Climate change threatens Northwest icons
The Skagit Valley Herald has a series this week about climate change. One story highlights the challenge to salmon survival:
Several recent studies using computer models indicate that climate change will affect salmon in several ways:
* Rising seas could reduce habitat size for young salmon, which may spend several weeks in the estuary preparing for the change from fresh water to saltwater.
* Lower summer stream flows could mean that juvenile salmon, especially coho, will have less habitat and food during the one to two years they spend in the river.
* Increased incidents of flooding will wash away more salmon eggs from streambeds.
* Warmer stream temperatures can cause the fish what amounts to heat exhaustion.
* Higher stream temperatures reduce the amount of dissolved oxygen, making it difficult for salmon to breathe.
* Warmer oceans, such as in an El Niño year, bring other species, such as squid, north where they compete with adult salmon for food.
* Warmer seas prevent the upwelling of the nutrient-rich cold water, reducing the amount of plankton and bait fish, which are an important part of the food web that salmon need.