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ANNUAL REPORT

TRINITY RIVER BASIN SALMON AND STEELHEAD MONITORING PROJECT

1989-1990 SEASON

CHAPTER III - JOB III

LIFE HISTORY, DISTRIBUTION, RUN SIZE AND ANGLER HARVEST OF STEELHEAD IN THE SOUTH FORK TRINITY RIVER BASIN

by

Carrie E. Wilson and Terry J. Mills

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ABSTRACT

The California Department of Fish and Game's Natural Stocks Assessment Project monitored adult steelhead (Oncorhynchus mykiss) migration at various weirs to determine an escapement estimate for adult steelhead into the South Fork Trinity River (SFTR) basin during the 1989-1990 season.

Based on the results of our creel survey, we estimate 1,473 anglers fished for adult steelhead within the SFTR basin during the 1989-90 season. We estimate they landed 110 adult, 41 half-pounder and 43 juvenile steelhead. The angler harvest rate, based on adult tag returns, was estimated to be 18%.

During the 1989-90 steelhead spawning season, we conducted adult spawning stock surveys on 22 streams tributary to the SFTR and to Hayfork Creek. These surveys covered 108.0 km, and we observed 26 adult steelhead and 365 redds.

We studied juvenile steelhead habitat utilization in Eltapom Creek, a tributary to the SFTR. We sampled cascade, pool, riffle, and run habitats, and determined the run and riffle areas to be the preferred habitat types.

We monitored juvenile steelhead emigration from the upper SFTR basin and the Hayfork Creek basin, capturing 738 juveniles in the SFTR, and 1,901 juveniles in Hayfork Creek. Peak emigration of Age 0+ steelhead occurred during May 1990, and peak emigration of Age 1+ steelhead occurred a month earlier during April 1990.

One hundred five sets of adult and 464 sets of juvenile steelhead scale samples were read and interpreted for indications of various life history characteristics.

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JOB OBJECTIVES

1. To determine the size, composition, distribution, and timing of the adult steelhead runs in the South Fork Trinity River basin.

2. To determine the angler harvest of adult steelhead in the South Fork Trinity River basin.

3. To determine the life history patterns of the South Fork Trinity River basin steelhead stocks.

4. To determine the seasonal use made by juvenile steelhead of various habitat types within selected South Fork Trinity River tributaries.

5. To describe relationships between habitat parameters and seasonal juvenile steelhead standing crops.

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INTRODUCTION

The life histories of steelhead (Oncorhynchus mykiss) populations within the South Fork Trinity River (SFTR) basin are of concern because little data are available regarding juvenile steelhead life history patterns, adult steelhead run sizes, spawner distributions, sport fishery yields and harvest rates. As a result of poor habitat management within the SFTR basin, the 1964 flood severely impacted the area causing spawning and rearing habitats within the basin to be severely damaged or, in some instances, lost through excessive siltation. A combination of human activities (such as road construction, timber harvest, and recreation) exacerbated by natural events (such as wildfire and flooding) continue to curtail steelhead production within the basin by degrading in-stream habitat quality. Restoration of salmon and steelhead habitat within the basin is a high priority of the Trinity River Basin Fish and Wildlife Task Force, the U. S. Forest Service ([USFS] Shasta-Trinity National Forest), and the California Department of Fish and Game (CDFG). These restoration efforts will be guided by knowledge of steelhead habitat requirements and life histories.

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METHODS

Staff of the CDFG's Natural Stocks Assessment Project (NSAP) assessed adult steelhead run timing, distribution, and run size within the SFTR basin during the season through the following combination of methods: 1) tagging immigrant fish at two weirs, 2) a creel survey, 3) hook-and-line fishing, 4) electrofishing, 5) weirs and traps for emigrant fish, and 6) spawner surveys. Juvenile steelhead emigration timing and abundance were assessed through weekly trapping of out-migrant fish.

Use of Standard Julian Week

Weekly sampling data collected by Project personnel at the weirs are presented in Julian Week (JW) format. Each JW is defined as 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 lumped into the 9th week, and the last day of the year into the 52nd week (Appendix 1). This procedure allows inter-annual comparisons of similar 7-day periods.

Adult Steelhead Run Timing in the SFTR Basin

To assess the timing of the adult steelhead run into the SFTR basin, we trapped and tagged immigrant adult steelhead at two weir sites within the SFTR basin (Figure 1). The Sandy Bar Weir was located on the SFTR at river km (RKM) 2.4, and operated from 14 September through 23 October 1989. The Hyampom Valley Weir was located on Hayfork Creek at RKM 41.0, and operated from 18 October 1989 through 6 January 1990. At each site, Alaskan style weirs were constructed using a series of panels 3.2 m high and 3.0 m long set 2.4 m apart and joined together to block the entire river. Each panel contained 1.9-cm EMT conduit pickets set 2.9 cm apart (46 per panel), secured through three aluminum channel sections on the face of the weir. A cubic trap consisting of welded conduit panels was constructed in the river thalweg, with an entrance made by opening a portion of the weir and connecting the weir and trap with a fyke entrance.

Each steelhead captured was examined for: 1) fin clips, 2) tags, 3) gill net scars (nicks in the leading edges of dorsal and pectoral fins, sometimes combined with vertical white scars on the head), 4) hook scars (of ocean origin when healed, of freshwater origin when not healed), 5) predator scars (inverted 'V' shaped marks, usually on the underbody), and 6) other scars of unknown origin. Each steelhead was measured to the nearest cm fork length (FL), and its sex recorded. A scale sample was removed from the left side of each weir-caught fish, in an area slightly posterior to the anterior insertion of the dorsal fin, just above the lateral line. Each scale sample was placed between waterproof paper within a coin envelope and labeled with collection date, collection site, method of collection, sex, and FL (cm) of the fish.

All fish captured at the Sandy Bar and Hyampom Valley weirs were marked with a 1/2 left ventral (LV) fin clip. Every third taggable fish received a discretely numbered $10-reward anchor tag. We did not tag fish which were excessively stressed by the weir capture and handling process, or those which appeared in generally poor physical condition, to avoid excessive tagging mortality. Angler harvest rates were estimated from reward tag returns. The tags and clips were applied with the intention of computing a Petersen population estimate (Ricker, 1975) based on the ratio of tagged to untagged fish observed in later recovery projects (creel census, electrofishing, hook-and-line fishing, weirs and traps for emigrant fish).

(Figure 1)

South Fork Trinity River Creel Survey

Angler harvest of steelhead within the basin was determined from a systematic stratified creel survey, conducted from 31 October 1989 through 1 April 1990. The creel survey was conducted in two subsections of the lower SFTR basin (Figure 2). The lower survey area extended from the confluence of the SFTR with the main-stem Trinity River upstream for a distance of 22.5 km. The upper, Hyampom, survey area extended through the Hyampom Valley from river km 33.0 to river km 50.7. These two creel survey areas cover the river reaches fished by the majority of anglers, as public access is limited outside of these two areas due to the lack of public roads. Angler access sites in each creel survey area were identified prior to the survey period. The creel survey was further stratified by JW (Appendix 1), day (weekend/weekday), and time periods (am/pm: dawn to noon and noon to dusk, respectively). We extrapolated data for each stratum that was not surveyed by using average values for strata from equivalent sampling periods (ie., for a missing weekday evening survey: the mean of all weekday pm's in that JW). Estimated and actual data were combined for season totals.

During the creel survey, clerks followed a set route based on a predetermined schedule, and examined each access site for anglers. Anglers observed fishing during the survey periods were contacted and interviewed for hours fished that day, success, angling method, and county or state of residence. Sport-caught steelhead we observed were measured (cm FL), and examined for fin clips and external tags. The numbers of any tag observed were recorded, the fish's sex determined, and its spawning condition noted. Scale samples were taken from creeled fish in the same manner as for fish from the Sandy Bar Weir. We classified steelhead < 25 cm (FL) as juveniles, > 25 cm and < 35 cm as half-pounders, and > 35 cm as adults (Kesner and Barnhart, 1972). Water clarity was measured each day with a secchi disk.

Tag Return and Steelhead Harvest Rates

We estimated sport harvest rate from the percent of $10-reward tags returned by anglers, based on the following assumptions: 1) a 100% response rate by anglers, 2) that all tagged fish caught in the sport fishery were recognized as such by anglers, 3) no tags were shed, and 4) there was no differential mortality between tagged and untagged fish. Tag return rate was determined from the number of tags observed during the creel census divided by the number of observed tags returned. The estimated harvest rate of adult steelhead within the SFTR basin was determined from the number of reward tags returned by anglers divided by the number of tags applied at the weirs.

(Figure 2)

Adult Steelhead Recovery

Electrofishing and Spawner Surveys

Project personnel conducted surveys, on foot, of tributary streams to the SFTR and Hayfork Creek to document steelhead spawner distribution and tributary entry timing. The surveys were conducted from 19 December 1989 through 19 April 1990. The areas surveyed included: 1) tributaries to the SFTR and to Hayfork Creek in the Hyampom Valley area, 2) tributaries to the SFTR in the upper SFTR basin near the town of Forest Glen, and 3) tributaries to Hayfork Creek near the town of Hayfork and in the upper Hayfork Creek drainage near the town of Wildwood (Figure 1). Specific creeks to be surveyed were selected to include those which historically attracted spawning steelhead, and to replicate areas examined last year (Mills and Wilson 1991) and in previous CDFG surveys (Miller 1975; Rogers 1972, 1973).

During each survey, two people walked designated stream reaches carrying field notebooks to record observed spawning behavior, individual redd number with location, redd site descriptions, and stream conditions. Redds were flagged with surveyors tape attached to nearby structures (such as root-wads, shrubs, or bushes) with the survey date and field notebook description number recorded on the tape. Initially, we also used backpack electrofishers as part of our adult recovery plan to recapture weir-tagged steelhead. Captured fish were measured (cm FL), and examined for tags and marks, then a scale sample was taken and the fish released.

Weirs, Traps and Hook-and-line Fishing

Traps and weirs were assembled on lower Hayfork Creek and on three tributaries to Hayfork Creek (Big Creek, Salt Creek and Tule Creek) to capture post-spawning steelhead emigrating from the basin. We constructed an Alaskan-style weir on Hayfork Creek and constructed weir panel traps on the tributaries. The weir panels were 1.2 m high x 1.5 m wide, and constructed of 1.9-cm EMT conduit with 3.2 cm horizontal bar spacing. The trap size varied with location. All steelhead recovered were measured (cm FL), given a left opercle punch, checked for spawning condition, tags, fin clips, or marks, then a scale sample was taken and the fish released.

Project personnel also used sport fishing equipment to recover adult steelhead via hook and line. All steelhead recovered were processed as stated above.

SFTR Adult Steelhead Escapement Estimate

We attempted to make an escapement estimate using the Petersen method of mark and recapture (Ricker 1975) by marking adult steelhead at the Sandy Bar and Hyampom Valley weirs and recovering them through: 1) traps and weirs for emigrating fish, 2) creel surveys, 3) electrofishing, and 4) hook-and-line fishing.

Juvenile Steelhead Emigration Studies

We monitored juvenile steelhead emigration patterns by systematically trapping at two sites within the SFTR basin; Lower Hayfork Creek, 305 m upstream of its confluence with the SFTR, and in the SFTR upstream of its confluence with Hayfork Creek, within 0.4 km either side of Hyampom Road bridge (Figure 1). Juvenile steelhead were captured using fyke nets attached to trap boxes. The nets were constructed of 1.3-cm nylon mesh, had a 1.8-m x 2.4-m upstream opening and extended 10.1 m to a trap attachment frame at the terminal end. Trap boxes were constructed of marine plywood and hardware cloth, and measured 0.8 m x 1.2 m at the opening and were 0.5 m deep. One or two fyke-net traps were placed in the river or stream overnight, for 16 to 24 hour periods, and examined the following morning.

Captured fish were identified to species and enumerated. Systematic subsamples of 50 individuals, maximum, of each species were measured for FL (mm), and scale samples were systematically taken from a maximum of 10 juvenile steelhead, each sampling day. In each case, respectively, this consisted of the first 50 or 10 individuals removed from the traps each day. Flows through the net were measured and total volume of stream flows were estimated to the nearest 0.3 m/sec using either a pygmy meter or a Marsh-McBirney flow meter. Water temperatures were monitored using hand-held thermometers or digital recording thermographs. When flow conditions permitted, we trapped on a weekly basis throughout most of the year, but increased trapping frequency to every third night during the spring period of peak juvenile steelhead emergence (17 April to 30 June 1990).

Habitat Use by Juvenile Steelhead

We studied seasonal habitat use by juvenile steelhead in Eltapom Creek (Figure 1). The creek had been surveyed previously and divided into 101 habitat units categorized into four basic habitat types: cascades, pools, riffles and runs (Glase and Barnhart 1989). We used the same habitat unit designations, added two more units, and sampled 52 of the 103 habitat units. Initially, we sampled the first 20 habitat units, beginning at the confluence with the SFTR and working upstream. Later, to reduce sampling effort, we randomly selected 32 of the remaining 83 units, in proportion to the relative numeric abundance of each of the four basic habitat types.

Sample units were isolated using block nets to prevent any immigration or emigration of fish, and then electrofished using either the two-step or the Zippin methods of removal-depletion for population assessment (Hankin 1986, Price 1982). All captured steelhead were counted, measured (mm FL), sampled for scales (first 5 fish per habitat unit), and then released. We took photos of each habitat unit we sampled. We recorded air and water temperatures, and water velocities (to the nearest 0.031 m/sec) for each of the 101 habitat units. Water velocities were measured at 60% of the total depth from the surface along a line transverse to the flow at points 1/4, 1/2, and 3/4 of the way across the stream. Stream length and width were measured to the nearest 0.03 m in each habitat unit.

Steelhead Life History Patterns

Steelhead life history patterns were described from intensive analysis of scales taken from both adult and juvenile fish. Adult steelhead scale samples had been collected from 1981 through 1984 by CDFG personnel who conducted reconnaissance level creel surveys within the SFTR basin, and by CDFG personnel operating the Sandy Bar Weir on the lower SFTR from 1984 through 1989. Additional scales were collected this year through the SFTR creel survey, electrofishing, adult emigrant weirs, and juvenile out-migrant trapping. All scales collected in the field were taken to the lab for processing. Each adult scale sample was cleaned, dried, then mounted between two glass microscope slides. Scale samples from juvenile steelhead did not usually require cleaning. The cleaning process involved soaking scales in distilled water to soften them. Softened scales were rubbed between thumb and forefinger to remove debris. If debris persisted, scales were soaked in a 5% detergent solution made up with distilled water, and then rubbed again as mentioned previously. Softened tissue and debris that continued to adhere to scales after these cleaning processes was peeled off using blunt tipped forceps.

Steelhead scales were examined to determine age, reproductive history, and freshwater life history. Adult steelhead scale samples were read using a microfiche reader with 43 power magnification. Years of freshwater residence, age at ocean entry, and number of ocean annuli, half-pounder checks, and spawning checks were all recorded. Scale measurements were taken to the nearest mm along a line approximately 15 degrees offset from the anterior-posterior axis. Freshwater and ocean growth were distinguished by the close spacing of circuli during the freshwater phase, becoming widely spaced upon ocean entry as growth rate increased. Annuli were determined by the cutting or crossing-over of circuli, incompleteness of circuli, and narrowing of the distance between circuli. A year of growth was considered to be the time from the formation of the last circulus of an annulus to the formation of the last circulus of the succeeding annulus. Circuli between annuli were counted and measured relative to the entire scale length. Scales were examined for half-pounder checks and for spawning checks present at annuli. Spawning checks are apparent when scales display overlapping circuli and areas of moderate to heavy lateral and anterior scale resorption. Small amounts of resorption often occur in the anterior portion of the scale but do not necessarily represent a spawning check. Half-pounder checks are characterized by a zone of closely spaced circuli relatively close to the circuli that distinguished ocean entry, indicating only a short period of time was spent in the ocean prior to re-entering freshwater. Half-pounder checks resemble a spawning check but lack the dense circuli overlap and accompanying resorption of scale edges seen on spawning checks (Hopelain 1987).

We have found the first two years of growth patterns on adult scales hard to interpret. Thus, emphasis was placed on a more intensive study of juvenile scales in order to better understand the patterns of scale development and growth associated with the early life history phase of juvenile fish. This will greatly assist in the interpretation of adult scales. Juvenile steelhead scale samples were read using the Optical Pattern Recognition System (OPRS). The OPRS method digitizes, measures, and records distances for each freshwater circuli on each scale examined. Statistical and graphic software was then used to analyze and provide graphic hard copy of the summarized scale data.

(continued)

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