Tahoe fish habitat improved in five years
Editor’s note: This is the sixth installment in the Tahoe Daily Tribune’s examination of the Tahoe Regional Planning Agency’s five-year evaluation of Lake Tahoe’s environment. Today, a look at the basin’s fisheries.
While the Tahoe Regional Planning Agency reported an improvement in fish habitat at Lake Tahoe over the last five years, future battles loom over the loss of native fish and the possible impact from beavers on spawning gamefish.
Since the last review of the basin’s environment, the TRPA found that a re-examination of the fish habitat in the lake and its tributaries has rated more of the habitat as excellent than before.
While 2,776 acres in Lake Tahoe were described as excellent habitat in 1982, more recent information has increased the acreage to 3,495.
A re-rating of the lake’s tributaries has upgraded some creeks while downgrading others, according to the 1996 Evaluation. The number of miles of streams rated as excellent habitat nearly doubled from the 1982 rating, increasing to 43 miles in 1996 compared to 24 miles in 1982.
Despite the improvements, the TRPA reported that both measures continue to fall short of the goals for fish habitat. The agency set a goal of 75 miles of excellent stream habitat and 5,948 acres of excellent lake habitat.
An important study by the Tahoe Research Group of spawning activity in Lake Tahoe was completed last year, and concluded that recreational activity and the presence of piers had little effect on the ability of the lake’s non-gamefish to spawn near the shore.
While the study may lend support to property owners who want to build new piers, the same study emphasized the importance of preserving the shoreline’s gravel spawning beds, according to Coleen Shade, a TRPA associate planner.
The 1996 evaluation gives the agency lower marks for preserving the Tahoe Basin’s native species. While populations of non-native gamefish in the lake appear stable, biologists are concerned that the only native gamefish still in the lake, the Mountain whitefish, is disappearing.
“We already lost the Lahontan cutthroat in the lake,” Shade said. “Here is the last species of gamefish that was native to Lake Tahoe; everything else was introduced. If we lost the Mountain whitefish, it would be a significant blow to the ecosystem.”
While the TRPA has a goal of supporting the reintroduction of the Lahontan cutthroat where possible, it opposed the U.S. Forest Service’s introduction of the native fish into the Upper Truckee River in 1988. The TRPA opposed the Forest Service’s use of the pesticide rotenone to remove other fish.
In the 1996 evaluation, the TRPA noted that two brook trout have now been found in the portion of the river where the Lahontan was planted, making the outcome of the program uncertain.
The agency is also calling for the completion of a management plan for beavers, which were introduced – or reintroduced – to the Tahoe Basin in the 1930s by the California Department of Fish and Game.
The presence of beavers in streams favored by spawning fish has made them a competitor to other introduced species and the subject of an ongoing debate. The report concluded that beavers present a substantial threat to the spawning behavior of kokanee salmon during low-water years.
In addition, abandoned beaver dams can be blown out during floods, depositing stored sediments downstream and scouring out stream beds.
In its conclusions, the TRPA said it should continue to look for opportunities to reintroduce the Lahontan cutthroat trout and native amphibians, principally the mountain yellow-legged frog. The agency also reaffirmed its goals of discouraging the introduction of non-native species, and increasing the amount of excellent fish habitat through the restoration of streams and preservation of feeding and spawning grounds.
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