Here are two great resources for learning about the local watershed and the salmon and crawdads who live here, from the California Department of Water Resources and the California WaterBlog.
First up, a question-and-answer with Hailey Wright, a CDWR environmental scientist, who discusses why floodplains are so ivital for California’s salmon population:
Can you explain the salmon lifecycle?
Salmon have a very interesting life cycle that has developed with the changing California landscape over the past 40 million years. There is diversity in this life cycle, but all salmon in California follow this general pattern.
Salmon hatch from their eggs in cold water tributaries throughout Northern California. They emerge from their gravel nest and live, feed, and grow for some time in fresh water before swimming downstream through the Delta, out through the San Francisco Bay, and into the ocean. Salmon spend one to four years in the ocean before retracing their steps back through the San Francisco Bay and up to the freshwater stream where they hatched.
From here, the females build nests called redds where they lay their eggs, and a male will swim over to fertilize them. The adult salmon will guard their redd until they die, allowing their carcasses to decompose and provide nutrients to the habitat their offspring will grow up in.
Read the full interview at Q/A: Why floodplains are important for California salmon. You can also watch Hailey Wright’s talk on juvenile salmon and their journey down the Sacramento River at CDWR’s YouTube Channel.
Unlike salmon, crawdads – also known as crayfish, crawfish and mudbugs – are not native to California. However, the little crustaceans have integrated themselves into the region’s food chain and ecosystems. According to UC Davis Prof. Peter Moyle:
… most are the result of introductions as food for people or as forage or bait for game fish. And most California crayfish live in novel ecosystems. These ecosystems have a biota that is a mixture of native and non-native species living in habitats that are highly altered by the continuous actions of people. Crayfish therefore fit right in, feeding on organic matter, algae, dead fish or anything else they can process, and then being eaten themselves by native predators such as otters, herons and pikeminnows, or by non-native predators such as centrarchid (sunfish family) basses and bullfrogs.
But it wasn’t all smooth sailing, and in some older ecosystems, the wide variety of crawdads that make their homes in California can present real problems. Moyle, a professor of wildlife, fish and conservation biology, breaks down how crawdads became “naturalized” in California, along with a breakdown of the different species you might find in the state’s waterways. Read more at Crawdads: Naturalized Californians.
Photo caption and credit: A signal crayfish female captured from the Iller River, southern Germany. Signal crayfish are originally from North America, and are one of the species that are found in the Sacramento-San Joaquin Delta. (Astacoldes / Wikimedia Commons)