Oncorhynchus mykiss aguabonita
A California Golden Trout from a small high Sierra stream
The California Golden Trout is often cited as being the most beautiful of the salmonids. These fish are native to the upper South Fork of the Kern River and Golden Trout Creek in the southern Sierra-Nevada Mountains of California and were historically found in about 450 miles of stream habitat (Trout Unlimited 2007). Due to its beauty and popularity with anglers the California golden trout has been widely stocked outside of its native range, especially in the high lakes of the Sierra and Rocky Mountain Ranges. The broodstock used for stocking golden trout outside their native range is slightly hybridized with hatchery rainbow trout, but still retains the appearance of the golden trout.
The habitat available within the native range of the California golden trout consists of small high altitude streams, and as such these fish only exhibit a stream resident life history type. The typical size of the home range for adult golden trout is between 55 and 165 feet of stream habitat, although ranges of up 1800 (~0.3 mile) have been observed (Matthews 1996). These golden trout prefer undercut banks or areas with sedge, although they are also associated with several other types of habitat as well. California golden trout are spring spawning fish, like other the subspecies of rainbow trout and typically spawn during mid-May after runoff has subsided and water temperatures have warmed up (Knapp and Vredenburg 1996). The preferred habitat for California golden trout is wider stream reaches that are typically associated with cattle grazing. Knapp et al. (1996) showed that California golden trout used smaller gravel, shallower areas and dig shallower nests than other salmonids.
Even though this trout is the official state fish of California, poor management has put them at a serious risk of extinction. As the California golden trout have long been isolated from contact with other species of trout, they are greatly impacted by the introduction of non-native fish. Introduced brook trout compete with them for food, brown trout prey on them and rainbow trout hybridize with them, leading to a loss of their genetic integrity. Cordes et al. (2006) showed that hybridization with introduced rainbow trout threatens the genetic integrity of California golden trout across their entire native range. Although the degree of hybridization varies from population to population, it is believed that the only completely pure population occurs in about a three mile stretch of Volcano Creek (Moyle et al. 2008).
The introduction of non-native fish is perhaps the greatest threat to the continued existence of golden trout, but degraded habitat conditions also pose a serious problem as well. In an effort to address these issues Congress designated the 306,000 acre Golden Trout Wilderness area in 1978, but grazing practices and recreational use continue to degrade the habitat to this day. Livestock grazing has occurred in the California golden trout's native range since the 1800's with cattle and sheep being the primary animals that are raised in the area. Knapp and Mathews (1996) showed that ungrazed stream reaches in the Golden Trout Wilderness had significantly higher densities and biomasses of trout when those that were grazed. Ungrazed areas also had great canopy shading, stream depth and smaller stream widths than what was found in grazed areas. It will be important that these issues are properly addressed, so that the world will continue to be graced by the beauty of the California golden trout.
The California golden trout is perhaps the most brilliantly colored salmonid. The backs of these fish can range from bronze or copper color to dark olive, which transitions to a golden yellow color that becomes quite intense below the lateral line. The belly in most individuals is a bright orange color, but the intensity of this coloring varies with age, size and maturity of the fish. Dark purple parr marks are present into adulthood in California golden trout within their native range, but have been known to fade on large lake dwelling fish stocked outside their native range. There is a red or pink stripe along the lateral and the same coloration is found on the gill plates. The fins are an orange or yellow color and the dorsal, anal and pelvic fins have a dark border outlined with white, or orange on the dorsal fin. The spots are round, large to moderate in size and are isolated above the lateral line and on the dorsal and caudal fins. Often times the spots are concentrated near the tail on the caudal peduncle, as is also common in many subspecies of cutthroat. This coupled with the fact that these fish also typically have orange cutthroat marks led to a great deal of confusion to whether golden trout should be aligned with cutthroat or rainbow trout. It was only with an improvement in techniques for analyzing the genetic makeup of these fish that it became evident that they are of the rainbow trout lineage.
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