Assessing freshwater life-stage vulnerability of an endangered Chinook salmon population to climate change influences on stream habitat

Abstract

tat and how species respond (Groves et al. 2012, Seney et al. 2013. Each stage of a species' life history may be affected differently by changes in its habitat. For example, Radchuk et al. (2013) ABSTRACT: We linked a set of climate, hydrology, landscape, and fish population models to estimate the relative influence of freshwater habitat variables on the abundance of a population of endangered stream-type Chinook salmon Oncorhynchus tshawytscha responding to a warming climate. The hydrology models estimated that increases in annual air temperature and winter precipitation would lead to increases in water temperature and changes in discharge, including higher flows during the egg-incubation period and lower flows during the summer rearing period. The spatially explicit population model estimated a resulting decline of 0 to 7% in the number of spawners, with 3 of 4 global climate models estimating a decline of 4 to 7%. Increased water temperature during the summer spawning period was the most limiting among habitat variables modeled, but our modeling suggested that aggressive habitat restoration (increasing forested area and reducing impervious area) could mitigate some spawner abundance reductions. Better knowledge of the links between climate changes and habitat response, including increased streambed scour due to the larger and more frequent winter high-discharge events predicted by our hydrology models, would improve our ability to estimate climate effects on populations. Future limitation by elevated summer water temperature, and potentially egg-pocket scour, would further stress an endangered population currently limited by the percentage of fine sediment around egg pockets. Identifying such changes demonstrates the utility of models that consider climate and integrate life-stage-specific habitat influences over a species' life cycle, thereby indicating restoration actions with the potential to benefit sensitive life stages.

Individual‐based simulations suggest mixed impacts of warmer temperatures and a nonnative predator on Chinook salmon

“…Planting riparian vegetation and increasing connections between mainstem habitat and cooler off‐channel habitats could reduce exposure by salmon to warm temperatures (Beechie et al 2012). Several studies have suggested that riparian restoration may reduce or even ameliorate the potential effects of increased water temperature expected over the next several decades (Bond et al 2015, Sun et al 2015, Honea et al 2016, Justice et al 2017). Care will need to be taken, however, when increasing connectivity with potentially cooler off‐channel habitats to ensure that these habitats will not become ecological traps due to the presence of nonnative warmwater predators like largemouth bass.…”

Global Warming of Salmon and Trout Rivers in the Northwestern U.S.: Road to Ruin or Path Through Purgatory?

“…As the NorWeST database and scenarios are periodically updated and improved, they could be used in development of spatially explicit, high‐resolution behavioral and bioenergetic models that encompass the full suite of freshwater salmon habitats and life stages (Honea et al. ; Crozier et al. ) or next‐generation species distribution models (Filipe et al.…”

“…Scenarios developed from the database provide spatially comprehensive thermal information that has contributed to an improved understanding of salmon migrations (Westley et al 2015;Palmer 2017), locations susceptible to nonnative species invasions (Al-Chokhachy et al 2016;Isaak et al 2016aIsaak et al , 2016bHowell, in press), and parameterization of distribution models that predict locations of climate refuge streams (Isaak et al 2015;Young et al 2016). As the NorWeST database and scenarios are periodically updated and improved, they could be used in development of spatially explicit, high-resolution behavioral and bioenergetic models that encompass the full suite of freshwater salmon habitats and life stages (Honea et al 2016;Crozier et al 2017) or next-generation species distribution models (Filipe et al 2017;Ver Hoef et al 2018) to further reduce remaining uncertainties and provide decision makers with ever more precise information.…”

Economic, ecological and genetic impacts of marine stock enhancement and sea ranching: A systematic review

“…Juvenile sockeye rear in lakes for 1–3 years, but some populations utilizing streams may migrate to sea soon after emergence (Burgner, ). A consistent catch decline in coho and Chinook salmon, which have complex life history patterns requiring they spend a longer time period in rivers and streams, suggests that the decline might be mainly caused by reduced survival rates of freshwater stages adversely affected by climate change (Honea, McClure, Jorgensen, & Scheuerell, ; Springer & van Vliet, ).…”