Policy statement for California Trout on planting of high elevation lakes in California.
California Trout places great emphasis on using objective science to determine policy. Many of our native trout are already listed as threatened, endangered, or species of concern. Now we have a new concern, amphibians are facing a global decline.
We face a dilemma over trout policy in the Sierra Nevada, and especially the high country above treeline. Over the years, starting with private activity, but mainly through the efforts of the California Department of Fish and Game, a recreational fishery was created in the lakes and streams. Both native and non-native trout have been planted, and non-native trout have been planted above native fisheries. This has resulted in downstream incursion to the detriment of native trout. Lakes have also been planted over and over even though the existing fish are reproducing. This has stunted the fish populations in these lakes; if left alone, it has been argued that some could become trophy trout lakes.
A more immediate problem is that introduced trout prey on Mountain Yellow-legged frogs. They prey on the tadpoles in high elevation lakes so efficiently that they can't co-exist. The result is a conflict because the frogs have declined to a point where they may be threatened with extinction.
To be sure the overall causes of frog decline are complex, and pesticides blown into the mountains as well as emergent diseases contribute to the decline of the frogs. Researchers have noted several factors that could be affecting these populations, including 1) Chytridiomycosis fungal infections, 2) Contaminants such as pesticides and acid rain, 3) Exotic species introductions such as trout and bull frogs, 4) Forest management practices, and 5) Ultra violet radiation. A substantial body of research seems to show that trout and frogs cannot co-exist in the high country lakes where the frogs are native and trout are not. The dilemma is what to do: keep the recreational fishery or reduce it or eliminate it altogether to save the frogs?
More than 70% of the lakes having trout have reproducing populations that are or would become essentially wild fish if trout stocking were halted. Backpack or horsepack trips into the high country to fish, especially to fish for wild California Golden trout, is a long standing tradition for many Californians. It is one millions of people would find truly difficult to give up.
On the other hand, maintaining bio-diversity within our wild lands is a constant struggle. Aldo Leopold once pointed out that a good tinkerer always saves all the parts, lest one be needed later. In the same way, while we've tinkered by planting trout, it would be a bad idea to let the frogs die out. The consequences are hard to predict and may be adverse to other species.
The historic range of the frogs includes meadow and stream habitat. The ecology of the Mountain Yellow-legged frog life history is not complete for mid-elevation sites, and the research on frogs in the high lakes is continuing. There is also much to be learned about the interaction of toxic contamination and disease on the fertility and immunity of the frogs. Scientists don't have all the answers so far.
It is encouraging that scientists have found lakes and streams that still have frogs. Many of these are isolated, however, and it appears necessary to remove trout from at least a few lakes in order to create habitat for viable populations that can withstand sudden adverse environmental events. Yet some proposals have suggested 20 to 30% of the lakes with trout should be gill netted to remove trout.
CalTrout feels that this is premature. Further study of habitat at low- to mid-elevations of the range of the Mountain Yellow-legged frog is prudent to determine which habitat type is best for recovery sites. The California Department of Fish and Game has recently announced a new policy intended to benefit the frogs by reducing the scope and frequency of trout planting in the Sierra Nevada. And the effects of diseases such as Chytridiomycosis fungal infections, which is present in the Sierra Nevada and has damaged or even eliminated populations of mountain dwelling frogs worldwide, needs to be assessed. It would make little sense to remove trout only to find the frogs perish anyway due to natural causes such as an epidemic disease.
Accordingly, CalTrout announces the following policy with regard to planting trout and removal of existing trout in the Sierra Nevada to help frogs:
1. Do not plant lakes that have self-sustaining fisheries.
2. Do not plant non-native fish above populations of native trout or other native fish species.
3. Set a target of not more than 10% of lakes having planted trout to be eradicated over the next 10-year period.
4. Make use of lakes already barren of trout for reintroduction of amphibians to the maximum extent feasible
5. Select for removal only lakes bearing species exotic to California such as Brook or Brown to the maximum extent feasible.
6. Select for removal only lakes without reproducing trout to the maximum extent feasible.
7. Select headwater lakes or isolated water bodies near known populations of amphibians until all habitat types have been tried to determine what is best for recovery of frogs.
8. Select only lakes without a history of high angler use or of producing trophy fish (16" or better for the High Sierra), and with low trout productivity to the maximum extent feasible.
This policy will allow scientists to fill in the gaps in the knowledge of the life history and habitat of the frogs and the way fish and frogs interact. After the fish are removed from a few lakes they can serve as “Living Laboratories,” for re-introductions of amphibians or other native species where historically they may have existed. We need to allow good science to proceed until there are facts to support the assumptions that are being made in the field.
We realize that this policy that allows some trout removals will not be acceptable to all of our members. Yet it is a logical and scientific solution to the dilemma. We encourage all members to get involved with the state and federal agencies working on this to help them determine which lakes are important to you and which ones are best suited to removal. A healthy environment with all the parts intact is worth conserving.