Previous Page TOC Next Page

ANNUAL REPORT

TRINITY RIVER BASIN SALMON AND STEELHEAD MONITORING PROJECT

1991-1992 SEASON

CHAPTER VI - JOB VI

SURVIVAL, AND CONTRIBUTIONS TO THE FISHERIES AND SPAWNER ESCAPEMENTS MADE BY STEELHEAD PRODUCED AT TRINITY RIVER HATCHERY

by

Bernard C. Aguilar

TOC

ABSTRACT

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 intermittently from 1 October 1991 through 18 March 1992. Unique combinations of fin clips were given to each group of fish to permit identification of brood year upon recapture. This season we marked 2,834 steelhead held over from the 1990 brood year with a right ventral fin clip, to be released as two-year-olds, and 968,025 steelhead from the 1991 brood year with a left ventral fin clip, to be released as yearlings.

We checked 80 steelhead from the 1990 brood year and 22,538 from the 1991 brood year for fin clip accuracy prior to release. We found 0.0% from brood year 1990 and 0.9% from brood year 1991 had poor fin clips.

We monitored adult steelhead returning to Trinity River Hatchery from 16 September 1991 through 27 March 1992, when migration was determined to have been completed. During that time, 295 steelhead returned to Trinity River Hatchery, of which 62.0% (183/295) were fin-clipped.

Steelhead were also checked for fin clips as they were recovered at the Willow Creek and Junction City weirs. Six hundred thirty-eight steelhead were recovered at the Willow Creek weir, of which 11.1% (71/638) were fin-clipped. One hundred three steelhead were recovered at the Junction City weir, of which 34.0% (35/103) were fin-clipped.

TOC

JOB OBJECTIVE

To determine relative return rates and contributions to spawning escapements and the fisheries made by steelhead produced at Trinity River Hatchery, and to evaluate experimental hatchery management practices aimed at increasing adult returns.

TOC

INTRODUCTION

The completion of the Trinity River Division of the Central Valley Project (15 May 1963) blocked access to approximately 16% of the historic steelhead spawning and rearing habitat in the Trinity River basin, and resulted in an approximately 80% reduction in flow past the Lewiston dam site (Hubbell, 1973; Ca. Dept. of Fish and Game, 1965). These project-induced reductions in fishery habitat and flow are among the major factors contributing to the decline of annual runs of steelhead in the Trinity River system.

In October 1984, U.S. Public Law 98-541 was enacted. This act, commonly referred to as the Trinity River Basin Fish and Wildlife Restoration Act, authorized the expenditure of $57 million over a 10-year period to implement a program to restore fish and wildlife populations in the Trinity system 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 needed to develop those recommendations. To differentiate between naturally-produced and hatchery-produced steelhead, all steelhead reared at Trinity River Hatchery from 1978 through 1981 were systematically fin clipped before being released. 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) continued to mark steelhead produced at Trinity River Hatchery (TRH) as part of the first half of our Project's efforts to meet the Job Objective. The second half, which began last season, includes the monitoring of adults returning to TRH.

TOC

METHODS

In-hatchery Fish Growth

The amount of feed given to fish reared at TRH is determined by taking weekly standard weight counts (number of fish per pound), and then fish are fed according to suggested manufacturers' recommendations (Gary Ramsden, Manager, Trinity River Hatchery, CDFG, pers. comm.). The average weights of individual fish, reported in this chapter, were based on these weight count data from TRH feeding schedules. Project personnel graded fish during the marking process and placed smaller fish into holding tanks until they could be moved into hatchery ponds for further growth.

Marking Operations

Staff of CDFG's TFIP marked steelhead at TRH inside two wooden sheds measuring 3 m X 3 m, positioned directly over the hatchery ponds. Positioning the sheds over the ponds allowed access for two crews of four markers each, to effectively net fish into each shed and mark them. Each shed was equipped with a four-station marking table and a holding tank (approximately 284 liters), through which fresh, hatchery pond-water was circulated. Fish were netted directly from the hatchery ponds and placed into the holding tank located inside the shed. A smaller holding sink, also equipped with circulating fresh, pond water, was located in the center of each marking table. One shed was equipped with a recirculating tricaine methanesulfonate (MS-222/) system (approximately 76 liters), which was changed at least once per day with fresh aqueous MS-222 solution. This system used 1.5 cups of MS-222 per week. The recirculating MS-222 system was installed to minimize fish mortality caused by overdoses of anaesthetic. The other shed had separate, non-circulating MS-222 sinks at the four work stations, with each marker responsible for controlling their own MS-222 concentrations. No comparisons were made of MS-222 usage between the two sheds. The temperatures of the fresh water and MS-222 solutions of both sheds were monitored regularly throughout the day.

Marking steelhead involved anaesthetizing them with MS-222, removing one or more of their fins by clipping, and releasing them into a pond reserved for marked fish. To keep count of fish marked, each marking station was equipped with a manual counter to tally each fish as it was marked. A combination of right ventral (RV) or left ventral (LV) and adipose (Ad) fin clips was used to differentiate each fish's brood year (BY) and age at release. Fish marked during this season were from the 1990 BY (given a RV fin clip), to be released as two-year-olds, and from the 1991 BY (given a LV fin clip), to be released as yearlings.

Numbers of fish released from TRH were estimated by TRH personnel, using the standard weight count method on a subsample of marked fish at the time of release.

Hatchery Mark Evaluations

We monitored the effectiveness of our fin-clipping operation by randomly checking steelhead one to four times per day throughout the marking period, to see how well the fins were removed. We netted a sample of fish as they exited each marking shed and checked them before they were placed into the hatchery ponds. We recorded the number of fish which were poorly fin-clipped, marked them with the appropriate fin clip, then placed them into the hatchery pond reserved for marked fish. Project personnel were notified immediately of any poorly fin-clipped fish, so that they could pay closer attention to marking.

To determine overall fin clip accuracy, we examined a sample of the marked steelhead just prior to release. These fish were anaesthetized with MS-222, measured to the nearest mm fork length (FL), and checked for how well the fin was removed during the marking process. Fin-clipping is considered a permanent mark if the rays are removed to the point of attachment to the bone (Stuart 1958; Eipper and Forney 1965; Jones 1979). Fins which were less than half removed were likely to regenerate, with fin rays appearing distorted at the location of the clip. Unless personnel checking for fin clips on returning adults specifically looked for distorted rays, fish that were poorly marked would be unrecognizable. We determined the number of effectively-marked fish by multiplying the percent of fish with poor fin clips by the total number of fish released, and subtracting this product from the total.

Fish Health Assessment

A subsample of marked fish were autopsied by a CDFG pathologist prior to release for health and general condition. A complete organosomatic analysis was done and results are on file with the pathologist, Region I, California Department of Fish and Game. Results reviewed in this report are confined only to general remarks by the pathologist. Project personnel also visually inspected the fish for general condition during the hatchery mark-evaluation process.

Recovery Operations

Project personnel monitored steelhead returning to TRH from 16 September 1991 through 27 March 1992. We examined the fish for fin clips, measured each to the nearest cm FL, and recorded their sex. Steelhead were also checked by Trinity River Project (TRP) personnel during their operation of the Willow Creek weir, located 132.0 km downstream of TRH, from 20 August through 13 December 1991, and at the Junction City weir, located 42.4 km downstream of TRH, from 21 May through 13 December 1991.

TOC

RESULTS AND DISCUSSION

In-hatchery Fish Growth

Brood Year 1990 (two-year-olds)

These fish were held over from last season, unmarked, because they did not meet minimum release size requirements. Holdover fish from this BY were reared at TRH, marked this season, and released as two-year-olds.

According to TRH feeding schedule records, the average weight of these fish in April 1991 was 20 fish/lb or 22.7 gm each. To minimize handling mortalities, weight counts were not taken on these fish from 12 September 1991 through 18 February 1992. At the time of release, their average individual weight was 412 gm (Figure 1).

FIGURE 1. Average weight of two-year-old steelhead from the 1990 brood year reared at Trinity River Hatchery from 18 April 1991 through 12 March 1992.

Brood Year 1991 (yearlings)

According to TRH feeding schedule records, these fish grew progressively throughout the rearing cycle. Beginning 11 September, TRH personnel graded fish by size, and feed was decreased for a short period. This resulted in a small drop of average individual weight from 12.8 to 10.8 gms. The average weight of marked fish at the time of release was 56.7 gms each (Figure 2).

FIGURE 2. Average weight of yearling steelhead from the 1991 brood year reared at Trinity River Hatchery from 9 May 1991 through 12 March 1992.

Between 16 January and 13 February 1992, the average individual weight of the smaller fish separated during the grading process temporarily declined, probably due to the high number of small fish placed into the pond during that period (Gary Ramsden, Manager, TRH, CDFG, pers. comm.). By 12 March 1992, the average weight of the smaller-grade fish was 23.9 gms (Figure 2). These small- grade fish will be held over at TRH, marked next season, and will be released as two-year-olds in the spring of 1993.

Marking Operations

This season, we marked 2,834 fish held over from the 1990 BY with a RV fin clip, to be released as two-year-olds, and 968,025 fish from the 1991 BY with a LV fin clip, to be released as yearlings. Both groups were released in March 1992 (Table 1). There were no experimental hatchery management practices to evaluate this season.

TABLE 1. Summary of steelhead fin-clipping operations at Trinity River Hatchery from 1 October 1991 through 18 March 1992.

Brood Year 1990 (two-year-olds)

We had previously marked 970,617 steelhead from this BY with an Ad+LV fin clip during the winter of 1990, and released them as yearlings in the spring of 1991 (Aguilar 1992). By the 1991 release date, approximately 3,000 fish from this BY were too small to mark, and so were held and reared at TRH a second year in order to reach the minimum release size of 152.4 mm (6 in) FL. We began marking a remaining 2,834 steelhead from this BY on 1 October 1991. These fish were reared at TRH until 16 March 1992, and released as two-year-olds into the mainstem Trinity River at TRH. The average weight of these fish at release was 2.4 fish/kg (Table 1).

Brood Year 1991 (yearlings)

We marked 438,184 steelhead from this BY with a LV fin clip from 1 October through 30 October 1991. Throughout this period, TRH personnel graded fish according to size. On 30 October, the management at TRH determined that the remaining fish (approximately 512,000) were too small and would need added rearing time to increase growth, so marking was temporarily discontinued.

We resumed marking on 6 January 1992, and marked 487,987 steelhead through 7 February 1992, when TRH management again determined the remaining fish (approximately 60,000) were too small to mark. Once again, marking was temporarily halted.

We resumed marking for the third time on 16 March 1992, the day pond screens were pulled to allow the fish to enter the mainstem Trinity River at TRH. We marked 41,854 steelhead through 18 March 1992. These fish were held at TRH until evaluation of hatchery marks could be made before they were released. The average size of fish from this BY at release was 17.5 fish/kg (Table 1). Approximately 10,000 - 11,000 fish from this BY that were considered too small to mark are being held at TRH. These fish will be marked next season and released as two-year-olds.

Hatchery Mark Evaluations

Brood Year 1990 (two-year-olds)

We examined a subsample of 80 steelhead from the 1990 BY to see how well their fins were removed during the marking process. We did not find any poorly fin-clipped fish, thus all steelhead released from this BY were considered effectively marked (Table 2).

According to TRH staff estimates, they released 1,909 steelhead from the 1990 BY, and had 925 mortalities during the holding period prior to release. At the release date, the FL of these fish ranged from 205 to 455 mm, and averaged 351.8 mm, with a sample S.D. of 5.36 (Figure 3).

TABLE 2. Summary of steelhead hatchery-mark evaluations from 1 October 1991 through 20 March 1992.

Brood Year 1991 (yearlings)

From 10 through 20 March 1992, we examined a subsample of 22,538 fish to assess the quality of their fin-clips. We measured the FLs of 4,500 of the fish in this subsample. We found 192 (0.9%) fish from this BY which were poorly fin-clipped. There were no mortalities recorded by TRH personnel, thus 959,313 (99.1%) of the steelhead from this BY were effectively marked and released (Table 2). Their FLs ranged from 75 to 283 mm, and averaged 183.6 mm FL with a sample SD of 1.95 (Figure 4).

FIGURE 3. Length frequency of marked two-year-old steelhead from the 1990 brood year released from Trinity River Hatchery on 16 March 1992.

FIGURE 4. Length frequency of marked yearling steelhead from the 1991 brood year released from Trinity River Hatchery on 16 March 1992.

Fish Health Assessment

Brood Year 1990 (two-year-olds)

A pathological health assessment by autopsy was not done because of the limited number of fish from this brood year. We checked 80 fish during the hatchery mark-evaluation procedure, and found a fungus-like growth on three fish. We also found some fin erosion. Overall, the fish released from this BY showed signs of stress, probably because of handling them at a larger size.

Brood Year 1991 (yearlings)

A subsample of 20 fish was collected at TRH by a CDFG pathologist, prior to the release of marked fish. A complete organosomatic analysis and autopsy were done. Results showed some dorsal fin wear and scale loss; however, the general condition of these fish, as determined by both the pathologist and Project personnel, appeared to be good.

Recovery Operations

Juvenile steelhead migrate to sea after spending one to three years in fresh water. They usually stay one to two years in salt water, 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).

A fraction of the Trinity River steelhead run has a unique life- history pattern in that they will stay less than one year in salt water, and return to fresh water after several months (Hopelain 1987). These fish are referred to as half-pounders.

This was the first year we expected to see returns of fish which were marked and released in 1990 (1988 and 1989 BYs). Steelhead produced at TRH were the majority (183/295) of returns to the hatchery during this reporting period, and made a significant contribution to spawner escapement.

Trinity River Hatchery

Many returning adult steelhead were lost at TRH before we could recover them, due to predation by otters. Otters took fish directly from the holding tanks and fish trap, and, occasionally, only body parts were found. Because of this, fewer eggs were taken, and we expect the number of steelhead available for marking will be considerably lower next season.

Project personnel monitored steelhead returning to TRH from 16 September 1991 through 27 March 1992, when migration was complete. During that period, 295 steelhead returned to TRH, of which 183 (62.0%) were fin-clipped. Of those: 24 (8.1%) were marked with a LV fin-clip, with FL ranging from 33 to 68 cm, indicating they were from the 1989 BY, returning as three-year-olds; 73 (24.7%) were marked with a RV fin-clip with FL ranging from 31 to 75 cm, indicating that the majority (65/73) of these were from the 1988 BY, returning as four-year-olds; 54 (18.3%) were marked with a Ad+RV fin-clip indicating they were from the 1989 BY; 31 (10.5%) were marked with a Ad+LV fin-clip indicating they were from the 1990 BY, and 1 was marked with a right pectoral fin-clip, of unknown origin. Last season, 927 steelhead returned to TRH, six of which were marked fish from the 1988 BY returning as three-year-olds.

Junction City Weir

Personnel from the TRP recovered 103 steelhead from the Junction City weir, 35 (34.0%) of which were fin-clipped. Of those: 5 (4.9%) were marked with a Ad+LV fin-clip indicating they were from the 1990 BY; 8 (7.8%) were marked with a Ad+RV fin-clip indicating they were from the 1989 BY; 10 (9.7%) were marked with a LV fin-clip indicating they were from the 1989 BY; and 12 (11.7%) were marked with a RV fin-clip indicating they were from the 1988 BY.

Willow Creek Weir

Personnel from the TRP recovered 638 steelhead at the Willow Creek weir, 71 (11.1%) of which were fin-clipped. Of those: 49 (7.7%) were marked with a RV fin-clip indicating they were from the 1988 BY; 9 (1.4%) were marked with a LV fin-clip indicating they were from the 1989 BY; 7 were marked with a Ad+RV fin-clip indicating they were from the 1989 BY; 4 were marked with a Ad+LV fin-clip indicating they were from the 1990 BY; and 2 had an adipose fin-clip only, of unknown origin. Adipose-clipped fish may have been previously marked with a corresponding ventral clip; however, regeneration may have occurred.

TOC

RECOMMENDATIONS

Marking should begin as late as possible next season, to allow as much time as possible for the fish to grow. This would prevent intermittent marking, and allow for continuous fin clipping throughout the season.

TOC

LITERATURE CITED

Aguilar, B. 1992. Survival and contribution to the fisheries and spawner escapement made by chinook salmon produced at Trinity River Hatchery. Chapter VI. Job VI. p. 158-169 In:K. Urquhart (ed.) Annual Report of the Trinity River Basin Salmon and Steelhead Monitoring Project, 1991 season. June 1992. 186 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.

California Dept. of Fish and Game. 1965. California Fish and Wildlife Plan. Volume III. Supporting Data. Part B-Inventory Salmon-Steelhead and Marine Resources. October 1, 1965. p. 323-679.

Eipper, A., and J. Forney. 1965. Evaluation of partial fin-clips for marking largemouth bass, walleyes, and rainbow trout. New York Fish and Game Journal 12:233-240.

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., 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., 1416 9th St., Sacramento, CA 95814.

Hopelain, J. S. 1987. Age, growth, and life history of Klamath River basin steelhead (Salmo gairdnerii), as determined from scale analysis. 33 p. (Mimeo). Available from Calif. Dept. of Fish and Game, Inland Fisheries Div., 1416 9th St., Sacramento, CA 95814.

Hubbell, P. M. 1973. Program to identify and correct salmon and steelhead problems in the Trinity River Basin. A report to the Trinity River Basin Fish and Wildlife Task Force. August 1973. 70 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., Sacramento, CA 95814.

Jones, R. 1979. Materials and methods used in marking experiments in fishery research. Food and Agriculture Organization of the United Nations, Fisheries Technical Paper Number 190 (FIRM/T190). Rome, Italy.

Moyle, P. B. 1976. Inland Fishes of California. p. 131-132. Univ. of Calif. Press, Berkeley, CA. 405 p.

Stuart, T. A. 1958. Marking and regeneration of fins. Freshwater Salmon Fisheries Research, Edinburgh, Scotland 22. In: Nielson, L. A., and D. L. Johnson, (eds.), Fisheries Techniques. American Fisheries Society. Virginia: Southern Printing Co.; 1983:p.215-237. (Tagging and Marking).

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., 1416 9th St., Sacramento, CA 95814.

Previous Page Page Top TOC Next Page