Life History, Distribution, and Status of Klamath Coho Salmon by Justin Graham INTRODUCTION The Klamath basin is an unusual and controversial watershed. The watershed, which lies in northern California and extends into southern Oregon, ranges from temperate rain forest to high desert. It is home to many endemic species of fish, one of which, the coho salmon (Oncorhynchus kisutch) is the topic of this paper. Many different lifestyles and economies have existed in Klamath basin. Practices such as fur trapping, mining, logging, ranching, and farming have all had their impact on the stability and management of the basin. Today, these practices have resulted in such an extensive decline of the system that the coho salmon have been put into a crisis situation. One of the characteristics that makes the Klamath basin stand out is its reversed longitudinal profile. Unlike most watersheds, which have high gradient, fast flowing headwaters that taper off to a low gradient, slow flowing mainstem, the Klamath is backwards. The Cascade volcanic arc has produced a watershed that has high mountains in the lower half and a low relief, high desert in the headwaters. This creates a situation where most of the water input is in the lower half of the basin, due to the frequent storms that move over the lower Klamath basin. The upper Klamath basin, which consists of high desert, is a system that is now controlled by dams and agriculture diversions. The lower Klamath, which is the part of the basin below the Iron Gate Dam, is mostly steep and rugged. The unique geology of the lower basin has produced four important tributaries: the Salmon River, Scott River, Trinity River and the Shasta River. Due to the complexity and uniqueness of the Trinity River, the focus of this paper will be on the other three tributaries. These three remaining tributaries supply most of the water for the Klamath mainstem and are important habitat for salmonids. While there are major agriculture diversions in the two valleys in the Shasta and Scott, the lower basin is generally less diverted than the upper Klamath basin. However, due to intense logging, ranching, mining, and agriculture in the valleys, the lower Klamath has become a degraded habitat, which has resulted in the decline of coho runs (Mount, personal communication, 2003). Page 1 of 13
The fish of the Klamath basin are of primary concern. Historically the basin used to be very productive, supporting many runs of anadromous species, as well as non-anadromous fishes. However, following the development of Iron Gate Dam, anadromous species are restricted to the lower Klamath. The historically fast-flowing, cool-water of the lower basin provided ample habitat for the native species to exploit, of which 13 are anadromous (class reader, 2003). However, due to intense watershed alteration, most of the species are now on the decline. The coho salmon is just one of the species in the basin that has been affected by the declining habitat. It requires cool, clean water to spawn and rear. Yet such habitat conditions have become increasingly difficult to find. Due to the distinctive conditions of the Klamath basin, the Klamath coho salmon, which are part of a broader group consisting of southern Oregon and northern California, have been recognized as an ESU (Evolutionarily Significant Unit) and have been listed as threatened under the Endangered Species Act (ESA) (National Marine Fisheries Service [NMFS], 2001). The status of the Klamath coho has prompted many debates over the use of water in the Klamath basin and the coho has become an icon for restoration efforts. The rest of this paper will talk about the distribution, life history, and present status of the Klamath coho salmon. LIFE HISTORY Spawning Coho salmon have a fairly simple salmonid life cycle. Their life is a three-year cycle with about 18 months spent in fresh water and 18 months spent in the ocean. The exception to this rule are jacks, which are two year old males that return to spawn and keep the genetic diversity between the three temporally spaced populations (Moyle, 2002). Coho spawn in streams that connect to the ocean or tributaries of these rivers. Migration up these rivers usually does not happen until winter or fall storms create enough flow to break the sandbars at the mouth of the river. Once there is enough flow for the salmon to enter the stream they cross into the lagoons and make their way upstream. In most of California the coho salmon spawn in small coastal creeks or tributary headwaters of larger rivers. The timing of return for coho varies with how far north they are. The general rule is that the farther north and the bigger the river, the Page 2 of 12
earlier in the season they return to their home stream (Moyle, 2002). According to Moyle (2002), coho salmon in the Klamath basin usually run between September and late December, with most of the fish runing in October and November. NMFS (2001) reported that earlier arrivals spawn in upstream tributaries and headwaters while later arrivals spawn in the mainstem and closer to the mouth. The spawning occurs from November to December in areas that have gravel deposits and slower velocity (Moyle, 2002; NMFS, 2001). The slower velocities provide aeration to the developing eggs, while the loose gravel protects the redd (nest) from potential predators. The location of the spawning sites helps facilitate the developing fry s removal once they mature enough to leave the redd (Moyle, 2002). When the female arrives at the spawn site, near a riffle or below a pool, she digs a redd for egg deposition. There are usually multiple redds per female and they are spaced closely upstream from each other. The spawning takes up to a week for each female and will result in 1,400-3,000 eggs with a few hundred embryos in each nest. Large males and small jacks fertilize the eggs. The female covers up the embryos with gravel after spawning and in some cases guards her nest for up to two weeks before dying (Moyle, 2002). Embryos and Fry The embryos incubate for 8-12 weeks before hatching (Moyle, 2002). The time it takes for incubation depends on many factors, including temperature, dissolved oxygen, water velocity, and gravel size (NMFS, 2001). Incubation in the Klamath system usually occurs in November through March. The hatchlings remain in the sediments until their egg yolks disappear, which takes two to three weeks (U.S. Bureau of Reclamation, 2001). While in the sediment the hatchlings can become subject to high scouring flows and heavy siltation, which may cause mortality close to 100 percent (Moyle, 2002). Hatchlings will also have higher mortality in disturbed watersheds compared to forested watersheds with stable stream systems (Mount and Moyle, 2003). Once they emerge from the sediments, which occurs from February to May, coho seek out marginal covered stream banks (U.S. Bureau of Reclamation, 2001, Moyle, 2002). Small shoals are formed, but these soon break up as coho salmon set up territories. Page 3 of 12
Juveniles The juveniles tend to rear in the river system for a year before moving out to sea. Juveniles are often called parr due to the vertical bands on their side (parr marks). They have 8-12 narrow parr marks that are widely spaced. All the fins are orange and spotless, with the exception of the adipose fin, which is speckled and gray (Moyle, 2002).. As they grow the juveniles mostly feed on insects, both aquatic and terrestrial, but will eat small fish as well (U.S. Bureau of Reclamation, 2001). During summer the coho move into deep pools that provide dense shade and have a lot of woody debris (Nickelson et al., 1992a, Brown et al., 1994). The pools provide a cool, well-oxygenated area for the juveniles to rear. Figure 1. Juvenile Coho salmon (Copyright 2000 William Leonard) During the summer, these pools can be important as a thermal refuge. As reported by Welsh, Hodgeson, and Harvey (2001) coho salmon cannot withstand temperatures above 23.4 C. A MWMT (maximum weekly maximum temperature) of 18.1 C or a MWAT (maximum weekly average temperature) of 16.8 C is lethal to the fish. These deep pools provide a refuge from the temperature and allow the juveniles to live through the summer. Although the pools are important rearing habitats, according to Kahler, Roni, and Quinn (2001) there is a portion of the population that moves around in the streams. These movers don t have established territories but move based on habitat size and depths, with a preference for deeper pools. Most of the movement occurs during the summer (Kahler et al., 2001). During the winter the coho salmon move away from high flow pools, such as plunge pools, and take up residence in side pools and alcoves (Nickelson et al. 1992a, Nickelson et al. 1992b). This movement is most likely due to the declining water temperature and an increase in flows due to winter storms (Nickelson et al., 1992b). These alcoves and side pools during the Page 4 of 12
winter are an important factor in overall coho sustainability and can be the ultimate limiting factor (Nickelson et al., 1992a, b). Once spring comes the juveniles start heading out to the mouth of the river. Smolts Downstream migration occurs between February and June (U.S. Bureau of Reclamation, 2001). During this time the juveniles loose their parr marks and develop a slivery coloration. The slivery fish, which look like juveniles with fading parr marks, are called smolts. The timing of migration is based on water level and moon phase, but is also determined genetically. The fish move downstream in pulses and spend time in low velocity sections of the river. Once they reach the estuary, the smolts stay in the system moving up and down with the currents (Moyle, 2002). Moyle (2002) suggested that staying in the estuary helps the young smolt adjust their osmoregulatory system to the increase in salt water before heading out to sea. Figure 2. Adult oceanic coho (American Fisheries Soc.) Once the smolts enter the ocean they stay around their parent river foraging on pelagic marine invertebrates. As they grow they increase in size and become a major pelagic predator feeding on small marine fishes. The coho tend to form schools that will dissipate when feeding starts. Once they get bigger, the coho move out to sea and may range as far north as Alaska and maybe even go into Baja Mexico (Moyle, 2002). However, due to the productive upwelling off the California coast, most of the coho tend to stay near the shore. An interesting note by Moyle (2002) is that fish from specific areas tend to congregate together in the ocean. Once reaching adult size, which ranges from 55-70cm and weights of 3-6kg, the coho look very similar to Page 5 of 12
chinook salmon (Moyle, 2002). The oceanic adults are silvery with a slight green tint. They have black spots on their back as well as their caudal fin. The coho has white gums and can be distinguished from the Chinook salmon by the presence of black gums (U.S. Bureau of Reclamation, 2001). Spawning Adults After being in the ocean for 18 months the adult coho develop spawning colors and head back to their parent stream. Coho salmon head up river to a suitable spawning site, which is usually a cool, shaded stream with a gravel bottom. Spawning coho take on a reddish color prior to spawning. Males have dark red sides that contrast to a green back and gray underside. Males develop a strongly hooked jaw and humped backs. The females develop a pinkish tone that is not as intense as the male and have only a slightly hooked jaw (Moyle, 2002). The females are accompanied by a dominant male and usually subordinate jacks. The mating pairs then select a spawning site and spawn before dying, thus renewing the cycle. DISTRIBUTION Coho salmon are a widely distributed species. They are present around the Northern Pacific Rim and comprise important fisheries in some of its habitat. Coho were historically found in the North Pacific Ocean. They extended from central California to Point Hope, Alaska, through the Aleutian Islands, and from Anadyr River, Russia, south to Hokkaido, Japan (NMFS, 2001). However, along the U.S. Pacific coast the numbers of coho salmon have declined or disappeared (Brown et al., 1994). This is especially true of the southern most coho. Historically they ranged as far south as Big Sur River, but now are present only in Scott and Waddell Creeks (Santa Cruz County) and in small populations North of San Francisco bay (Moyle, 2002). Most of the populations in California are either gone or reduced, due to habitat degradation and loss. According to Brown et al. (1994) at least 70% of native coho salmon in California streams have been lost since the 1960 s and are still continuing to decline. Of the 582 historic coho salmon streams only 248 have documented information on their status, and of these 248 only 54% still contain coho salmon (Brown et al., 1994). In the Klamath basin the numbers of coho salmon have been severely reduced. Iron Gate Dam has prevented access to the upper basin. However, according to Moyle (2002) historically Page 6 of 12
the coho went up the Klamath River as high as Klamath Falls, Oregon, which is above the Iron Gate Dam. The coho used to go up past the Lewiston Dam in the Trinity River but are now prevented from going farther upstream. In the Klamath, the coho still have access to most of the Figure 3. Map of tributaries tributaries below the Iron Gate Dam. U.S. Bureau of Reclamation (2001) reported that the coho were historically in the Shasta River and Scott River, both important tributaries of the Klamath. They also noted that coho presently occur in Bogus Creek, Shasta River, Humbug Creek, Empire Creek, Beaver Creek, Horse Creek, Scott River, Seiad Creek, Grider Creek, Thompson Creek, Indian Creek, Elk Creek, Clear Creek, Dillon Creek, Salmon River, Camp Creek, Red Cap Creek, Trinity River, Turwar Creek, Blue Creek, Tectah Creek, and Pine Creek. The Shasta Page 7 of 12
River comprises 38 miles of habitat and the Scott River comprises 88 miles of coho salmon habitat (U.S. Bureau of Reclamation, 2001); however, reduced flows, diversions, and high temperatures, all of which are detrimental to the coho, degrade most of this habitat. Due to the degraded habitat and small population sizes all populations of the coho in California have been listed as threatened under the ESA (U.S. Bureau of Reclamation, 2001). STATUS While the coho salmon may be producing productive fisheries in some of its northern range, in California and to more of an extent in the Klamath basin the coho have been dramatically decreasing (Brown et al., 1994). What was once a thriving fishery has now been reduced by 90-95 percent of its historical numbers. The Klamath basin, which used to receive 15,000-20,000 fish historically, now only has a run of 1,700-3,100 coho salmon (Brown et al., 1994). The dramatic decline of the coho salmon in California has lead to the listing of both ESUs. The Southern Oregon-Northern California Coast ESU and the Central California ESU were listed in 1996 and 1997 as Threatened by the NMFS, with the Central California ESU in danger of extinction (Moyle, 2002). The Klamath basin had an annual return of spawning fish that numbered between 15,400-20,000 fish (Brown et al., 1994). The number of fish that came through the system supported a fishery that was used by the Native Americans and early settlers of the area (see the paper by Sabrina Litton). The reasons for the decline vary from system to system but are mainly caused by decreased habitat, overexploitation, degradation of streams, and poor ocean conditions. According to Moyle (2002) during the 1940s the estimated population of spawning coho salmon in California was between 200,000 and 500,000. During the 1960s this number had already dropped significantly to 100,000 coho salmon. Further reductions were seen in the 1980s with a number of spawning adults around 33,500 (Moyle, 2002). According to Brown et al. (1994) at least 70% of native coho salmon in California streams have been lost since the 1960 s and are still continuing to decline (refer to figure 3). Of the 582 historic coho salmon streams only 248 have documented information on their status, and of these 248 only 54% still contain coho salmon (Brown et al., 1994). Page 8 of 12
To compound this issue of declining numbers, hatchery fish promote the decline of natural populations. If carefully managed, hatcheries can be a benefit a small population of natural fish by providing short-term protection from variation in the environment. They can also help accelerate the growth of the population size (California Department of Fish and Game [CDFG], 2002). However, if stocks are taken from outside of the area, as in the case of the Klamath, then poorly adapted fish may result in a decline of genetic quality. Hatcheries can counteract the effect of years of natural and environmental selection on the wild population. Figure 4. Estimated population size of adult Coho salmon in California from 1900 to 2000 (Based on Brown et al., 1994) This leads to a generic coho salmon that is less well adapted to the basin. Along with declining genetic quality, hatcheries promote increased competition. When hatchery fish are released they migrate downstream in large numbers impacting the native coho salmon. This can lead to an increased mortality rate and can be a major problem with using hatcheries. In Klamath basin, the hatchery fish can make up 57 percent of the total run and often have genetic origins from outside of California. In Klamath many populations of coho contained Page 9 of 12
fish with recent hatchery ancestry (Moyle, 2002). Most of the fish currently returning to the river belong to the Iron Gate and Trinity hatcheries, with natural spawning producing only a minor fraction of returning coho. However, due to a heavy stocking period in the late 1960s, most of this hatchery stock is from outside the system (Brown et al., 1994). Currently 17 of 25 historic coho salmon streams in the Klamath system still have small amounts of juvenile coho (Mount and Moyle, 2003). Figure 5. Population cycles of Coho salmon (Moyle 2003). The decline of coho salmon in California streams can be due to many factors (see Figure 4). These factors include degraded habitat, logging, urbanization, agriculture, mining, introduced fish and diseases, overharvesting, and interactions with hatchery raised fish (Moyle, 2002). While these are all human activities, many natural problems can result in some population loss. Landslides, floods, and poor oceanic conditions can lead to a loss in coho numbers. Landslides and floods can damage spawning grounds or bury the gravel beds with the developing fry. If stream conditions decline, then juveniles are most affected, reducing the numbers available for future runs. Poor ocean conditions can reduce the adult population leading Page 10 of 12
to a reduction in spawners. While natural occurrences are needed to maintain historic populations, they can wipe out low populations such as the ones in California. If a landslide occurs on a stretch of spawning habitat, it may eliminate that year class from the population. Aside from natural declines in population, human caused declines are a big problem in the Klamath basin. Two major problems in Klamath basin have been logging and agriculture. Logging and associated roads created areas of reduced riparian cover and increased silt load into the stream. These reduced the number of pools, which are extremely important for coho. The reduced cover also helped to raise the temperature of the system and further impacted the coho salmon (Welsh et al., 2001). Diversions due to agriculture have also resulted in loss of water and habitat for the coho in the Klamath River (see the papers by Sarah Null and Mike Bezemek). The dams of the upper basin have blocked off long stretches of spawning habitat. Diversions and farming in the lower basin valleys have increased temperatures and lowered water quality (see papers by Sabrina Litton and Raffi Moughamian). Increased temperatures can also result in competition between coho salmon and steelhead. Typically, the steelhead and coho usually segregate by habitat, with coho in the pools and steelhead in the riffle (Harvey and Nakamoto, 1996). This keeps the competition between the two species to a minimum. When temperatures get too high, the two species crowd together in thermal refugia. This creates areas of high fish density. According to Harvey and Nakamoto (1996) if Steelhead were present near the coho, there was a negative impact on the coho s growth. While the coho are competing against different species, they are also competing against themselves. Hatchery fish are a problem for the wild natural populations because of the large numbers put into the system. The hatchery fish are usually larger and size is related to aggression in salmonids (Harvey and Nakamoto, 1996). As noted by Rhodes and Quinn (1998) in their experiment on territory contests between hatchery and natural coho the hatchery fish usually won. This results in a decreased number of natural coho in the system. All of these factors, both natural and human derived, have resulted in the decrease of the coho salmon in the Klamath basin. Page 11 of 12
CONCLUSION The Klamath basin is a complex system with many different fish species. The coho are of particular concern. They provide food for many species, including humans, and are important predators. They have been declining in numbers for many years and have shown no signs of stopping. If nothing is done to prevent the decline of the Klamath coho salmon, their numbers will continue to dwindle. Through a long history of human land and water use the coho have declined. Although plans have been established and tried to bring the coho back to large populations, nothing has worked so far. Klamath coho are special fish that are worth preserving. It deserves our attention and restoration efforts. Coho salmon in the basin have dropped so significantly that the only way to bring them back is to start restoring habitat and redesigning hatcheries. Redesigning dams, returning water to the system and restoring riparian habitat is crucial to the coho s survival. It is in our hands to see this magnificent fish back on the road to recover. REFERENCES Brown, Larry R., Peter B. Moyle, and Ronald M. Yoshiyama. Historical Decline and Current Status of Coho Salmon in California. North American Journal of Fisheries Management 14 (1994): 237-261. California Department of Fish and Game. Status Review of California Coho Salmon North of San Francisco. April 2002 Harvey, Bret C., and Rodney J. Nakamoto. Effects of Steelhead Density on Growth of Coho Salmon in a Small Coastal California Stream. Transactions of the American Fisheries Society 125 (1996): 237-243. Kahler, Thomas H., Philip Roni, and Thomas P. Quinn. Summer movement and growth of juvenile anadromous salmonids in small western Washington streams. Canadian Journal of Fisheries and Aquatic Sciences 58 (2001): 1947-1956. Mount, J. and Moyle, P. 2003. Ecology and Geomorphology of Streams: Class Reader. Spring Quarter, 2003. University of California, Davis. Moyle, Peter B. Inland Fishes of California: Revised and Expanded. Berkeley and Los Angeles: University of California Press, 2002. National Marine Fisheries Service Southwest Region. Biological Opinion: Ongoing Klamath Project Operations. April 6, 2001. Page 12 of 12
Nickelson, Thomas E., Mario F. Solazzi, Steven L. Johnson, and Jeffrey D. Rodgers. Effectiveness of Selected Stream Improvement Techniques to Create Suitable Summer and Winter Rearing Habitat for Juvenile Coho Salmon (Oncorhynchus kisutch) in Oregon Coastal Streams. Canadian Journal of Fisheries and Aquatic Sciences 49 (1992): 790-794. Nickelson, Thomas E., Mario F. Solazzi, Steven L. Johnson, and Jeffrey D. Rodgers. Seasonal Changes in Habitat Use by Juvenile Coho Salmon (Oncorhynchus kisutch) in Oregon Coastal Streams. Canadian Journal of Fisheries and Aquatic Sciences 49 (1992): 783-789. Nickelson, Thomas E., Mario F. Solazzi, and Steven L. Johnson. Use of Hatchery Coho Salmon (Oncorhynchus kisutch) Presmolts to Rebuild Wild Populations in Oregon Coastal Streams. Canadian Journal of Fisheries and Aquatic Sciences 43 (1986): 2443-2449. Rhodes, J. S., and T. P. Quinn. Factors affecting the outcome of territorial contests between hatchery and naturally reared Coho salmon parr in the laboratory. Journal of Fish Biology 53 (1998): 1220-1230. U.S. Bureau of Reclamation Mid-Pacific Region Klamath Area Office. Biological Assessment of the Klamath Project s Continuing Operations on Southern Oregon/Northern California ESU Coho Salmon and Critical Habitat for Southern Oregon/Northern California ESU Coho Salmon. Oregon: January 22, 2001. Welsh, Jr. Hartwell H., Garth R. Hodgson, and Bret C. Harvey. Distribution of juvenile Coho Salmon in Relation to Water Temperatures in Tributaries of the Mattole River, California. North American Journal of Fisheries Management 21 (2001): 464-470. Page 13 of 12