U.S. Dept Commerce/NOAA/NMFS/NWFSC/Publications
SESSION II : Stock Status and Carrying Capacity
Session Chair: D. W. Chapman, Don Chapman Consultants, Inc., Boise, Idaho
James W. Mullan
U.S. Fish and Wildlife Service
Leavenworth, Washington 98826
It is widely believed that chinook salmon stocks in the mid-Columbia River we severely depressed. Here I develop a paradigm that demonstrates that populations are stable and that the streams in this region now rear chinook salmon at carrying capacity.
The Wenatchee, Entiat, and Methow Rivers support wild spring chinook salmon. Leavenworth National Fish Hatchery (NFH) releases about 2.4 million spring chinook salmon yearlings annually to Icicle Creek, a tributary of the Wenatchee River. Entiat and Winthrop NFHs release about 1.0 million yearlings to the Entiat and Methow River.
I assessed escapements to the Wenatchee, Entiat, and Methow Rivers as the differences between adult counts at appropriate dams. Wild adult escapement equaled interdam count less fish that returned to hatcheries or were harvested. I divided spawner/redd ratios of 2.4 (Kohn 1988 for the Methow River; Hollowed 1983 for the Yakima River) and 3.1 (Meekin 1967 for the Mathew River) into interdam counts of wild spring and summer/fall chinook salmon, respectively, to account for prespawning mortality. I used an egg deposition of 4,600 per spring chinook salmon female (12-year average at Leavenworth NFH) and 5,240 per summer/fall female (Mathews and Meekin 1971). Annual losses of stream salmonids we universally high (Alexander 1979), and I assumed 50% overwinter mortality for age-0 chinook salmon.
About half of the area used by anadromous fish in the three drainages has been physically measured. Samples were expanded to account for total wetted area (1,476 ha) at low flow in September. Fish densities were assessed by snorkelers (Schell and Griffith 1984), sodium cyanide census (Wiley 1984), or both, in 2.1% (31.3 ha) of the was, 1983-87. Snorkel counts of juveniles were calibrated against cyanide censuses (Hillman et al., in press). Sampled fish habitat was ranked with Binns' (1982) Habitat Quality Index (HQI, which rates late summer flow, annual flow variation, water temperature, food, cover, water velocity, nitrate nitrogen, and stream width with an index of nonsalmonids substituted for bank erosion.
A mean of 8,431 naturally-produced spring chinook salmon returned to the Wenatchee (4,465), Entiat (1,247), and Methow (2,719) Rivers 1967-87. I assumed mean per-project adult loss of 5% (Northwest Power Planning Council 1986), then calculated mean adult abundance at the Columbia River mouth as 12,600. In-river catch averaged 20% (3-39%, Oregon Department of Fish and Wildlife and Washington Department of Fisheries 1988), which should increase adults to 15,750. A 10% correction for ocean harvest (Northwest Power Planning Council 1986) yields a total run of 17,400. I found suggestions of an inverse relationship between spawning escapement and total run 4 years later (Fig. 1). Hatchery spring chinook salmon abundance fluctuated in much the same manner, which suggests the ubiquitous importance of ocean survival (Fig. 2).
I extrapolated rearing densities for the total drainage rearing uses by HQI ranking, and produced a range in late-summer or early-fall population estimates (Table 1). For example, I multiplied a homogenous stream reach area, with HQI of 20, by the poor density value (2.5 age-0 chinook/100 m2) and the fair value (3.8 age-0 chinook/100 m2). Egg-to-fall fingerling survival of naturally produced spring chinook salmon thus ranged from 2.7 to 13.3%; and smolt-to-adult survival from 1.6 to 8.1%. Mean hatchery smolt-to-adult survival ranged from 0.16 to 0.55%, 1976-88. Naturally produced smolts were about 10- 80 times as viable as hatchery smolts (Table 2).
Spring chinook salmon typically ascend to headwaters during high water in spring, and their offspring rear there for a yew or more before smolting (this produces a stream-annulus on scales). Ocean-annulus chinook salmon usually return in summer and fall and spawn downstream from spring chinook salmon, and their offspring leave these milder climes at age-0. Stream fish are less common at sea and apparently distribute widely there. The more common ocean-annulus chinook salmon occur more frequently in coastal waters (Mullan 1987).
Mean escapement to the Wenatchee (12,012), Enlist (100), and Methow (3,385) Rivers for naturally- produced chinook salmon with ocean-type first annuli from 1967 to 1987 was 15,497. Corrected for 5% interdam. loss, incidental in-river catches of 9%, and mean harvest of 75% in 1967-84 (Northwest Power Planning Council 1986) and more recent harvests of about 40%, total run size was about 88,600 naturally- produced ocean-type chinook salmon (Wenatchee—68,600; Entiat—570; Methow—19,350). Although mean harvest data we not specifically available for all years, it is apparent that the trend in escapements to the Wenatchee River in the past 27 years was relatively stable. This suggests that the habitat was fully seeded even at low escapements (Fig. 3).
I estimated juvenile migrants with three different statistics (Table 3). I adopted an estimated output of about 20 smolts per 100 m2 because most summer/fall chinook habitat ranks poor to fair in summer but good to excellent in spring, when shoreline vegetation floods. Estimated egg-to-migrant survival for wild summer/fall chinook salmon ranged from 4.8 to 15.2%, excluding a 45% aberrant value for the Entiat River (Table 3). The Entiat River is at best marginally suitable for summer/fall chinook salmon (Mullan 1987). Most probable migrant-to-adult survival was 2.2 to 14.2% (Table 3).
Temporal variation in abundance causes problems in population estimates based on standing crop (Hall and Knight 1981). The range in age-0 chinook salmon densities (0.6-21.2/100 m2) during September 1985-88 in an experimental section of Icicle Creek was 100% of mean abundance (10.5/100 in2) (Mullan 1989, unpublished). Hillman and Chapman (1989) observed only a small difference between age-0 chinook salmon densities in the Wenatchee River in September 1986 (1.4/100 in2) and 1987 (1.1/100 in2). The mean density observed by snorkeling was higher in late August 1985 (2.4/100 in2). This range in standing crop encompasses the variation (Table 1) used in estimating chinook salmon abundance.
Survival rates in Table 3 lie within hounds of those reported by others. Major and Mighell (1969) estimated that 5.4-16.4% of potential spring chinook egg deposition survived to smolt in the Yakima River. Fast et al. (1988) reported 4.2-6.5% egg-to-smolt survival in the Yakima system.
Rum of adult stream chinook salmon in the undammed Fraser River average only 19,000 to 31,500 (U.S.-Canada 1984), compared to 17,400 for the mid-Columbia. The Wenatchee, Entiat, and Methow Rivers contribute only 2% of the average flow of the mid-Columbia River, and there is no evidence that these streams ever produced mom fish than they now do (Mullan 1987).
Low returns of hatchery Chinook salmon (Mullan 1987) seem to lie outside the purview of fish health and genetics. This is not to say that diseases and genetics are unimportant, but I see hints that the behavior of Chinook salmon in hatcheries is conditioned—like that of Pavlov's famous dogs—differently from that of wild fish. For example, large age-0 and yearling spring chinook salmon released to Icicle Creek do not orient to cover, remain at the water surface, and drift downstream in the channel regardless of season. They haw no apparent social structure and frenzy when hit by light at night (Hillman and Mullan 1989). Recently-hatched fry released to Icicle Creek, by contrast, quickly remove themselves from strong currents and mimic the behavior of naturally-produced Chinook as described by Hillman at al. (1989a, b). Exceptions to low hatchery returns almost invariably involve chinook salmon least exposed to hatchery life (Heard 1987).
I thank K. Williams, G. Rhodos, T. Hillman, and J. McIntyre for Crucial contributions.
Alexander, G. R. 1979. Predators of fish in Coldwater streams. In H. Clapper (editor), Predator-prey systems in fisheries management, p. 53-170. Sport Fishing Institute, Washington, D.C.
Binns, N. A. 1982. Habitat quality index procedures manual. Wyoming Game and Fish Department, Cheyenne, WY, 209 p.
Fast, D. E., J. D. Hubble, and B. D. Watson. 1988. Yakima River spring Chinook enhancement study. Annual report, Yakima Indian Nation to Bonneville Power Administration, Contract DE-A179- 83BP39461, 101 p. (Available from Bonneville Power Administration, U.S. Department of Energy, P.O. Box 3621, Portland, OR 97208.)
Hall, J. D., and N. J. Knight. 1981. Natural variation in abundance of salmonid populations and its implications for design of impact studies. Report to Corvallis Environmental Research Lab, Contract EPA-600/3-81-021, 85 p. (Available from Oregon State University, Department of Fisheries and Wildlife, Corvallis, OR 97331.)
Heard, W. R. (editor). 1987. Report of the 1987 Alaska Chinook salmon workshop. NWAFC Processed Rep. 88-06, 244 p. Alaska Fish. Cent., Ned. Mar. Fish. Serv., NOAA, P.O. Box 210155, Auke Bay, AK 99821.
Hillman, T. W., and D. W. Chapman. 1989. Abundance, growth, and movement of juvenile Chinook salmon and steelhead. In Don Chapman Consultants (editors), Slimmer and winter ecology of juvenile Chinook salmon and steelhead trout in the Wenatchee River, Washington, p. 1-41. Report to Chelan County Public Utility District, Wenatchee, Washington. (Available from Don Chapman Consultants, P.O. Box 1362, McCall, ID 83638.)
Hillman, T. W., D. W. Chapman, and J. S. Griffith. 1989a. Seasonal habitat use and behavioral interaction of juvenile chinook salmon and steelhead. 1: Daytime habitat selection. In Don Chapman Consultants (editors), Summer and winter ecology of juvenile chinook salmon and steelhead trout in the Wenatchee River, Washington, p. 42-82. Report to Chelan County Public Utility District, Wenatchee, Washington. (Available from Don Chapman Consultants, P.O. Box 1362, McCall, ID 83638.)
Hillman, T. W., D. W. Chapman, and J. S. Griffith. 1989b. Seasonal habitat use and behavioral interaction of juvenile chinook salmon and steelhead. II: Nighttime habitat selection. In Don Chapman Consultants (editors), Summer and winter ecology of juvenile chinook salmon and steelhead trout in the Wenatchee River, Washington, p. 83-108. Report to Chelan County Public Utility District, Wenatchee, Washington. (Available from Don Chapman Consultants, P.O. Box 1362, McCall, ID 83638.)
Hillman, T. W., and J. W. Mullan. 1989. Effect of hatchery releases on the abundance and behavior of wild juvenile salmonids. In Don Chapman Consultants (editors), Summer and winter ecology of juvenile chinook salmon and steelhead trout in the Wenatchee River, Washington, p. 265-285. Report to Chelan County Public Utility District, Wenatchee, Washington. (Available from Don Chapman Consultants, P.O. Box 1362, McCall, ID 83638.)
Hillman, T. W., J. W. Mullan, and J. S. Griffith. In press. Accuracy of underwater counts of juvenile chinook and coho salmon and steelhead. N. Am. J. Fish. Manage.
Hollowed, J. 1983. Age, sex and size of Yakima Basin spring chinook (Oncorhynchus tshawytscha), from catch and escapements 1980-1983. Information Report 83-9, Yakima Indian Nation. (Available from Yakima Indian Nation, P.O. Box 151, Toppenish, WA 98948.)
Kohn, M. 1988. Spring and summer chinook [salmon] spawning ground surveys, Methow and Okanogan River Basins, 1988. Report of Yakima Indian Nation to Chelan Co. PUB, Wenatchee, Washington. 41 p. (Available from Yakima Indian Nation, P.O. Box 151, Toppenish, WA 98948.)
Major, R. L., and J. L. Mighell. 1969. Egg-to-migrant survival of spring chinook salmon (Oncorhynchus tshawytscha in the Yakima River, Washington. Fish. Bull., U.S. 67(2):347-359.
Mathews, S. B., and T. I. Meekin. 1971. Fecundity of fall chinook salmon from the upper Columbia River. Washington Department of Fisheries, Tech. Rep. 6:29-37.
Meekin, T. K. 1967. Report on the 1966 Wells Dam chinook tagging study. Report to Douglas County PUB, Contract 001-01-022-4201. Washington Department of Fisheries, Olympia, Washington. 41 p. (Available from Douglas County PUD, 1151 Valley Mall Parkway, East Wenatchee, WA 98801.)
Mullan, J. W. 1987. Status and propagation of chinook salmon in the mid-Columbia River through 1985. U.S. Fish and Wildlife Service Biol. Rep. 89(3):1-111.
Mullan, J. W. 1989. Growth, survival, and production of salmon and steelhead in a controlled section of Icicle Creek, Washington. Unpubl. manuscr., 55 p. U.S. Fish and Wildlife Service, Leavenworth, Washington.
Northwest Power Planning Council. 1986. Compilation of information on salmon and steelhead losses in the Columbia River Basin, 25 p. (Available from Northwest Power Plannin Council, 851 SW Sixth Ave., Suite 1100, Portland, OR 97204.)
Oregon Department of Fish and Wildlife and Washington Department of Fisheries. 1988. Status report: Columbia River fish runs and fisheries, 1960-87. Portland, Oregon and Olympia, Washington. 83 p. (Available from ODFW, P.O. Box 59, Portland, OR 97207.)
Schell, D. D., and J. S. Griffith. 1984. Use of underwater observations to estimate cutthroat trout abundance in the Yellowstone River. N. Am. J. Fish. Manage. 4:479-487.
U.S.-Canada Technical Committee on Chinook Salmon. 1984. Report to advisors to the U.S.- Canada negotiations on the limitations of salmon interceptions, 46 p. (Available from U.S. Fish and Wildlife Service, FAO, Leavenworth, WA 98826.)
Wiley, R. W. 1984. A review of sodium cyanide for use in sampling stream fishes. N. Am. J. Fish. Manage. 4:249-256.
Figure 1. Spawning escapement, natural spring chinook salmon to Wenatchee River.
Figure 2. Leavenworth hatchery releases of spring chinook salmon.
Figure 3. Interdam escapements of summer/fall chinook salmon to Wenatchee River.
Table 1. Average (weighted) densities (number of fish/100 m2) of age-0 chinook salmon, age-0 steelhead trout, steelhead trout, steelhead trout parr, and total salmonids (exclusive of mountain whitefish) according to habitat quality indexing (HQI) of poor, fair, average, good, and excellent for mid-Columbia River tributaries.
Densities (No. fish/100 m2)
* Includes rainbow/steelhead >200 mm, cutthroat trout, eastern brook trout, bull trout, and hatchery coho salmon.
Table 2. Life table for spring chinook salmon in mid-Columbia River tributaries.
|Spawning area (ha)||244||102||397|
|Rearing area (ha)||732||102||642|
|Number of fall fingerlings (000)||227.7-365.3||74.6-111.4||302.4-690.5|
|Egg-to-fall fingerling survival||2.7-4.3%||3.1-4.7%||5.8-13.3%|
|Fall fingerling-to-smolt survival||50%||50%||50%|
|Number of smolts (000)||113.8-182.7||37.3-55.7||151.2-345.3|
|Average run size(1967-87)||9,215||2,573||5,611|
Average hatchery smolt-
Viability of naturally
produced smolts vs.
Table 3. Life table for summer/fall chinook salmon in mid-Columbia River tributaries with migration estimates from three sources.
|Item||Wenatchee River drainage||Entiat River drainage||Methow River drainage|
|Average run size (1967-87)||68,600||570||19,350|
|Spawning area (ha)||488||22||245|
|Rearing area (ha)||same||same||same|
|Number eggs deposited||20,300,000||169,000||5,700,000|
|(1 g yield/m2; 5 g mean wt.)||976,500||43,700||490,700|
|(19.9 fish/100 m2)||971,000||43,500||488,200|
|(35.2 fish/100 m2)||1,718,563||76,951||863,556|
|Summary of above|
|Number migrants (000)||482.4-1,718.6||21.6-77.0||242.4-863.6|
|Egg-to-migrant survival||4.8-8.5%||25.9-45.5%||8.5- 15.2%|
|Migrant-to-adult survival||4.0-7.1%||0.7- 2.6%||2.2- 8.0%|
a Observed from experimental section of Icicle Creek, 1986-89.
b Estimated from Table 1, density according to HQI rating of excellent.
c Wenatchee R. June densities minus July densities (Hillman and Chapman 1989).
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