Staff of the California Department of Fish and Game's Trinity Fisheries Investigations Project conducted a trapping and coded-wire tagging operation for naturally produced, juvenile chinook salmon (Oncorhynchus tshawytscha) on the mainstem Trinity River below Lewiston Dam from 14 January through 14 June 1993.
We trapped 56,968 juvenile chinook salmon, 1,069 juvenile coho salmon (O. kisutch), and 864 juvenile steelhead (O. mykiss) at four locations during the study. Peak catch-per-unit-effort for juvenile chinook salmon, measured at the trapping site where we had the most consistent effort, occurred in mid-May. Weekly average fork lengths of trapped juvenile chinook salmon increased throughout the trapping period.
We adipose fin-clipped and implanted coded-wire tags into 48,423 juvenile chinook salmon, a sub-sample of which ranged in size from 29 to 118 mm, averaging 56.0 mm fork length. After adjusting for tagging mortality, tag shedding, and poor fin clips, we effectively coded-wire tagged and released 44,565 juvenile chinook salmon.
Adult chinook salmon, coded-wire tagged as juveniles by this Project, were recovered this season in the Indian gill-net fishery, at Trinity River Hatchery, and during the salmon spawner surveys. Four adults from the 1988 brood year were recovered as four-year-olds, and two from the 1990 brood year were recovered as two-year-olds.
To capture, mark (adipose fin-clip), tag (binary-coded wire), and release representative groups (up to 100,000 fish/group) of naturally produced chinook salmon fry/fingerlings in the mainstem Trinity River and/or selected Trinity River tributary streams, for use in subsequent determinations of their survival and contributions as adults to the ocean and river fisheries and spawning escapements.
The Trinity River system in Northern California is a major producer of chinook salmon (hereafter called chinook) for the Klamath River basin. Knowledge of fry- or fingerling-to-adult survival, harvest, and spawner escapement of these stocks is crucial to wise management of chinook in the basin.
Recent legislation (U. S. Public Law 98-541, enacted in 1984) has resulted in a major effort to restore the fishery resources in the Trinity River basin to pre-Trinity-Project conditions. Emphasis for this effort is placed on naturally produced chinook. Survival, catch, and escapement data for these fish will help to evaluate the effectiveness of these restoration efforts.
Previous coded-wire-tagging studies of juvenile chinook in the Trinity River basin have focused on hatchery-produced chinook and made references to naturally produced chinook based on those results (Heubach and Hubbell 1979; Heubach 1980; Maria and Heubach 1981, 1984a, 1984b, 1984c).
In this study, the California Department of Fish and Game's (CDFG) Trinity Fisheries Investigations Project (TFIP) personnel trapped, adipose fin-clipped, coded-wire tagged, and released naturally produced juvenile chinook. Subsequent studies of these fish as adults, by TFIP and other projects of the CDFG's Klamath-Trinity Program, will be used to determine survival, harvest, and spawning escapement for this important component of the Trinity River basin's chinook stocks.
Weekly sampling data collected by Project personnel at the trapping sites are presented in Julian week (JW) format. Each JW is one of a consecutive set of 52 weekly periods, beginning 1 January, regardless of the day of the week on which 1 January falls. The extra day in leap years is added to the ninth week, and the last day of the year is included in the 52nd week (Appendix 1). This procedure allows between-year comparisons of identical weekly periods.
We conducted trapping at three primary sites in the mainstem Trinity River this season (Figure 1). Site names and river km (RKM) locations were Lewiston at RKM 177, Hard Hat at RKM 148 and Sky Ranch at RKM 134. A fourth site at Ambrose (RKM 172) was trapped infrequently this season; a total of six trap-nights. One trap-night is defined as one fyke net set for one night. Our primary objective was to capture up to 100,000 juvenile chinook for coded-wire tagging. To that end, we trapped sporadically at each of the sites to locate the site that would produce the highest numbers of fish at a given time. We concentrated on the Hard Hat and Sky Ranch sites as numbers of fish captured there increased.
Our trapping apparatus consisted of from one to nine fyke nets measuring 3.1 m wide by 1.2 m high at the mouth, by 7.6 m long, tapering to a 0.33-m-square exit leading into dual live boxes. Fyke nets were attached, at their mouth, to a 2.5-cm-diameter galvanized pipe frame of the same dimensions as the net mouth, which was connected by ropes to metal posts driven into the stream bed. The nets were normally set in the late afternoon and recovered mid-morning the next day, when all fish trapped were counted and a sub-sample of each species was measured to the nearest mm fork length (FL).
FIGURE 1. Map of the Trinity River below Lewiston Dam showing the four trapping sites used in 1993.
This season coded-wire tagging took place only at the Hard Hat and Sky Ranch sites. The tagging operations were located adjacent to the trapping sites, and conducted inside a 5.5-m-long office trailer converted for that purpose. A 3.5-KW generator was used to supply the electrical needs of the operation (tagging machines, pumps, lights).
Captured juvenile chinook were anesthetized with tricaine methanesulfonate (MS-2221/); their adipose fin was removed (Ad-clip); and a coded-wire nose tag (CWT) was implanted. Tag injectors and quality control devices were purchased from Northwest Marine Technology.
Because of the small size of the fish captured, half-length CWTs were used. Between two and four tagging machines were employed, depending on availability of fish for tagging.
A sample of 100 fish from each day's tagging was held for quality control, and the remainder were released back into the river at the trapping site each evening. Fish in the quality control sample were held in cages in the river and, after a minimum of 24 hours, checked for mortality, tag retention, and Ad-clip quality. Tag retention was determined by passing fish through an electronic tag (metal) detector, and Ad-clip quality was determined by direct examination.
As part of ongoing studies, the CDFG recovered Ad-clipped and CWTed fish from among ocean- and inland-harvested fish, and hatchery and natural spawner returns. Heads from Ad-clipped fish were collected and their CWTs removed and decoded.
We began trapping on 14 January 1993 (JW 2) and continued at varying locations and intensity through 14 June 1993 (JW 24). We discontinued trapping in early June because of decreasing catches and increasing river temperatures. The release of over 2.8 million spring- and fall-run chinook from Trinity River Hatchery (TRH) during 16-18 June 1993 (JW 24-25) further precluded trapping of only naturally produced fish for the remainder of the season.
We captured 56,968 juvenile chinook this season. Totals by site were 293 at Lewiston, 362 at Ambrose, 13,689 at Hard Hat and, 42,624 at Sky Ranch (Appendices 2, 3, 4, and 5).
Catch-per-unit-effort (CPUE), defined as the weekly average number of fish caught per-trap-per-night-fished, varied considerably between trapping sites. The highest CPUE (394 fish/trap/night) was at the Sky Ranch site during JW 20. Maximum CPUE for each of the other sites included 159 at Hard Hat during JW 13, 77 at Ambrose during JW 10, and 51 at Lewiston during JW 4 (Figure 2, and Appendices 2, 3, 4, and 5).
We measured 9,451 chinook during the trapping season. These fish ranged in FL from 29 to 118 mm. Weekly average FLs of fish at the four trapping sites increased through time (Figure 3, Appendices 2, 3, 4, and 5). The entire week's catch at the Hard Hat site during JW 4 consisted of three yearling chinook which averaged 112.7 mm FL. At the Sky Ranch site, where we trapped every week through the season except one, the weekly average FL of juvenile chinook was 36.7 mm in mid-January and increased to 76.9 mm by mid-June.
We caught a total of 864 steelhead at all sites throughout the trapping season (Appendices 2, 3, 4, and 5). Catches were relatively low until mid-March, when increased numbers of hatchery-produced steelhead were captured, coincident with hatchery releases. We found that 4.9% (42/864) of the steelhead captured this season were fin-clipped, indicating they were from TRH.
We caught 1,069 coho salmon this season. We captured young-of-the-year coho beginning 18 March (JW 11) at the Sky Ranch site. CPUEs of both yearling and young-of-the-year were relatively low from that time on. The highest CPUE for coho was at the Hard Hat site (21 fish/trap/night) which occurred during the third week of March (JW 13) (Appendix 4).
Tagging operations began 26 March and continued through 26 May 1993. During this period, we marked (Ad-clip+CWT) and released 48,423 juvenile chinook at the Hard Hat and Sky Ranch sites combined.
We tagged 10,092 juvenile chinook with CWT code 0601080402 at the Hard Hat site. Tagging at this site began 26 March and continued through 9 April 1993. Independent, non-overlapping estimates of tagging mortalities, poor fin-clips, and CWT shedding were based on quality control groups. After subtracting these estimates from the total tagged, we effectively marked and released 9,816 juvenile chinook from this site (Table 1).
We tagged 38,331 juvenile chinook with CWT codes 0601080403 through 0601080407 at the Sky Ranch site. Tagging began 11 May and continued through 26 May 1993. We effectively marked and released 34,749 juvenile chinook from this site (Table 1).
TABLE 1. Naturally produced juvenile chinook salmon coded-wire-tagging in the mainstem Trinity River during 1993.
|
Coded-wire tag code |
Tagging site |
Dates of release |
Number tagged |
Estimated tagging mortalities |
Poor fin-clips |
Tags shed |
Number effectively tagged |
|
0601080402 |
Hard Hat |
03/26-04/09/93 |
10,092 |
144 |
15 |
117 |
9,816 |
|
0601080403 |
Sky Ranch |
05/11-05/14/93 |
8,214 |
131 |
21 |
282 |
7,780 |
|
0601080404 |
Sky Ranch |
05/14-05/16/93 |
7,912 |
116 |
0 |
302 |
7,494 |
|
0601080405 |
Sky Ranch |
05/16-05/18/93 |
6,846 |
73 |
58 |
147 |
6,568 |
|
0601080406 |
Sky Ranch |
05/18-05/26/93 |
5,582 |
568 |
39 |
61 |
4,914 |
|
0601080407 |
Sky Ranch |
05/18-05/26/93 |
9,777 |
1,565 |
58 |
161 |
7,993 |
|
TOTALS |
48,423 |
2,597 |
191 |
1,070 |
44,565 |
The CDFG's Ocean Salmon Project estimated two chinook from the 1988 brood year (BY), CWTed by this Project in 1989, (Zuspan 1991), were recovered as four-year-olds this season in the Indian gill-net fishery (R. Dixon, CDFG, pers. comm.). Additionally, one chinook salmon from the 1988 BY, and two from the 1990 BY (two-year-olds) were recovered at Trinity River Hatchery. One chinook salmon from the 1988 BY was also recovered during this season's salmon spawner survey (see Chapter I). No recoveries of Project-CWTed fish were reported this year from the in-river sport or ocean fisheries (Table 2).
TABLE 2. Adult recoveries of coded-wire tagged naturally produced chinook salmon during the 1992-93 season.
|
Recovery source | ||||||||
|
Coded-wire tag code |
Brood year |
Indian gill-net fishery |
In-river sport fishery |
Spawner survey |
Trinity River Hatchery |
Ocean harvest |
Average size (mm) |
Age (yr) |
|
B61306 |
1988 |
2 |
1 |
1 |
731 |
4 |
||
|
0601080112 |
1990 |
1 |
460 |
2 |
||||
|
0601080114 |
1990 |
1 |
420 |
2 |
||||
|
Totals: |
2 |
0 |
1 |
4 |
0 | |||
We were unable to capture enough juvenile chinook to reach our goal of tagging 100,000 naturally produced fish this year. Although we continued an intensive program of trapping up to 80% of the river's cross-section on a seven-day-a-week basis, our total season's trapping effort was below that of the past two years. Trapping effort this year was only 74% of last year's (327 vs. 442 trap-nights), and 87% of 1991 (327 vs. 374). As a result of the decreased trapping effort, total catch was 70% of last year (56,986/81,851), and 64% (56,986/89,208) of the 1991 total catch (Appendix 6).
As noted for the past two years (Zuspan 1992, 1994), the overall juvenile chinook CPUE has decreased. This is the direct result of poor escapement of the progenitors of each season's juvenile chinook. Natural (non-hatchery) spawner escapement for chinook salmon (spring- and fall-run) upstream of Junction City was the lowest since 1989, only 11.8% of the 1989 run (4,090 vs. 34,587), 70.4% of the 1990 run (4,090 vs. 5,811), and 75.0% of the 1991 run (4,090 vs. 5,453).
While it seems unlikely that there is a linear relationship between adult escapement and production, trapping during the last four years suggests an important correlation.
1. Job 2 activities should be continued in FY 1993-94.
2. In the event of a low adult chinook salmon escapement in 1993, the Project should be prepared to increase trapping effort, which will require the purchase and construction of additional trapping equipment.
3. We should continue efforts to recover coded-wire-tagged chinook harvested by anglers or returning to TRH. Efforts to recover naturally spawned code-wire-tagged fish should be increased.
Aguilar, B. 1992. Survival and contributions to the fisheries and spawner escapements made by steelhead produced at Trinity River Hatchery. Chapter VI. Job VI. pp. 136-140. In: K. Urquhart (ed.), Annual Report of the Trinity River Basin Salmon and Steelhead Monitoring Project, 1989-1990 Season. June 1992. 140 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.
Heubach, B., and P. Hubbell. 1979. FY 1978 progress report. Task V. Salmon tagging and release monitoring. pp. 1-5. In: P. M. Hubbell (ed.), Evaluation Report--FY 1978. Trinity River Basin Fish and Wildlife Task Force Priority Work Item No. 5. January 1979. 65 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.
Heubach, B. 1980. FY 1979 progress report. Task V. Salmon tagging and release monitoring. pp. 75-79. In: P. M. Hubbell (ed.), Progress Report. Fishery Investigations - Trinity River. Trinity River Basin Fish and Wildlife Task Force Priority Work Item No. 5. September 1980. 141 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.
Maria, D., and B. Heubach. 1981. FY 1980 progress report. Task V. Salmon tagging and release monitoring. pp. 7-12. In: P. M. Hubbell (ed.), Progress Report. Fishery Investigations - Trinity River. Trinity River Basin Fish and Wildlife Task Force Priority Work Item No. 5. Tasks II, V and VII. December 1981. 23 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.
Maria, D., and B. Heubach. 1984a. FY 1981 progress report. Task V. Salmon tagging and release monitoring. pp. 6-15. In: P. M. Hubbell (ed.), Progress Report. Fishery Investigations - Trinity River. Trinity River Basin Fish and Wildlife Task Force Priority Work Item No. 5. Tasks II, V, VII. October 1984. 24 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.
Maria, D., and B. Heubach. 1984b. FY 1982 progress report. Task V. Salmon tagging and release monitoring. pp. 5-13. In: P. M. Hubbell (ed.), Progress Report. Fishery Investigations - Trinity River. Trinity River Basin Fish and Wildlife Task Force Priority Work Item No. 5. Tasks II, V. November 1984. 13 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.
Maria, D., and B. Heubach. 1984c. FY 1983 progress report. Task V. Salmon tagging and release monitoring. pp. 1-11. In: P. M. Hubbell (ed.), Progress Report. Fishery Investigations - Trinity River. Trinity River Basin Fish and Wildlife Task Force Priority Work Item No. 5. Task V. November 1984. 11 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.
Zuspan, M. 1991. Capture and coded-wire tagging of naturally produced chinook in the Trinity River Basin. Chapter II. Job II. pp. 24-33. In: R. Carpenter and K.Urquhart (eds.), Annual Report of the Trinity River Basin Salmon and Steelhead Monitoring Project, 1988-1989 Season. August 1991. 51 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.
Zuspan, M. 1991. 1992. Capture and coded-wire tagging of naturally produced chinook in the Trinity River Basin. Chapter II. Job II. pp. 32-49. In: K. Urquhart and R. Carpenter (eds.), Annual Report of the Trinity River Basin Salmon and Steelhead Monitoring Project, 1990-1991 Season. December 1992. 186 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.
Zuspan, M. 1991. 1994. Capture and coded-wire tagging of naturally produced chinook in the Trinity River Basin. Chapter II. Job II. pp. 38-50. In: K. Urquhart and R. M. Kano (eds.), Annual Report of the Trinity River Basin Salmon and Steelhead Monitoring Project, 1991-1992 Season. February 1994. 235 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.
APPENDIX 1. List of Julian weeks and their calendar equivalents.
APPENDIX 2. Summary of juvenile salmonid trapping in the Trinity River at the Lewiston trap site…
APPENDIX 3. . Summary of juvenile salmonid trapping in the Trinity River at the Ambrose trap site…
APPENDIX 4. . Summary of juvenile salmonid trapping in the Trinity River at the Hard Hat trap site…
APPENDIX 5. . Summary of juvenile salmonid trapping in the Trinity River at the Sky Ranch trap site…
