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) in the main stem Trinity River below Lewiston Dam from 22 February through 26 June 1990.
We trapped 176,381 juvenile chinook salmon, 31,705 juvenile coho salmon (O. kisutch), and 6,164 juvenile steelhead (O. mykiss) at two sites during the study. At both sites, catch-per-unit-effort of juvenile chinook salmon peaked during the week of 21 May 1990, declining thereafter. Weekly average fork lengths of trapped fish tended to increase throughout the trapping period.
We adipose fin-clipped and implanted coded-wire tags into 140,898 juvenile chinook salmon. After adjusting for tagging mortality, tag shedding, and poor fin clips, we effectively coded-wire tagged and released 112,133 juvenile chinook salmon.
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 or fingerlings in the main stem Trinity River and/or selected Trinity River tributary streams. These fish will be sampled, subsequently, by other projects to determine their survival, 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 spawning escapement of these stocks is crucial to wise management of chinook in the basin.
Recent legislation (Public Law 98-541) 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 system 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) trapped, coded-wire tagged, and released naturally produced juvenile chinook. Subsequent studies of these fish as adults, by other projects of CDFG's Klamath-Trinity Program, will be used to determine survival, harvest, and spawning escapement for this important component of the Trinity River system's chinook stocks.
The current study began in 1989. This is the second annual report on the capture and coded-wire tagging of naturally produced juvenile chinook from the Trinity River system.
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 7-day 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 7-day periods.
Trapping was conducted at two sites in the main stem Trinity River this season. The first site (Lewiston Site) was located at river kilometer (RKM) 175.4, 3.1 km downstream of Lewiston Dam. The second site (Indian Creek Site) was located 21.9 km downstream of the Lewiston Site near Indian Creek at RKM 153.5 (Figure 1).
The Lewiston Site was upstream of any significant tributary and downstream of highly productive chinook spawning beds located in the main-stem Trinity River. The site's location above major tributaries made it relatively immune from large fluctuations in stream flow due to storm events. Trapping at the Lewiston Site began JW 8 (19 February 1990) and continued through JW 26 (25 June 1990).
Trapping at the Indian Creek Site began JW 15 (09 April 1990) and continued to JW 26 (15 June 1990). This site was used when juvenile chinook catches at the Lewiston Site had diminished and the coded-wire tagging program could no longer be effectively continued at that location.
Trapping at both sites was conducted using between one to four fyke nets measuring 3.1 m wide, by 1.2 m high at the opening, by 7.6 m long, tapering to a 0.33-m by 0.3-m exit leading into dual live boxes. Fyke nets were attached, at their mouth, to a 2.5-cm (1-in) diameter galvanized pipe frame of the same dimensions as the net opening, which was connected by ropes to metal posts driven into the stream bed.
The primary objective of the trapping effort was to capture up to 100,000 juvenile chinook for coded-wire tagging. All fish trapped were counted and a sample of each species was measured to the nearest mm of fork length (FL).
The tagging sites were located adjacent to the trapping sites. Tagging was conducted inside a 4.9 m x 4.9 m (16 ft x 16 ft) canvas tent. A 3.5-KW portable generator was used to supply the electrical needs of the operation (tagging machines, pumps, lights).
Captured juvenile chinook were anesthetized with tricaine methanesulfonate (MS222), their adipose fin removed, and a coded-wire tag implanted. Tag injectors and quality control devices used in the operation were purchased from Northwest Marine Technology 1/. Because of the small size of the fish captured, 1/2-length tags were used. Two tagging stations were normally employed.
A subsample of 100 tagged fish was reserved each day for quality control. All other tagged fish were released throughout the day into the river at the tagging site. Fish in the quality control sample were put into holding cages kept in the river and, after a minimum of 24 hours, checked for mortality, tag retention, and adipose fin-clip (Ad-clip) effectiveness. Tag retention was determined by passing fish through the electronic tag (metal) detector, and Ad-clip effectiveness was determined by direct examination.
We captured 99,239 juvenile chinook at the Lewiston Site this season. Weekly average catch-per-night peaked in mid-March at 1,974 fish per trap and again in mid-May at 4,656 fish per trap (Figure 2, Appendix 2). The first peak was composed exclusively of naturally produced fish while the second was composed mostly of fish produced at Trinity River Hatchery (TRH). Hatchery fish were identified by the presence an Ad-clip and by the timing of hatchery releases.
Weekly average fork lengths (FLs) of juvenile chinook captured at the Lewiston Site ranged from 36.0 to 86.1 mm through the trapping season (Figure 3, Appendix 2). During the first seven weeks of trapping the average FL remained constant at about 36 mm, ranging from 35.9 to 37 mm (Figure 3, Appendix 2). The constant size indicates little growth was taking place during this time and juvenile chinook were emigrating shortly after emergence.
We captured 30,389 juvenile coho salmon and 4,708 juvenile steelhead this season. Juvenile coho salmon weekly average catch-per-night peaked in mid-April at 562 fish per trap. Juvenile steelhead catch was sporadic with a maximum weekly average catch-per-night of 370 fish per trap in late April (Appendix 2). Coho salmon young-of-the-year (YOY) were first noted on 19 March 1990. Steelhead YOY were first captured 20 April 1990, prior to this only yearling and yearling-plus steelhead were observed.
Tagging operations began 19 March and continued through 18 April 1990. Three coded-wire tag groups totaling 81,513 juvenile chinook were tagged and re-released at the Lewiston Site during this period. These fish ranged from 32 to 67 mm FL, averaging 37.2 mm FL.
Independent, non-overlapping estimates of tagging mortality, tag shedding, and poor Ad-clips based on the quality control groups were 2.6%, 14.2%, and 1.2%, respectively. Based on these estimates, we effectively coded-wire tagged and released 66,784 juvenile chinook from the Lewiston Site (Table 1).
We captured 77,142 juvenile chinook at the Indian Creek Site this season. Weekly average catch-per-night peaked in mid-April at 2,225 fish per trap and again in mid-May at 3,203 fish per trap (Figure 4, Appendix 3).
The first peak was composed exclusively of naturally produced fish while the second was composed of mostly TRH-produced fish, based on the presence of Ad-clipped fish and the timing of hatchery releases.
Weekly average FLs of chinook salmon ranged from 47.5 to 79.3 mm through the trapping season at this site (Figure 5, Appendix 3)
(Figure 4) (Figure 5) (Appendix 3)
We captured 1,316 coho salmon and 1,456 steelhead this season. Weekly average catch per-trap per-night of coho salmon peaked in early May at 351 fish per trap. Steelhead catches were relatively low, ranging from 0 to 54 fish per-trap per-night (Appendix 3). Coho salmon YOY were observed from the first day of trapping on 9 April 1990. Steelhead YOY were first captured 1 May 1990, and only yearling and yearling-plus steelhead were seen prior to this.
Tagging operations began 18 April and continued through 3 May 1990. Two coded-wire tag groups totaling 59,385 juvenile chinook were tagged and released at the Indian Creek Site during this period. These fish ranged from 38 to 73 mm FL, averaging 54.6 mm FL.
Independent, non-overlapping estimates of tagging mortality, tag shedding, and poor Ad-clips based on the quality control groups were 14.8%, 7.7%, and 1.1%, respectively. Based on these estimates, we effectively coded-wire tagged and released 45,349 juvenile chinook at the Indian Creek Site (Table 1).
Our trapping and coded-wire tagging operations successfully met the goal of tagging 100,000 naturally produced chinook this season.
The choice of trapping sites, with their relative immunity from stream flow fluctuations, was probably responsible for the success of this year's tagging program. Last year, in a similar effort, the trapping site was located downstream of several major tributaries at RKM 130. Spring storms made trapping at that site inefficient or impossible. As a result, only 24,874 chinook salmon were trapped during the 1988-89 season (Zuspan, 1991b).
The small size of fish encountered at the Lewiston Site may pose a potential problem for coded-wire tagging there. Nearly all the juvenile chinook tagged at that site were newly emergent fish averaging about 36 mm FL. This year, most juvenile chinook produced in this area of the river emigrated shortly after emergence. This is probably related to intense competition caused by the large number of fish produced in this small section of the Trinity River. The CDFG estimates that, in 1989, this upper 3.1 km of river accounted for 42.0% of the natural chinook spawning that took place in upper 64.3 km of the Trinity River below Lewiston Dam (Zuspan, 1992). Tagging fish at such a small size may adversely effect their survival. Also, these small, newly emergent fish will not yet have undergone as much naturally imposed mortality as larger, older emigrating fish. A comparison of the survival between the larger chinook tagged at the Indian Creek Site and those tagged at the Lewiston Site will be possible when these fish return as adults in two to five years (most will return in three years).
1. Job 2 activities should be continued in FY 1990-91.
2. Trapping locations used in FY 1989-1990 should be used again in FY 1990-1991.
Heubach, B., and P. Hubbell. 1979. FY 1978 Progress Report. Task V. Salmon Tagging and Release Monitoring. p. 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. Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, Ca. 95814.
Heubach, B. 1980. FY 1979 Progress Report. Task V. Salmon Tagging and Release Monitoring. p. 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. Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, Ca. 95814.
Maria, D., and B. Heubach. 1981. FY 1980 Progress Report. Task V. Salmon Tagging and release monitoring. p. 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. Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, Ca. 95814.
Maria, D., and B. Heubach. 1984a. FY 1981 Progress Report. Task V. Salmon Tagging and Release Monitoring. p. 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. Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, Ca. 95814.
Maria, D., and B. Heubach. 1984b. FY 1982 Progress Report. Task V. Salmon Tagging and Release Monitoring. p. 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. Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, Ca. 95814.
Maria, D., and B. Heubach. 1984c. FY 1983 Progress Report. Task V. Salmon Tagging and Release Monitoring. p. 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. Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, Ca. 95814.
Zuspan, M. 1991b. Capture and Coded-wire Tagging of Naturally Produced Chinook in the Trinity River Basin. Chapter II. Job II. p. 24-33. In: Carpenter, R. 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. Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, Ca. 95814.
Zuspan, M. 1992. Salmon Spawner Surveys in the Upper Trinity River Basin. Chapter I. Job I. p. 1-29. In: Urquhart, K. (ed.), Annual Report of the Trinity River Basin Salmon and Steelhead Monitoring Project, 1989-1990 Season. March 1992. 140 p. Available from Calif. Dept. Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, Ca. 95814.
