California:Central Coast fish face extinction
Two fish found along the Central Coast face extinction, says the
report. The South-central California coast steelhead, which is found
in the Pajaro River and other more southern watersheds, is primarily
losing out due to alterations of natural stream flow patterns.
Historic runs totaled more than 27,000 adults, but today there are
fewer than 5,000 of the fish in California’s waters—during dry seasons
this drops below 2,000. A fish that shares a similar name, the Central
California Coast steelhead, has also declined by as much as 90 percent
in local streams. Fifty years ago, the San Lorenzo River supported
19,000 fish each year, and coastal tributaries were home to 24,000.
T
he fish were listed as a federally endangered species in 1997, a
finding that was reaffirmed in 2006. Due to water diversions,
populations continue to dwindle. “Because these species are at the
southernmost end of their range, they will also be impacted as water
temperatures increase due to global warming,” says Feierabend.
Sedimentation is also named as a critical problem—as20winter rains
pour down in the Santa Cruz Mountains, soil loosened by development
and road construction flows into rivers and streams. “Over time
sediment has come down and filled in rocky places where fish used to
rear,” says Kocher. “The pools in the rivers are becoming to shallow,
and this impacts the water temperature.” Most fish need cool, deep
pools in order to spawn and grow, and sedimentation changes both
conditions. Along with wells that detract from the base flow into
rivers, and homes that use too much water from local streams, Kocher
blames sedimentation and deforestation for the loss of local coho
salmon runs over the last 30 years. Because the young rear for one to
two years in cold-water streams, they need protective cover provided
by falling trees, and as dense coastal rainforests have been logged,
the fish have dwindled away. Although populations were partially
revitalized in the early 20th century, modern efforts have been
unsuccessful—likely due to sedimentation, and ongoing development of
forested land, says Kocher.
http://www.gtweekly.com/20081222310132/news/environment/can-native-fish-species-be-saved
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