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California's Native Fish Crisis

Caltrout Issues Report on Native Fish CrisisCalTrout issues a detailed status report of California native fish. Warning: Large PDF File.


Status of McCloud River Redband Trout

Due to confusion about what is a pure form of the McCloud River redband, a clear and accurate status is hard to come by. Their population is concenrated in a couple of small creeks such as Sheepheaven Creek. Unfortunately, these creeks have been degraded by logging and grazing. The introduction of hatchery rainbow trout and heavy angling pressure in the upper stretches of the Upper McCloud have not stacked the deck in their favor either.

Conservation Efforts

A conversation agreement limits the stocking of trout above Middle Falls to trout other than rainbow trout. In 1998, however, brook trout were planted. The best policy might be to consider not dropping hatchery fish in this watershed.

The McCloud River Redband - Genetically Distinct?

The native redband trout in the upper McCloud River drainage are thought to be a relict subspecies of non-anadromous rainbow trout adapted to harsh, fragmented environments. The phylogenetic position of the McCloud redband with Oncorhynchus mykiss has been the subject of debate for over 50 years. In 1994, due to concerns regarding hybridization with hatchery fish, habitat reduction during an extended drought, and potential hydropower development, the McCloud redband was listed as a Category 1 species under the Endangered Species Act (Federal Register, Vol. 219, Nov. 15, 1994, page 58982). In 1995, Category 1 designation was changed to "Candidate" (Federal Register, Vol. 61, February 28, 1996, page 7596). This change was not a change in status but a change in nomenclature only. Presently, this fish is believed to be restricted to several small streams in the upper river basin as well as to the main stem of the McCloud River above Middle Falls.

There is some uncertainty regarding the status of redband trout as a listable taxonomic unit under the Endangered Species Act. Largely, this is a question of whether populations of McCloud redband persist which are genetically distinct from hatchery rainbow. Molecular genetics investigations in progress may provide guidance to resolve this issue. To the extent that the disagreement arises over the definition of "distinct population segment," resolution of the issue may be more elusive.

Further Genetic Study is Needed

In general, redband trout constitute a special group of yet undescribed native western North American trout of the genus Oncorhynchus. The phylogenetic position of the McCloud redband within O. mykiss has been debated for over 50 years beginning with the first discovery of what was reported as a southern Sierra golden trout by Wales (1939) based only on external appearance. Several contemporary geneticists, using electrophoretic genetic analyses, have indicted that McCloud redband appear to be a non-anadromous rainbow trout (Oncorhynchus mykiss) of ancient coastal origin which has adapted to harsh, fragmented environments (Behnke 1992, Berg 1994). Recent preliminary investigations (Nielsen, et al., 1996) using microsatellite and mitochondrial DNA sequencing infer not only a close genetic affinity with contemporary coastal trout and steelhead but also with Rio Santo Domingo trout and Little Kern golden trout. However, additional microsatellite loci and trout populations need to be analyzed to confirm these preliminary results and relationships better described between different upper McCloud River populations and introduced hatchery strains of rainbow trout. Despite the current ambiguity of its phylogenetic or taxonomic status, the McCloud redband is currently classified as a Species of Special Concern by the California Department of Fish and Game.

Much confusion and debate remains regarding the systematics of the McCloud redband. The exact relationship that McCloud redband share with coastal trout, steelhead, golden trout, and redband trout populations from other drainages may never be fully understood since it is unknown whether a genetically pure indigenous population of McCloud redband actually exists. Berg (1994) indicated his concern that the introductions, by stocking, of hatchery rainbow trout strains within the upper McCloud River drainage may have led to some degree of genetic introgression with indigenous trout within the upper McCloud River basin. His concern, which, in part, has prompted the current candidate species status of McCloud redband, has not been validated with the recent preliminary genetic findings (Nielsen et al., 1996). Current belief is that the genetic makeup identified in some of the putative redband populations in the upper McCloud River basin may be sufficiently unique to warrant their protection and conservation. However, as of June, 1998, further studies to determine which of the remaining population segments (some of which are usually isolated from main stem populations by barriers or naturally dry stream channels) are unique versus hybridized with introduced hatchery strains are pending completion.

Redband Genetics

Beginning in 1978, Dr. Graham Gall and research associates from the University of California at Davis analyzed putative redband trout collected from the upper McCloud River system. The analysis compared meristic, chromosomal and electrophoretic traits. The report to the CDFG Threatened Trout Committee stated that the upper McCloud River populations from each system had many characteristics in common with each other but differed from other redband populations including those found at Goose Lake and Pit River, and from Kern River golden trout, plus Kern River and coastal rainbow trout.

A definitive description of the current range of redband is complicated by the inability to clearly identify the extent to which McCloud redband may be hybridized with hatchery strains of rainbow, or its relationship to other populations of interior rainbow trout. This is the case for three reasons:
1. Meristic, protein electrophoresis and molecular systematic descriptions of McCloud redband, to date, provide conflicting information to describe distinct, identifiable population(s) of redband trout in the upper McCloud River basin and those, if any, that are hybridized with rainbow;
2. An informal sampling of streams in the upper McCloud River basin has been conducted to determine those streams bearing O. mykiss, redband or otherwise. However, without a clear understanding of how to distinguish a putative redband from other O. mykiss, and without a rigorous sampling design to determine absence, precise descriptions of historic or current range are not available.
3. Some McCloud redband populations appear to be of a different genotype from other populations within the upper McCloud River basin based on the preliminary microsatellite analysis although no barriers exist which would prevent these populations from mixing with or interbreeding with other McCloud redband populations within the upper McCloud River. For example, some upper McCloud River basin tributary streams went totally dry and were therefore fishless for some period of time during the most recent extended drought period and now contain "new" McCloud redband populations which could only have been established from putative redband of the main stem McCloud or one of the McCloud River's tributaries. Yet, these newly established populations may be genetically different from all other populations within the upper McCloud River basin based on a preliminary analysis of a portion of the samples collected using a limited number of DNA microsatellites; more rigorous sampling and analysis that is currently under way may help to resolve these issues.

(Redband Trout Conversation Agreement, Shasta-Trinity National Forest)