Conservation News
Steelhead Ponzi Scheme In The Central Valley
by Dougald Scott
Steelhead Ponzi Scheme In The Central Valley
by Dougald Scott
Maybe we should thank Mr. L. Ryan Broddrick, the Director of California Department of Fish and Game (CDFG). Under his direction the population of Sacramento Valley steelhead was increased by 2.3 million fish! This feat was accomplished, not by environmental improvement or by sound management science, but rather by writing a letter. To know how this came about some background information is necessary.
All Central Valley (Sacramento and San Joaquin drainages) steelhead are listed as "threatened" under the Endangered Species Act, and are designated as the "California Central Valley Steelhead ESU." ESU stands for Evolutionarily Significant Unit, and is in by the Endangered Species Act to designate a population that is reproductively isolated, and an important component in the evolutionary legacy of the species.
As most California fly fishers know, steelhead are the migratory form of rainbow trout (Onchorynchus mykiss). Steelhead are hatched in fresh water streams and after a time in fresh water, migrate downstream to the ocean. These fish grow rapidly in the ocean environment and return to their stream of origin as adults to spawn. Unlike the Pacific salmon, steelhead do not die after spawning, and generally have a much more flexible life cycle.
Migratory steelhead and resident rainbow trout often occupy the same stream. Both are considered O. mykiss, and the degree of interaction between the two forms is apparently variable. Current methods of genetic profiling cannot distinguish between the two life history forms. However, microchemical analysis of ear bones can reveal whether an adult fish's parent was a steelhead or a resident. Using microchemical analysis, tests on 30 Deschutes River steelhead showed all had mothers that were steelhead and 28 rainbows showed all had mothers that were rainbows. On the other hand, data from the Babine River indicate some degree of mixing in the two forms. World renown salmonid biologist Robert J. Behnke sums it up. "There are no genetic differences (detected) by the technique used to define that genetic difference, but there are obviously genetic differences that determine this migratory behavior."
Resident rainbow trout are present along with steelhead in suitable habitats in the Central Valley, however there is no conclusive research on the reproductive isolation in these forms. Basically no one knows how much reproductive isolation separates steelhead and resident rainbow trout in the Central Valley ESU.
So, how did Director Broddrick create 2.3 million steelhead with the stroke of his pen? He counted all of the resident trout in the system as steelhead (he actually estimated the number using highly questionable methods, see below). In a letter to National Marine Fisheries Service (NMFS) last November, he recommended that the following changes be made to the listing of the Central Valley Steelhead ESU:
* Divide the ESU into Northern and Southern ESUs at the Delta.
* Delist the Northern ESU (remove all protections from steelhead in the Sacramento drainage) and continue listing the Southern ESU.
It should be noted here that NMFS planned on maintaining the Central Valley Steelhead ESU listing as threatened. Director Broddrick in his letter, attempts to change their minds.
What is his justification and rationale for splitting the ESU? The letter states that the Delta, specifically the Stockton Deepwater Ship Channel, presents a barrier to migrating fish because of low Oxygen. This barrier in turn causes reproductive isolation between the north and south.
As to delisting the proposed Northern ESU, the Director cites a large increase in abundance (obtained by counting resident trout and hatchery produced juveniles) as justification for delisting.
Needless to say, once this letter was circulated among sport fishing groups and professional biologists, there was quite an uproar. The Northern California Council of the Federation of Fly Fishers (with which our club is affiliated), Trout Unlimited, and CalTrout, have taken positions opposing the Director's recommendations. These groups have written letters, and met with Mr. Broddrick, and are in further negotiations with the State Resources Agency.
The California-Nevada Chapter of the American Fisheries Society, representing more than 500 professional fisheries scientists in California and Nevada also vigorously opposed Mr. Broddick's recommendations. In a letter to NMFS, and in great detail, they refute his justifications for splitting and delisting the ESUs. Here are some of the points they make:
* There is no genetic evidence to support splitting the Central Valley ESU.
* There is no scientific evidence of a low Oxygen barrier in the San Joaquin River serving as an isolating mechanism.
CDFG derived their Sacramento River steelhead abundance estimates based on density estimates from other streams, most of which have only resident trout and no steelhead. Data from the Upper Sacramento River (above Shasta Dam) was heavily relied on. Estimates were further skewed because the comparison streams have very different environmental characteristics (500-700 cfs in the Upper Sac above Shasta Dam, compared to 4,500-14,000 cfs in the river below the Dam).
Estimates include hatchery produced juveniles as equivalent to returning adults (Dr. Behnke has noted that steelhead raised in hatcheries are more likely to interbreed with rainbows than wild steelhead).
Scientific studies show that the population of anadromous steelhead in the Sacramento River drainage is declining, and so is the production of naturally produced juveniles. Their fisheries experts are not aware of any data that indicate the risk of extinction has been reduced.
The statement that all O. mykiss are "genetically pre-disposed to migrate to the ocean throughout the Central Valley" is unsupported by scientific studies.
Since there are no scientific studies to support the delisting of Sacramento River steelhead, what is driving this proposal? No one I've talked to knows for sure, but I suspect it has to do with water storage. California's population is continuing to increase at a rapid rate as is its demand for water. There is talk of increasing the height of Shasta Dam and increasing storage capacity at other sites as well. These projects will meet much less resistance if the drainages do not contain a listed species.
You can help protect Central Valley Steelhead by communicating your concerns to your legislators, and the Governor. You can also support NCCFFF, Cal Trout, and Trout Unlimited, our main advocates for this issue.