riverscapes and flow regimes, reducing their capacity to absorb geophysical and environmental changes. In western North America and elsewhere, alterations in natural flow regimes and swimways through dams, levees, and floodplain development, work in concert with fire regime, forest management practices, as well as agriculture and urban development, to change recovery trajectories of river systems. Hydroregime scenarios for coho salmon, Oncorhynchus kisutch (Walbaum, 1792), were investigated in Washington and Oregon, USA, where long‐term records of discharge, water temperature, and upstream fish passage are available. This novel approach combines hydrological and ecological data in a single visualization, providing empirical foundations for understanding upstream behavioural movement and tolerances of native fishes. The timing of coho salmon movement with respect to temperature and discharge were compared with scenarios representing possible future hydrological conditions associated with a changing climate. This approach provides a framework for the study of future hydrological alterations in other locations, and can inform local and regional conservation planning, particularly in view of water management policy. Management implications and recommendations for action that may expand the capacity of riverscapes to absorb perturbations are discussed.

Patterns of River Discharge and Temperature Differentially Influence Migration and Spawn Timing for Coho Salmon in the Umpqua River Basin, Oregon

“…The possible earlier arrival of males or larger individuals (as was demonstrated by Dickerson et al 2005) could also be important in the midriver‐migration timing that we described at Winchester Dam. This would be particularly relevant when considering future changes in climate that may disproportionately affect the earliest and latest migrants (Flitcroft et al 2019). While these considerations of sex were beyond the scope of this study, it is an important topic and one that merits further research.…”

“…Predictable patterns of temperature and discharge create an envelope of environmental conditions, or hydrologic regimes, within which aquatic species have developed specialized adaptations over time (Schlosser 1991). The life history phenology of aquatic species reflects adaptations that allow individuals to thrive with different seasonal combinations of temperature and discharge (Schlosser 1991; Flitcroft et al 2016, 2019). Predictable hydrologic regimes may be particularly relevant for anadromous species such as Pacific salmon that undertake substantial oceanic and riverine migrations and possess complex life histories (Murray and McPhail 1988; Groot and Margolis 1991; Montgomery et al 1999).…”

Theory and practice to conserve freshwater biodiversity in the Anthropocene

“…Biodiversity conservation that is linked to livelihoods of local communities is explored in large provinces such as the Andes (Tognelli et al, ), the Amazon (Reis et al, ) and Lake Victoria (van Soesbergen, Sassen, Kimsey & Hill, ). Water planning that includes life‐history needs of specific species is described in the Columbia River Basin of the USA (coho salmon; Flitcroft et al, ) and in discrete systems such as the Hunter Valley in Australia (Linke, Turak, Gulbrandsen Asmyhr, & Hose, ), Greek lakes (Stefanidis, Sarika, & Papastergiadou, ) and Lake Ontario (North America) (Zolderdo et al, ). Taken together, these manuscripts are intended to convey the scope and complexity of freshwater conservation in this time of global transformation, as systems from the atmosphere to the Earth's crust adjust to vast human‐derived change.…”

“…The natural flow regimes of rivers are currently threatened by physical modifications to watercourses and through the fragmentation of flows (Poff et al, ). Moreover, as noted above, climate change induces changes to flows and water temperature (Reid et al, ), making flows less predictable and more ‘flashy.’ In this issue, Flitcroft et al () use coho salmon ( Oncorhynchus kisutch ) as a model organism to demonstrate how species‐specific life history and ecological knowledge can be integrated with data on current and projected future river discharge and water temperatures derived from climate models. These integrated datasets can then be used to assist in developing an adaptive management framework for sustainable fish populations in the face of climate change.…”

The relationship between hydroregime and coho salmon (Oncorhynchus kisutch) redd construction in the Smith River, Oregon

“…At a population‐scale, native fish species are adapted, through their life histories, to the magnitude and predictability of recurring hydrologic events in a region (Poff et al, 1997; Schlosser, 1991), though specific survival pathways vary (Lytle & Poff, 2004). For example, expressed behaviour of salmon includes variability in annual timing of spawning among populations, which may be linked to specific characteristics of the hydroregime in different drainage basins (Flitcroft et al, 2016, 2019). Understanding salmonid spawning in response to environmental conditions, such as river discharge and temperature, may inform management or vulnerability assessments of endangered salmon populations.…”