BOGUS CREEK SALMON STUDIES 2002

BOGUS CREEK SALMON STUDIES 2002 BY: JEANNINE RICHEY California Department of Fish and Game KLAMATH RIVER PROJECT 303 SOUTH STREET YREKA, CALIFORNIA 96097 (530) 842-3109

California Department of Fish and Game Klamath River Project Bogus Creek Salmon Studies, 2002 Chinook Escapement in Bogus Creek, Siskiyou County September 16, 2002 to November 25, 2002 Jeannine Richey ABSTRACT The California Department of Fish and Game s (CDFG), Klamath River Project (KRP) conducts spawning ground surveys (carcass surveys) on Bogus Creek (Fig. 1) annually, during the fall-run Chinook salmon (Oncorhynchus tshawytscha) spawning season. The purpose of these surveys is to determine the abundance and timing of the migration of adult fall-run Chinook salmon into Bogus Creek and to characterize the run in terms of age and sex composition. Chinook salmon passing through the Bogus Creek fish marking weir (weir, Fig. 2) are marked with an opercle punch, which is used for the population estimate (derived from mark and recapture methodology). A total of 1,398 fall-run Chinook salmon were observed at the weir during the 2002 spawning season. Of these, 678 (48%) were males, and 720 (52%) were females. The peak of the run (as observed at the weir) occurred on October 16, 2002, with 126 Chinook passing through the weir during operational hours (Fig. 3). Male Chinook observed at the weir ranged in size from 47 cm to 105 cm (Fig. 4). Analysis of the length frequency distribution for male Chinook (using data collected at the weir) indicates grilse were < 63 cm in fork length. Based on this determination, the Chinook run in Bogus Creek was comprised of 396 (2.2%) grilse, 8,254 adult males, and 9,185 females. Female Chinook salmon ranged in fork length from 60 cm to 95 cm (Fig. 5). 2,006 Chinook carcasses were counted in Reach 1 (the lower 0.3 miles of Bogus Creek, downstream of the weir). Upstream of the weir, a total of 7,557 Chinook salmon carcasses were examined during the spawning ground surveys (Reaches 2 and 3), 667 of these were recaptures (marked with an opercle punch). The sum of this direct count for Reach 1 and the result of the Peterson estimate for Reaches 2 and 3 yielded a total estimate of 17,835 Chinook salmon entering Bogus Creek during the 2002 spawning season. Chinook salmon heads (containing CWTs) were collected from a total of 40 ad-clipped fish that were recovered either at the weir or during spawning ground survey efforts. Based on the expansion of CWT data collected, an estimated 1,330 Chinook salmon from Iron Gate Hatchery (IGH) entered Bogus Creek during the 2002 spawning season (Table 1). Therefore, hatchery origin Chinook salmon comprised approximately 7.5% of the Bogus Creek Chinook salmon run. The 2002 Chinook salmon run in Bogus Creek was the third largest (17,835) recorded (Fig. 6) since the beginning of the Klamath River Project (1978), surpassed only by 1995 (46,432) and 2000 (35,051). The percent contribution of Bogus Creek escapement to total in-river run and escapement also peaked in 1995, at 19% and 21%, respectively (Fig. 8). No coho salmon (Oncorhynchus kisutch) or steelhead (Oncorhynchus mykiss) were observed at the weir or during the fall Chinook salmon spawning ground surveys for 2002. INTRODUCTION Study Location and Run Timing Bogus Creek is located on the east side of the Klamath River (between river mile 189 and 190) in Siskiyou County, approximately 120 miles north of Redding, near the Oregon border (Fig. 1) and immediately downstream of the IGH (a mitigation hatchery, established in 1966). Fall-run Chinook

salmon return to Bogus Creek to spawn from mid September to early November. The coho salmon spawning run occurs from late October to early January and steelhead run from November to March. Fish Marking Weir The purpose of the weir is to mark Chinook with an opercle punch, which is used for the Petersen mark and recapture population estimate (Ricker 1975) and to collect the biological data necessary to characterize the run (sex composition, fork lengths, and scale samples). The CDFG received funds from the Klamath River Basin Conservation Area Restoration Program to aid in the operation of the weir and conduct spawning ground surveys on Bogus Creek during the 2002 Chinook spawning season. Klamath Restoration Program The Klamath River Basin Conservation Area Restoration Program was established in 1986 by the Klamath Act (Public Law 99-552). The purpose of this 20-year program is to restore anadromous fish in the Klamath River basin, primarily salmon and steelhead. The Klamath Act established two federal advisory committees: the Klamath River Basin Fisheries Task Force (Task Force) and the Klamath Fishery Management Council (KFMC). The KMFC and the Task Force consist of members from various interest groups including commercial and recreational fishermen, Native American tribes, as well as state and federal agencies. The goal of the KMFC and the Task Force is to ensure continued viable populations of anadromous fish in the Klamath Basin by managing in-river and ocean harvest of Klamath Basin anadromous fish and providing funding for restoration projects. Klamath River Project and Bogus Creek Study The Bogus Creek study is one component of the KRP (initiated in 1978). The goals of the KRP include obtaining information on species composition, spawning distribution, fork length frequency and sex ratios for salmonids (primarily Chinook) in various tributaries to the Klamath River including the Salmon, Scott, and Shasta rivers, as well as Bogus Creek and a dozen other small tributaries. Bogus Creek is particularly important because it is a major salmon spawning tributary, despite its small size. For example, during the 1996-98 spawning seasons, an average of 30.6% (8,914) of the total number of natural adult spawners above the Trinity River confluence were estimated to have entered Bogus Creek to spawn. Therefore, a significant portion of natural escapement to the Klamath Basin would be unaccounted for if the Bogus Creek studies were not conducted. In addition to providing valuable escapement estimates to the KMFC and the Pacific Fisheries Management Council for the effective management of Klamath Basin Salmonids, the Bogus Creek studies provide an additional opportunity to recover CWTs and collect scale samples (which are used in the final determination of age composition). Bogus Creek Study Objectives Summarized: A) Determine the in-river run size (escapement) of fall Chinook salmon returning to Bogus Creek during the 2002 spawning season. B) Determine run timing, spawning distribution, length frequency distribution, and sex ratio for fall Chinook in Bogus Creek. C) Collect scale samples and recover heads (containing coded wire tags) from adipose finclipped Chinook in order to determine age composition of the run. D) Collect biological data for all coho salmon and steelhead observed during the Chinook spawning season. 2

Figure 1. Location of Bogus Creek, tributary to the Klamath River, Siskiyou County. 3

MATERIALS AND METHODS Coded-Wire Tagging During March and April of each year, staff of the KRP insert CWTs into 200,000 fingerling (90 fish/lb) and 120,000 yearling Chinook salmon at Iron Gate Hatchery (IGH). All tagged fish are marked with an adipose fin clip, which allows identification and recovery of the CWTs when the salmon return during subsequent spawning seasons. The fingerlings receive a ½ length tag while yearlings receive a full length tag. These tags contain a code that allows identification of four separate groups of fingerlings and three groups of yearlings. One of these yearling groups are raised at Fall Creek Hatchery, which is adjacent to Fall Creek (a tributary to Iron Gate Reservoir), an excellent source of high quality water. 2002 was the first year that Fall Creek yearlings carried a unique code, which may provide the necessary data to determine if Fall Creek yearlings have a higher survival rate than IGH yearlings. Weir Operation The removable weir was installed on September 16 th and operated until November 7, 2002. The weir was operated for 7 hours a day, 7 days a week, throughout the Chinook salmon spawning season. All Chinook salmon passing through the weir (Fig. 2) were measured (fork length), examined for the presence of any tags, fin clips or other abnormal marks and/or scars, and sexed. All adipose fin clipped (ad-clipped) fish were sacrificed for coded wire tag recovery and analysis. Chinook without adipose clips were marked with a hole punch on the left operculum and then released upstream of the weir for subsequent recovery during the spawning ground surveys. Figure 2. Location of Chinook marking weir and spawning ground survey reaches in Bogus Creek, Siskiyou County. 4

Spawning Ground Surveys Spawning ground surveys were conducted twice a week, each Monday and Thursday throughout the Chinook salmon spawning season. The first survey was conducted on October 17 th, while the last survey was on November 25, 2002. A total of eleven surveys were performed throughout the season. For the purpose of the spawning ground surveys, Bogus Creek was divided into 3 reaches (Fig. 2). Reach 1 covered the area from the mouth of Bogus Creek to the weir, approximately 0.3 miles in length. Reach 2 extended from the weir to a small waterfall approximately 0.65 miles upstream. Reach 3 began at the waterfall and continued upstream for approximately 2.25 miles. Each survey was conducted by three crews (one crew per reach), consisting of a minimum of two people for each crew. All salmon carcasses encountered during the surveys were examined for the presence of an opercle punch, adipose fin clip or tag. Heads and scale samples were collected for all ad-clipped fish (as well as fork length and sex) in order to recover the coded wire tag for subsequent age determination. Fork length and sex were determined and a scale sample was collected for a sub sample of Chinook encountered during the survey. Female carcasses were examined internally to determine spawning success; those with greater than 50% of their eggs still remaining in their body cavity were identified as pre-spawn mortalities. Once examined, all carcasses were cut in two to prevent recounting during subsequent surveys. Population Estimate The Chinook salmon spawner escapement for the area of Bogus Creek upstream of the fish marking weir was derived using the Chapman version of the Petersen mark/recapture formula as follows: N = (M+1)(C+1) (R+1) Where: M = The number of salmon marked at the weir. C = The number of marked and unmarked salmon examined in the carcass survey and as wash backs at the weir. R = The number of marked salmon recovered in the carcass survey and as wash backs at the weir. To estimate the total escapement to Bogus Creek the number of Chinook salmon carcasses observed downstream of the weir (a direct count for Reach 1) was added to the Petersen estimate for the area of Bogus Creek upstream of the weir (Reach 2 and 3). Hatchery contribution of Chinook was derived by multiplying the number of CWTs observed for each CWT group by its production multiplier value (the inverse of the proportion of each group of juveniles that were tagged). For Reaches 2 and 3, an additional expansion (the inverse of the number of fish handled during spawning ground surveys divided by the Peterson estimate) is applied. Therefore, the sum of each tag group observed in Reaches 2 and 3 is multiplied by the sample expansion value. RESULTS Weir The first Chinook processed at the weir passed through the weir on September 16, 2002 (the day of the weir installation). On November 7, 2002, the last day of weir operation for the 2002 season, 12 Chinook (2 females, 10 males) were observed passing through the weir. The peak of the run (as observed at the 5

weir) occurred on October 16, 2002, when 126 Chinook passed through the weir during operational hours (Fig. 3). A total of 1,398 Chinook were observed at the weir during the 2002 spawning season. Of these, 6 were ad-clipped, 678 (48%) were males, and 720 (52%) were females. Male Chinook ranged in size from 47 cm to 105 cm (Fig. 4). Analysis of the length frequency distribution for male Chinook (using data collected at the weir) indicates grilse were < 63 cm in fork length. Based on this determination, the Chinook run in Bogus Creek was comprised of 396 (2.2%) grilse, 8,254 adult males, and 9,185 females. Female Chinook salmon ranged in fork length from 60 cm to 95 cm (Fig. 5). Spawning Ground Surveys A total of 2,006 Chinook carcasses were counted in Reach 1 (the lower 0.3 miles of Bogus Creek, downstream of the weir). Upstream of the weir, a total of 7,557 Chinook salmon carcasses were examined during the spawning ground surveys (Reaches 2 and 3), 667 of these were recaptures (marked with an opercle punch). The sum of this direct count for Reach 1 and the result of the Peterson estimate for Reaches 2 and 3 yielded a total estimate of 17,835 Chinook salmon entering Bogus Creek during the 2002 spawning season. Hatchery Contribution Chinook salmon heads (containing CWTs) were collected from a total of 35 ad-clipped fish that were recovered either at the weir (6) or during spawning ground survey efforts (29). Based on the expansion of CWT data collected, an estimated 1,330 Chinook salmon from IGH entered Bogus Creek during the 2002 spawning season (Table 1). Therefore, hatchery origin Chinook salmon comprised approximately 7.5% of the Bogus Creek Chinook salmon run. 140 120 Chinook (Total = 1,398) 100 Number of Chinook Observed 80 60 40 20 0 9/16 9/18 9/20 9/22 9/24 9/26 9/28 9/30 10/2 10/4 10/6 10/8 10/10 10/12 10/14 10/16 10/18 10/20 10/22 10/24 10/26 10/28 10/30 11/1 11/3 11/5 11/7 Date Figure 3. Chinook salmon run timing observed at the Bogus Creek Fish Marking Weir, 2002 (operated 7 hours per day). 6

80 70 Male Chinook (N=678) 60 Grilse Adults 50 Frequency 40 30 20 10 0 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 Fork Length (cm) Figure 4. Length-frequency distribution for male Chinook salmon observed at the Bogus Creek Fish Marking Weir, 2002. 80 70 Female Chinook (N=720) 60 Frequency 50 40 30 20 10 0 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 Fork Length (cm) Figure 5. Length-frequency distribution for female Chinook salmon observed at the Bogus Creek Fish Marking Weir, 2002. 7

Table 1. Estimated contribution of Chinook from Iron Gate Hatchery to total run in Bogus Creek based on coded-wire tags (CWT) recovered from fall-run Chinook salmon in Bogus Creek, during the 2002 spawning season. Number CWT Release Location Brood Year Release Type Production Multiplier Expanded Sample Expansion Total Estimate Bogus Creek Fish Marking Weir 1 601020301 IGH 1998 Ff 26.38 26 1 26 1 601020303 IGH 1998 Ff 26.38 26 1 26 1 601020310 IGH 1999 Ff 27.49 27 1 27 1 601020311 IGH 1999 Ff 27.49 27 1 27 2 601020312 IGH 1999 Ff 27.49 55 1 55 Subtotal = 163 Spawning Ground Survey, Reach 1 3 601020301 IGH 1998 Ff 26.38 79 1 79 1 601020302 IGH 1998 Ff 26.38 26 1 26 1 601020303 IGH 1998 Ff 26.38 26 1 26 2 601020304 IGH 1998 Ff 26.38 53 1 53 3 601020309 IGH 1999 Ff 27.49 82 1 82 2 601020310 IGH 1999 Ff 27.49 55 1 55 3 601020311 IGH 1999 Ff 27.49 82 1 82 1 601020312 IGH 1999 Ff 27.49 27 1 27 Subtotal = 432 Spawning Ground Survey, Reach 2 and 3 2 200000 IGH 1998 Ff 27.49 55 2.09 115 1 400000 IGH 1998 Ff 27.49 27 2.09 58 2 601020301 IGH 1998 Ff 26.38 53 2.09 111 2 601020302 IGH 1998 Ff 26.38 53 2.09 111 1 601020303 IGH 1998 Ff 26.38 26 2.09 55 1 601020304 IGH 1998 Ff 26.38 26 2.09 55 2 601020309 IGH 1999 Ff 27.49 55 2.09 115 2 601020311 IGH 1999 Ff 27.49 55 2.09 115 Subtotal = 735 Total Estimated Contribution = 1,330 CWT codes 100000-400000 assume 1999 Ff expansion rate for 3 year olds Ff = Fall-run Chinook fingerling, Fy = Fall-run Chinook yearling Unreadable CWTs: 100000=No CWT, 200000=CWT lost, 400000=CWT unreadable The production multiplier value is the inverse of the proportion initially tagged. The sample expansion value is the inverse of the number of fish handled during spawning ground surveys divided by the Peterson estimate. Coho and Steelhead No coho salmon or steelhead trout were observed at the weir or during the fall Chinook salmon spawning ground surveys for 2002. 8

DISCUSSION Historic Chinook Runs The 2002 Chinook salmon run in Bogus Creek was the third largest (17,835) recorded (Fig. 6) since the beginning of the Klamath River Project (1978), surpassed only by 1995 (46,432) and 2000 (35,051). During the 1995 Chinook salmon spawning season, the gates at IGH were closed at times; therefore a significant portion of the IGH Chinook returns were diverted to nearby Bogus Creek (Fig. 1). The largest in-river run of Chinook also occurred in 1995 (245,427), which was double the average run (123,281) for the same period (Table 2 and Fig. 7). As expected, total Chinook spawner escapement for this period also peaked in 1995 (Table 2). The percent contribution of Bogus Creek escapement to total in-river run and escapement also peaked in 1995, at 19% and 21%, respectively (Fig. 8). In comparison, the peak contribution of IGH to total in-river run and escapement (34% and 44%, respectively) occurred in 1993 (Fig. 9). However, if all of the Chinook returning to IGH in 1995 had entered IGH, then 1995 would have been the peak contribution year for IGH as well. 50,000 45,000 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5,000 0 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 Year Figure 6. Total (includes adults and grilse) Chinook salmon escapement to Bogus Creek from 1978 to 2002. 9

Table 2. Historic fall-run Chinook salmon totals (includes adults and grilse) for the Klamath basin, Iron Gate Hatchery, and Bogus Creek. Year* In-River Run (IRR) Spawner Escapement (SE) Iron Gate Hatchery (IGH) Bogus Creek Low flow years Totals Totals % of IRR Totals % of IRR % of SE Totals % of IRR % of SE 1978 115,587 90,135 78.0 7,870 6.8 8.7 5,579 4.8 6.2 1979 62,864 42,255 67.2 2,558 4.1 6.1 5,938 9.4 14.1 1980 82,318 57,683 70.1 2,863 3.5 5.0 5,070 6.2 8.8 1981 108,171 56,333 52.1 2,595 2.4 4.6 3,642 3.4 6.5 1982 105,900 67,076 63.3 10,186 9.6 15.2 7,143 6.7 10.6 1983 61,335 47,960 78.2 8,885 14.5 18.5 3,048 5.0 6.4 1984 55,408 30,375 54.8 6,094 11.0 20.1 3,504 6.3 11.5 1985 133,730 104,487 78.1 22,110 16.5 21.2 4,647 3.5 4.4 1986 239,366 180,263 75.3 18,557 7.8 10.3 7,308 3.1 4.1 1987 227,799 143,890 63.2 17,014 7.5 11.8 10,956 4.8 7.6 1988 215,322 130,749 60.7 16,715 7.8 12.8 16,440 7.6 12.6 1989 133,117 72,438 54.4 11,690 8.8 16.1 2,662 2.0 3.7 1990 40,214 25,705 63.9 7,040 17.5 27.4 785 2.0 3.1 1991 34,353 19,121 55.7 4,067 11.8 21.3 1,281 3.7 6.7 1992 40,346 28,479 70.6 7,318 18.1 25.7 1,154 2.9 4.1 1993 64,740 48,945 75.6 21,711 33.5 44.4 3,716 5.7 7.6 1994 78,269 60,850 77.7 14,566 18.6 23.9 8,260 10.6 13.6 1995 245,427 217,312 88.5 22,940 9.3 10.6 46,432 18.9 21.4 1996 184,903 108,325 58.6 14,165 7.7 13.1 10,797 5.8 10.0 1997 91,642 70,303 76.7 13,727 15.0 19.5 10,030 10.9 14.3 1998 95,210 75,157 78.9 15,326 16.1 20.4 6,835 7.2 9.1 1999 70,190 50,088 71.4 14,120 20.1 28.2 6,165 8.8 12.3 2000 228,114 188,642 82.7 72,474 31.8 38.4 35,051 15.4 18.6 2001 198,398 142,323 71.7 38,568 19.4 27.1 12,575 6.3 8.8 2002 169,298 99,045 58.5 24,961 14.7 25.2 17,835 10.5 18.0 Average 123,281 86,318 69.0 15,925 13.4 19.0 9,474 6.9 9.8 MAX 245,427 217,312 88.5 72,474 33.5 44.4 46,432 18.9 21.4 MIN 34,353 19,121 52.1 2,558 2.4 4.6 785 2.0 3.1 STDEV 69,718 53,994 10.0 14,459 7.8 9.9 10,517 4.1 4.9 *For the 1995 season, the gates at IGH were closed at times; therefore a significant portion of the IGH returns were diverted to Bogus Creek. 10

300,000 250,000 200,000 150,000 100,000 50,000 0 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 Year 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 Figure 7. Total in-river run of Chinook in Klamath River, 1978 to 2002. 50 45 % of Chinook In-River Run % of Chinook Spawner Escapement 40 35 % Contribution 30 25 20 15 10 5 0 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 Year Figure 9. Percent contribution of Iron Gate Hatchery (California Department of Fish and Game) Chinook salmon to total Chinook spawner escapement and total Chinook in-river run 1978 to 2002. 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 11

50 45 % of Chinook In-River Run % of Chinook Spawner Escapement 40 35 % Contribution 30 25 20 15 10 5 0 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 Year Figure 9. Percent contribution of Iron Gate Hatchery (California Department of Fish and Game) Chinook salmon to total Chinook spawner escapement and total Chinook in-river run 1978 to 2002. 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 Historic Proportions of Grilse The length-frequency distribution for grilse observed during 2002 does not match the bell curve observed for adults, indicating a lower than normal number of grilse was observed. In comparison, the length-frequency distribution for male Chinook salmon observed at the weir, during the 2001 spawning season, reflects a normal, bimodal distribution, with one peak for grilse and the other for adults (Fig. 10). This difference is also reflected in percentages of grilse observed. During the 2001 spawning season 5.2% of the run were grilse, compared to 2002 where only 2.2% of the run were grilse. The lowest percentage of grilse for the period 1978 to 2002 (1.1%) was observed during the 2000 spawning season (Fig. 11 and 12). The highest percentage of grilse in Bogus Creek was observed in 1992 (48.2%) (Fig. 12). From 1978 to 1989, at least 10% of the run were grilse in 10 out of 12 years. In contrast, from 1990 to 2002 the proportion of grilse exceeded 10% for only 3 of the 13 years. The average number of grilse during this 25 year period (Fig. 12) was 748 (13.7% of the total run). 12

80 70 Male Chinook (N=1,313) 60 50 Frequency 40 Grilse Adults 30 20 10 0 32 35 38 41 44 47 50 53 56 59 62 65 68 Fork Length (cm) Figure 10. Length-frequency distribution for male Chinook salmon observed during the Bogus Creek spawning ground surveys, 2001. 120 71 74 77 80 83 86 89 92 95 98 101 104 107 110 Male Chinook (N=1,241) 100 Grilse Adults 80 Frequency 60 40 20 0 32 35 38 41 44 47 50 53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 98 101 104 107 110 Fork Length (cm) Figure 11. Length-frequency distribution for male Chinook salmon observed during the Bogus Creek spawning ground surveys, 2000. 13

60% 50% 40% Percent of Grilse 30% 20% 10% 0% 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 Year Figure 12. Historical percentages of Chinook grilse observed in Bogus Creek, Siskiyou County. 2002 Fish Kills Fish kills on the Klamath River have been documented in several years, most recently in September of 2002. Columnaris (Flavobacter columnare) and ICH (Ichthypthirius multifilis) were responsible for the 2002 fish kill, which resulted in the loss of at least 33,000 adult salmonids (CDFG 2003). The fish kill extended from the mouth of Klamath River to Coon Creek Falls (36 river miles). Low flows coupled with increased water temperature and fish densities (due to the low flows and potentially inadequate fish passage) stressed fish to the point that they were susceptible to the naturally occurring pathogens. If these fish kills had not occurred, the number of Chinook entering Bogus Creek during the 2002 spawning season would likely have been higher than 17,835. Other recent fish kills include the June 2000 and June 1998 fish kills. The 2000 fish kill occurred in late June (CDFG 2000), in the mainstem of the Klamath River, between Coon Creek and Pecwan Creek (64 river miles). Estimates of the number of fish killed (primarily young-of-the-year) range from 10,000 to 300,000. Direct mortality was believed to be caused by two pathogens, ceratomyxosis (Ceratomyxa shasta) and columnaris, which occur naturally in the Klamath River. The presence of unseasonably high air temperatures during the spring and early of summer of 2000 lead to mainstem water temperatures above 24 o C (75 o F) in June. IGH Chinook tend to be resistant to C. shasta at temperatures 16 o C (61 o F), therefore elevated river temperatures appear to exacerbate this disease (Foott et al. 1999). At least 240,000 juvenile Chinook perished during the June 1998 fish kill, caused by columnaris and bacterial septicemia (Williamson and Foott 1998). 14

Current and Future Studies Staff of the KRP are currently analyzing historical CWT returns. The data from various CWT groups will provide information on return and straying rates for these groups. There are several other areas to investigate in regards to Bogus Creek: 1. Is there a relation between flow or water temperature and abundance of salmonids observed in Bogus Creek? 2. Has there been a change in the size of Chinook? (A decrease in the size of coho salmon females has been observed in other areas). 3. Has there been a shift in the run timing for Chinook? ACKNOWLEDGEMENTS The California Department of Fish and Game would like to thank Siskiyou County High School students who assisted KRP staff in completing spawning ground surveys on Bogus Creek. Their contribution was integral to the success of the project. REFERENCES California Department of Fish and Game. 2003. September 2002 Klamath River Fish Kill: Preliminary Analysis of Contributing Factors. 63pp. California Department of Fish and Game. 2000. Documentation of the Klamath River Fish Kill, June 2000. California Department of Fish and Game Memo. Redding, California. 27pp. Foott, J.S., J.D. Williamson, and K.C. True. 1999. Health, physiology and migration characteristics of Iron Gate Hatchery Chinook, 1995 Releases. U.S. Fish and Wildlife Service, California Nevada Fish Health Center, Anderson, CA. Ricker, W.E. 1975. Computation and interpretation of biological statistics of fish populations. Bulletin of the Fisheries Research Board of Canada, Bulletin 191; Department of Fisheries and Oceans, Ottawa, Canada. 382pp. Williamson, J.D. and J.S. Foott. 1998. FY98 Investigational Report: DIAGNOSTIC EVALUATION OF MORIBUND JUVENILE SALMONIDS IN THE TRINITY AND KLAMATH RIVERS (JUNE SEPTEMBER 1998). U.S. Fish and Wildlife Service, California Nevada Fish Health Center, Anderson, CA. 15

Appendix A Fall-run Chinook Salmon Escapement Estimate, Bogus Creek 2002 I. Petersen estimate (for Reaches 2 and 3): The Chapman version of the Petersen mark and recapture formula (Ricker 1975) was used to estimate spawner escapement, as follows: where N = (M+1)(C+1) (R+1) N = The estimated Chinook escapement for Reaches 2 and 3 (upstream of weir) M = The number of Chinook marked at the weir (and released upstream of weir) C = The number of Chinook carcasses that were examined (captured) in Reaches 2 and 3 and in the washback sample at the weir. R = The number of marked (opercule punched) Chinook that were recaptured in Reaches 2 and 3 and in the washback sample at the weir. M = 1,398 C = 7,557 R = 667 Peterson estimate (N) = 15,829 Lower Limit = 14,674 Upper Limit = 17,075 95% Confidence Intervals of R: x 1 = 719.58 x 2 = 618.26 II. Total estimate of Chinook escapement for Bogus Creek 2002: Estimate for Reach 2 and 3 = 15,829 Count below weir (Reach 1) = 2,006 Total estimate = 17,835 16

Appendix B Copies of Bogus Creek Computer Data, 2002 Spawning Ground Survey Data Fish Marking Weir Data Weir Wash Back Data 17