Abstracts of Fisheries Management Reports, Technical Circulars and Project Reports of the Fisheries Branch Daiva O. Zaldokas & Debra L. Aird B.C. Fisheries Branch, 2204 Main Mall, U.B.C., Vancouver, B.C. V6T 1Z4 Fisheries Technical Circular No. 91 1992 CARIBOO REGIONAL FISHERIES REPORTS Lirette M.G. and D. Tredger. 1991. Polley and Bootjack Lakes Creel Survey, 1990. B.C. Environment, Williams Lake, B.C. Regional Fish. Rep. No. CA 911:21p. A creel survey was conducted on two popular sport fishing lakes in the Cariboo, Polley and Bootjack lakes. Between June 2 and September 2, 1990, 407 anglers were interviewed and 151 rainbow trout were sampled to provide information on the recreational fisheries of these lakes. The number of boats angling on Polley and Bootjack lakes were counted from shore and aircraft to determine total effort. Anglers fished an estimated 7,891 hours (3,446 days) to catch 15,412 trout (11,825 harvested) from Polley Lake during the May to September fishery. Bootjack Lake anglers fished 5,670 hours (2,324 days) to catch 7,515 trout (5,829 harvested). The trout captured from both lakes averaged 290 mm (145 to 360 mm) and were mainly 4+ years old (2+ to 6+). Over 80% of the fish harvested appeared to have spent at least one year rearing in their nursery stream prior to migrating to Polley and Bootjack lakes. Doligan, R.B. and M.G. Lirette. 1991. Fisheries Assessment of Upper Maud Creek. B.C. Environment, Williams Lake, B.C. Regional Fish. Rep. No. CA 912:12p. An exploratory assessment of juvenile rainbow trout in the "upper" Maud Creek drainage was conducted to determine current abundance and provide estimates of potential migrant production to Maud Lake. Rainbow trout fry were found in high densities at all sample sites in both Maud (4.3/m2) and Rudy Creeks (3.2/m2). Collectively, the total population of juvenile rainbow trout was estimated to be in excess of 110,00 fish. Gill net sampling for rainbow trout in Sandy Lake confirmed the presence of sport-fish in this lake. Water quality and quantity requirements to protect the fishery resource are discussed. Lirette, M.G. 1991. West Road (Blackwater) River air survey of angler use, 1990. B.C. Environment, Williams Lake, B.C. Regional Fish. Rep. No. CA 913:25p. An air survey of angling use in the West Road River watershed was carried out between June 21 and September 17, 1990. Boats on fifteen lakes and boats/vehicles on or near seven sections of the river were counted on approximately eleven weekend days and nine weekday days. Mean boat count for weekend and weekdays varied for lakes and stream sections depending on their accessibility. Good access resulted in high weekend use while poor access to lakes or stream sections resulted in higher weekday use. Mean boat counts were used to estimate angler use in days fished. The largest fisheries were on Tsacha Lake (1843 angler days), Marmot Lake (1672 days) and zone 2 (1095 days) and zone 3 (1047 days) of the Blackwater River mainstem. The total estimated use on the Blackwater River was 4,333 angler days. The air survey data provides a relative comparison of angler use between lakes and river section in the watershed. It also provides the means to monitor future changes in the various lake and stream fisheries of the West Road River. Survey costs and effectiveness are discussed. Griffith, R.P. 1991. Blackwater (West Road) River Assessment of Existing and Potential Resident Rainbow Trout Production Downstream of Kluskoil Lake. R.P. Griffith and Associates, Sidney, B.C. for B.C. Environment, Williams Lake, B.C. Region Fish. Rep. No. CA-914:176p. During the period of critical low flows in September 1990, an assessment was conducted of existing and potential fish production in the Blackwater (West Road) River drainage below Kluskoil Lake. Results were based on intensive field sampling and sophisticated analytical methodologies. Electrofishing in juvenile habitat resulted in the capture of 11 different fish species. Rainbow trout was the species with highest frequency of occurrence, followed by chinook salmon, the only other salmonid species captured. Non-salmonids were principally found in mainstem areas (Blackwater, Nazko, and Baezaeko rivers). Rainbow juveniles were found at few mainstem sites (and in low numbers), but were by far the most numerous species in the 12 smaller tributaries that were sampled. Based on production modelling, rainbow fry and parr densities in mainstem habitat were grossly below theoretical capacities. Similarly, standing stock of rainbow fry was well below respective capacity in most of the smaller streams sampled. In contrast, rainbow parr appeared to be near (or above) capacity in all of the smaller streams where they occurred. In terms of mainstem populations of catchable-size fish, various estimates indicate that the Blackwater system (below Kluskoil Lake) is functioning at about half its theoretical potential, based on production modelling for such populations. The cause appears to be lack of recruitment. Survival of rainbow fry seems low in mainstem habitats (due to non-salmonid predators and competitors), emphasizing the importance of older recruits (parr) from tributaries. All indications suggest that a limitation in suitable habitat for parr is imposing a similar limitation on mainstem recruitment, and ultimately the numbers of catchable-sized fish in mainstem areas (notably the Blackwater River). The principal limiting factor appears to be the severity of low flows in most tributary streams, exerting greatest impact on parr habitat. since the current level of mainstem recruitment appears to rely on all available parr production, all smaller tributaries (and their flows) should be afforded full habitat protection (even small producers). Habitat enhancement should focus on increasing the abundance/availability of parr habitat in tributaries by such means as barrier/obstruction removal and/or flow augmentation (if feasible). Various options are suggested.