Santa Ynez River - Ecology

Ecology

In the 1940s the Santa Ynez River was thought to have the largest run of Steelhead trout (Oncorhyncus mykiss) south of San Francisco Bay. Prior to the completion of Cachuma Dam in 1953, the steelhead run on the Santa Ynez River was estimated to be as high as 25,000 adults. Three decades earlier, in 1920, the Gibraltar Dam was built and blocked access to spawning in the upper watershed, so early twentieth century steelhead runs were likely much higher still. The National Marine Fisheries Service listed the Southern California steelhead Evolutionarily Significant Unit (ESU) as endangered in 1997 due to a 99% decline in its population in the twentieth century. The southern steelhead is the most endangered steelhead ESU in California, and the West Coast of North America. A wild rainbow trout population above the Cachuma Dam probably provides outgoing smolts which become steelhead trout in the ocean, however a low percentage of outgoing smolt survive the migration because of low to no flows or predation in the coastal estuary. Genetic analysis of the steelhead in the Santa Ynez River watershed has shown them to be of native and not hatchery stocks.

The lower Santa Ynez River in the Lompoc area, and lower tributary Salsipuedes Creek has about a dozen California Golden beaver (Castor canadensis subauratus) dams, however in wet years steelhead can generally get around, over, or through beaver dams, and steelhead are common in rivers and streams where beaver are numerous. In addition, high winter flows disrupt the beaver dams and allow steelhead passage. The beavers may play a critical role for steelhead populations as their ponds replenish aquifers, allowing groundwater to recharge streams in dry summers, and provide perennial pools for oversummering trout smolt. In fact, salmonid abundance and fish size increases when beaver are present. Evidence that beaver were once extant in southern California coastal streams includes an adult male beaver skull collected by mammalogist Dr. John Hornung in May, 1906 "along the Sespe River in Ventura County" which is now housed in the Berkeley Museum of Vertebrate Zoology. There is a Chumash pictograph of a beaver at Painted Rock in the nearby Cuyama River watershed. In addition the Barbareño and Ventureño Chumash had a Beaver Dance. The Chumash word for beaver is Chipik, spelled "č’ǝpǝk’" in Barbareño and "tšǝ’pǝk" in Ventureño, and "č’ɨpɨk" in Ineseño (Samala) (Timothy Henry personal communication 2011-01-23). Taken together, these facts support the hypothesis that beaver ranged throughout Santa Barbara County, California. Finally, Father Pedro Font, on the second de Anza Expedition in 1776, described the coastal Chumash women as wearing beaver capes. However, the Santa Ynez River beaver were likely trapped out until re-introduction in the 1940s by the California Department of Fish and Game.

The endangered Tidewater goby (Eucyclogobius newberryi) is also found in the creek's brackish coastal lagoon and several miles upstream in sections of stream impounded by beavers which provide ideal slow-moving water habitat for gobies.