Use of Habitat Types by Steelhead Trout (Oncorhynchus mykiss) During Summer Low Flow Conditions in Lower Hayfork Creek
by Patrick Higgins, Fisheries Biologist
Pacific Watershed Associates
Abstract: A dive survey was conducted on four reaches of lower Hayfork Creek from August 22 to August 25, 1994 to determine the use of various habitat types by juvenile steelhead trout during summer low flow conditions. Approximately 2,916 meters (9477 ft.) of Hayfork Creek were surveyed and 1,859 steelhead trout (Oncorhynchus mykiss) counted. The age composition of fish counted were: 930 young of the year steelhead, 407 yearlings, 514 steelhead trout two years old or older and 8 adult summer steelhead. It is possible fish counted in the older age juvenile category may in fact be resident trout but that determination will require further study. Juvenile steelhead favored environments with turbulence, such as riffles and step runs. Densities of steelhead juveniles in pools and quiet water habitats was greater in reaches of Hayfork Creek below cold water tributaries such as Minor Creek and Corral Bottom Creek.
Introduction
Hayfork Creek was reputed by local residents to be an excellent trout fishing stream which supported spring chinook salmon up to the falls above the East Fork Hayfork Creek until about 1960 (Pacific Watershed Associates, 1994). In recent years spring chinook are rarely counted in Hayfork Creek and steelhead trout juveniles and resident trout have declined considerably according to local accounts. High water temperatures, low flows and other water quality problems related to agricultural and domestic activity in Hayfork Valley are suspected to be limiting salmonid production (Trinity County, 1987; Frink et al., 1990). While salmonids prefer water temperatures under 680 F (Reiser and Bjornn, 1979), the stream temperature in lower Hayfork Creek at Hyampom has been measured at 840 F (U.S. Forest Service, 1991).
The Action Plan for Restoration of the South Fork Trinity River Watershed and its Fisheries (Pacific Watershed Associates, 1994) recommended increasing flows and improving water quality in the Hayfork sub-basin as a priority. A South Fork Trinity River Cooperative Resource Management Planning (CRMP) group has been formed to help restore fisheries and revitalize the economy of the basin. With the help of the Natural Resource Conservation Service (NRCS) and the Trinity County Resource Conservation District (RCD), the CRMP has won cooperation and funding for pilot projects to improve efficiency of water use and restore riparian zones in Hayfork Valley. If these projects are successful and further measures are implemented, then flows and water quality in Hayfork Creek may improve substantially over the next several years.
A U.S. Forest Service (USFS) habitat typing survey of lower Hayfork Creek in 1990 found that the number of steelhead juveniles per unit of habitat area was low relative to many other South Fork Trinity River tributaries (Arey and Gilroy, 1993). The highest densities of steelhead juveniles occurred in low gradient riffles, cascades, step runs and step pools. McCaslin et al. (1988) also found the greatest concentration of juvenile steelhead in turbulent environments during a dive sweep of lower Hayfork Creek to enumerate summer steelhead.
This study was performed on behalf of the CRMP to obtain additional baseline information on how juvenile steelhead are using various habitat types in lower Hayfork Creek during times of low flows and high stream temperatures. This study can serve in part to judge the effectiveness of current efforts to improve conditions in the creek. Fish densities should increase after flows are increased and stream temperatures decline. Habitat selection by juvenile steelhead may include more quiet water environments such as runs and pools, if efforts to moderate stream temperature are successful.
Four reaches of lower Hayfork Creek were surveyed from August 22-25, 1994. Students from Hayfork High School participated in the dive to help augment man power and to receive training in fisheries monitoring techniques. A secondary goal of the exercise was to expose students to potential career paths in natural resources. The monitoring survey was made possible by the USFS which supplied transportation, two crew members as well as dive gear and liability insurance coverage for volunteers. Safety training for volunteers was required by the USFS and Joe Zustak, fisheries biologist with Shasta Trinity National Forest, provided such training before the survey began. The study was funded by the U.S. Bureau of Reclamation Office in Weaverville as part of the Trinity River Restoration Program.
Methods
Four stream reaches of lower Hayfork Creek were surveyed: one just below Nine Mile Bridge, another just downstream of Miner Creek and two in the vicinity of Bar 717 Ranch (Figure 1) . Habitat types were identified using the system devised by McCain et al. (1990), but only lengths and widths of habitat units were measured. Fish were counted in every habitat unit as opposed to every fifth occurrence of each habitat which is the custom in a normal habitat typing survey. In most cases, habitat units were identified from downstream, dive sweeps conducted to count fish and habitat lengths and widths measured subsequently.
Divers counted fish by moving upstream three or four abreast, depending on stream width, similar to methods described by Hankin and Reeves (1988). While Hankin and Reeves (1988) recommend that divers attempt to count all fish independently and then compare results, observation of the entire width of Hayfork Creek from one vantage point was not possible. Therefore, each diver occupied a lane in the stream and was responsible for counting fish in that particular stream area. To avoid double counting, divers advanced in a line and conferred when fish traveled across the stream into different lanes. Sub-totals were compiled and recorded on Plexiglas dive slates at various points in long habitat units.
Ages of juvenile steelhead were estimated using standard age groupings by size, used by Shasta Trinity National Forest (Joe Zustak, personal communication). Fish less than 100 mm (4 in.) were considered to be young of the year (0+), juvenile steelhead trout between 100-150 mm (4-6 in.) in length were counted as yearlings (1+) and fish greater than 150 mm were noted as two year old steelhead trout (2+). Steelhead longer than 400 mm (16 inches) were counted as adult summer steelhead.
Results and Discussion
Approximately 2,950 meters (1.8 miles) of lower Hayfork Creek were surveyed and 1,859 salmonids counted. The break down of age classes was 930 young of the year (O+) steelhead, 407 yearling (1+) steelhead, 514 older age steelhead juveniles (>150 mm) and 8 adult summer steelhead. Of the trout longer than 150 mm, 113 were estimated to be between 300-450 mm in length which could indicate that there is a resident trout component of the population or a 3+ steelhead juvenile life history. The number of salmonids was highest in reaches below the influx of cold water tributaries such as Miner Creek and Corral Creek.
Reach 1 (Below Nine Mile Bridge): This reach spanned 667 meters to a point just downstream of the convergence of Hayfork Creek with Judd Creek. Fifteen habitat units were sampled with six habitat types present. Table 1 lists the length and width of each habitat type and the number of salmonids by age class present in Reach 1 of Lower Hayfork Creek. Low gradient riffles, runs, glides and main channel pools all accounted for three habitat units each with the latter type comprising the greatest habitat area (Figure 2). A long step run and a high gradient riffle made up the remainder of habitats sampled.
Table 1. Habitat typing and steelhead juvenile utilization data for Reach 1 (below Nine Mile Bridge) in Lower Hayfork Creek.
Habitat Name Habitat Length Av. AREA 2+ SH 1+ SH 0+ SH Summer
# Width SH
main channel 17 42.0 10.5 441.00 3 0 2 0
pool
glide 14 15.2 10.1 153.52 0 0 0 0
low grade 1 15.6 4.8 74.88 0 0 0 0
riffle
glide 14 31.2 9.0 280.80 0 0 0 0
run 15 25.0 3.8 95.00 0 0 6 0
main channel 17 45.8 10.2 467.16 0 0 0 1
pool
low grade 1 12.3 4.2 51.66 0 0 0 0
riffle
main channel 17 52.3 10.8 564.84 0 0 2 0
pool
low grade 1 34.6 7.0 242.20 0 0 2 0
riffle
run 15 16.5 5.4 89.10 2 5 0 0
step run 16 134.0 10.8 1447.20 1 5 36 0
main channel 17 116.1 12.5 1451.25 0 1 3 0
pool
high grade 2 35.0 5.6 196.00 0 0 6 0
riffle
run 15 31.2 6.5 202.80 0 0 5 0
glide 14 27.0 10.2 275.40 0 0 0 0
Totals 633.8 6032.81 6 11 62 1
Figure 2. Cumulative area for each habitat type in square meters for Reach 1 of Lower Hayfork Creek (below Nine Mile Bridge).
Juvenile steelhead densities were extremely low in all habitat types of Reach 1 averaging just 0.0131 fish per square meter. Only juvenile steelhead were counted of which 66 were young of the year. Turbulent stream environments such as high and low gradient riffles and step had higher densities of juvenile steelhead than pools (Figure 3). Glides had no steelhead at all. The highest number of steelhead juveniles counted was in the lone step run. In runs and pools, young steelhead were often concentrated at the head of the habitat unit where some turbulence existed.
The water temperature during this first day of the survey was 630F at 10:00 hrs. but by 16:00 hrs. the water temperature had risen to 700 F. The moderate stream temperature for Hayfork Creek for this period of summer was influenced by night time temperatures the evening prior in the low 40's (F). The high air temperature on Monday, August 22, was 78 F. One main channel pool was found to be stratified, although it was only 8 feet deep. Surface temperatures at 13:15 hrs. was 67 F while the temperature at the bottom of the pool was 65 F. The latter pool did have 2+ steelhead juveniles present.
Figure 3. Densities of juvenile steelhead per square meter by habitat type in Reach 1 of lower Hayfork Creek. below Nine Mile Bridge.
Speckled dace (Rhinichthys osculus) were present in every habitat unit in very high densities in Reach 1. Some Klamath small scale suckers (Catostomas rimiculus) were present, however, no adult specimens were noted and densities of juvenile suckers were much lower than in reaches surveyed subsequently. Some problems with fish health were apparent. Dace and suckers had numerous ectoparasites and protuberances. Although dace and suckers often prefer quiet water habitats, these fish were often in riffles in Reach 1. Juvenile steelhead young of the year (0+) were noted feeding in sub-dominant positions in schools of speckled dace in riffle habitats.
Reach 2 (Below Miner Creek): Reach 2 began with a high gradient riffle approximately 15 meters below the confluence of Miner Creek and extended 700 meters downstream. Habitat types in this reach only were measured proceeding downstream in the morning and fish counted while moving back upstream later in the day. Table 2 shows the habitat types encountered, their relative length, average width and the number of steelhead by age class counted in each unit. Much of Reach 2 was dominated by boulders which resulted in pocket water being the most frequently encountered habitat type and also the greatest habitat area (Figure 4). High gradient riffles, cascades, runs and main channel pools were the next most prevalent habitat types with three each being found. A trench pool, one boulder formed pool and a long step run comprised the rest of the habitats inventoried.
Table 2. Habitat typing and steelhead juvenile utilization data for Reach 2 (below Miner Creek) in Lower Hayfork Creek.
Habitat Name Habitat Length Av. Area 2+ SH 1+ 0+ Summer SH
# Width SH SH
high grade riffle 2 80.2 8.1 649.62 6 15 63 0
main channel pool 17 54.0 15.0 810.00 25 20 22 0
high grade riffle 2 37.0 6.6 244.20 1 0 23 0
step run 16 108.8 7.0 761.60 3 11 71 0
main channel pool 17 19.0 9.2 174.80 2 4 20 0
pocket water 21 15.0 10.3 154.50 0 3 6 0
cascade 3 14.5 9.2 133.40 2 3 15 0
run 15 21.5 7.3 156.95 1 7 17 0
main channel pool 17 27.4 9.2 252.08 13 24 38 2
pocket water 21 45.9 7.1 325.89 2 0 15 0
cascade 3 9.5 9.4 89.30 1 3 18 0
lateral scour 20 28.8 8.3 239.04 1 3 10 0
boulder pool
run 15 9.7 6.9 66.93 1 1 3 0
trench pool 8 45.8 11.1 508.38 44 20 15 1
pocket water 21 41.5 14.8 614.20 2 1 15 0
cascade 3 29.3 8.2 240.26 3 9 45 0
pocket water 21 62.7 9.8 614.46 0 8 34 0
run 15 49.6 9.1 451.36 3 11 9 0
Totals 700.2 6486.97 110 143 439 3
Figure 2. Cumulative area for each habitat type in square meters for Reach 2 of Lower Hayfork Creek (below Miner Creek).
Densities of juvenile steelhead were an order of magnitude higher in Reach 2 than in Reach 1 with a density of 0.1066 juvenile steelhead per square meter and a total of 692 fish counted. The greatest concentration of juvenile steelhead were found in cascades, step runs and high gradient riffles, respectively (Figure 5). However, quiet water environments had significantly more fish than in Reach 1, although fish were often congregated around cold water sources such as springs or at the bottom of stratified pools. Speckled dace were less abundant in Reach 2 but suckers were more numerous with many older age suckers present. Fish health problems were still very apparent. One dead sucker approximately 200 mm was found with numerous signs of pathological conditions.
Air temperature at 10:10 hrs. was 690 F and water temperature was 670 F but by 16:00 hrs. the air temperature was 840 F and the water temperature was 720 F. The lone trench pool was found to be stratified, as the surface temperature was 710 F but the bottom temperature 660 F. Forty four
Figure 5. Juvenile steelhead densities per square meter by habitat type in Reach 2 of lower Hayfork Creek below Miner Creek.
2+ steelhead and an adult summer steelhead were counted in this trench pool and numerous young of the year, yearling steelhead were present. Most of the 0+ and 1+ juvenile steelhead were at the front of the trench pool, associated with falling water. The other significant concentration of steelhead was found in a main channel pool that was only 8 feet deep but that had a spring source in the bottom of the pool. While the surface temperature had risen to 720 F, a pocket of water 610 F was discovered at the bottom of the pool. Sixty of the 75 steelhead and rainbow trout sighted in this pool were in an extremely small (less than 3 square meters) area around this spring source. At the end of the day, a mixture of approximately 20 yearling and 2+ steelhead trout were seen congregating in the cool water at the mouth of Miner Creek where water depth was only 30-50 cm.
Reach 3 (Bar 717 Upstream to Just Above Corral Creek): This reach extended upstream of the seasonal car bridge at Bar 717 for approximately 905 meters to just above the mouth of Corral Creek. Nine different habitat types were found in this reach and 702 steelhead trout counted. The lowest four habitat units in Reach 4 were surveyed and fish counted on the afternoon of Wednesday, August 24 with the remainder of Reach 3 covered on the following day. There were three step runs in Reach 3 and two each of high gradient riffles, pocket water, boulder formed pools, lateral scour boulder pools, main channel pools and plunge pools. Hayfork Creek in Reach 3 had several sections with braided channel, including segments of runs, step runs and a cascade. Main channel pools, boulder pools and lateral scour boulder pools were the predominant habitats by area in Reach 3 (Figure 6). Table 4 lists all habitat types, including length, average width and area, as well as all steelhead counted in each unit.
Figure 6. The area of various habitat types in Reach 3 in square meters.
Reach 3 below Corral Creek had steelhead juvenile densities of 0.054 fish per square meter and a total of 699 young steelhead counted. Habitats with turbulence again had a fair representation of juvenile steelhead (Figure 7) but pools and runs also had significant numbers of older age steelhead juveniles and three summer steelhead. Concentrations of salmonids often occurred at the head of pools near water falls. Reach 3 was unique in that 2 year old steelhead were the most abundant age class. Many fish over 300 mm were noted in this reach as well. Speckled dace and sucker abundance in Reach 3 was very similar to that in Reach 2.
Table 3. Habitat typing and steelhead juvenile utilization data for Reach 3 (below Corral Creek) in Lower Hayfork Creek.
Habitat Name Habitat Length Av. Area 2+ 1+ SH 0+ Summer SH
# Width SH SH
main channel 17 194.0 16.2 3142.80 0 0 0 0
pool
step run 16 75.3 6.1 459.33 27 3 3 0
lateral scour 20 53.2 12.6 670.32 3 0 0 0
boulder pool
step run 16 41.0 12.8 524.80 2 2 0 0
plunge pool 9 15.0 11.3 169.50 7 5 5 0
step run 16 15.3 4.3 65.79 2 8 4 0
step run 16 21.1 2.1 44.31 2 5 4 0
lateral scour 20 71.0 16.0 1136.00 58 20 8 3
boulder pool
high grade 2 26.0 13.0 338.00 14 17 26 0
riffle
lateral scour 20 124.0 14.8 1835.20 37 15 7 0
boulder pool
pocket water 21 34.0 10.3 350.20 22 18 23 0
lateral scour 20 26.6 11.0 292.60 32 10 12 0
boulder pool
step run 16 37.8 7.9 298.62 6 9 15 0
plunge pool 9 23.6 10.1 238.36 19 14 20 0
run 15 9.7 4.6 44.62 12 6 4 0
cascade 3 17.2 5.6 96.32 9 6 16 0
run 15 12.1 6.1 73.81 10 10 8 0
high grade 2 10.8 4.0 43.20 0 2 7 0
riffle
lateral scour 20 45.3 29.0 1313.70 39 20 17 0
boulder pool
pocket water 21 57.4 11.8 677.32 6 4 10 0
main channel 17 42.3 22.1 934.83 19 4 6 0
pool
Totals 952.7 12749.63 326 178 195 3
Corral Creek had a substantial moderating influence on the temperature of the main stem of Hayfork Creek which was reflected in higher concentrations of salmonids in quiet water environments just below its entry. Large boulders were prevalent throughout the reach and provided elements of habitat complexity. Most of the stream reach was very confined. The combination of roughness elements, hydraulic energy and low levels of fine sediment combined to form deep scour pockets and cave-like hollows under boulders in numerous places.
Figure 7. Juvenile salmonid densities (fish/square meter) in various habitat types in Reach 3 of lower Hayfork Creek below Corral Creek.
No salmonids were found in a 194 meter long pool unit at the lower end of Reach 3. Salmonid densities remained extremely low in the two step runs and the lateral scour boulder pool, which were the last three units checked on Wednesday afternoon (8/24). The only concentration of steelhead juveniles found in the four habitats were wedged under a boulder and protected by a log in a step run. Ten fresh piles of otter scat (consisting mostly of crayfish parts) were discovered on a point bar mid-way through the 194 meter "fishless" pool on Thursday morning. Avoidance behavior by steelhead trout may have skewed results in the lower end of Reach 3, decreasing the number of fish counted.
One lateral scour boulder pool, approximately 5 meters in depth, was worthy of note. Dozens of large boulders formed a series of narrows and caves in the rear of the pool. The pool also had the highest number of fish counted in any other individual habitat during the four days of the survey. Three adult summer steelhead, 58 2+ steelhead, 20 yearlings and eight young of the year were counted. Approximately one third of the salmonids were in front of the pool taking advantage of turbulence associated with a water fall. The balance of the fish were disbursed throughout the pool. The next highest concentration of salmonids was in the pool immediately below the convergence of Corral Creek. Fish were disbursed throughout the pool, presumably because cool temperatures prevailed. Corral Creek was approximately 650 F while the main stem of Hayfork Creek above the convergence was over 750 F. The water temperature at Bar 717 at 16:30 hrs. on Wednesday (8/24) was 720 F while on Thursday (8/25) at the same time the water temperature was 740 F. The air temperature on Thursday afternoon was 950 F.
Reach 4 (Bar 717 Above and Below Grassy Flat Creek): The dive team was allowed access to Hayfork Creek across the Bar 717 Ranch. Reach 3 covered approximately 640 meters with the reach centered around the mouth of Grassy Flat Creek. The length, average width and area of each habitat type surveyed in Reach 4 is listed in Table 4 along with results of fish counts. Boulder formed pools and high gradient riffles were the dominant habitat types with four of each found. By habitat area, runs and boulder formed pools were the predominant habitat types (Figure 8).
Table 4. Habitat typing and steelhead juvenile utilization data for Reach 4 in Lower Hayfork Creek (above and below Grassy Flat Creek..
Habitat Name Habitat Length Av. Area 2+ 1+ SH 0+ Summer
# Width SH SH SH
lateral scour 20 63.4 13.0 824.20 0 1 5 0
boulder pool
high grade 2 21.4 9.5 203.30 5 8 27 0
riffle
lateral scour 20 19.4 6.9 133.86 8 10 22 0
boulder pool
high grade 2 49.9 6.8 339.32 12 16 22 0
riffle
lateral scour 20 89.0 16.9 1504.10 4 12 18 1
boulder pool
high grade 2 23.0 10.0 230.00 0 1 44 0
riffle
lateral scour 20 35.3 13.6 480.08 5 1 7 0
boulder pool
high grade 2 36.3 7.2 261.36 4 8 66 0
riffle
lateral scour 20 47.6 25.5 1213.80 2 1 6 0
boulder pool
low grade 1 18.5 15.0 277.50 0 0 2 0
riffle
run 15 236.0 15.3 3610.80 32 16 10 0
Totals 639.8 9078.32 72 74 229 1
Juvenile steelhead densities in Reach 4 were 0.0413 fish per square meter with 375 fish counted, not including summer steelhead. Young of the year steelhead showed a strong preference for high gradient riffles, although 1+ and 2+ steelhead were also found in these turbulent environments (Figure 8). Densities of fish in boulder formed pools were very low. Speckled dace were more numerous in this reach than in Reach 2 or 3 but less than in Reach 1 and were intermixed in riffle habitats with 0+ steelhead. Suckers in various size classes were present in many habitats.
Figure 8. The relative proportion of habitat types surveyed in Reach 4 of Lower Hayfork Creek above and below Grassy Flat Creek.
Figure 9. Juvenile salmonid densities (fish/square meter) in various habitat types in Reach 4 of lower Hayfork Creek above and below Grassy Flat Creek.
The furthest upstream portion of Reach 3 was a run 236 meters long. Few fish were seen through more than 150 meters except three 2+ steelhead trout in a spring area along the right bank. Hayfork Creek spilled into the top of this run through a braided channel which was split into a high gradient riffle and a cascade. The run habitat continued above as a side channel with no visible inlet. The water in this area was apparently percolating under the gravel bar and the temperature in this isolated area was quite cold (650 F) . Over 40 2+ juvenile steelhead were counted in one school in this area. One small boulder formed pool (19.4 m long) had 39 steelhead juveniles but most of the fish were taking advantage of turbulence that provided cover in over 1/3 of the pool. The largest boulder formed pool below Grassy Flat Creek was over 20 feet deep with a boulder/cobble substrate. Thirty juvenile steelhead congregated near a spring on the left bank and one summer steelhead was sighted under turbulence near the front of the pool. . At the beginning of the survey, the water temperature was 66 F while air temperatures at 09:35 hrs. was 67 F.
Aquatic Organisms Other Than Fish
Crayfish were present in all reaches surveyed but were in particularly high abundance in Reach 1 where riffles sometimes harbored more than 4 adults per square meter. Young of the year crayfish in Reach 1 were found by the dozens in quiet water areas of pools in among detritus. Western pond turtles were seen in all reaches throughout the survey. Fresh water clams or mussels were found in a run habitat type in Reach 2 and measured 17.5 mm by 100 mm. In the large pool below Grassy Flat Creek in Reach 4 an extensive bed of these clams covered much of the bottom below a spring source on the left bank. Three western pond turtles, including one full grown adult, were seen in this pool.
Conclusion
This survey found the overall density of juvenile steelhead in the four reaches of lower Hayfork Creek to be 0.054 which is very similar to the 0.061 density found by Arey and Gilroy (1993) for all reaches of lower Hayfork. However, there was a substantial difference in fish densities between reaches, with Reach 1 having by far the lowest number and density of juvenile steelhead. Fish densities were ten times greater in Reach 2 below Miner Creek than in Reach 1 and five times higher in Reach 3 and 4. Water quality and water flows at Nine Mile Bridge show the effects of agricultural and domestic activity in Hayfork Valley. Warmer water seemed to be conveying a competitive advantage to speckled dace over salmonids in Reach 1 similar to what Reeves (1988) found in the Umpqua River for red side shiners and juvenile steelhead.
Flows from larger cold water tributaries such as Miner Creek and Corral Creek help to improve water quality and allow increased rearing habitat for juvenile salmonids in some reaches. In Reach 1 almost all steelhead were grouped in turbulent environments such as riffles. The use of these habitats may be related to increased oxygen availability that may help salmonids cope with the stress of high water temperatures during summer low flow conditions. Pool habitats in Reach 2 and 3 showed the highest use (Figure 10), although this is somewhat skewed in the reach below Miner Creek because of one pool with a spring source and a high number of fish. This increased pool use may reflect less stressful water temperatures. Hayfork Creek tends to warm back up as it travels through open gorge areas that expose it to the full arc of the summer sun. The decreased use of pools in Reach 4 may in part reflect the natural increases in stream temperature
Figure 10. The density of all age classes of juvenile steelhead in all pools by reach in lower Hayfork Creek.
Because of acute water temperature problems in the South Fork Trinity River watershed, there are few areas where juvenile steelhead can rear over summer (PWA, 1994). Tempertures over 800 F have been recorded for both the lower South Fork Trinity River and lower Hayfork Creek at Hyampom. In order to survive to adulthood, steelhead in California typically need to reside in freshwater for two to three years (Barnhart, 1986). Cold water refuge areas below cold tributaries in lower Hayfork Creek may be extremely important in helping juvenile steelhead survive to an older age and subsequently recruit into the adult steelhead population. Activities in the watersheds of all major Hayfork tributaries such as Bear Creek, Miner Creek and Corral Creek should be managed carefully so as not to increase water temperature or sediment load which would decrease the buffering capability of these streams on lower Hayfork Creek.
A follow up study should be conducted to determine whether the larger rainbow trout in lower Hayfork Creek are residents or evidence of a 3+ steelhead life history. This could be done fairly easily with scales samples. Noting the changes over time of the relative abundance of steelhead and speckled dace in Reach 1 through use of electrofishing could show changes in community structure over time as water flows increase in Hayfork Creek and water temperatures drop.
References
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Barnhart, R.A. 1986. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Pacific Southwest), steelhead. USFWS Biol. Rep. 82 (11.60) funded in part
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CA.
Reeves, G. 1985. Competition between redside shiners and steelhead trout in the Umpqua River,
Oregon. Doctoral thesis, Oregon State University, Corvalis, OR.
Reiser, D.W. and T.C. Bjornn. 1979. Habitat Requirements of Anadromous Salmonids. In: Influence of Forest and Rangeland Management on Anadromous Fish Habitat in the Western United States. USDA USFS, Gen. Tech. Pub. PNW-96.
Trinity County. 1987. Memo to the Board of Supervisors on Hayfork Valley Critical Water Resources Overlay Zone, 8/27/87. Trinity Co. Planning Dept., Weaverville, CA, 23 p.
USDA Forest Service. 1991. South Fork Trinity River Watershed and Fisheries Monitoring Program, 1991 Progress Report. USDA Forest Service, Shasta-Trinity National Forest, Redding, CA,
49 p. + appendices.
Zustak, Joe. Personal communication. USFS Fisheries Biologist, Shasta Trinity National Forest, Redding, California.