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Chapter Six— Why All the Fuss about Preserving Wild Stocks of Salmon and Steelhead?
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Chapter Six—
Why All the Fuss about Preserving Wild Stocks of Salmon and Steelhead?

Patrick Higgins

California's wild salmon and steelhead populations have an uphill battle for survival. Habitat for these fishes shrinks yearly due to a number of factors, such as logging and water development for agricultural irrigation and domestic use to accommodate California's burgeoning human population. To solve problems for the fish, many would argue that we should supplant wild fish production with hatcheries. Many fishery professionals disagree: that is not a wise course of action, and California has better options. My purpose here is to show why this is so.

Natural Selection

To the untrained eye, it may be very difficult to distinguish between a wild fish and one raised in a hatchery. The genetic information within each wild salmon or steelhead and those reared in a hatchery may vary considerably, however, and those genetic differences may have a profound effect on the long-term viability of California's salmon and steelhead runs and the costs to society to maintain them.

California's salmon and steelhead populations have a wide range of behavioral and physical characteristics that are controlled


by the genetic code within each fish. That code has been molded by the success or failure of thousands of generations of these fish interacting with the physical and biological conditions of California's environment.

Behavioral traits allow salmon and steelhead to survive despite long-term trends toward a drier climate and seasonal droughts throughout much of the state. If a run of steelhead spawns in the upper reach of a stream that is near a spring, for example, and the lower stretches of the creek dry up in summer, the offspring may have genes that tell them to stay near the spring. Also responding to genetic signals, the fry of earlier-spawning chinook salmon in the same stream might migrate downstream quickly after emerging from the gravel to avoid this problem.

Variations of such patterns may also be observed. For example, runs of coho salmon and steelhead adapted to small coastal streams near Santa Cruz are flexible in the time of their return to fresh water. If rains come early, some of these fish may return in October. Should drought conditions exist, they may not spawn until January. Indeed, some southern California coastal streams host steelhead runs that return only in years of abundant rainfall.

One of California's last substantial runs of summer steelhead on the Middle Fork of the Eel serves as a classic example of genetically controlled survival strategies. As the last snow melts from the Yolla Belly Mountains, these fish battle up the steep, rocky Middle Fork gorge. Streamflows drop rapidly, but the summer steelhead seek shelter in deep pools that are cold on the bottom. Here they wait, often as if in suspended animation, until fall rains allow them to spawn in tributaries. The offspring of all the steelhead in this drainage are also able to thrive in summer water temperatures that are consistently above seventy degrees. Less hardy strains of steelhead fry would be lethargic and susceptible to disease in these elevated water temperatures.

Many of California's rivers once had numerous distinct runs of salmon and steelhead returning throughout the year. The evolution of variations in timing between runs in the same river is due at least in part to biological interactions changing genetic makeup. By entering the river and spawning at different times, competition for spawning and rearing areas is minimized. As fry of the different runs emerge from the gravel, they take turns using different parts


Natural home. This small tributary of the Smith River in northern coastal
California illustrates ideal nursery habitat for juvenile salmonids: forest
canopy and streamside vegetation, oxygenated flow, deep pools,
and cobbles and gravel streambed.
(California Trout, Inc.)


of the stream habitat. Chinook salmon may be the first to return to spawn in the fall, followed by coho salmon, and finally steelhead in mid to late winter. As the chinook salmon emerge, they feed in the slow water at the edges of the stream. By the time the coho salmon fry emerge, the chinook salmon are feeding in swifter, deeper waters and beginning to move downstream. Thus competition for food and space is minimized.

California's stream systems are endowed with salmon and steelhead specifically adapted to the geology, hydrology, and ecology peculiar to each. Many of these native strains have been lost where habitat was completely destroyed, but others have survived against amazing odds. For example, suburban development in Pacifica, south of San Francisco, caused a whole tributary of San Pedro Creek to be placed in a culvert. Years afterward, steelhead in that tributary were still spawning far up that (dark culvert in the gravels deposited in it. Where native strains remain they must be protected. The preservation of even remnant runs could play an important role in rebuilding the state's salmon and steelhead stocks.

Restoring Salmon and Steelhead Runs

In recent years considerable efforts have been made to restore habitat and salmon and steelhead runs in California rivers. Hill-slopes have been stabilized, streamside vegetation replanted, and structures to improve habitat placed in streams. Runs of salmon and steelhead in these watersheds are typically depressed when these restoration projects are initiated.

Some of the few returning adult fish are trapped and spawned artificially and eggs raised in "hatchboxes" to increase survival rates. These native fish survive well in their restored habitat and begin to reproduce naturally. As we continue efforts to restore California's fishery habitat, we may begin to encounter areas where no remnants of native strains exist. The more wild populations of salmon and steelhead that remain throughout the state, the better the chances are that the appropriate genetic strains for natural reproduction in the widest range of environments will have been retained.

Genetic engineering is much in the news these days, and one might get the impression that if we needed a fish with certain


characteristics, we could just mold the DNA of a salmon or steelhead. Actually, we are only now beginning to decipher the genetic code of these fishes. We know that there are more than a thousand different points of information, or loci, on the gene. Of these loci, we understand the function of only a dozen or so. Physical or behavioral traits can also result from interplay between combinations of genetic sites—combinations that are almost infinite in number. In short, these fish have evolved adaptive mechanisms that we do not understand. We cannot genetically engineer traits for survival, therefore, unless we retain these fish and copy from their genomes. Although salmon and steelhead sperm can be preserved by freezing, there is no known way to preserve the eggs of these fishes.

If we lose this precious genetic resource, our watersheds may remain perpetually underseeded or we will have to rely more and more on artificial rearing to maintain poorly adapted populations. Costs will escalate to maintain salmon and steelhead in the state, valuable genetic resources for future aquaculture or enhancement efforts will be lost, and an important part of our heritage will have disappeared as well.

Problems with Hatchery Production

California's first hatchery was opened in 1872 on the McCloud River, a tributary of the Sacramento. Despite this early start on artificial production and a tremendous investment in hatchery facilities associated with California water projects, hatchery success in rebuilding or maintaining stocks has been a hit-and-miss proposition. Problems with disease or human error in operation can cause catastrophic fish kills. Heavy dependence on hatchery-produced salmon and steelhead is a very expensive solution to diminishing runs of these fish and one fraught with problems.

Typically, hatcheries in the past selected the first fish returning to the hatchery for breeding purposes. Hatchery managers wanted to capture enough adult fish at the earliest opportunity to acquire sufficient numbers of eggs to utilize fully the incubation and rearing capacity of their facility. We now realize that this method may have saved only a fraction of the genetic information and survival strategies that existed in the genes of a broader cross section of the


salmon or steelhead in that drainage. Apart from the obvious effect of causing runs in hatchery-dependent rivers to be early and of short duration, various life-history patterns and survival strategies are lost when genetic diversity is restricted in this fashion. Ocean migration and other patterns are often virtually uniform in hatchery stocks. As ocean conditions or streamflows vary from year to year, the diverse strategies of wild fish can dramatically increase their chances for survival over hatchery fish. Returns of salmon and steelhead that are genetically restricted are subject to much wider fluctuations in rates of return. By retaining stock diversity, populations of these fishes will be more stable.

If genetic diversity becomes too restricted, reproductive capacity declines. This phenomenon, called inbreeding depression, results in decreasing hatchery production, which may ultimately necessitate replacement of the entire hatchery broodstock. A disease outbreak can be devastating in a hatchery if the strain being raised lacks genetic resistance to the pathogen. The Coleman Hatchery on Battle Creek, a Sacramento River tributary, has had continuing problems with outbreaks of disease. In worst-case scenarios, whole broodstocks from hatcheries may need to be replaced because of disease.

Human error can result in tremendous fish kills, which can greatly alter returns in hatchery-dependent rivers. In the summer of 1986, Iron Gate Hatchery on the upper Klamath River experienced a fish kill of one to three million juvenile chinook salmon being reared in cold hatchery water. As repairs were being made to the dam upstream, water was being released from the surface instead of from the bottom of the lake behind the dam. Water temperatures below the dam were in the high seventies, and when the young fish were released almost all of them died.

But hatcheries are not all bad. Despite the problems inherent in hatchery production, hatcheries play a vital role in supplanting losses where habitat has been irretrievably lost. In the 1960s, new feeding methods and ways of combating disease were discovered, and production levels at hatcheries generally increased. Recent investments by commercial fishermen on improvements to Sacramento and San Joaquin River fish-rearing facilities through the Salmon Stamp Program have also resulted in substantial increases in hatchery production in the state. As hatchery production increases, negative side effects on native strains can occur, so special


care must be taken by hatcheries in basins where viable wild populations still exist.

The Impact of Hatchery Fish on Wild Populations

Fishery professionals used to believe that hatchery programs which produced numbers of fish above the numbers of naturally produced offspring had little or no negative impact on wild runs. We are now, however, discovering that hatchery programs and the way in which hatchery fish are transferred and planted can have substantial negative effects on wild fish.

California has opted for large hatchery facilities on just a few rivers as opposed to smaller facilities on a greater number of streams. On the surface, the strategy is easy enough to understand: large hatcheries have larger production capabilities and therefore lower cost per fish produced. Also, most of these facilities were funded in association with dams for mitigation. When these large hatcheries have surpluses of juvenile fish, the fish are often transferred to "enhance" populations in other streams. The fish may be poorly adapted to the watershed to which they are introduced. They are also sometimes planted without regard for the carrying capacity of the stream. Competition for food and space can greatly reduce the number of native juveniles in these systems.

Hatchery fish often do not survive as well in the stream or ocean as wild fish, yet as thousands or millions of fry or smolts are planted in streams, they outcompete native populations because of sheer numbers. Hatchery fish are taught to respond positively to humans or machines moving along raceways to feed them. In the wild, such movement over the water might be a predatory bird or animal. Wild fish stake out territories where little energy is required to stay in feeding position but much food is delivered. Hatchery fish may not be imprinted to behave in this fashion. We are just now gaining greater understanding about timing the release of these young fish. If they are not released to begin migration when genetic cues normally would induce such behavior, they may not even go to the ocean at all.

Transferred stocks are often poorly adapted to conditions in host streams. Coho salmon from hatcheries on large northstate rivers


have been planted in short coastal streams near Santa Cruz. The genetic information they contain gears them for a journey of several hundred miles, but the systems to which they have been transferred are only a few miles long. Coho salmon returning to the Klamath, for instance, never encounter low streamflows near the mouth and begin their upstream migration several months before spawning. When these fish are transplanted, they might return to spawn when the Santa Cruz area streams are almost dry. Native stocks of California coho salmon have declined seriously, partly because of such stock transfers.

Straying of returning adult spawners is also a problem with hatchery fish. Instead of returning to the hatchery, they may continue upstream, enter a tributary below the hatchery, or return to a different river system. This problem is compounded if the salmon or steelhead are planted away from the hatchery facility, as in the estuary of the river or in an entirely different stream.

Hatcheries often plant juvenile salmon in estuaries because the number that survive to maturity is greatly increased. Intermixing of hatchery and wild stocks may, however, introduce genes into the wild population that decrease survival. A prime example of this is when introduced fish lack resistance to a disease organism present in their new environment. The result can be catastrophic.

Wild fish can also be severely affected by overfishing when harvested in mixed-stock fisheries with hatchery fish. Hatchery stocks can sustain harvests of up to 90 percent, while wild populations may be jeopardized by any harvest pressure over 65 percent. The reason for the difference is the higher survival rate of eggs reared in hatchery trays over eggs that are exposed to the many hazards of the natural environment. To maintain maximum genetic diversity and protect wild runs, harvest quotas must be set to preserve the more vulnerable native fish.

If harvests are kept at a rate to sustain wild populations, thousands or even tens of thousands of surplus fish may return to the hatchery gate. Huge concentrations of fish in the stretches of river below these hatcheries overwhelm the river's spawning and rearing capacity. Many fish that are not allowed in the hatchery die without reproducing. These massive runs encourage poachers, who rationalize their "sport" by saying that the fish will otherwise be wasted.


Legitimate sportfishing in rivers supporting these huge hatchery runs may also reach levels that deplete native runs.

Hatchery returns may also mask problems with native stocks and create false impressions of the overall health of the salmon and steelhead runs in certain basins. While runs to the hatcheries in the Klamath/Trinity River system have boomed since 1984, wild fish in drainages like the South Fork of the Trinity have not rebounded at all. Wild stocks were overharvested for so long that rebuilding will take many years. Habitat problems may also be besetting these native fish.

Study of the decline in populations of older forty- to seventy-pound Klamath River salmon has revealed a perplexing facet of this problem. Commercial and sportfishing pressure over the years has reduced the numbers of four- or five-year-old fish to the extent that they have nearly disappeared from the Klamath and other California streams. Spawning females of these stocks produce up to ten thousand eggs. Such fish may be genetically adapted to spawning deep in large rivers, using habitat where smaller salmon are unable to reproduce successfully. Without fish to utilize it, this habitat may not be used for spawning. As ocean fishing regulations have tightened in recent years, more of these large fish seem to be returning.

But another set of problems must be dealt with. The large-mesh gillnets used in the Indian fishery on the Klamath River selectively harvest the largest returning salmon, thus thwarting efforts to restore these important stocks. The large mesh does permit the escape of smaller steelhead, however, an important sport fish in the Klamath basin. A shift to smaller nets would, therefore, not only reduce the value of the Indian salmon catch but also produce negative side effects on the important sport fishery, which contributes significantly to the local economy. Solutions to problems of preserving diverse runs are never simple.

How to Protect Wild Stocks

To protect California's remaining wild salmon and steelhead we must, first and foremost, fight to protect remaining habitat. As we work to restore California's salmon and steelhead resource, we are


finding the task oftentimes difficult and costly, so preservation of existing habitat makes economic good sense as well.

In areas like the North Coast, where considerable habitat remains that can support wild salmon and steelhead, care must be taken to lessen the negative effects of hatchery fish on wild fish. The original fish used as parents or broodstock at the hatchery should be taken from a wide spectrum of the native run. New wild fish should be captured periodically and used in breeding. In this way the fitness of the hatchery strain is maintained, and if some straying occurs, negative impacts are minimized. If a stream's entire run of salmon or steelhead is extinct, broodstock should be chosen from the nearest similar basin so that natural production has a greater chance of being reestablished. Selective breeding at the hatchery for large size (or any other trait) should be avoided. While individual fish in returning runs might tend to be larger, many traits that would contribute to long-term survival might be lost.

California hatchery managers need to pay more attention to the carrying capacity of the stream or river where juveniles are released. In years when tremendous numbers of progeny are reared, survival rates may be very low after release because the natural system is incapable of supporting the young fish. Survival of wild fish under these crowded circumstances might also be very low.

Salmon or steelhead juveniles generally should not be planted away from their hatchery of origin. Young fish released at the hatchery are more properly imprinted and therefore stray much less to spawn with wild fish. Transferring juvenile salmonids between basins should be avoided under most circumstances.

Hatchery juveniles are often much larger than wild salmon and steelhead young at the time of their release. Hatchery programs should release fish equal in size to native fish in the same habitat so they will not prey upon wild young or have an unfair competitive advantage in seeking food or habitat.

Hatchery fish should be harvested more intensively than wild fish. If hatchery fish were all marked, they could be selectively harvested in the river and in the ocean, and wild fish released. British Columbia, Washington, and Idaho currently manage their steelhead in this manner. British Columbia's anglers initially grumbled at not being permitted to keep unmarked steelhead, but now fishing has improved so dramatically that they are extremely happy


with this management strategy. Managing salmon in this fashion is more complex logistically, but it may be a worthwhile strategy to explore.

The California Department of Fish and Game is caught in a bind on the issue of protecting wild stocks. As the state's population increases, problems of fishing pressure also increase. Many decision makers within the department see the only solution as increasing artificial production of salmon and steelhead. In certain cases, like the San Joaquin River, where the native fish have been wiped out, hatcheries may be the only solution. But much of the state's salmonid habitat remains viable, and more effort is needed to maintain and enhance wild salmon and steelhead populations by employing management strategies to put harvest in balance with production wherever possible.

In the long run, preservation of wild fish makes economic good sense. When wild fish come back to spawn, it doesn't cost California's taxpayers a dime.


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