Staff of the California Department of Fish and Game's Trinity Fisheries Investigations Project conducted a steelhead, Oncorhynchus mykiss, marking program at Trinity River Hatchery from 5 February to 3 April 1990. Unique combinations of fin clips were given to each group of fish to permit identification of brood year and release type upon recapture. We fin-clipped 405,997 yearlings, 50,490 two-year-olds, and 144,800 holdover yearling steelhead this season. Holdovers will be released next year after they have reached the minimum release length of 152 mm fork length.
We checked 900 steelhead for fin-clip accuracy, and all were found to have been properly clipped.
1. To determine relative return rates, and contributions to spawning escapements and the fisheries made by steelhead produced at Trinity River Hatchery.
2. To evaluate experimental hatchery management practices aimed at increasing adult returns.
The completion of the Trinity River Division of the Central Valley Project (15 May 1963) blocked access to a significant part of the historic steelhead spawning and rearing habitat in the Trinity River basin, and resulted in significant downstream flow reductions. These project-induced reductions in fishery habitat have resulted in the decline of annual runs of steelhead.
In October 1984, Public Law 98-541 was passed by Congress to mitigate for Trinity project-induced fish and wildlife losses. This act, commonly referred to as the Trinity River Basin Fish and Wildlife Restoration Act, authorizes the expenditure of $57 million over a 10-year period to implement a program to restore fish and wildlife populations to pre-dam conditions.
One of the major goals of the California Department of Fish and Game's (CDFG) Klamath-Trinity Program is to develop fishery harvest management recommendations which are compatible with the goal of restoring full, natural salmon and steelhead production in the Trinity River and its tributaries downstream from Lewiston Dam.
Knowledge of hatchery and naturally produced steelhead escapements into the Trinity River is a necessary component both for making recommendations and determining the effectiveness of those recommendations. All steelhead reared at Trinity River Hatchery from 1978 through 1981 were systematically fin clipped before being released. Fin clipping of steelhead in the Trinity River basin have been sporadic to non-existent at Trinity River Hatchery since 1981. Run size and escapement estimates of hatchery-produced and naturally produced steelhead were made during the 1978-79, 1980-81, and 1982-83 seasons. (Heubach and Hubbell 1980, Heubach,1984, Zuspan et al. 1985).
This year, staff of CDFG's Trinity Fisheries Investigations Project (TFIP) marked steelhead produced at Trinity River Hatchery (TRH) as part of the first phase in meeting the Job Objectives. The second phase will include the monitoring of adult returns beginning in the winter of 1990, and will be discussed in future annual reports.
Staff of CDFG's TFIP marked steelhead at TRH inside a 3-m X 3-m wooden shed positioned directly over the hatchery pond. Positioning the shed over the pond allowed easy access for a crew of four markers to effectively net fish into the shed.
Marking steelhead involved anaesthetizing them with tricaine methanesulfonate (MS-222), removing one or more of their fins by clipping, and releasing them into a pond reserved for marked fish. A combination of right or left ventral fin and adipose fin clips was used to differentiate each fish's brood year and release type. Counts of marked fish which were released were made by TRH personnel doing standard weight counts on a subsample of the marked fish at the time of their release.
To determine fin-clip accuracy, a sample of 900 fish was selected just prior to release. Fish were anaesthetized with MS-222, measured to nearest mm fork length (FL), and checked for proper fin clips. Male steelhead were also checked for signs of precocious sexual development, which was determined by the extrusion of milt when each fish was squeezed.
We marked three groups of steelhead this season. Two-year-olds from the 1988 brood year (BY), released in 1990; yearlings from the 1989 BY, released in 1990; and holdovers from the 1989 BY, to be released in spring 1991 (Table 1).
Two-year-old steelhead were marked from 5 February through 15 February 1990; yearling steelhead from 15 February through 18 March 1990; and holdover steelhead from 18 March through 3 April 1990, when marking operations were curtailed. Marking operations were halted on that date because of rising water temperature which could have lead to increased mortalities. An estimated 110,000 holdovers remain to be fin-clipped at a later date. Holdovers which had been clipped were moved to holding ponds at the Old Sawmill Site on the outskirts of Lewiston, (river km 175.4) because of a lack of space at TRH. These fish are scheduled to be released in April 1991.
All steelhead released appeared to be in good condition, and we noted no apparent deformations or pathological conditions.
We measured the FL's of 300 two-year-old steelhead on 7 March 1990, and checked them for fin-clip accuracy. Average FL was 26.6 cm, and they ranged from 16 to 40 cm FL (+ 4.77 s.d.). We observed eight precocious males (2.7% of the subsample), and did not find any fish with poor fin clips.
We measured the FL's of 600 yearling steelhead (BY 89) on 30 March 1990 and checked them for fin-clip accuracy. Their average FL was 159.2 mm (+ 18.4 mm s.d.), and they ranged from 107 to 230 mm FL. Of the 600 fish checked, 31.8% (191/600) were smaller than our target of a 152-mm minimum-release size. We did not observe any fish with poor fin clips.
Quality control for the holdovers will not be done until marking for these fish is completed, probably in October 1990.
Juvenile steelhead migrate out to sea after spending one to three years in fresh water. They usually stay one to two years in salt water, and then return to freshwater to spawn when they are 38 to 69 cm in total length. Life history patterns of steelhead are variable, however, and growth rates may vary (Moyle 1976). However, a fraction of the Trinity River steelhead run have a unique life history pattern in that they will stay less than one year in salt water, and return as half-pounders after several months (Hopelain 1987).
Recovery operations at TRH are scheduled to begin during spring 1991 when fin-clipped fish from the 1988 and 1989 BY's are first expected to return, and will be discussed in next year's annual report.
Personnel should be increased from one crew of four to two crews of four persons and two marking sheds should be used for marking next year, in order to speed up the marking process and increase the numbers of steelhead that can be marked within the allotted time.
Heubach, B. 1984. Progress Report, 1981-82 Season. Task VI. Trinity River salmon and steelhead tagging program. p. 49-106. 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 I and VI. December 1984. 106 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, CA. 95814.
Heubach, B. and P. M. Hubbell. 1980. FY 1979 Progress Report. Task VI. Lower Trinity River salmon and steelhead tagging program. p. 80-132. 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.-Room 1251, 1416 9th St., Sacramento, CA. 95814.
Hopelain, J. S. 1987. Age, growth, and life history of Klamath River basin steelhead (Salmo gairdneri), as determined from scale analysis. 33 p. (Mimeo). Available from Calif. Dept. of Fish and Game, Inland Fisheries Div.-Room 1251, 1416 9th St., Sacramento, CA 95814.
Moyle, P. B. 1976. Inland Fishes of California. p. 131-132. Univ. of Calif. Press, Berkeley, Ca. 405 p.
Zuspan, M., D. Maria, and B. Heubach. 1985. Progress Report, 1982-83 Season. Task IV. Trinity River salmon and steelhead tagging program. p. 62-146. In: P. M. Hubbell (ed.), Progress Report. Fishery Investigations--Trinity River. Trinity River Basin Fish and Wildlife Task Force Priority Work Item No. 5. January 1985. 84 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, CA. 95814.
