Juvenile Salmonid Monitoring on the Lower Trinity River, California, 2001

Transcription

1 Juvenile Salmonid Monitoring on the Lower Trinity River, California, 21 Prepared By: Seth W. Naman Scott Turo Tim Hayden Yurok Tribal Fisheries Program Hwy 96 Box 196 Hoopa, CA Trinity River Division Technical Report Number TR-4-1 January 24

2 TABLE OF CONTENTS EXECUTIVE SUMMARY...1 INTRODUCTION...2 MATERIALS AND METHODS...2 TRAP DESIGN AND OPERATION...4 TRAP SITE DESCRIPTION...4 BIOLOGICAL SAMPLING PROTOCOL...4 HATCHERY AND NATURAL ESTIMATES...4 Chinook Salmon...5 Coho Salmon...6 Steelhead...6 ABUNDANCE INDEX...6 MIGRATION RATES...6 FLOW MEASUREMENTS...7 WATER TEMPERATURE...7 RESULTS AND DISCUSSION...7 RIVER FLOW...8 WATER TEMPERATURE...9 CHINOOK SALMON...9 Capture Summary...9 Hatchery and Natural Stocks...11 Abundance Index...11 Emigration Timing...12 Size...13 Migration Rate...14 COHO SALMON...15 Capture Summary...15 Hatchery and Natural Stocks...16 Abundance Index...16 Emigration Timing...17 Size...17 Migration Rate...17 STEELHEAD...18 Capture Summary...18 Hatchery and Natural Stocks...19 Abundance Index...19 Emigration Timing...2 Size...2 Migration Rates...2 OTHER SPECIES...21 RECOMMENDATIONS...21 ACKNOWLEDGMENTS...21 APPENDIX...22 REFERENCES...26 ii

3 LIST OF EQUATIONS Equation Equation Equation Equation Equation LIST OF TABLES Table 1 Total numbers of juvenile chinook salmon captured in the Trinity River near Weitchpec, California over a four-year period... 1 Table 2 Estimated migration rates of TRH chinook captured in a rotary screw trap, lower Trinity River California, Table 3 Total numbers of juvenile coho salmon captured in the Trinity River near Weitchpec, California over a four-year period with a rotary screw trap Table 4 Total numbers of juvenile steelhead captured in the Trinity River near Weitchpec, California over a four-year period with a rotary screw trap LIST OF FIGURES Figure 1 Map of the Klamath River basin... 3 Figure 2 Average daily discharge at USGS Hoopa gauge (rkm 2.8), and the percent of river discharge sampled with a rotary screw trap, lower Trinity River, California, Figure 3 Minimum and maximum daily temperature of the lower Trinity River near Weitchpec California, Figure 4 Hatchery and natural chinook salmon catch and river discharge by week, lower Trinity River rotary screw trap, California, Figure 5 Hatchery and natural chinook salmon abundance and river discharge by week, lower Trinity River rotary screw trap, California, Figure 6 Hatchery and natural chinook salmon emigration timing by week, lower Trinity River rotary screw trap, California, Figure 7 Mean weekly fork length and standard deviation of juvenile chinook salmon sampled with a rotary screw trap, lower Trinity River, California, Figure 8 Hatchery and natural coho salmon catch and river discharge by week, lower Trinity River rotary screw trap, California, Figure 9 Hatchery and natural coho salmon abundance and river discharge by week, lower Trinity River rotary screw trap, California, Figure 1 Hatchery and natural coho salmon emigration timing by week, lower Trinity River rotary screw trap, California, Figure 11 Hatchery and natural steelhead catch and river discharge by week, lower Trinity River rotary screw trap, California, Figure 12 Hatchery and natural steelhead abundance and river discharge by week, lower Trinity River rotary screw trap, California, Figure 13 Hatchery and natural steelhead emigration timing by week, lower Trinity River rotary screw trap, California, iii

4 EXECUTIVE SUMMARY This report summarizes juvenile salmonid emigration monitoring in 21 conducted by the Yurok Tribal Fisheries Program near Weitchpec, California. Capture data was used to calculate abundance indices for juvenile chinook salmon, coho salmon and steelhead. Agelength analysis, migration rates, natural and hatchery contributions, capture data for pacific lamprey and green sturgeon, as well as river discharge and temperature monitoring information are also included in this report. Personnel operated a rotary screw trap in the lower Trinity River at Weitchpec a total of 189 days, from 29 March through 8 November 21. During that time, 4,292 chinook salmon, 85 coho salmon, 283 steelhead, and 242 pacific lamprey were captured. No green sturgeon were captured in 21. Of the 4,292 chinook salmon that were captured, 149 possessed adipose fin clips. As determined from coded wire tag expansions, 616 chinook salmon were captured from Trinity River Hatchery for a total hatchery contribution of 14%. Of those, 138 were spring-run and 478 were fall-run chinook salmon. The remainders, 3676, were assumed to be of natural origin. The chinook salmon abundance index was 9,594, of which 7,42 (8%) were from Trinity River Hatchery. It was estimated that of those hatchery fish, 1,972 were spring-run and 5,448 were fall-run. Mean migration rates for 13 coded wire tag groups of fall chinook salmon released in the spring ranged from 6 to 18 river kilometers per day (rkm/d) while seven coded wire tag groups of spring chinook salmon released in the spring migrated from 12 to 64 rkm/d. The mean migration rate of fall chinook salmon released in the fall was 42 rkm/d while spring yearling chinook salmon released in the fall migrated at a rate of 24 rkm/d. Juvenile steelhead captures totaled 283 individuals from a variety of age classes, 19 (39%) of which were from the Trinity River Hatchery. The steelhead abundance index was 6,626, of which 3,157 (48%) were from Trinity River Hatchery. Only 85 yearling coho were captured and 69 (81%) of those were from Trinity River Hatchery. The abundance index for coho salmon was 2,94, of which 1,747 (83%) were from Trinity River Hatchery. Catch rates for all species were generally lower in 21 than the catch rates of screw trapping operations conducted on the lower Trinity River in previous years at nearby locations. Changes in river level and annual variability in the river channel resulting in low capture rates in 21 caused us to move the screw trap to different locations in the immediate area above the confluence with the Klamath River. For comparison, the total amount of chinook salmon, coho salmon, and steelhead captured in 1998, 1999 and 2 are also presented in this document. Results suggest that screw trap location and positioning may affect catch rates, thereby affecting abundance indices and making comparisons between years difficult.

5 INTRODUCTION The Trinity River is the largest tributary to the Klamath River, draining approximately 7,69 km 2 in California. The Klamath River system is the second largest river system in California draining approximately 26, km 2 in California, and 14, km 2 in Oregon (Figure 1). It once supported large anadromous populations of fall and spring run chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), steelhead (O. mykiss) as well as Pacific Lamprey (Lamptera tridentata), and green sturgeon (Acipenser medirostris) that supported commercial and recreational fisheries, as well as cultural, subsistence, and commercial needs of native tribes throughout the region. The Klamath-Trinity River basin is an important producer of anadromous salmonids and the number one producer of steelhead trout in California (Hopelain 1998). In their 1984 paper, Leidy and Leidy stated that the Klamath River supported the largest coho salmon run in California and ranked second to the Sacramento River in production of chinook salmon. In 1957 construction began on the Trinity River Division of Bureau of Reclamation s Central Valley Project (CVP), which transfers water from the Klamath Basin to the Sacramento Basin. The Division consists of a series of dams, lakes, power plants, a tunnel, and other related facilities. Lewiston Dam, part of the CVP, was constructed in 1963 near Lewiston, California and is now the upper most limit of anadromous fish migration on the Trinity River. At times, 9% of the of the Trinity River s flow was diverted to the Sacramento Basin, contributing to the decline of chinook salmon and coho salmon (Stene 1994). Trinity River Hatchery (TRH), located at the base of Lewiston Dam, was constructed to mitigate for the loss of 19 miles of anadromous fish habitat upstream of the dam (USFWS 1982). Out of concern for declines in anadromous fish populations, Congress enacted the Trinity River Fish and Wildlife Restoration Act (P.L ) in This act directed the Secretary of the Interior to take actions necessary to restore the fisheries resources of the Trinity River Basin. The Central Valley Project Improvement Act (CVPIA) of 1992 (P.L ) legislated alterations in the operation of the CVP for the improvement of fish and wildlife habitat and resources. In 2, then secretary of the interior Bruce Babbit signed the Record of Decision, or ROD, clearing the way for implementation of restoration activities on the Trinity River. However, full implementation of river levels as set forth in the ROD has been halted due to ongoing litigation. Previous fisheries investigations have focused primarily on adult returns in relation to harvest allocation and escapement objectives. Understanding run timing differences between natural and hatchery out-migrants is valuable to understanding density dependent factors associated with habitat use and suitability. Juvenile salmonid life histories are primarily affected by riverine conditions; therefore, annual monitoring of salmonid emigration may help to evaluate the effectiveness of Trinity River restoration. MATERIALS AND METHODS The equipment and methods used to capture, anaesthetize and enumerate out-migrant fish were consistent with long-term trapping activities being conducted by the U.S. Fish and Wildlife Service (USFWS). Weekly abundance indices were also calculated following standard protocols 2

6 adopted by the USFWS (USFWS 1994). Catch data for 1998 are from Weskamp and Voight (21). Catch data for 1999 and 2 are from Weskamp (24). Klamath River watershed boundary Klamath River Pacific ocean Screw trap location Figure 1 Map of the Klamath River basin 3

7 Trap Design and Operation An eight-foot diameter rotary screw trap, manufactured by E.G. Solutions Inc. of Corvallis, Oregon, was used to collect emigrant juvenile salmonids in the Trinity River near Weitchpec, California in 21. It was equipped with a 2.4 m diameter cone that was supported by two aluminum-covered foam pontoons measuring 6.6 m in length. The cone funneled fish into a 1.2 m x 1.8 m live well. The trap was positioned and held in place with a.95 cm galvanized steel cable from a dual anchor point system located on the bank. Trap Site Description On 31 March 21, the screw trap was installed in a run,.4 kilometers upstream from the confluence with the Klamath River, approximately 2 meters upstream from the 2 and 1999 trapping locations. It was moved approximately 11 meters downstream on 5 April in an attempt to increase the amount of fish captured. On 2 October, the screw trap was relocated approximately 13 meters downstream from the previous site to the head of Pearson s Hole and was fished there the remainder of the season. Biological Sampling Protocol The trap was operated 24 hours a day, seven days a week throughout the sampling period with the exception of downtime due to high flows, debris, or repairs. Personnel checked the trap once a day, but during peak emigration periods, it was checked several times a day during the night and early morning hours to minimize fish stress and holding density. Batches of 2-3 fish were netted from the live well and placed into five-gallon buckets containing fresh river water. Three to five fish at a time were then placed into a separate bucket and anaesthetized with a solution of.6 g of tricane methanesulfonate (MS-222) in 1 liters of water. Salmonids were identified by species and age class. A random sample (up to 3 fish) of each salmonid species was measured to the nearest millimeter by fork length and the remainders were tallied. Age 1 + and older steelhead were classified as either parr or smolt based on physical appearance and checked for ad-clips. Coho salmon were examined for right maxillary clips. Up to five ad-clipped chinook salmon per day were collected for recovery and decoding of coded wire tags (CWT). Decoded CWTs allowed for the differentiation of tag group and release date. All non-salmonids were identified to species and a random sub-sample of ten was measured to fork length or total length and the remainders tallied. Hatchery and Natural Estimates Chinook salmon, coho salmon, and steelhead were categorized as being either of hatchery or natural origin based on hatchery marks and hatchery release data provided by TRH. Natural fish were defined as the progeny of river or tributary spawning adults regardless of parental genetics. The contribution of both hatchery and natural stocks to the catch and abundance indices were calculated for each salmonid species. 4

8 Chinook Salmon All collected ad-clipped fish were passed through a magnetic field detector manufactured by Northwest Marine Technology to determine the presence or absence of a CWT. The snout of each fish that registered positive for a tag was dissected until the CWT was recovered. The head of each fish that registered a negative for a tag was dissolved in a solution of potassium hydroxide. A magnet was then stirred through the resultant slurry. If the tag was not recovered, the fish was considered an ad-clipped fish without a tag. Recovered tags were decoded using a dissection microscope. Recoveries of CWTs were summed by tag code group for each week. The number of CWT fish captured for each code group was estimated by multiplying the number of CWTs recovered by an expansion factor (E) that accounted for sub sampling of adclipped fish, tags that were lost during dissection and unreadable tags. The expansion factor was calculated with the following equation: E = (C/MS)(AD/H)(T/TR) Equation 1 Where: C = Number of chinook salmon captured MS = Number of chinook salmon examined for ad-clips AD = Number of ad-clipped chinook salmon captured H = Number of ad-clipped chinook salmon collected T = Number of chinook salmon containing tags TR = Number of tags recovered During 21 the expansion factor was 1. throughout the bulk of the season (Appendix Table 3). A production multiplier was used to account for unmarked chinook salmon in the release group for each given tag code. The expanded estimates for each tag code group were multiplied by the production multiplier specific to that group. The production multiplier (PM) equation is as follows: PM = (r + r p + r nm )/r Equation 2 Where: r r p r nm = Number of CWT fish in a release group = Number of ad-clipped chinook salmon without a CWT = Number of unmarked chinook salmon in a release group The estimated hatchery contribution attributable to a specific tag code for a given week was calculated with the following formula: # Hatchery code i = (# recovered code I ) * (E code I ) * (PM code I ) Equation 3 The total weekly estimated hatchery contribution to the catch was the sum of all hatchery fish attributed to specific CWT codes. The weekly contribution of naturally produced chinook 5

9 salmon was estimated by subtracting the estimated hatchery contribution from the total weekly catch. Coho Salmon Because all coho released from TRH were marked with a right maxillary clip, the amount of naturally produced coho salmon was determined by subtracting the amount of hatchery coho salmon captured from the total amount captured. Steelhead Because all steelhead released from TRH were marked with an ad-clip, the amount of naturally produced steelhead was determined by subtracting the amount of hatchery steelhead from the total amount captured. Abundance Index Catch effort data were recorded and evaluated for each sampling day. Trends in emigration were analyzed on a weekly basis using abundance indices given by the following formula: Where: Index w = (Catch w /(Q s / Q))/(# days sampled during week / # days in week) Equation 4 Catch w Q Q s = Weekly catch of a species = Mean weekly river volume = Mean weekly river volume sampled The discharged based abundance index should be used in conjunction with the following assumptions; catch rates are directly proportional to the percentage of river flow sampled, individuals are evenly dispersed in the water column and individuals from a given species are equally susceptible to capture. These index values are a means of monitoring relative abundance, and should not be substituted for estimates of total emigration. Migration Rates Initial migration rates were calculated for all hatchery chinook salmon tag code groups released in 21. This rate was derived by dividing total distance in river kilometers (rkm) traveled by the number of days elapsed from the initial day of release to the capture of the first individual for each tag code group. Mean migration rates of chinook salmon were calculated using the following formula with the fastest and slowest 1% of individuals excluded: Mean migration rate = (# * rkm/d * (Q/Q s )) Equation 5 (# * (Q/Q s )) 6

10 Where: # = Daily expanded CWT code or fin clip counts Distance traveled divided by number of days taken rkm/d = to reach trap after median release date Q = Mean daily river volume = Mean daily river volume sampled Q s When the expanded number of individuals captured for a specific tag code group was less than ten, all individuals were included in the calculation. Because chinook salmon were volitionally released from TRH, the median day of release was used when calculating mean migration rates. Additionally, daily mean migration rates were weighted by the proportion of river flow that was sampled to reflect fish passing the sampling area that were not captured. Flow Measurements River discharge through the screw trap cone was estimated daily throughout the season with a Marsh McBirney model 2 portable flow meter, and then averaged into weekly increments. Daily cone flow estimates were then compared to average daily river discharge data obtained from the USGS Hoopa gauge #11-53 in the lower Trinity River in order to estimate the proportion of the total river flow sampled by the screw trap each day. Water Temperature Water temperature was monitored in conjunction with emigrant trapping activities. An Optic Stow-Away temperature logger (Onset Corp. model TBI ) was deployed adjacent to the lower Trinity River trap site and recorded maximum, minimum, and average water temperature every thirty minutes throughout the trapping period. These observations were then summed into daily maximum and minimum water temperatures. RESULTS AND DISCUSSION The 21 lower Trinity River out-migrant trapping effort began on 29 March and continued through 8 November. The trap was fished effectively for 189 nights, longer in duration than any screw-trapping season conducted by the YTFP prior to 21. On 16 May, a large rainstorm caused the river to rise rapidly. These unexpected, high flows broke one of the aluminum support arms that aid in moving the cone up and down. The cone was then raised with a come-along, and the trap was moved to the shore until repairs were complete. On 3 May, the trap was repaired and launched back in the river. At low flows, the rotation time (RPM) of the cone itself was too slow, making it possible for fish that enter the trap to escape back upstream. In past years it was not uncommon for unfavorable conditions to develop throughout the trapping season that forced adjustments in trap location and 21 was no exception. 7

11 Catch data from screw trapping operations at the Weitchpec, California site are presented for four consecutive years for chinook salmon, coho salmon and steelhead. The results are highly variable. An array of factors such as screw trap location and positioning and physical changes in the river channel may be responsible for these variations. While these factors are not known for certain, it is clear that one must use caution when attempting to draw inferences from annual catch and abundance data. River Flow As river discharge progressively decreased throughout the season, the percent of river discharge sampled progressively increased (Figure 2). Mean weekly river discharge Mean weekly discharge sampled River discharge (cfs) 5, 4, 3, 2, 1, 31 Mar 21 Apr 12 May 2 Jun 23 Jun 14 Jul 4 Aug 25 Aug 15 Sep 6 Oct 27 Oct Discharge sampled (%) Figure 2 Average daily discharge at USGS Hoopa gauge (rkm 2.8), and the percent of river discharge sampled with a rotary screw trap, lower Trinity River, California, 21 During the 21 trapping season, weekly average river flow at the USGS Hoopa Gauge (11-53) ranged from 4,573 cfs during the first week of operation to 58 cfs when the trap was removed on 8 November. The season peak flow of 5,1 cfs occurred on 29 March, the first day of trapping operations. The discharge that was sampled averaged 78.1 cfs throughout the season. The percent of total river discharge sampled ranged from a low of 3.3% to a high of 13.5% with a season average of 7.1%. 8

12 Water Temperature The temperature range during 21 in the lower Trinity River was C. The season low minimum temperature of 8.1 C occurred on 6 April. Temperature steadily increased from that point and peaked at a season high maximum temperature of 26.5 C on 6 July. Then temperature seemed to linger above 2 C until approximately mid-august at which point temperature began to steadily decrease (Figure 3). Maximum temperature Minimum temperature Temperature ( C) Mar 11 Apr 2 May 23 May 13 Jun 4 Jul 25 Jul 15 Aug 5 Sep 26 Sep Figure 3 Minimum and maximum daily temperature of the lower Trinity River near Weitchpec California, 21 Capture Summary Chinook Salmon During the 21 juvenile emigrant monitoring season, 4,292 chinook salmon were captured (Appendix Table 1). Of these, 616 were determined to be from TRH for a total hatchery contribution of 14%. The peak weekly capture of naturally produced chinook salmon, which was also the peak weekly capture period for the season, occurred during the week ending 21 April. The largest one day capture (n = 222) occurred on 17 April. The first capture of an ad-clipped chinook salmon occurred on 11 June and that date was used to mark the arrival of hatchery reared fish at the trapping site. Captures of spring-released hatchery produced chinook salmon peaked the week ending 23 June, while captures of their fall-released counterparts peaked the week ending 13 October (Figure 4). 9

13 River discharge Natural chinook salmon catch Hatchery chinook salmon catch 8 5, Chinook salmon (n ) , 3, 2, 1, River discharge (cfs) 31 Mar 21 Apr 12 May 2 Jun 23 Jun 14 Jul 4 Aug 25 Aug 15 Sep 6 Oct 27 Oct Figure 4 Hatchery and natural chinook salmon catch and river discharge by week, lower Trinity River rotary screw trap, California, 21 Capture results for 21, along with chinook salmon screw trap capture data from similar locations on the Lower Trinity River for three previous years, are presented in Table 1. Table 1 Total numbers of juvenile chinook salmon captured in the Trinity River near Weitchpec, California over a four-year period with a rotary screw trap Number of days sampled Sampling dates Amount released from TRH a Chinook salmon Hatchery Natural captured (n) n % n % Year May-3 Sep 3,698,925 12,319 9,92 8 2, May-13 Sep 3,199,62 31,719 13, , Apr-12 Sep 3,813,979 4,123 1, , Mar-8 Nov 3,27,329 4, , a Total chinook salmon released from TRH only includes fish released in the spring Estimates of hatchery contribution in 21 were the lowest in any of the four years, in fact, nearly the opposite hatchery and natural composition of Total chinook salmon released from TRH only includes fish released in the spring and not those liberated in the fall because 21 was the only year that sampling dates made possible the potential to capture fall released hatchery fish. Yet the amount of hatchery fish captured in 21 was just a fraction of the 1

14 number caught in previous years. While the amount of chinook salmon released in the spring from TRH remained relatively constant from 1998 to 21, the amount of hatchery chinook salmon captured in screw traps in the lower Trinity River in the same years was highly variable. Hatchery and Natural Stocks Spring release tag groups of chinook salmon were volitionally liberated from 6-13 June and fall release tag groups, held at the hatchery until the fall and released at a larger size than those in the spring, were volitionally released from 1-1 October. Of the 149 ad-clipped chinook salmon captured, 146 were collected and a total of 14 coded wire tags were recovered in order to discern origin and release group (Appendix Table 1). It was determined that 3% (n = 138) of the total chinook salmon catch was TRH spring run, while 11% (n = 478) were TRH fall run, for a hatchery contribution of 14% (n = 616) (Appendix Table 1). Abundance Index The abundance index for chinook salmon was 9,594 for the period between 29 March and 8 November (Figure 5). River discharge Natural chinook salmon abundance Hatchery chinook salmon abundance 2, 5, Chinook salmon (n ) 16, 12, 8, 4, 3, 2, River discharge (cfs) 4, 1, 31 Mar 21 Apr 12 May 2 Jun 23 Jun 14 Jul 4 Aug 25 Aug 15 Sep 6 Oct 27 Oct Figure 5 Hatchery and natural chinook salmon abundance and river discharge by week, lower Trinity River rotary screw trap, California, 21 Of these, 7,42 (8%) were produced by TRH and the remaining 83,174 (92%) were assumed to be of natural origin. Peak periods of abundance of natural and hatchery chinook salmon corresponded to the peak capture periods mentioned above (Appendix Table 2). Over half (n = 2,188) of the chinook salmon were captured prior to the arrival the first ad-clipped chinook 11

15 on 11 June. Although some of these fish may have been from TRH, it was not possible to determine their origin and subsequently, all were assumed to be of natural origin. Note the increase in mid-october of hatchery fish that corresponded to fall releases from TRH. Emigration Timing The first chinook salmon was captured on 29 March, and small numbers were consistently observed through the first week of trapping (Figure 6). Hatchery chinook salmon timing Natural chinook salmon timing Percent of total capture Mar 21 Apr 12 May 2 Jun 23 Jun 14 Jul 4 Aug 25 Aug 15 Sep 6 Oct 27 Oct Figure 6 Hatchery and natural chinook salmon emigration timing by week, lower Trinity River rotary screw trap, California, 21 Approximately 5% of natural chinook salmon were caught during or prior to the week ending 19 May and the majority of the rest were captured prior to the week ending 25 August. There were obvious increases in the percent of total capture of hatchery chinook salmon coinciding with spring and fall hatchery releases. 12

16 Size Of the total chinook salmon captured, 2,811 (66%) were measured to fork length. The size range was mm, with a season mean length of 8 mm. Weekly mean fork length steadily increased through the spring into early summer with a climax of 79 mm occurring towards the middle of July reflecting the peak capture period of spring released hatchery fish. Weekly mean fork length remained relatively static through August and September and then greatly increased beginning the week ending 6 October with the arrival of fall released hatchery groups. The largest weekly mean fork length for the fall period was 146 mm, which occurred during the week ending 27 October (Figure 7) Fork length (mm) Mar 21 Apr 12 May 2 Jun 23 Jun 14 Jul 4 Aug 25 Aug 15 Sep 6 Oct 27 Oct Figure 7 Mean weekly fork length and standard deviation of juvenile chinook salmon sampled with a rotary screw trap, lower Trinity River, California, 21 13

17 Migration Rate Twenty-two different coded wire tagged (CWT) groups of hatchery-reared fish were released from TRH. Migration rates were calculated for all groups except because no individuals from that tag group were captured (Table 2). Table 2 Estimated migration rates of TRH chinook salmon captured in a rotary screw trap, lower Trinity River California, 21 CWT group Run Initial Release date Number released Percent of Number CWT Number captured group captured (expanded) captured Days elapsed to initial capture Initial migration rate (rkm/d) Mean migration rate (rkm/d) Fall 6 Jun 228, Fall 6 Jun 15, Fall 6 Jun 136, Fall 6 Jun 137, Fall 6 Jun 26, Fall 6 Jun 11, Fall 6 Jun 141, Fall 6 Jun 232, Fall 6 Jun 129,893 NA NA NA Fall 6 Jun 112, Fall 6 Jun 136, Fall 6 Jun 232, Fall 6 Jun 14, Spring 6 Jun 139, Spring 6 Jun 137, Spring 6 Jun 13, Spring 6 Jun 139, Spring 6 Jun 212, Spring 6 Jun 143, Spring 6 Jun 237, Spring 1 Oct 41, Fall 1 Oct 872, Initial migration rates ranged from 6 km/d to 46 km/d; mean migration rates ranged from 6 to 64 km/d. In general, chinook salmon released in the fall from TRH seemed to travel faster than those released in the spring. For some tag groups, the mean migration rate was faster than the initial migration, most likely due to small sample size and/or the method used to calculate migration rates. 14

18 Coho Salmon Capture Summary In total, 85 coho salmon smolts, but no fry, were captured in 21. Of those smolts, 69 (81%) were from TRH and 16 (19%) were of natural origin (Appendix Table 1). The peak capture period for both hatchery and natural coho salmon occurred the week ending 19 May (Figure 8). River discharge Natural coho salmon catch Hatchery coho salmon catch Coho salmon (n ) Mar 21 Apr 12 May 2 Jun 23 Jun 14 Jul 4 Aug 25 Aug 15 Sep 6 Oct 27 Oct 5, 4, 3, 2, 1, River discharge (cfs) Figure 8 Hatchery and natural coho salmon catch and river discharge by week, lower Trinity River rotary screw trap, California, 21 Unfortunately, a log was detained in the trap on 21 May causing damages severe enough to warrant repair during the following week that has, in the past, proved to be a time when many juvenile coho salmon are captured. Capture results from 21, along with coho salmon screw trap capture data from similar locations on the Lower Trinity River for three previous years, are presented in Table 3. The amount of hatchery coho salmon released from TRH in 1998 and 21 was similar; however total coho catch in 1998 exceeded total coho catch in 21 by more than a factor of ten. Table 3 Total numbers of juvenile coho salmon captured in the Trinity River near Weitchpec, California over a four-year period with a rotary screw trap Year Number of days sampled Sample dates Amount released from TRH Total coho salmon Hatchery Natural captured (n) n % n % May-3 Sep 516, May-13 Sep 519, Apr-12 Sep 493, Mar-8 Nov 513,

19 Hatchery and Natural Stocks One group of TRH yearling coho totaling 513,4 fish was volitionally released from March 21. All hatchery coho salmon were right maxillary clipped making differentiation between hatchery and natural fish straightforward. Out of the 85 coho salmon captured in 21, 82% (n = 69) were from TRH. This percentage compared favorably with the results of screw trapping operations at similar locations in previous years. Abundance Index The abundance index estimate for coho salmon was 2,772 (Appendix Table 2). The Hatchery reared coho salmon abundance index was 2,378 or 86% of the total. The timing of peak abundance corresponded to the peak capture periods described for coho salmon above (Figure 9). River discharge Natural coho salmon abundance Hatchery coho salmon abundance Coho salmon (n ) Mar 21 Apr 12 May 2 Jun 23 Jun 14 Jul 4 Aug 25 Aug 15 Sep 6 Oct 27 Oct 5, 4, 3, 2, 1, River discharge (cfs) Figure 9 Hatchery and natural coho salmon abundance and river discharge by week, lower Trinity River rotary screw trap, California, 21 16

20 Emigration Timing All hatchery coho salmon were captured during or prior to the week ending 9 June. Approximately 8% of the total natural coho salmon were captured before or during the week ending 9 June and a few individuals were captured through the remainder of the season (Figure 1). Hatchery coho salmon timing Natural coho salmon timing Percent of total capture Mar 21 Apr 12 May 2 Jun 23 Jun 14 Jul 4 Aug 25 Aug 15 Sep 6 Oct 27 Oct Figure 1 Hatchery and natural coho salmon emigration timing by week, lower Trinity River rotary screw trap, California, 21 Size All coho that were captured in 21 (n = 85) were measured to fork length. TRH coho were consistently greater in size than natural coho salmon. Natural coho salmon ranged in size from 15 to 139 mm with an average fork length of 115 mm. Hatchery coho salmon ranged in size from 143 to 25 mm with an average fork length of 161 mm. Migration Rate No migration rates were calculated for hatchery coho released in 21 because the screw trap was not installed prior to the first emigrant passing the trap site. 17

21 Steelhead Capture Summary During the 21 trapping season, 283 steelhead were captured. Of these, 19 were hatchery smolts while 3, 9, and 54 were natural fry, parr, and smolt, respectively (Appendix Table 1). The peak capture of hatchery fish occurred the week ending 7 April and the timing was consistent with the overall peak capture period. Natural steelhead fry and parr captures were highest the week ending 31 March; the first week the trap was installed. Captures of natural smolts came to a climax the week ending 19 May (Figure 11). Less than three steelhead were caught per week thereafter. River discharge Natural steelhead catch Hatchery steelhead catch 5 5, Steelhead (n ) , 3, 2, 1, River discharge (cfs) 31 Mar 21 Apr 12 May 2 Jun 23 Jun 14 Jul 4 Aug 25 Aug 15 Sep 6 Oct 27 Oct Figure 11 Hatchery and natural steelhead catch and river discharge by week, lower Trinity River rotary screw trap, California, 21 Capture results from 21, along with steelhead screw trap capture data from similar locations on the Lower Trinity River for three previous years, are presented in Table 4. Table 4 Total numbers of juvenile steelhead captured in the Trinity River near Weitchpec, California over a four-year period with a rotary screw trap Number of days Amount released Total steelhead Hatchery Natural Year sampled Sampling dates from TRH captured (n) n % n % May-3 Sep 811,513 2,252 1, May-13 Sep 611,443 1, Apr-12 Sep 382, Mar-8 Nov 822,

22 Comparing 1998 and 21, because a similar number of steelhead were released from TRH, the difference in the amount of hatchery steelhead that were captured was roughly ten fold, even though there was about 3% more sampling time in 21. More than twice as many hatchery steelhead were captured in 2 than in 21 even though the amount released from TRH in 2 was less than half the number released in 21. Hatchery and Natural Stocks Six groups of steelhead smolts totaling 822,55 individuals were volitionally released from TRH from March 21. All were marked with adipose fin clips allowing for straightforward identification of hatchery fish. A total of 19 steelhead smolts from TRH were captured during the trapping season for a total hatchery contribution of 39%. This percentage compares somewhat favorably with 1998 when a similar number of fish were released from TRH. Abundance Index The abundance index of steelhead was 6,963 (Appendix Table 2). Of these, 3,177 were from TRH for a total hatchery contribution of 46 % during the 21 trapping season. The peak abundance periods for hatchery smolts and natural fry, parr, and smolts corresponded to the timing of peak capture described for steelhead above (Figure 12). River discharge Natural steelhead abundance Hatchery steelhead abundance 1,5 5, Steelhead (n ) 1, , 3, 2, 1, River discharge (cfs) 31 Mar 21 Apr 12 May 2 Jun 23 Jun 14 Jul 4 Aug 25 Aug 15 Sep 6 Oct 27 Oct Figure 12 Hatchery and natural steelhead abundance and river discharge by week, lower Trinity River rotary screw trap, California, 21 19

23 Emigration Timing All hatchery steelhead were captured during or prior to the week ending 2 June. Approximately 8% of the total natural steelhead were captured before or during the week ending 2 June and a few individuals continued to be captured for the remainder of the season (Figure 13). Hatchery steelhead timing Natural steelhead timing Percent of total capture Mar 21 Apr 12 May 2 Jun 23 Jun 14 Jul 4 Aug 25 Aug 15 Sep 6 Oct 27 Oct Figure 13 Hatchery and natural steelhead emigration timing by week, lower Trinity River rotary screw trap, California, 21 Size All steelhead that were captured (n = 283) were measured to fork length; data are presented below. Steelhead Sample size (n) Range (mm) Season mean (mm) Fry Parr Smolt (natural) Smolt (hatchery) Hatchery reared smolts appeared to be, on average, larger than those that were naturally spawned. Migration Rates No migration rates were calculated for TRH steelhead because of the likelihood that hatchery emigrants passed the trap location prior to the commencement of trapping on 29 March. 2

24 Other Species During the 21 trapping season, biological data were collected on Pacific lamprey. There were no green sturgeon captured in 21. Catch of pacific lamprey totaled 242 individuals; 112 were adults and 13 were ammocoetes. In 1998, 1,464 pacific lamprey were captured on the lower Trinity River; 19 adults and 1,445 ammocoetes (Weskamp and Voight 21). RECOMMENDATIONS No methods are currently in place to evaluate the violation of assumptions inherent with discharge based indices. The calculation of an index based on trap efficiency rather than discharge would address the shortcomings of the discharge based methods. When data is generated by the trap efficiency method, a more clear understanding of sampling bias associated with rotary screw traps will emerge. This will allow for more accurate indices and thus improve the reliability of data, both future and historical, for adaptive management decisions. Additionally, efficiency based abundance estimates provide a quantifiable estimate that can be assigned confidence intervals. This fulfills the needs identified in Trinity River Flow Evaluation for production inputs for SALMOD and other modeling programs. To improve index reliability during times in the sampling season when efficiency based estimates cannot be preformed due to a limited sample size, a staff gauge needs to be calibrated and operated continuously at each trap site. This will improve the accuracy of discharge-based indices by allowing a more precise calculation of the percent of discharge sampled by each rotary screw trap. Secondly, this would normalize abundance indices between trapping sites throughout the entire Klamath Basin to provide more compatible data between sites. Continuing the operation of multiple rotary screw traps throughout the Klamath Basin may help manage salmon stocks and allow for the assessment of migration patterns throughout the geographic area. Additionally, monitoring emigration timing of both hatchery and natural fish provides critical information regarding the impacts of hatchery fish on natural populations. To increase the validity and usefulness of basin wide data, all parties working in the Klamath Basin need to retain consistent protocols concerning both data gathering and trap operation. Additionally, implementation of a common database among all involved parties would ensure the compatibility of shared data and provide a larger data set for the analysis of biological information. ACKNOWLEDGMENTS The Yurok Tribal Fisheries Program would like to acknowledge the Bureau of Reclamation for funding this project. We would also like to acknowledge the efforts of our tribal technicians that made this project possible including: Richard Myers II, Morneen Wilson, Jamie Holt, Barry McCovey and Ruby McCovey. We would also like to acknowledge the cooperation of the Arcata Fish and Wildlife field office for their assistance and the support of this project. 21

25 APPENDIX 22

26 Appendix Table 1 Total number of juvenile salmonids and Pacific Lamprey captured by week in the rotary screw trap, lower Trinity River, California, 21 Weekly average discharge Chinook salmon Steelhead Coho salmon Hatchery Natural Hatchery Natural Hatchery Pacific Lamprey Number Discharge Percent of Week of days through discharge ending sampled (cfs) cone (cfs) sampled Natural Spring Fall Total Fry Parr Smolt Smolt Total Fry Smolt Smolt Total Adult Ammocoete 31 Mar 3 4,573 NA NA Apr 7 3, Apr 7 2, Apr 7 2, Apr 7 3, May 7 3, May 7 3, May 5 3, May 3,136 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA 2 Jun 5 2, Jun 7 2, Jun 7 1, Jun 7 1, Jun 7 1, Jul Jul Jul Jul Aug Aug Aug Aug Sep 885 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA 8 Sep Sep Sep Sep Oct Oct Oct Oct Nov Nov Totals 189 NA NA NA 3, ,

27 Appendix Table 2 Weekly abundance indices for juvenile salmonids captured at the rotary screw trap lower Trinity River, California, 21 Weekly average discharge Chinook salmon Steelhead Coho salmon Hatchery Natural Hatchery Natural Hatchery Number Discharge Percent of Week of days through discharge Ending sampled (cfs) cone (cfs) sampled Natural Spring Fall Total Fry Parr Smolt Smolt Total Fry Smolt Smolt Total 31 Mar 3 4,573 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA 7 Apr 7 3, ,925 1, ,335 1, Apr 7 2, ,851 3, Apr 7 2, ,81 18, Apr 7 3, ,316 13, May 7 3, ,77 4, , May 7 3, ,644 2, May 5 3, ,261 2, ,38 2, May 3,136 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA 2 Jun 5 2, ,341 9, Jun 7 2, ,368 2, Jun 7 1, , , Jun 7 1, , ,199 5,916 3 Jun 7 1, , , Jul , , Jul ,635 1, Jul , , Jul , , Aug ,7 1,7 11 Aug Aug Aug ,132 1, Sep 885 NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA 8 Sep Sep Sep Sep Oct Oct , Oct Oct N o v Nov Totals 189 NA NA NA 83,174 1,972 5,448 9, ,22 1,587 3,177 6, ,378 2,772 24

28 Appendix Table 3 The production multiplier (in parentheses), expansion factor (E), number captured (n), and expanded capture (n e ) by week of all chinook salmon coded wire tag groups (except because none were captured) volitionally released by Trinity River Hatchery Week (4.16) (4.17) (4.17) (4.6) (4.6) (4.6) (4.5) (4.5) (4.5) (4.49) (4.12) (4.12) (4.5) (4.11) (4.21) (4.21) (4.21) (4.51) (4.51) (4.3) (4.5) Ending E n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e n n e 31 Mar 1 7 Apr 1 14 Apr 1 21 Apr 1 28 Apr 1 5 May 1 12 May 1 19 May 1 26 May 1 2 Jun 1 9 Jun 1 16 Jun Jun Jun Ju l Jul 1 21 Jul Jul Aug 1 11 Aug 1 18 Aug 1 25 Aug 1 1 Sep 1 8 Sep 1 15 Sep 1 22 Sep 1 29 Sep 1 6 Oct Oct Oct Oct Nov Nov

29 REFERENCES 1. Hopelain, J. S Age, Growth, and Life History of Klamath River Basin Steelhead Trout (Oncorhyncus mykiss irideus) As Determined From Scale Analysis. California Fish and Game, Inland Fisheries Division. Administrative Report No Leidy, R.A. and G.R. Leidy Life Stage Periodicities of Anadromous Salmonids in the Klamath River Basin, Northwestern California. US Fish and Wildlife Service, Sacramento CA. 3. Stene, E Central Valley Project Trinity River Division. Bureau of Reclamation History Program. Available (January 24). 4. USFWS Klamath River Fisheries Investigation Program. Annual Report. Arcata Fish and Wildlife Office, Arcata, CA. 5. USFWS Juvenile salmonid monitoring on the Trinity and Klamath Rivers, Annual report of the Klamath River Fisheries Assessment Program. Arcata Fish and Wildlife Office, Arcata, CA. 6. Voight, H. N., and D. R. Weskamp. 21. Juvenile salmonid emigration monitoring on the Lower Klamath and Trinity Rivers, California, Yurok Tribal Fisheries Program Technical Report No. 8, Klamath, California. 7. Weskamp, D.R. 24. Juvenile salmonid emigration monitoring on the Lower Trinity River, California, Yurok Tribal Fisheries Program Technical Report No. 1, Klamath, California. 26