Original Habitat and the Evolutionary Adaptation Process
Genetic diversity is key to the remarkable salmon. Where they go–how they apportion the environment to utilize every piece of space, every morsel of available food–how they have survived–is the result of thousands of generations with survival of the fittest, not as a generality, but as a response to a particular environment. Today’s salmon, notable in part because they have four chromosomes per trait instead of two like most creatures, are the product of a multiple succession of reproductions. They are the survivors over some thousands of years. The Dungeness strain developed since this river was formed, since the last Great Ice Age when ice some 4,000 ft thick melted.
In those early millennia, when fish returning in the early part of the year spawned in the lower reaches, later arrivals dug out and spawned on top of their redds; the earlier laid eggs were lost. Those spawning high in the headwaters were undisturbed by the late comers, and so lived to come back on the next cycle. In this manner populations were developed and tailored to a particular niche. Not only place of spawning–some in main stem, some in upper reaches, some in tributaries or side channels–but times of spawning were also determined by the apportionment of resources in a play dominated by death as the great sculptor of the race. Different times of spawning resulted in different times of emergence of the fry; if all emerged at once the food supply could be overwhelmed, so parents for the following generation were determined by the young which hatched when food was available. Even the immune systems of these fish are adapted to infectious organisms encountered in their native environment. Broad geographic regions evolved salmon which were programmed to use different parts of the ocean for their marine development. The Puget Sound types, as classified for Endangered Species listing, extend from the Elwha River east to the north fork of the Nooksak River, and spend their time in marine waters near the continental shelf and around estuaries. The coastal Chinook, those from rivers west of the Elwha, take a wide swing into the Pacific Ocean and towards the Aleutian Islands. Not only are the ocean foods more efficiently grazed by this dispersion, natural disasters also would have less chance to wipe out the widely ranging family of salmon.
We can only imagine the number of environmental particulars which shaped the stock inhabiting each river system. That there are many and that these are of tremendous importance we can, however, know because it is very difficult to transfer salmon indigenous in one river system to another with long term successful maintenance of the stock. Transplants have been frequently attempted with far more failures than successes.
Native wild salmonids were tailored to a Dungeness river which was heavily forested with large trees. Surveyor’s field notes and maps of vegetative cover in 1858 indicate forests along the entire length of the river. These trees gave shade which cooled the river water. Their roots stabilized the banks. Leaf litter falling in the water supported insect larvae (shredders) which are a large part of the juvenile salmon diet. Trees falling in the river piled up into huge log jams. Log jams formed when trees fell into the river and were either held by their ball of roots , were caught by other trees,or floated to a catching point such as a narrow canyon or a sharp corner of a meander. Floating trees or brush were trapped and the log jam built up. A few log jams can be seen today in relatively undisturbed areas such as the Hoh, South Hoh, Elwha or Lyre rivers; they can extend for hundreds of feet and be 40 ft. high. Large conifers–in the Dungeness area as much as 12 feet in diameter–formed the underpinnings of the longest lasting, and most stable log jams. The end result was a structure which often remained in place for decades. An entire tributary, or a significant portion of the river might be spanned. When the height of the stable log jam was above the height of flood waters, flows were slowed going through the pile of trees, but rushed around the sides, where they curled towards the middle of the jam and dug a deep pool. Some log jams were mistakenly removed, as fish passage was thought to be impeded: this very rarely happens.
Fish sheltered both in the tangle of logs, and in the pool downstream. Log jams were a virtual cafeteria, complete with respite from rushing water. Insects fed on the logs and brush and dropped into the water. The jams also caught carcasses of spawned out salmon, which provided more high quality food for developing fish. The tangle provided hiding places from predators. Little fish ducked into nooks and crannies ; the over cover protected big and small fish from birds and mammals. Forests in the upper reaches of the watershed caught rain and fed it slowly into the ground, tempering floodwater at its source.
The river meandered, and on the inside of the bends water flow slowed, dropped sediments and shoaled. Outer parts of the bends carried faster water which cut the bank, dug pools and eventually moved the meander downstream. With time, some meanders partially separated from the river channel and the connecting channel formed a backwater which made ideal places for fish to rest, feed, and even, for some, to spawn.
Water flow was critical at its two extremes. Under the condition of low flows, fish could be stranded in isolated pools or side channels. Returning adults have trouble humping over shallow areas. This difficulty probably shaped the original population of Dungeness spring Chinooks, a big fish which migrated into the river originally on April 15, with the run peaking in May, and coinciding with spring high flows.
Another effect of low flow is increased water temperature. Infectious organisms also are encouraged by the warm water, such as a gill parasite, Dermocystidium. With rising temperature the water is able to hold less oxygen to meet the respiratory needs of fish. Slight decreases in dissolved oxygen limit salmonid growth, development and activity. Fish returning from the sea at a time of unsuitably low flows were “selected out”, and not only were broad population run times adjusted by genetic change to promote survival, but individual behavior was also affected. Fishermen even today observe fish waiting at the entrance to a river for rains to increase the flow before they move upstream to spawn.
Anything that holds up the passage of returning fish is critical to their ability to reproduce. These fish do not eat after they leave salt water. Some stop eating miles out to sea; some continue to feed in the estuary, but they get no nourishment from the river. They must finish their sexual maturation, get eggs and sperm ready for discharge, and reach their spawning grounds entirely on the fuel obtained earlier. The higher up the fish must go to spawn, the more energy is consumed to get there and time of travel becomes increasingly important. Too much energy consumed on the trip means eggs do not mature properly or the fish may be too exhausted to dig a redd and mate.
Perhaps even more critical, however, than low flow was the high flow condition. Side channels and deep pools, especially those downstream of large log jams, were enough in the original environment to provide shelter even when water levels rose several feet. The log jams strained out part of the woody debris which otherwise would severely beat and rake any fish not in protected waters. With high water the river overflowed to its wide flood plain where the water spread out, moved slowly, and dropped sediments, enriching the land while protecting the fish.
Everything which slowed the rate of flow: the slower travel of rain from the upper watershed, the curving meanders of the river, the log jams and woody debris, the roots of trees on the shores, alders and shrubs in the shoaled areas, also served to protect the all-important nursery of eelgrass in Dungeness Bay estuary from being smothered under silt and gravel. It is here that food is needed such as herring, sand lance and juvenile crabs etc. to nourish smolts and juveniles before their first ocean exposure. It is here that the biochemical adjustments must take place to allow them to tolerate the greater saltiness of the sea.
A little over a century ago settlers came. Man altered the land and the river. Both the upper and lower watersheds were logged, and there were slides. The river bottom was cleared to produce food. The side branches of the river were cut off. Flooding was regarded as an evil, so dikes were constructed. The need for meanders was not understood and the river was straightened. As a result, with each rain more water hits the river quickly and transits the river with little loss of its down rushing energy. Woody material in the river was removed: partly by the water’s energy, partly on purpose as it was now seen as hazardous. The increased energy of the water flow cuts the river sides and picks up rocks from the bottom so that deep pools are filled in and the lower river is filling up to a point where the town of Dungeness is at serious risk of flooding. The Dungeness Bay is filling in with loss of much of its eelgrass. Irrigation was discovered as a way to make the near-desert prairie productive, and was most needed during summer months when flows were low. Water rights were issued which if they were actually used would totally dry up the river. A cooperative effort is reducing greatly the irrigation water withdrawals, but water remaining in the river in August is still not as much as the fish need.
A hatchery was constructed on the river and upstream spawners were blocked. Man also altered the fish themselves. The first step was erection about 1932 of a fish rack to trap fish as broodstock for the hatchery. It was a “permanent” structure with slats which could be removed when desired for fish passage. In the spring chicken wire or a net would be strung along the top so fish could not jump over it. In April it would be closed to trap Chinook salmon. This blocked the summer steelhead, coming in July 4th, the rarest salmonid which spawns high up in the watershed. It is regarded as the number one game fish in this country and possibly in the world because of the great vigor it has developed in order to make it up to the high reaches over great obstacles.
As the rack was operated, it blocked passage all summer long, usually until about Labor Day, to the upper Dungeness River (above the hatchery) of spring Chinook, summer steelhead, early pinks, early coho, and Dolly Varden/bull trout. It is likely that sea run cutthroat could have gotten through. But the summer steelhead were exhausted by then. It was activated again for capture of oho in October and blocked winter steelhead coming in Nov. first. The rack was left in until Christmas. It was a major cause of the decline of upper river species, forcing them to use the lower river or die without successful spawning. Despite this, up to the 1960’s the Dungeness River was a real live river with successful spawning in the entire river. The rack was repeatedly breached by floods and was replaced. According to a WDFW report, the rack was permanently removed in 1982 (pg. 4, Dungeness River Chinook Salmon Rebuilding Project Progress Report 1992-1993, publ. June 1995).
The river was subsequently stocked with fish from other drainages with different migration characteristics and lacking the special adaptation of native fish to this river. Spring Chinook from the Cowlitz River were first introduced. Records are poor, and many transfers are undocumented. We do know that fish identified by behavior and genetics as Elwha fish have been identified in the Dungeness, and the following records were cited in the above report: In 1966, over 800,000 fingerlings from the Green River were released. In 1967 over 400,000 fingerlings from Issaquah, in 1969 128,000 from Hood Canal, in 1970 fingerlings numbering over 600,000 from Minter Creek, and in 1972 yearlings weighing 9 lb. and numbering 167,207 were taken from Hood Canal and released in the Dungeness. The genetic contribution of these introductions to the native fish is presently unquantified. From 1966 -72 “the total number of nonnative fish released during this time period roughly equaled the number of native fish released from the Dungeness Hatchery during the same time frame.” (ibid. pg. 7). Perhaps the variable strains are related to the variability in spawning distribution sites now observed. A significant difference was found in redd distribution and spawn timing for redds deposited in the lower river than in the mid and upper river, but it is unclear whether two stocks can be clearly discerned. Recommendation was made that genetic stock identification analysis be performed as soon as possible, since a Captive Broodstock Program is under way since 1992 to try to recover the Chinook stock of the Dungeness River.
Releases of fish from this captive broodstock program are showing aberrant behavior: The juvenile fish are preferring to remain in the river or its tributaries as much as an extra year, unlike the behavior of native fish which head for the estuary and salt water without such a delay. This captive brood program is experimental and we must wait for further returns to discover whether sufficient native genetic capacity has been retained for survival at sea and eventual reproduction.
The attempt to convert an upriver Chinook stock into a downriver stock is an exercise in futility as long as the habitat is as hostile as it is. The upriver area has good habitat, good holes, but the fish were mostly kept out for 60 years. Rebuilding this stock is our best hope for recovery of the native Chinook.
There still is a need for rehabilitation of the lower river and its estuary for rearing and for transport of Chinook to the upper reaches. It must also be realized that other salmonids such as late run steelhead, late coho, lower river pinks, late chum, etc. utilize almost totally the 10.8 miles of the lower river and its tributaries. These are part of the total biomass which is depended on for food for those species spawning in the upper river.
For the lower river, needs are: high and low water refugia, better access to tributaries and side channels, excessive flows attenuated by meanders and log jams, deep pools and stable spawning gravel. Dikes need to be set back and bridge constrictions relieved.
Salmon of the Dungeness River:
The salmonids are the spring Chinook, pinks, summer steelhead, winter steelhead, coho, chum, sea-run cutthroat, Dolly Varden/bull trout, and the resident rainbow trout.
Dungeness Spring Chinook:
Historically consisted only of early spring Chinook. They are adapted to the upper Dungeness River and the Gray Wolf. Entry of returning adults to the river from the sea occurs starting April 15 with the numbers peaking May 15th. Typically farmers would start fishing in Dungeness Bay April 10th to catch them before river entry. Spawning peak is August 25th. Introduced strains have diluted the stock with later spring and summer Chinook. Runs of 2 to 3,000 adult fish were common in the early 1940’s. Up to the early 1960’s their runs supported 20 to 30 sports fishing boats per tide. The main reason for the decline is the effect of the rack at the hatchery, habitat loss by flood control and excessive water withdrawal. Note that these are mainstem spawners and hence vulnerable to high and low flow damage; they also spend more time than other types of salmonids in the now-degraded Dungeness Bay estuary. In 1997 only 50 fish returned, and the stock from this and related watersheds (Puget Sound Chinook) is proposed for listing as a threatened species.
Historically consisted of a numerous upper, and a less numerous lower river stock. The major part of the (early/upper river) runs of adults returning from the sea entered the river 20 July to September, and spawned from Aug. 15 through Sept 15. Later (lower river) stock entered the river in early October and spawned to Oct. 15th. Since they spawned in the lower river they didn’t have far to go. The last great year of record, in 1963, over 400,000 pinks returned. The runs previous to record keeping were thought to be much higher Since 1963 the stocks have dwindled, in some years only 2,500 returning. The lower river segment is even more depressed than the upper river component.
Cause of decline: Habitat loss by flood control, WDFW dam on Canyon Creek, excessive water withdrawal, over fishing on mixed stocks in the Straits.
Dungeness Summer Steelhead:
Upper river stock (above R.M. 15 approx.)
Entry: July – Oct. 1st, Spawning Feb., March. historic abundance difficult to quantify. Personal observations suggest 250 to 400 fish.
Present status unknown, perhaps 75 fish.
Cause of decline: Habitat loss, water withdrawal, rack on the river, interbreeding with unsuitable hatchery stock (Skamania). Note that these fish spend two years in the river before migrating to sea and are particularly susceptible to what is now a hostile environment. This is the fish that swims faster, travels furthest upstream, and jumps higher, even over some falls.
Dungeness Winter Steelhead:
Historically consisted of early up river and later lower river stocks. Entry is Nov. through June 15th, spawning Jan 15 through June 30. Historic abundance probably in excess of 5,000. Dungeness River was often in the top 25 streams in Washington and once was among the top ten.
Present status: last redd counts indicate about 350 fish, almost all late segment.
Cause of decline: habitat loss, rack on the river, flood control, water withdrawal, dam on Canyon creek, exploitation of early hatchery run which resulted in over fishing of early segment. Loss of nutrient as huge pink run was lost.
Entry: Oct. 1 – Dec. 1, spawning Nov. 10 – Jan 15th.
Historic abundance: perhaps 20,000.
Present: unknown due to large and constant infusion of hatchery stock of mixed lineage.
Consists of a small, very early segment (Aug. 15) and a large segment of common run with timing Nov. 1 – Dec. 15th. Abundance of early run perhaps 200, later stock perhaps 5,000.
Present: Early segment probably extinct. Late segment perhaps 300 – 400 in better years. Are using Beebe Creek.
Dungeness Sea-run Cutthroat:
Historically utilized the lower 15 miles of river.
Entry: Sept. 15 – Nov. 15. Spawning peaks 15 Feb. – 15 March. Spawns in tributaries.
Historic abundance: perhaps 300 – 400 fish.
Present: unknown. Seldom seen now.
Causes of decline: water withdrawal, flood control, habitat loss, loss of the pink salmon–their eggs and fry (food source).
Dungeness Dolly Varden/Bull Trout:
Historically these were both sea-run and resident types. Although similar Dolly Vardens are Salvelinus malma and bull trout are Salvelinus confluentus. Very abundant–no numbers, but common to catch 10 – 15 fish weighing, up to 6.5 lb. in better holes. Found from lower reaches to upper watershed.
Present: still wide spread, but greatly reduced numbers. Can catch 6 – 8 fish on better days, with very occasional fish of 5 lb. Causes of decline: incidental catch in coho and steelhead nets, habitat loss, water withdrawals, food loss incurred through decimated pink run.
Dungeness Resident Rainbow Trout:
Taxonomically these are the same fish as the steelhead. They exist in considerable numbers in the upper reaches of the river and its tributaries. Some weigh over 3 lb.
Copyright © Dick Goin,1998