Guadalupe River (California) - Habitat and Wildlife

Habitat and Wildlife

Early written documents record the local presence of migrating salmon in the ‘'Rio Guadalupe'’ dating as far back as the 18th century. Both steelhead trout (Oncorhynchus mykiss) and King salmon are extant in the river, making San Jose the southernmost major U. S. city with known salmon spawning runs, the other cities being Anchorage, Alaska; Seattle, Washington; Portland, Oregon and Sacramento, California. Runs of up to 1,000 Chinook or King Salmon (Oncorhynchus tshawytscha) swam up the Guadalupe River each fall in the 1990s, but have all but vanished in the current decade apparently blocked from access to breeding grounds by impassable culverts, weirs and overly wide, exposed and flat concrete paved channels installed by the SCVWD. By 2006 less than 40 King salmon were counted, although two managed to get up to Los Gatos that year and spawn below the California State Route 17 Freeway bridge over Los Gatos Creek in back of the Pruneyard Shopping Center. No Chinook have been seen until November, 2011 when they were documented with photo and video, the apparent offspring of the 2006 spawners.

Coho salmon (Oncorhynchus kisutch) were observed in the Guadalupe River system by longtime local residents and anglers, made mostly between the 1920s to 1960s. The fact that there were multiple historical accounts, and that some were from individuals qualified to identify salmon, and based on the presence of continued suitable habitat conditions for Coho in the upper watershed, it has been determined that Coho were once extant. However, the good spawning habitat in the upper reaches have been blocked by the construction of multiple dams.

On the Los Gatos Creek tributary a population of California Golden beavers (Castor canadensis subauratus) has been re-established between Lake Elsman and Lexington Reservoir. The beaver were re-introduced to the portion of Los Gatos Creek where it enters Lexington Reservoir sometime prior to 1997, and recently, a beaver reportedly served as "a hearty meal" for a local mountain lion. Historical evidence of beaver in the area includes reference by Captain John Sutter who around 1840 recorded that 1,500 beaver pelts were sold "at a trifling value" by the Indians to Mission San José. In 1840, from the port of Alviso, California, beaver pelts, cattle hides and tallow were shipped to San Francisco. In addition, in 1828 fur trapper Michel La Framboise travelled from the Bonaventura River to San Francisco and then the missions of San José, San Francisco Solano and San Rafael Arcángel. La Framboise stated that "the Bay of San Francisco abounds in beaver", and that he "made his best hunt in the vicinity of the missions". Finally, the Smithsonian Institution houses a Golden beaver skull collected by zoologist James Graham Cooper in Santa Clara, California on Dec. 31, 1855. Golden beaver were apparently wiped out by trappers in the South Bay sometime after the end of the California Fur Rush.

Caspian terns (Hydroprogne caspia), North America's largest tern, return to the Bay every spring to nest, migrating from as far away as Colombia. According to scientists from the U.S. Geological Survey, Caspian tern populations in the South Bay are declining at the same time that high levels of mercury are being found in their eggs. The highest mercury levels found in animals from the Bay were in the eggs of Caspian and Forster's (Sterna forsteri) terns that nest near the Cargill salt ponds at the mouth of the Guadalupe River. A study conducted by the U.S. Fish and Wildlife Service has found that nearly three-quarters of the eggs examined from black-crowned night heron (Nycticorax nycticorax) nests in the Guadalupe watershed contained mercury exceeding thresholds known to kill the embryos of other bird species.