Not all of the planet's species suffer without a fight due to climate change. Researchers have found at least one kind of fish in Alaska that adjusts its migrations to match climate-induced changes in salmon spawning so it can feast on salmon eggs, a vital food source.
The Dolly Varden, a kind of char common in southeast Alaska, is an example of a species being resilient to climate change because of its ability of adjust to climate-driven alterations in its food and habitat, researchers say.
If the timing of the availability of their usual prey is disrupted, some species can lose their access to food, while others -- like the Dolly Varden -- have managed to create a climate change experience with a happy ending, the researchers report in the journal Freshwater Biology.
How do they do it?
Instead of gathering their migration cues from variables in their environment such as stream flows or water temperatures, the Dolly Varden appear to time their migration based on the presence and numbers of the salmon themselves, the study found.
"Despite warming temperatures and shifting salmon migrations, Dolly Varden do a great job of following their food," says study lead author Chris Sergeant of the National Park Service. "Species that can handle a high degree of variability are the ones that should be most resilient to further changes associated with climate."
The Dolly Varden need to follow salmon migrations closely since eggs from any single salmon species may be available during a narrow summer spawning window of just two to six weeks.
During that small window the char gorge on the eggs, which are rich in energy because of the same fatty acids that make fish so healthy for humans.
And it's a moving window; research has shown coho and pink salmon in southeast Alaska are now migrating to their traditional spawning grounds 10 to 17 days earlier, with sockeye salmon migrating 8 days earlier.
That hasn't proved a problem to seagoing Dolly Varden, the study found; they've precisely adjusted their own migrations from the sea back to freshwater streams and rivers to stay in close contact with the salmon.
That's despite significant changes in environmental variables such as precipitation and temperature that are often considered prime drivers and animal migrations, researchers say.
The Dolly Varden are capable of ignoring those variable in favor of the simple act of watching salmon pass by and detecting the presence of their eggs by smell.
Their adaptability suggests that at least some species can accommodate climate-induced changes in migrations of their prey, all in pursuit of a steady food supply, the researchers say.
