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KRIS Web Background Pages: Sensitive Amphibians
Ten Mile River Basin amphibian data come from annual electrofishing of twenty four aquatic vertebrate monitoring stations since 1993 that are currently maintained by Hawthorne Timber Company. The electrofishing surveys were conducted at the same time each year, and would offer high quality data for interpretation of local population trends over the last nine years except that the focus of the surveys was salmonid fishes and, according to HTC staff, the consistency of effort toward capturing amphibians varied. Consequently, these data are used in KRIS Ten Mile only to note various amphibian species present and distributed among the 24 Ten Mile River Basin stations, and to show possible trends based on repeating patterns in the data among several sites. No study has yet examined the relationships between riparian habitat change in the Ten Mile River Basin and these sensitive amphibian data, but such relationships may be explored in KRIS Ten Mile by comparing USFS vegetation data to amphibian data at particular sites. Studies in the Mattole Basin have examined linkages between riparian conditions and amphibian populations, and these represent the best information available on the topic in northwestern California.
KRIS Ten Mile River charts derived from data provided by Hawthorne Timber Company
The following charts represent amphibian data in three tributaries of the South Fork, where a pattern of decline for Pacific Giant Salamander is repeated. A similar pattern is evident for Bald Hill Creek in the North Fork, and Lower Bear Haven Creek in the Middle Fork.
Number of amphibians captured in Lower Smith Creek | Number of amphibians captured in Lower Campbell Creek, . | Number of amphibians captured in Churchman Creek. |
In addition to the number of animals captured, amphibian data is presented in KRIS Ten Mile as density and biomass for each site. Biomass may be a particularly good companion metric for monitoring Pacific giant salamander and other species where individual size varies greatly. Biomass and density values for amphibian data in the Ten Mile River Basin should not be used for comparison among sites because they under-represent true values in some cases. This bias is particularly large where high fish abundance saturated netters with their primary task of monitoring fish.
References
Ambrose, J., and D. Hines. 1998. Ten Mile River Watershed 1997 Instream Monitoring Results. Georgia-Pacific West Inc. dba The Timber Company. Fort Bragg, CA. 51 pp.
Welsh, H.H. Redwood Sciences Laboratory, Arcata, CA.
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