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

Juvenile Steelhead Habitat Utilization

Juvenile steelhead utilization of the five basic habitat types was evaluated in Eltapom Creek in the fall of 1992 (1-3 September). Prior to sampling, we identified 72 individual habitat units consisting of 2.8% cascades, 37.5% pools, 13.9% riffles, 16.7% runs, and 29.2% step-runs. We selected 24 of these units to sample: 1 cascade, 9 pools, 4 riffles, 3 runs, and 7 step-runs.

We captured a total of 481 juvenile steelhead during our sampling. The catch was composed of 80% (384 fish) Age 0+, 18% (86 fish) Age 1+, and 2% (11 fish) Age 2+ steelhead. We estimated the standing crop of juvenile steelhead at 1,594 fish (Table 13).

TABLE 13. Juvenile steelhead habitat utilization observed in Eltapom Creek during fall 1992 (1-3 September).

Habitat type	Number of units	Total area (m2)	Sampled area (m2)	Age	Number of fish caught	Density (fish/m2)	Standing crop estimate
Cascade	2	72.5	65.0	0+	8	0.123	9
				1+	8	0.123	9
				2+	1	0.015	1
				All	17	0.261	19
Pool	27	1518.0	337.0	0+	91	0.270	410
				1+	48	0.142	216
				2+	4	0.012	18
				All	143	0.424	644
Riffle	10	9681.0	2954.0	0+	71	0.024	233
				1+	8	0.003	26
				2+	0	0.000	0
				All	79	0.027	259
Run	12	9494.0	3685.0	0+	98	0.027	252
				1+	12	0.003	31
				2+	2	0.001	5
				All	112	0.029	288
Step-run	21	17333.0	4452.0	0	116	0.026	452
				1+	10	0.002	39
				2+	4	0.001	16
				All	130	0.029	507
Overall	72	38098.4	11493.1	0+	384	0.033	1273
				1+	86	0.007	285
				2+	11	0.001	36
				All	481	0.042	1594
a/ Sampling not conducted

The highest densities of Age 0+ steelhead were observed in pools (0.27 fish/m²) followed by cascades (0.12 fish/m²) (Table 13). Riffle, run, and step-run densities were similar for Age 0+ fish (0.02 to 0.03 fish/m²). The highest densities of Age 1+ steelhead occurred in pools and cascades (0.14 and 0.12 fish/m², respectively). Lower densities of Age 1+ fish were found in riffles, runs, and step-runs (0.002 to 0.003 fish/m²). Age 2+ fish densities were highest in cascades and pools (0.015 and 0.012 fish/m², respectively). Age 2+ steelhead were also found in runs and step-runs at very low densities. Age 2+ fish were not observed in riffles during fall 1992.

Densities and standing crop estimates of juvenile steelhead have ranged widely during the last four years. The numbers of juvenile fish utilizing the available habitat in Eltapom Creek during the fall has not correlated with the number of redds observed in our spring spawning surveys (Mills and Wilson 1991; (Wilson and Mills 1992; and Wilson and Collins 1992, 1994). A possible explanation is the seasonal variation in precipitation rates. High flow periods would have an effect on emigration patterns; passive migration by young-of-the-year (Age 0+ fish) may be increased during high flow events. Data collection needs to be continued to include normal precipitation years, so a more accurate analysis can be performed on these data.

Sampling was not conducted in the spring of 1993, because high flows in Eltapom Creek and the SFTR restricted access.

Steelhead Life-history Patterns

No juvenile steelhead scales were analyzed this year because of a lack of time and trained personnel.

RECOMMENDATIONS

1. Creel surveys in the SFTR basin should continue during the 1993-94 fiscal year to document angler use. Additional information is needed on harvest levels, especially during low-flow conditions.

2. Adult steelhead spawning surveys should begin by mid-February, weather permitting.

3. Steelhead spawning habitat studies, conducted in conjunction with the spawning surveys, should be continued throughout the basin. Habitat types should be quantified during these surveys to document spawning area available to steelhead.

4. The operation of adult salmonid capture weirs in Hayfork Creek and in the SFTR at Forest Glen to capture emigrant, post-spawning steelhead should continue.

5. Juvenile steelhead habitat utilization studies should continue. A direct observation survey by snorkeling, with comparison counts by electrofishing, should be conducted on various tributaries of the SFTR and Hayfork Creek. Juvenile salmonid densities in relation to habitat, brood year production, and rearing conditions throughout the basin can be assessed through these surveys.

6. Steelhead life-history studies through scale analysis should continue, with emphasis on the juvenile freshwater phase, to assess the juvenile age structure in the basin, and to determine if distinctive scale circuli patterns exist. Later, these patterns should be compared to the freshwater portions on adult scales to better understand the total life-history patterns of steelhead within the SFTR basin.

ACKNOWLEDGEMENTS

The authors thank Judith Jackson for her assistance in preparing the tables for this report, and the entire staff of the Natural Stocks Assessment Project working on the South Fork Trinity River for their assistance in field work and data collection.

LITERATURE CITED

Hampton, M. 1988. Development of habitat preference criteria for anadromous salmonids of the Trinity River. Available from U.S. Dept. Int., Fish and Wildl. Serv., Div. Ecol. Serv., Sacramento, California. 93 p.

Hunter, C. J. 1991. Better trout habitat: A guide to stream restoration and management. Island Press, Washington, D.C. 320 p.

Jong, H. W., and T. J. Mills 1993. Anadromous salmonid escapement studies, South Fork Trinity River, 1984 through 1990. Final Performance Report. Federal Aid in Sport Fish Restoration Act. California. Project No. F-51-R, Subproject No. IX, Study No. 9, Job No. 1. 130 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., P.O. Box 944209, Sacramento, CA 95814.

Miller, E. E. 1975. A steelhead spawning survey of the tributaries of the upper Trinity River and upper Hayfork Creek drainages, 1973. Calif. Dept. of Fish and Game, Anad. Fish. Admin. Rep. No. 75-5. 8 p.

Mills, T. J., and C. E. Wilson. 1991. Life history, distribution, run size, and angler harvest of steelhead in the South Fork Trinity River basin. Chapter III. Job III. pp. 34-51. In: R. Carpenter and K. Urquhart (eds.), Annual Report of the Trinity River Basin Salmon and Steelhead Monitoring Project, 1988-1989 Season. 51 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., P.O. Box 944209, Sacramento, CA 95814.

Ricker, W. E. 1975. Computation and interpretation of biological statistics of fish populations. Bull. Fish. Res. Board Can. #191. 382 p.

Rogers, D. W. 1972. A steelhead spawning survey of the tributaries of the upper Trinity River and upper Hayfork Creek drainages, 1971. Calif. Dept. of Fish and Game, Anad. Fish. Admin. Rep. No. 72-12. 6 p.

Rogers, D. W. 1973. A steelhead spawning survey of the tributaries of the upper Trinity River and upper Hayfork Creek drainages, 1972. Calif. Dept. of Fish and Game, Anad. Fish. Admin. Rep. No. 73-5a. 8 p.

Wilson, C. E., and B. W. Collins. 1992. Life history, distribution, run size, and angler harvest of steelhead in the South Fork Trinity River basin. Chapter III. Job III. pp. 50-92. In: K. Urquhart and R. Carpenter (eds.), Annual Report of the Trinity River Basin Salmon and Steelhead Monitoring Project, 1990-1991 Season. December 1992. 186 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., P.O. Box 944209, Sacramento, CA 95814.

Wilson, C. E., and B. W. Collins. 1994. Life history, distribution, run size, and angler harvest of steelhead in the South Fork Trinity River basin. Chapter III. Job III. pp. 56-102. In: K. Urquhart and R. M. Kano (eds.), Annual Report of the Trinity River Basin Salmon and Steelhead Monitoring Project, 1991-1992 Season. February 1994. 235 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., P.O. Box 944209, Sacramento, CA 95814.

Wilson, C. E., and T. J. Mills. 1992. Life history, distribution, run size, and angler harvest of steelhead in the South Fork Trinity River basin. Chapter III. Job III. pp. 44-81. In: K. Urquhart (ed.), Annual Report of the Trinity River Basin Salmon and Steelhead Monitoring Project, 1989-1990 Season. June 1992. 140 p. Available from Calif. Dept. of Fish and Game, Inland Fish. Div., 1416 9th St., P.O. Box 944209, Sacramento, CA 95814.

APPENDICES

APPENDIX 1. List of Julian weeks and their calendar date equivalents.

APPENDIX 2. Length of time between capture for salmonids tagged and released at Willow Creek Weir in the Trinity River, and their recapture at Sandy Bar Weir in the South Fork Trinity River during the 1992-93 season.