Fall Chinook
Fall chinook salmon are native to the Coquille River system and an important stock to the local and state economy.
A few fall chinook enter tidewater beginning as early as July and continue through mid December with a peak usually in early October. Spawning occurs from October through mid January with a peak usually in mid November.
Based on spawning ground surveys, the population has expanded since the late 1950s. The fall chinook salmon run appears to be in good condition and has been generally increasing throughout the last 20 to 30 years. The run generates a popular recreational fishery in tidewater and the lower section of all forks of the river, as well as contributing to Oregon ocean commercial and recreational fisheries.
Data from coded-wire-tagged fish for broods 1983 to 1986 show the distribution of catch in the ocean as 45percent to Oregon, 3 percent to California, 40 percent to British Columbia, 4 percent to Washington, and 8 percent to Alaska.
In the past there have been large catches of fall Chinook salmon in the Coquille River System for both the recreational and commercial fisheries. Both the commercial and recreational catches have fluctuated dramatically. Commercially there was a high of over 27,000 fish caught in 1948 and recreationally there was a high of nearly 3,000 fish caught in 1964.
Fall chinook salmon have been affected in the past by commercial gillnet fishing, splash dams, and logging practices. Not only were splash dams barriers to migration, sluicing of stream structure and spawning gravel greatly affected fall chinook salmon populations. The quality of the existing habitat varies from poor to excellent depending on recent land-use patterns. Factors such as low summer stream flow, high summer temperature, reduction of stream-side cover, industrial and municipal wastes, and water withdrawal have all influenced the natural production of fall chinook salmon in the Coquille River basin.
The South Fork of the Coquille River is a gravel-rich system and spawning habitat is not a limiting factor for natural production of fall chinook salmon. Spawning gravel in the East, North, and Middle forks of the Coquille River is less abundant but probably not limiting overall production.
Water temperature during the summer is probably the most significant factor limiting natural production because of the Coquille River are quite warm forcing most juvenile fall chinook salmon to move downstream from freshwater rearing areas into tidewater during summer months. Mid-day water temperature in the South Fork below Powers often exceeds 70 F. Few salmonids of any kind were found residing in a 6.5 mile section of the South Fork around Powers in a survey in 1989 by USFS biologists.
On the other hand, juvenile chinook salmon were present in good numbers in cooler upstream areas within the Siskiyou National Forest. This observation and information on past changes in the basin suggest that mainstem freshwater areas likely accounted for a major rearing habitat historically when higher flows. However, based on comparative observations on other south coast rivers, reductions in the present summer stream temperature by increasing flow and providing shade from tall trees would likely be the biggest benefit to populations attempting to rear in the lower portions of the major forks. This benefit would also accrue to the upper tidewater areas. Efforts by DEQ to correct causes of low dissolved oxygen in the tidewater area would also benefit the natural rearing potential for juvenile fall chinook salmon.
Despite limitations on natural rearing of juveniles below historical levels, the wild population is still large and healthy. Because of the large spawning population and abundance of wild fry in the spring, additions of hatchbox fry are not likely to benefit the population and may produce additional problems for wild fish already competing for the limited available habitat. The only exception may be in the lower portion of some larger tributary streams that may not be suitable for juvenile coho salmon or winter steelhead. However, if the spawning and rearing conditions were suitable for fall chinook salmon, these areas would likely already be colonized by the large existing wild population.
We do not know the present carrying capacity for fall chinook salmon in the Coquille River system or have an estimate of the expected increase in capacity from habitat restoration, but the increase in natural production from an expanded rearing area in the main forks and upper estuary would likely be quite large.
Unlike the Coos River where estuarine rearing area is large compared to the smaller spawning area, the Coquille River basin has a small estuary. We believe the lower part of the estuary now limits production of fall Chinook salmon because of the loss of habitat in the upper estuary and freshwater areas of the main forks. Even though we do not know the actual carrying capacity of the lower estuary, size of juveniles can be used to decide if the population is limited by its habitat. When populations are below the carrying capacity of their habitat, the fish grow to a much larger size than when the fish approach or exceed the carrying capacity of their habitat (Nicholas and Hankin 1988). Comparative studies along the coast of Oregon indicate that the lower Coquille Estuary is one of the systems that are well seeded with relatively small fish at the end of their rearing period in mid September. Studies of scales from returning adults also showed that survivors in the estuary were 2 to 3 cm larger than the average size of juveniles in the estuary in mid September. Juvenile fall Chinook salmon in the Coquille River estuary sampled in mid September from the years 1978 through 1991 averaged 11.2 cm mean fork length. And mean less than 12 cm in each year. Evidence of a no-growth period was also observed in the estuary further suggesting a limited carrying capacity. This information leads us to believe that release of any additional fish into the estuary before the wild fish grow to their maximum size would be detrimental to the wild population by producing more crowded conditions and further limitations in growth of the wild juveniles.
Since the 1981 brood year, fall Chinook salmon fry have been released from hatchboxes and widely distributed throughout the drainage. The release of fry has averaged from 60,000 to 400,000 fry over the last eight years. Releases of presmolts have also been made beginning with the 1983 brood. In 1984,1989,1990, 1991, and 1992 there were 19,622, 44,332,31,792, 36,738, and 14,308 presmolt released at Wolf or Cunningham creeks and quickly entered the estuary.
In the fall of 1984, annual smolt releases were started into the Coquille River system. Smolts have been widely distributed in the basin. Since the 1983 brood year, about 75,000 smolts have been released annually in upstream area and about 25,000 smolts have been released in Ferry Creek below Bandon Hatchery. No fall Chinook salmon smolts were released in 1990. In 1991 all autumn releases were confined to Ferry Creek and Sevenmile Creek, tributaries in the lower estuary. We hope that these juveniles will not compete with the wild juveniles because of our late release. We also hope the returning adults will be caught in large numbers and the remainder will home to the lower tributaries to avoid interaction with the wild population upstream.