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CHAPTER IV. RUN-SIZE, ANGLER HARVEST, AND SPAWNER ESCAPEMENT OF CHINOOK AND COHO SALMON IN THE TRINITY RIVER BASIN (Continued).

Recovery of Tagged Fish

Tagging Mortalities

Spring-run Chinook Salmon.

We trapped 1,512 spring chinook at JCW, and released 46 of them untagged. Fifty-two (3.5%) of the 1,466 fish we tagged were recovered dead at the weir and in the river surveys, or were reported as such by anglers. Therefore, 1,414 spring chinook (27 grilse and 1,387 adults) were effectively tagged at JCW during the 1989-90 season, including 462 fish with reward tags (21 grilse and 441 adults). The mean FL of those fish recovered or reported dead was 67.2 cm, essentially the same size as the fish we originally trapped at the weirs (Table 2).

Fall-run Chinook Salmon.

We trapped 1,392 fall chinook at WCW, 26 of which were released untagged and 10 (1.9% of those tagged) were later recovered dead at the weir or reported as dead by anglers. Therefore, 1,356 fall chinook (87 grilse and 1,269 adults) were effectively tagged at WCW in the 1989-90 season, including 300 fish with reward tags (38 grilse and 262 adults). The mean FL of fish categorized as tagging mortalities was 65.5 cm, similar to the fall chinook we trapped at the weirs (Table 4).

We trapped 541 fall chinook at JCW, 21 were released untagged, and one (<1%) tagged fish was recovered dead. Therefore, 519 fall chinook (17 grilse and 502 adults) were effectively tagged and released at JCW.

Coho Salmon.

We trapped 471 adult coho at WCW, released six untagged, and 2 (<1.0%) were recovered dead. Thus 463 adult coho were effectively tagged at WCW, including 125 reward tagged fish.

At JCW, we trapped 660 coho, released 21 fish untagged, and there were no tagging mortalities. Thus, 639 adult coho were effectively tagged at JCW.

Reward Tag Returns by Anglers

Spring-run Chinook Salmon.

Anglers returned 46 reward tags (4 grilse and 42 adult) of 462 effectively reward-tagged spring chinook (21 grilse and 441 adults), for an overall harvest rate of 10%. The harvest rate of grilse appeared to be over twice that of adults, but so few grilse were reward tagged and harvested that the difference was not statistically significant (X2=0.9, p=0.35).

The mean FL of the spring chinook caught by anglers was 63.9 cm FL slightly smaller than those effectively reward tagged (65.4 cm FL). The number of days between tagging and reported recapture ranged from 3 to 86 d, for a mean of 32 d.

Fall-run Chinook Salmon.

Anglers returned 21 tags (2 grilse and 19 adults) of 300 effectively reward tagged fall chinook (38 grilse and 262 adults) for a harvest rate of 7.0%.

The mean FL of the 21 harvested fall chinook was 64.6 cm FL, slightly larger than the 300 effectively reward tagged fish (63.6 cm FL).

The time between tagging and recapture for sport-caught fall chinook ranged from 3 to 48 d for a mean of 19 d.

Capture locations for fall chinook tagged at WCW were reported by 65 anglers, and 26 anglers (40%) indicated they had caught their fish upstream of JCW. Therefore, we assume 40% of all the fall chinook migrating past WCW which were later caught by anglers, were caught upstream of JCW.

Coho Salmon.

Only two reward tags from the 125 effectively tagged adult coho were returned by anglers for a harvest rate of 1.6%. These fish were 53 cm and 65 cm FL, and had been at liberty for 18 d and 16 d, respectively.

Two reward and two non-reward tags from coho were returned by anglers, one of which was from a fish caught upstream of JCW. Therefore, we assume 25% of all the coho migrating past WCW which were later caught by anglers, were caught upstream of JCW.

Salmon Spawner Survey

Spring-run Chinook Salmon.

Personnel of the TFIP recovered 86 Project-tagged spring chinook, 83 of which were tagged at JCW and three at WCW. The recovery rates in the spawner survey of JCW- and WCW-tagged spring chinook were 5.9% and 4.9%, respectively.

The sizes of the fish recovered from JCW ranged from 46 to 82 cm FL and averaged 67.6 cm FL, almost identical to the mean FL of all effectively-tagged fish (67.5 cm FL).

The WCW-tagged spring chinook were recovered in the spawner survey from 63 to 70 d after tagging, for a mean of 66 d, whereas JCW-tagged spring chinook were recovered in the survey from 30 to 197 d after tagging, for a mean of 95 d.

Fall-run Chinook Salmon.

Personnel of the TRIP recovered 121 Project-tagged fall chinook, 53 of which had been tagged at WCW and 68 at JCW. One of these fish was tagged at WCW on 14 September 1989, recovered and rereleased at JCW on 3 October, and subsequently found in the spawner survey on 7 November 1989. The recovery rates of Project-tagged fall chinook in the spawner survey were 3.9% and 13.1% for fish trapped at WCW and JCW, respectively.

The WCW-tagged fish recovered in the spawner survey ranged from 43 to 82 cm FL and averaged 66.6 cm FL, whereas those from JCW ranged from 40 to 111 cm FL and averaged 66.5 cm FL. The mean FLs of the two groups of spaghetti-tagged chinook salmon recovered in the spawner survey were approximately 1 cm greater than the original groups of effectively tagged fish from each respective weir (Table 4).

Fall chinook from WCW were recovered in the spawner survey from 25 to 101 d after being trapped and tagged, averaging 53 d. Those from JCW were recovered from 6 to 77 d after trapping and tagging, averaging 32 d. The 21 d difference in the mean number of days between tagging and recovery for each of the two weirs is the same as the mean number of days it took fall chinook to migrate between WCW and JCW.

Coho Salmon.

Spawner survey personnel recovered 100 Project- tagged coho, 29 of which were tagged at WCW and 71 at JCW. One of these coho was trapped at WCW on 29 September 1989, recovered and rereleased at JCW on 19 October, and found in the spawner survey 15 November 1989. Recovery rates of WCW- and JCW-tagged coho in the spawner survey were 6.3% and 11.2%, respectively.

The WCW-tagged coho recovered in the spawner survey ranged from 58 to 76 cm FL, averaging 65.9 cm FL, whereas JCW-tagged coho were from 57 to 75 cm FL, averaging 66.7 cm FL. The mean FLs of the recovered fish were similar to the averages for all fish effectively tagged at each respective weir (Table 6).

The WCW-tagged coho were recovered in the spawner survey 20 to 70 d after trapping, for a mean of 44 d. Tagged coho from JCW were recovered from 6 to 55 d after being tagged, for a mean of 24 d.

Trinity River Hatchery

Spring-run Chinook Salmon.

On the first day that fish were sorted at TRH, 901 of 919 chinook salmon entering the hatchery were spring chinook (based on CWT data). On all sampling days in September 1989, >90% of the chinook salmon entering TRH were spring chinook. The median entry date of spring chinook at TRH occurred on 21 September 1989 (Table 7). Spring and fall chinook each comprised approximately 50% of the chinook that entered TRH on 2 and 5 October. Thereafter, >90% of the chinook that entered TRH were fall chinook (Figure 8). The last spring chinook entered the hatchery on 19 October 1989. We estimate 5,000 spring chinook (17 grilse and 4,983 adults) entered TRH during the 1989-90 season.

We recovered 268 spring chinook at TRH that were spaghetti-tagged at JCW (4 grilse and 264 adults). Their median arrival date was 21 September 1989, the same as the arrival date for all spring chinook combined (Table 7). We also recaptured 11 spring chinook (all adults) at TRH that had been tagged at WCW. Their median arrival date was 10 October 1989. None of the spring chinook tagged at either weir had shed their spaghetti tag. We also recovered one spring chinook that had been tagged in the lower Klamath River. The recovery rates at TRH of WCW- and JCW-tagged spring chinook were 18.0% and 19.0%, respectively.

The sizes of the JCW-tagged spring chinook entering TRH ranged from 43 to 92 cm FL for a mean of 66.2 cm FL, 1.4 cm less then the mean FL of all effectively-tagged spring chinook from JCW (Table 2). However, the difference was not statistically significant (t=1.4, p>0.10).

The JCW-tagged spring chinook were recaptured at TRH from 16 to 116 d after they were tagged and released, for a mean of 73 d. In contrast, the spring chinook tagged at WCW were at liberty from 33 to 60 d, for a mean of 45 d. The WCW fish migrated at an average rate of 4.7 km/d. No migration rate was computed for JCW-tagged spring chinook, since these fish may have been holding in the river around JCW rather than actively migrating upstream as they were past WCW, which is lower in the system.

We recovered 671 CWTs from 723 hatchery-marked (Ad+CWT) spring chinook that entered TRH during the 1989-90 season. Fish from the 1985 and 1986 BY release groups of yearlings comprised 88% of the CWT spring chinook we recaptured (Table 8). The median entry date of the hatchery-marked spring chinook was 21 September 1989, the same as that for all spring chinook combined (Table 8).

Table 7

Figure 8

Table 8

Fall-run Chinook Salmon.

Based on our analysis of CWTs, a few fall chinook were recovered during the first sampling day at TRH and throughout September, but they did not begin to enter TRH in large numbers until 2 October 1989 (Figure 8). We estimate the median entry date of fall chinook occurred on 26 October, and the last chinook salmon entered TRH on 18 December 1989 (Table 7). We estimate 11,371 fall chinook (239 grilse and 11,132 adults) entered TRH during the 1989-90 season.

Three hundred thirty fall chinook tagged at WCW (5 grilse and 325 adults) entered TRH, which equaled 24.3% of those we effectively tagged at that site. This total included two fish that shed their spaghetti tag. The median entry date of the tagged fish was 26 October 1989, the same as the median entry date for all fall chinook combined.

The WCW-tagged fall chinook entering TRH ranged from 45 to 86 cm FL, for a mean of 65.0 cm FL, similar to the mean size (65.4 cm) of all fish effectively tagged at WCW (Table 4).

Fall chinook tagged at WCW entered TRH from 12 to 71 d after they had been tagged and released, for a mean of 36 d. Their mean migration rate upstream of WCW was 3.7 km/d, slightly slower than the spring chinook tagged at WCW. The faster migration rate of spring chinook is not surprising, since they begin spawning before fall chinook.

We recaptured 198 fall chinook (3 grilse and 195 adults) at TRH that had been tagged at JCW, including nine fish that had originally been tagged at WCW, and two that had originally been tagged in the lower Klamath River. Thus, 38.2% of the fall chinook tagged at JCW were recaptured at TRH. The median entry date of fish tagged at JCW was the same as that for all fall chinook combined, 23 October 1989.

Fall chinook tagged at JCW and recaptured at TRH ranged from 40 to 111 cm FL, for a mean of 65.7 cm FL, which was almost identical to the average for all fall chinook effectively tagged at JCW (Table 4).

Fall chinook tagged at JCW were recovered from 6 to 42 d later at TRH, for a mean of 14 d for migration between the two points. Their mean migration rate was 3.2 km/d, slightly slower than the fall chinook tagged at WCW. The mean number of days it took fall chinook from JCW to enter TRH was three weeks less than it took fall chinook from WCW. The latter difference is equal to the mean migration time for fall chinook between WCW and JCW.

We also recovered 52 fall chinook that had been tagged in the lower Klamath River, 18 at the mouth and 34 at river km 5.1. Collectively, fall chinook tagged in the lower Klamath River took from 30 to 71 d to reach TRH, for a mean of 45 d. Their mean migration rate over the 248.5 km between the river mouth and the hatchery was 5.5 km/d.

We recovered CWTs from 1,120 of the 1,170 marked (Ad+CWT) fall chinook that entered TRH (Table 9). As with spring chinook, yearling releases of the 1985 and 1986 BYs comprised 89% of the CWT fall chinook recovered. The median entry date of the marked fall chinook was 26 October 1989, the same as for all fall chinook combined (Table 7).

Coho Salmon.

Coho began entering TRH on 12 October 1989. The numbers of coho entering the hatchery increased through 22 November, the median entry date, and then decreased through the end of the run on 8 January 1990 (Table 7). We recovered 4,970 coho entering TRH during the 1989-90 season.

We recovered 122 coho (all adults) at TRH that had been tagged at WCW, which equals 26.3% of the total coho effectively tagged at WCW (Table 6). Their median entry date at TRH was approximately a week before that of all coho combined, and was probably due to the WCW Weir being removed before the completion of the coho run, which prevented us from distributing tagged coho into the latter part of the run (Figure 6). One tagged coho had shed its spaghetti tag. The WCW-tagged coho we recaptured at TRH ranged from 49 to 72 cm FL, for a mean of 65.4 cm FL, equal to the average size of all fish effectively tagged at WCW (Table 6).

Coho tagged at WCW took from 18 to 69 d to enter TRH, for a mean of 37 d. Their mean migration rate upstream of WCW was 3.6 km/d, similar to the rate of the WCW-tagged fall chinook.

We recaptured 251 coho (all adults) at TRH that had been tagged at JCW, which equals 39.3% of the total coho effectively tagged at JCW. Their median entry date to TRH was the same as for all coho combined, 22 November 1989. None of these coho had lost their spaghetti tag.

The JCW-tagged coho recaptured at TRH ranged from 52 to 75 cm FL, for a mean of 66.0 cm FL, similar to the average size of all coho effectively tagged at JCW (Table 6).

The JCW-tagged coho took from 3 to 71 d to migrate from the weir to TRH, for a mean of 13 d and a mean migration rate of 3.5 km/d, similar to the migration rate of coho tagged at WCW. Some of these fish moved very quickly, as four coho were recaptured at TRH three days after tagging at JCW and had migrated at a mean pace of 15 km/d.

Three coho tagged in the lower Klamath River at river km 5.1 were recaptured at TRH. They had been tagged and released from 50 to 58 d earlier, for a mean of 55 d and a mean migration rate of 4.4 km/d.

(Table 9)

We recovered 421 CWTs from 492 marked (Ad+CWT) coho at TRH (Table 10). The median entry date of marked coho was 22 October 1989, the same as for all coho combined. All of the CWT coho recovered, and probably even those that had shed tags, were fish from the 1986 BY released in March 1988.

Run-size, Angler Harvest, and Spawner Escapement Estimates

Run-size estimates of spring chinook upstream of JCW and fall chinook and coho upstream of both WCW and JCW were not stratified as grilse or adults this year, because too few tagged grilse were recaptured at TRH to have grilse estimates with 95% confidence limits within +10% of the run-size estimate. Therefore, we used the proportions of grilse and adult chinook salmon in each run trapped at the respective weirs for the grilse/adult compositions of the spring run upstream of JCW and the fall run above WCW and JCW. Since no grilse coho were trapped at either weir, we assumed the grilse/adult composition of the coho runs above both weirs to be the same as the grilse/adult composition of the coho that entered TRH.

Spring-run Chinook Salmon

We estimate 26,306 spring chinook (including those eventually harvested) migrated into the Trinity River basin upstream of JCW during the 1989-90 season (Table 11), and that 10% (2,630) of the spring run was caught by anglers (Table 12). Thus, the spawning escapement above JCW was 23,676 fish, including the 5,000 spring chinook that entered TRH (Table 12).

We made no attempt to determine the run size and angler harvest of spring chinook upstream of WCW because the fish trapped there represented a very small segment of the run.

Fall-run Chinook Salmon

We estimate that 46,622 fall chinook (including those eventually harvested) migrated into the Trinity River basin upstream of WCW during the 1989-90 season, and 29,716 of these fish continued their migration upstream of JCW (Table 11). We estimate that 3,263 (7%) of the fall chinook passing WCW were harvested by anglers, and 1,308 of these fish were caught upstream of JCW (Table 12). Therefore, we assume that 43,359 fall chinook spawned in the Trinity River basin upstream of WCW, and that 28,408 of those fish spawned in the Trinity upstream of JCW, including the 11,371 fall chinook that entered TRH (Table 12).

Coho Salmon

We estimate that 18,752 coho (including those eventually harvested) migrated into the Trinity River basin upstream of WCW during the 1989-90 season, and 12,625 of these fish continued their migration upstream of JCW (Table 11). We estimate that 300 (1.6%) of the coho were harvested by anglers upstream of WCW, 76 of which were caught upstream of JCW (Table 12). Thus, the spawning escapement estimate for coho upstream of WCW was 18,452 fish, including 12,549 fish that spawned upstream of JCW, 4,970 of which entered TRH (Table 12).

(Table 10) (Table 11)(Table 12)

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RECOMMENDATIONS

1. Tag and recapture operations of adult spring-run and fall-run chinook and coho salmon being conducted in the Trinity River basin should be continued during the 1990-91 migration season, using the capture sites near Willow Creek and Junction City.

2. In addition to chinook and coho salmon, steelhead trout should be added to the tag and recapture studies during the 1990-91 season.

3. A portion of the chinook and coho salmon, and steelhead trout trapped at Willow Creek Weir should be tagged with $20 reward tags to determine the extent of angler non-response of $10 reward tags.

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LITERATURE CITED

Chapman, D.G. 1948. A mathematical study of confidence limits of salmon populations calculated from sample tag ratios. Int. Pac. Sal. Fish. Comm. Bull. 2, p. 69-85.

Dixon, W., and F. Massey. 1969. Introduction to statistical analysis. McGraw-Hill Book Co., New York, N.Y. 638 p.

Gibbs, E. D. 1956. A report on the king salmon, Oncorhynchus tshawytscha, in the upper Trinity River, 1955. Calif. Dept. Fish and Game, Inland Fish. Admin. Rep. No. 56-10. 14 p.

Heubach, B. 1984. Progress Report 1981-82 Season. Task VI. Trinity River salmon and steelhead tagging program. p. 49-106. In: Paul 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. Dec. 1984. 106 p. Available from Calif. Dept. Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, CA. 95814.

La Faunce, D. A. 1965a. King (chinook) salmon spawning escapement in the upper Trinity River, 1963. Calif. Dept. Fish and Game2, Mar. Res. Admin. Rep. No. 65-3. 10 p.

_______________. 1965b. A steelhead spawning survey of the upper Trinity River system, 1964. Calif. Dept. Fish and Game, Mar. Res. Admin. Rep. No. 65-4. 5 p.

_______________. 1967. A king salmon spawning survey of the South Fork Trinity River, 1964. Calif. Dept. Fish and Game, Mar. Res. Admin. Rep. No. 67-10. 13 p.

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

Moffett, J. W., and S. H. Smith. 1950. Biological investigations of the fishery resources of Trinity River, California. USFWS Spec. Sci. Rep.--Fish. Bull. No. 12. 71 p.

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

Rogers, D. W. 1970. A king salmon spawning escapement and spawning habitat survey in the upper Trinity River and its tributaries, 1968. Calif. Dept. Fish and Game, Anad. Fish. Admin. Rep. No. 70-16. 13 p.

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

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

____________. 1973b. King salmon (Oncorhynchus tshawytscha) and silver salmon (Oncorhynchus kisutch) spawning escapement and spawning habitat in the upper Trinity River, 1970. Calif. Dept. Fish and Game, Anad. Fish. Admin. Rep. No. 73-10. 14 p.

____________. 1982. A spawning escapement survey of anadromous salmonids in the upper Trinity River, 1971. Calif. Dept. Fish and Game, Anad. Fish. Admin. Rep. No. 82-2. 11 p.

Schaffter, R. E., B. Heubach and P. M. Hubbell. 1979. FY 1978 Progress Report. Task IV. Upper Trinity River spring- and fall-run king salmon study. 8 p. In: Paul M. Hubbell (ed.), Fishery Investigations. Trinity River Basin Fish and Wildlife Task Force Priority Work Item No. 5, Evaluation Report--FY 1978 Activities. Jan. 1979. 102 p. Available from Calif. Dept. Fish and Game, Inland Fish. Div.-Room 1251, 1416 9th St., Sacramento, CA. 95814.

Smith, G. E. 1975. Anadromous salmonid spawning escapements in the upper Trinity River, California, 1969. Calif. Dept. Fish and Game, Anad. Fish. Admin. Rep. No. 75-7. 17 p.

Weber, G. 1965. North coast king salmon spawning stock survey, 1956-57 season. Calif. Dept. Fish and Game, Mar. Res. Admin. Rep. No. 65-1. 34 p.

Appendix 1

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