California's wild and native trout species face a host of threats including loss of water and habitat, pollution, sedimentation, invasive species, and spawning impediments.
Loss of water and habitat
Simply put, fish need water. And different species of fish need different water environments. Trout are known as a "cold water" species, which means they thrive in the high-elevation lakes or in fast-moving, snow-fed streams that barely get above 68 degrees Fahrenheit. Take water from the stream and you slow down its flow regimen. Slow down its flow, the steam warms up and the trout struggle.
Over 80% of California's human-developed water is used for commercial agriculture, 60% for four crops - alfalfa, cotton, rice and pasturage (livestock). This leaves our cities, factories and wild life fighting for the remaining 20%. And while cities and factories spend plenty of time and money ensuring a steady supply of water, it is up to small organizations like CalTrout to make sure that California's natural heritage isn't cheated.
Pollution
Runoff from agriculture is the primary culprit for increased pollution of vital riparian habitats. What makes runoff so insidious is that it is nonpoint-source pollution - which means there is no easily-identifiable point of entry into the environment, such as a pipe. Rather, pesticides, salts and fertilizers seep into the watershed.
Pollutants also enter watersheds through train derailments. While derailments are intermittent, they can be devastating. The 1991 spill on the Upper Sacramento River, for instance killed all aquatic life for miles. And they're more frequent than most people imagine. In 2004, there were over 1300 rail accidents nationwide. To see what CalTrout is doing about rail safety click here.
Sedimentation
Sediment build-up leads to shallower, slower and warmer streams harming cold-water species like trout. Sedimentation can result from cattle-grazing, logging, off-road vehicles or even heavy foot-traffic. These activities also result in collapsed stream banks. As any angler will tell you, trout love to lurk in undercut stream banks. Collapsing stream banks and sedimentation usually go hand-in-hand. For a look at what CalTrout is doing about stream restoration check out our pilot project on Hat Creek, click here
Invasive Species
The movement of people and goods all over the world is not without costs. Hitchhikers like the New Zealand Mudsnail are unwelcome intruders into native habitats. Invasive species can harm natives in several ways:
- Predation. Non-native fish can feed on native species, especially the juveniles.
- Competition. Invasives can imperil native fish by crowding them out of the food chain, or even, as in the case of the New Zealand Mudsnail, by eating the creatures that serve as food for the macroinvertabrates that trout feed on. To learn more about the New Zealand Mudsnail click here.
- Hybridization. Introduced fish species often interbreed with native species, diluting native stocks. In CalTrout's Golden Trout Project, our first goal was to genetically identify pure strains of our state fish. To learn more about CalTrout's work to identify the California Golden Trout click here.
Spawning Impediments
Steelhead trout, like salmon, are anadromous. Born and reared in freshwater streams, as juveniles they migrate to estuaries, adjust to saltwater and then migrate to the ocean to mature into adults. As they begin to sexually mature they return to the streams of their birth to spawn and then attempt to return to the ocean to repeat the cycle.
But many of the Pacific's best habitats for anadramous fish are now blocked by dams. While fish ladders can help salmon and steelhead overcome these barriers, they are no replacement for a natural unimpeded river.
There's little chance that these dams, that do everything from generate power to provide flood control, will be coming down soon. But there are over 1200 obsolete dams in that state that are prime targets for removal. Ringe Dam in Southern California is just such a dam. Built in 1926, the dam was so silted up by the 1950s as to be rendered useless. Where once 1000 steelhead thrived now between 20 and 50 remain. Click here for more about Ringe Dam.
