The environmental changes acting on wildlife is not just a temperature change but also other physical changes in freshwater and the ocean, which affect both the habitat and food available to salmon. There are also increasing contaminants in the environment and changes in the abundance and distribution of other species that compete with or prey on salmon. As their populations change in size or hatcheries breed salmon selectively, the genetic variability in those populations changes too. These are all drivers of change in salmon.
Salmon also respond in many different ways -- through their behavior, morphology (body shape), growth rates, performance, survival, and population growth rate or productivity. They may also adapt to climate change, as described in wild sockeye salmon.
Because salmon are exceptionally well studied relative to many other taxa, the extensive literature documenting drivers and responses in salmon is helpful in understanding the processes likely to affect many other species.
Thus the literature on salmon is a great case study of biological impacts of climate change more generally. To clarify what is known, we conduct annual literature reviews of studies addressing climate impacts on salmon, particularly salmon in the Pacific Northwest.
Here we show the percentage of papers in the scientific literature that address some of these topics, out of about 2000 relevant papers 2010-2019. We show the range of drivers that affect salmon’s response to the environment and the range of responses that have been measured in salmon. All of these papers help explain their cumulative response to climate change.