KRIS Web Background Pages: Fish Populations
Fisheries data in KRIS Big River come from the California Department of Fish and Game (CDFG), the Mendocino Redwood Company (MRC), and the Hawthorne Timber Company (HTC).
CDFG historical surveys during the 1960s for the Big River basin have less detail than for the nearby Noyo River. No fish sampling took place but they provide useful information about distribution of coho and their abundance relative to steelhead. Fifty CDFG reports for various tributaries are in the KRIS Bibliography in the Big River section. CDFG data from electrofishing is available for some streams in the KRIS Big River project area as a result data collection by Weldon Jones and Scott Harris. Caspar Creek is included as a sub-basin within the KRIS Big River, and was subject to several fisheries investigations, including downstream migrant trapping and long-term electrofishing by CDFG. James Burns of CDFG operated a cranberry-type downstream migrant trap in 1964 and 1967.
Mendocino Redwood Company inherited from Louisiana Pacific Corp four sites in the Big River basin which had been subject to quantitative electrofishing (blocking nets and multiple passes) each year since 1990. In 1994, MRC adopted a less quantitative approach which entailed only monitoring fish and amphibians throughout its land in the Big River area. The MRC Fish Distribution data set includes these non-quantitative samples from 15-30 sites for the years 1994-1996, and 2000.
Hawthorne Timber Company fisheries data in KRIS Big River comes from multiple-pass electrofishing of one site in the Little North Fork Big River and another in Two Log Creek that was done once annually from 1993 to 2000. Sites are representative reaches proximal to temperature and sediment monitoring stations. Data collected during the surveys include habitat area, number of vertebrates captured by species, and species biomass per site. KRIS Big River charts of HTC electrofishing data are presented for each site as either a time-series (1993-2000) or the total catch by species per year. See Amphibian Data in KRIS Big River for information on frogs and salamanders.
|The chart at left shows the number of fish by species captured by electrofishing in the North Fork Big River in 1996. This data is part of the CDFG bio-sample database which provides a snapshot of aquatic vertebrate community structure for several sites in the Big River area, but a time-series data set for only Caspar Creek (see below). The data in this chart show a fish community dominated by steelhead trout. Coho have been found in low numbers in the North Fork by MRC in some years.|
|The density of fish by species captured by
electrofishing the same 30 meter long site in lower Caspar Creek
in the years 1986-1999 is shown at left. Samples were taken in the
mainstem Caspar Creek below the convergence in August and September. The
pattern in the data suggests a shift from coho dominance in early
samples to steelhead being more prevalent in most years since 1990.
Data comes from the California Department of Fish and Game, and represents one of the few long-term data records from the region.
|This chart shows the number of fish counted by species during MRC snorkeler surveys of three sites in the South Fork Big River in 1996. Coho were not found at any of the locations, while the relative abundance of steelhead to stickleback was consistent. Data provided by MRC|
|This chart summarizes 1996 electrofishing captures at 24 sites throughout the South Fork Big River and Daugherty Creek subbasins. It shows a fish community structure dominated by steelhead trout. The coho were found predominantly in the reach of Daugherty Creek above Gates Creek. Data for each site was provided by MRC.|
|Quantitative electrofishing of Gates Creek by Louisiana Pacific represents a unique dataset for the Big River basin. The other three LP sites were not monitored for four continuous years, but data from them can be accessed through a Source Table in KRIS Big River. No coho were captured at this site in Gates Creek and age classes of steelhead were not noted. The chart shows density, biomass, and number of steelhead captured and allows for interpretation of population structure over four years. Data provided by Mendocino Redwood Company.|
|This chart shows the number of fish captured by electrofishing site BIG8 on the Little North Fork Big River from 1993 to 2000. Coho, stickleback and lamprey captures fluctuate widely at this site. Unfortunately, only one site was monitored in the stream. Biomass and density data are also available in the source table data. Data from HTC.|
Downstream migrant trap sampling is a better method for gauging fish community structure. Traps are operated for several months and fish are measured as they are counted. Data reveal migration timing, size and age and species composition. The Caspar Creek trap does not capture the entire stream flow, and has not been calibrated to allow extrapolation and calculation of populations.
|The chart at left shows the total catch from the Caspar Creek outmigrant trap in 1999. Coho salmon outmigrants were more numerous than steelhead trout outmigrants and the ratio of yearlings to young-of-the year captured was close to one for both species. These features of the dataset vary according to year and can be used as indicators of anadromous fish productivity. Numbers of fish trapped cannot be construed as a fish population estimate because of unknown trap efficiency. Data provided by CDFG.|
|The downstream migrant trap results for Caspar Creek for 1999 by week are displayed in the chart at left. The data show that coho young of the year moved downstream in early to mid-April while yearlings moved out slightly later. Steelhead migrations peaked in early May but lasted into June. Data from CDFG.|
|The chart at left shows the size of coho
juveniles captured in downstream migrant traps on Caspar
Creek in 1998. The greatest number of fish were caught in May with
April catches also substantial. Increased size in later months reflects
growth in the stream prior to ocean entry. Coho juveniles that enter the
ocean at a very small size have a much smaller chance of recruiting into
the adult population. Data from CDFG.
(See KRIS Bibliography for CDFG Big River references)
Adams, P.B., M.J. Bowers, H.E. Fish, T.E. Laidig, and K.R. Silberberg. 1999. Historical and Current Presence-Absence of Coho Salmon (Oncorhynchus kisutch) in the Central California Coast Evolutionarily Significant Unit. National Marine Fisheries Service, Southwest Fisheries Science Center. Administrative Report SC-99-02. 24 pp.
Burns, J. 1972. Some Effects of Logging and Associated Road Construction on Northern California Streams. Transactions of the American Fisheries Society, Vol. 101, No.1: 1-17.
Brown, L.R., P.B. Moyle, and R.M. Yoshiyama. 1994. Historical Decline and Current Status of Coho Salmon in California. North American Journal of Fisheries Management. 14(2):237-261.
Maahs, M. 1999. Fort Bragg's World's Biggest Salmon BBQ: a brief history of the Salmon Restoration Association and their work. Salmon Restoration Association. Fort Bragg, CA.
Maahs, M. Unpublished(a). A salmon spawning survey for portions of Ten Mile, Caspar Creek and Garcia River. 1995-96. Prepared for Humboldt County Resource Conservation District. Salmon Trollers Marketing Association, Inc. Fort Bragg, CA. 31 pp.
Maahs, M. Unpublished(b). The 1996-97 salmonid spawning survey for portions of the Ten Mile River, Garcia River and Caspar Creek. Prepared for Humboldt County Resource Conservation District. Salmon Trollers Marketing Association, Inc. Fort Bragg, CA. 31 pp.