sign in sign up
<<
Home , Klamath River

S. D. G.

Life History, Status, and Distribution of Klamath River Chinook

By Jafet Andersson

INTRODUCTION

The Klamath River Basin on the - border is a diverse, unusual and important watershed (Figure 1). It is diverse in its geology, climate and vegetation; unusual in its geomorphology, and important from aspects as diverse as supporting endangered fish species, providing for American Indian tribes, and supplying farmers with water for . Geomorphologically, the basin stretches from in the Upper Basin (above the Iron Gate ) characterised by large natural lakes and low relief, to the mountainous Lower Basin characterised by steeper terrain and higher topographic complexity. The watershed in specific has bedrock dominated upper reaches, a central alluvial valley, a west side with steep-gradient tributaries, an east side with low-gradient tributaries and a steep bedrock gorge just above the junction with the Klamath main stem [refer to (Sanchez, 2003) in this volume for more detail]. The mountainous Lower Basin interacts with the meteorological conditions dominated by Pacific storms to produce the characteristic spatial climate distribution in the region. The further from the ocean, the lower the precipitation as water is successively released (mostly as snow) over the mountains in the west. This pattern influences the densely forested Scott River watershed in that the west side is much more moist than the valley and the east side. The hydrograph is snowmelt dominated with the bulk of the being released in the spring [refer to (Anderson, 2003 and Chambers, 2003) in this volume for more detail]. There are 19 native and 13 alien fish species in the Lower (Mount and Moyle, 2003). Nearly all native species spend some of their life in salt water while most alien species are entirely freshwater based. Important fishes of the Lower Klamath include the federally recognised threatened ( kisutch), the declining steelhead (O. mykiss) and the largest and most abundant salmonid, the (O. tshawytscha). Due to the importance of anadromous1 fishes for tribal, sport and commercial fisheries there has been extensive support for restoration of these fish populations. Although focus has centred on the threatened coho, long-term holistic management of all native species

Page 1 of 21 J. C. M. Andersson May 5, 2003 is needed to prevent additional species of being threatened, and to consider - at times counterintuitive - ecosystem interactions. For this purpose, the natural history of the chinook salmon (with focus on the Lower Klamath Basin above the Trinity River confluence) is reviewed in terms of its life history (the developmental history of an organism from birth to death) and status (the population size and spatial distribution in a temporal perspective).

Figure 1. The Klamath River Basin ( source Klamath Basin fish and Water Management Symposium, http://www.humboldt.edu/~extended/klamath/klamathmap.html)

1 Anadromous fish spawn in freshwater but migrate to the sea and spend their adult life in the ocean

Page 2 of 21 J. C. M. Andersson May 5, 2003

LIFE HISTORY

Chinook salmon (Oncorhynchus tshawytscha) is an anadromous fish with a broad range of life history patterns. In general, it is characterised by a life cycle that begins in freshwater where the eggs are laid, where the alevins emerge and where the fry rear until they metamorphose into smolts (smoltification) in preparation for their ocean life as adults in the sea. The cycle is completed as the spawning adults migrate back into the rivers to lay their eggs (Healey, 1991). In the Klamath River Basin, there are, broadly speaking, two distinct chinook populations: the spring run2 and the fall run. Moyle (2002) indicates that a late fall run may also have existed, but it is either poorly documented or extinct. For management purposes, the National Marine Fisheries Services (NMFS) recognises two populations: the Southern Oregon and Coastal California ESU3 (including the Klamath chinook below the Trinity River confluence) and the Upper Klamath and Trinity Rivers ESU (including both the fall run and the spring run chinook salmon from the Klamath River based on their genetic similarity; Myers et al., 1998). The distinct differences between the spring run and the fall run life histories may, however, merit a managerial differentiation (Moyle, 2002). The spring run differ from the fall run in that the adults enter the river before they are ready to spawn and reside in deep pools for 2-4 months before they spawn whereas the fall run adults spawn closely after they reach their spawning destination (Moyle, 2002). In addition, the spring run juveniles remain in the streams for a year or longer before their seaward migration (from which the term "stream-type" originates), whereas the fall run juveniles are generally less than a year old before they migrate to the sea (from which the term "ocean-type" originates) (Healey, 1991). The spring run juveniles are, furthermore, more territorial due to their larger size resulting from their relatively longer pool residence time in comparison with the fall run juveniles (Moyle, 2002). Below follows a discussion of the different life history stages of chinook salmon with particular focus on general timing and habitat requirements for each stage.

Egg An adult female lays between 2,000 and 17,000 eggs (averaging about 9 mm in diameter) depending, in part, on female size and geographic position such that larger females lay more eggs and females at lower latitudes lay fewer eggs (Healey, 1991; Myers et al., 1998).The

2 A run is a large group of fish migrating in order to spawn

Page 3 of 21 J. C. M. Andersson May 5, 2003 eggs are laid down in a gravel spawning bed - also known as a redd - at the head of a riffle in several depressions created during a few days of digging by the female. At the time of deposition, usually more than one male release their sperm into the depressions which are subsequently covered by gravel (Allen and Hassler, 1986). Eggs are incubated for about 30 days in the fall and winter before they hatch (Nawa and Frissell, 1993).

Figure 2. Chinook salmon egg (source Columbia Environmental Research Centre: http://www.cerc.cr.usgs.gov) Redds vary greatly in water depth, water velocity and depth of gravel overlaying the eggs (e.g. 5-720 cm, 10-189 cms-1, and 10-80 cm respectively), such that meaningful averages are hard to establish (Healey, 1991). Sub-gravel flow does, however, seem to be of overriding importance in the choice of redd site because of its role of bringing oxygen to and removing metabolic waste from the eggs (Allen and Hassler, 1986). It has been suggested that chinook eggs are more sensitive than other Pacific to low sub-gravel flows due to the high surface-to-volume ratio of their relatively large eggs that thus require higher rates of oxygenation (Healey, 1991). Silver et al. (1963) noted that, at least at about 11ºC, oxygen levels during incubation were influencing the size of chinook at hatching even near oxygen saturation. A study conducted at Mill Creek, California indicated that mortality increased rapidly as oxygen concentration decreased (3.9% at 13 ppm and 37.9% at less than 5 ppm respectively) presumably because of decreased water flows through the gravel (Gangmark and Bakkala, 1960). The water flow through the gravel is affected by depth of water above it since more water increases the hydraulic head (the pressure) in the gravel (Allen and Hassler,

3 An ESU is an Evolutionary Significant Unit (Myers et al., 1998)

Page 4 of 21 J. C. M. Andersson May 5, 2003

1986). Siltation is also an important determinant of gravel throughflow in that the silt clogs up the gravel and thus decreases the flow through it (Healey, 1991). Egg mortality is influenced by the temperature at which the eggs are incubated such that 3-16ºC constitutes the upper and lower limits for 50% pre-hatch mortality at constant temperatures. At variable temperatures, the mortality is reduced (Healey, 1991). Ideal incubation temperatures are 5.5-12.8 (McCullough, 1999). Hatching time is inversely proportional to temperature of incubation; at 16ºC e.g., eggs hatch after ca 32 days. Other sources of egg mortality include predation by other fish species and by invertebrates (e.g. oligochaete worms) if the eggs are not buried deep enough, shock from scouring and high concentrations of toxic chemicals (Allen and Hassler, 1986). All in all, these and many other factors in the chinook life cycle add up to the 1:1 ratio between adult female parent and adult female spawner in the next generation (Healey, 1991).

Alevin Newly hatched chinooks that still have the yolk sac attached are termed alevins (Figure 3). Alevins emerge from the eggs in general between January and March (Trihey & Associates, 1996), but the timing varies from year to year. Alevins remain in the same habitat as the eggs (the redd) until the nutrients in the yolk sac are used up, which takes about 2-4 weeks (Nawa and Frissell, 1993).

Figure 3. Chinook alevin (source Columbia Environmental Research Centre: http://www.cerc.cr.usgs.gov) In addition to the habitat requirements of the eggs, alevins need adequate amounts of water in the gravel surrounding them. In the event of both short recurrent, and prolonged single-event dewatering of the redds, development rate decreases and survival plummets. A

Page 5 of 21 J. C. M. Andersson May 5, 2003 study found that the survival rate for alevins experiencing recurrent one hour dewaterings or a single six hour dewatering event was a mere 4% (Healey, 1991).

Fry & Fingerling When the nutrients of the yolk sac are nearly gone, the chinook starts feeding on its own in the water column, develops neutral buoyancy and social behaviour (Allen and Hassler, 1986). This is the fry-fingerling stage of the chinook life cycle (fry being 30-45mm and fingerlings 50-120mm in fork length (Healey, 1991)). Fry are also known as parr in reflectance of the distinctive darker stripes on their sides (Figure 4) (Moyle, 2002).

Figure 4. Chinook salmon fry (source USFWS: http://cybersalmon.fws.gov/chin.html) In the Klamath Basin, it is generally observed that juveniles migrate downstream throughout the year (USFWS, 1998). However, most fall run fry begin their tail-first downstream migration closely after emergence from the gravel between March and July (July being dominated by fingerlings), peaking in May (USFWS, 1998). In the Scott River the peak occurs from mid-April to mid-May with some degree of variation depending on the temperature conditions of the rearing grounds (Chesney, 2002 and USFWS, 1998); although in the migrant fry were observed as early as mid-January (USFWS, 1998). Some fall run fry remain in the river during the summer and subsequently migrate in October, while a few even wait until early spring the following year before they head downstream (Trihey & Associates, 1996). Spring run chinook fry emerge from the redds between March and June, rear through the summer and fall in the cool headwaters and migrate to the sea mainly in the following spring (Trihey & Associates, 1996). Spring run fry are believed to migrate downstream slightly later than the fall run because the spring run eggs develop slower in the cooler headwaters where their redds are. The juveniles that remain in the river rear both in the mainstem and the larger tributaries principally from January to July (USFWS, 1998). Principally fall run juveniles utilise the Klamath for rearing throughout the sampling season between March and September (Wallace, 2000).

Page 6 of 21 J. C. M. Andersson May 5, 2003

The mechanisms of the onset of the downstream migration are not yet fully determined, but it is believed that factors that may influence the process (Healey, 1991) include water flow (spring snowmelt water), inheritance, and competition. Competition may, for example, be with the one year older and larger juvenile coho salmon (O. kisutch) that inhabit similar habitats, which may force the smaller chinook to migrate as both species are territorial and compete for food. In addition, it has been observed that downstream movement occurs mainly at night and that it is suppressed by bright moonlight (Allen and Hassler, 1986). Chinook fry rear at suitable locations in the river as they move downstream but Healey (1991) also notes that the estuary provides important rearing habitats as well (with abundant food), especially for the fall run chinook. A Snake River study found chinook fry rearing at various depths and water velocities but, that they were concentrated to sites with relatively small substrate particle sizes, shallower water, and water of lower velocity (Everest and Chapman, 1972). Chinook seems to prefer boulder and rubble substrate, water with low turbidity, and moving water slower than 30 cms-1 (Healey, 1991). Juveniles benefit from both the relatively high velocities in the central part of the channel for drift feeding and the lower velocities behind boulders and large woody debris for rest (Trihey & Associates, 1996). A study conducted in the Big Qualicum River found that chinook fry emerged earlier and were thus larger than coho at any given point in time (Lister and Genoe, 1970). It found that smaller fish resided in the marginal low velocity stream areas while larger fish inhabited the higher velocity midstream areas. As a result, a natural habitat segregation between chinook and coho fry occurs, reducing competition to a certain degree. High turbidity adversely influences the feeding ability of juvenile salmon, but slightly turbid waters can aid the juveniles in their pursuit of avoiding predators (Newcombe and MacDonald, 1991). Suspended sediment can further clog up interstitial spaces between cobbles and boulders in which fry hide from predators, high water flows and where aquatic invertebrates such as larval and adult insects - the main juvenile food source - dwell among the streambed vegetation. McCullough (1999) notes that temperatures above 17ºC are associated with increased stress in the form of disease and predation, that the optimal chinook fry rearing temperature is around 13ºC, but that they can feed and grow at temperatures as high as 24ºC in otherwise stress-free environments. Streambed vegetation aids in providing relief from the warm waters especially for spring run fry that reside in the freshwater during the warm summer months, in addition to hiding the juveniles from predators (Moyle, 2002). Small-scale diversity of habitat is thus important for juvenile chinook rearing. Fish and invertebrate predation are the two most important causes of mortality during the chinook

Page 7 of 21 J. C. M. Andersson May 5, 2003 freshwater residence (Healey, 1991). Other salmonids (including hatchery reared chinook and steelhead) may also cause elevated rates of mortality as they compete for rearing habitat space both in the mainstem and in the estuary (Kelsey et al. 2002).

Smoltification Smoltification is the physiological transformation that juveniles go through as they prepare for saltwater residence. It principally involves the development of osmoregulatory4 capabilities to cope with the increased salt concentration of the ocean (Weitkamp, 2001), but other changes, such as lengthening of scales and tails, and change to a more silvery colour also take place (Figure 5).

Figure 5. Chinook Salmon smolt (source USFWS: http://cybersalmon.fws.gov/chin.html) Smoltification occurs at different sizes, locations and times of the year. In general however, fall run fry grow to smolt size in the last month of estuarine residence, whereas spring run metamorphose into relatively large smolts in the mainstem right before they reach the estuary in the spring (Healey, 1991). The spring run smolts stay only for a short period of time in the estuary before they head out into the ocean. The fall run fry growth in the estuary appears to be correlated with egg and fry size such that larger fry outgrow potential predators more quickly than smaller fry (Healey, 1991). This may be important in the context of hatchery fish, as they tend to have larger egg sizes on average than wild fish and may thus outcompete the wild fry as they tend to cohabit in the estuary along with many other species (Allen and Hassler, 1986). Larger spring run smolts reside at the delta front and at near-shore areas close to the river mouth, whereas metamorphosing fall run fry tend to prefer tidal channel habitats with low channel bank elevation and several refugia in which they can reside when the tide is out (Healey, 1991). Salinities of the fry habitat range from 0-20 ppm and is proportional to size. Because of the changing salinity in the estuary as the tide moves in and out, the juveniles

4 Osmoregulation is the mechanism by which water flow into and out of cells is regulated.

Page 8 of 21 J. C. M. Andersson May 5, 2003 change location with the tide. The juveniles prefer deeper waters, boulders and rubble, but reside in areas with smaller sized sediment as well (Allen and Hassler, 1986). The pool depth is proportional to size such that larger chinook inhabit deeper pools (Healey, 1991). In the Sacramento - San Joaquin River estuary, high mortality rates has been observed for emigrating smolts at 22-24ºC (Baker et al. 1995). In general, McCullough (1999) notes temperatures as low as 13ºC can prevent smoltification. Size also influence the choice of food such that small fry concentrate on catching zooplankton and invertebrates, whereas larger smolts focus on insects (e.g. chironomid larvae) and other small fish (e.g. chum salmon fry and juvenile herring) (Healey, 1991).

Ocean adults

Figure 6. Chinook salmon ocean stage adult (source USFWS: http://cybersalmon.fws.gov/chin.html) In the estuary and subsequently upon entering the ocean, the chinook salmon grows quickly on small marine fishes (e.g. herring and anchovy), crustaceans (e.g. shrimp) and squid (Healey, 1991) until it reaches its adult size of 40-100cm in fork length, the largest of the Pacific salmon species. Length is correlated with age such that two-year adults are around 40cm long, and 6-year adults around 1m. The fall run chinook is larger than the spring run in every year-class due to the slower growth of the spring run during its first year of life (Healey, 1991). Some data suggests that fall run chinook spend almost their entire marine life near shore, close to their home river. Spring run chinook, on the other hand often disperse further off-shore (Allen and Hassler, 1986). Chinook appear to be most abundant at depths between 40 and 80m, but both regional and seasonal variation may occur (Healey, 1991). Most adults begin their return, upon a poorly defined set of migratory triggers, to the Klamath River in their third and fourth years, but five-year-olds and two-year-old males do also occur to a lesser extent (KRTAT, 2003).

Page 9 of 21 J. C. M. Andersson May 5, 2003

Spawning adults The last stage in the life of a chinook salmon is the return to freshwater as an adult to spawn and die. Chinook adults metamorphose from the silvery ocean form into the characteristic dark maroon to olive brown spawning colours (Figure 7). During the upward migration, they stop feeding as their digestive tract degrades and live increasingly on their body fat. Males get hooked jaws with sharp teeth, humped backs and their ability to heal injuries and fight disease declines (Allen and Hassler, 1986). The ability for chinook to find their way back to their home stream in order to spawn is mainly related to the long-term olfaction memory of the salmon, but is also aided by their vision (Healey, 1991) and may be stimulated by higher streamflow and changes in water turbidity, temperature and oxygen content (Allen and Hassler, 1986). This homing instinct seems to be weaker in the spring run compared with the fall run but is generally relatively strong.

Figure 7. Chinook spawning stage male and female adult (source Kitsap , Washington: http://www.kitsapgov.com/) The fall run adults mainly enter the Klamath River beginning in late July, peaking in September near the mouth of the Trinity River, and continuing into December (Trihey & Associates, 1996; USFWS, 1998). Since 1930, when the run took place between July and September, the peak has shifted about 3 weeks (Snyder, 1931). Redd surveys between 1993 and 1996 found that fall run chinook initiated spawning in the mainstem Klamath River close after the upstream migration between October and November, peaking in the last week of October (USFWS, 1998), but other sources indicate that spawning is spread out during a longer period in the fall (Trihey & Associates, 1996).

Page 10 of 21 J. C. M. Andersson May 5, 2003

The spring run adults, which currently only remain in the Salmon and Trinity Rivers (Barnhart, 1994), enter the Klamath River between March and July, with the peak in May - June (Myers et al., 1998). In relief from the high summer temperatures, they reside in deep (usually >2m), relatively cool, bedrock pools with moderate water velocities until September when they start laying their eggs (peaking in October) in tributary streams (Trihey & Associates, 1996). The holding pools are usually close to the spawning areas, and the adults may utilise more than one pool during the summer holding season (Moyle, 2002). Most adults migrate upstream during the day and may thus be inhibited by high day temperatures. McCullough (1999) draws the following conclusions from various studies regarding temperature: higher temperatures increase the metabolic rate of the adults and thus deplete their limited energy reserves; higher temperatures decrease the strength of the immune system; 15.6ºC represents the threshold for the increased onset of diseases; adults are more sensitive to high temperatures than juveniles are; and 21.1ºC represents a barrier to migration, while in the , 19ºC represented partial blockage to migration for adults. Allen and Hassler (1986) note, however, that adult spring run chinook migrating upstream may have much lower tolerance limits (3.3-13.3ºC) than fall run chinook. Adults held at 19ºC for 1.5 months displayed near total mortality. Adults use thermal refugia (e.g. deep pools) to escape high temperatures and become thermally stressed when the holding areas are above 15ºC. 12.8ºC represents an inhibitory temperature for spawning and no spawning occurs above 16ºC. Adults held at 17.5-19ºC vs. at 14-15.5ºC for two weeks prior to spawning displayed lower gamete production, higher pre-hatch mortality, decreased size of the eggs, and smaller alevins. An important factor influencing the water temperatures to which the adults are exposed is the amount of shade that the surrounding riparian vegetation provides (Moyle, 2002). The more vegetation that covers the channel, the lower the water temperature in the stream [refer to (Moughamian, 2003) in this volume for more detail]. Additional constraints for the migrating adults include low dissolved oxygen (below 5 mg/l), shallow water (below 24 cm) and high sustained water velocity (above 2.5 m/s) (Allen and Hassler, 1986). Migrating adults may also be constrained by high levels of suspended sediment (turbidities above 4,000 ppm), but actual silt deposition on the gravel spawning areas is likely to be more detrimental for the overall sustenance of the population. After spawning on a suitable gravel bed in their home stream for one to two weeks, the adult females defend their eggs from intruders for another week or so. They subsequently start deteriorating rapidly and die within two to four weeks due to, for example, the onset of a fungal disease facilitated by the decline of their immune system (Allen and Hassler, 1986).

Page 11 of 21 J. C. M. Andersson May 5, 2003

STATUS - POPULATION SIZE AND DISTRIBUTION

Chinook salmon is currently the most abundant salmon species in the Klamath Basin (KRTAT, 2003). Beneath this broad statement however lies considerable temporal, spatial and life history related variability that will be summarised below. There are indications that the total fall run population may have been as large as 500,000 in the Klamath River including both fish from below and above Trinity River (with a majority from above the confluence) (Moyle, 2002). This estimate includes, however, both chinook and coho salmon and possibly other salmonids in the basin as well. Total in-river and ocean catches between 1916 and 1927 have been estimated to be between 120,000 and 250,000 fish associated with a significantly larger potential spawner population (Mount and Moyle, 2003). In his classical study, Snyder (1931) documents a depletion of the salmon stock. In 1915, 40 fishing boats caught around 100,000 salmon, whereas in 1926, 126 fishing boats only caught around 40,000 salmon apparently irrespective of imposed regulatory pressures (Snyder, 1931 and Moyle, 2002). Recent data for the fall run indicates that the population has fluctuated between 27,000 and 218,000 the last 25 years (Figure 8). Specifically considering the spring run life history strategy, Snyder (1931) notes that the spring run was "scarcely evident" (p. 121) and that it "was once very pronounced but … is now of relatively little economic importance." (p. 19) Moyle (2002) further notes that the spring run may have been larger than 100,000 because it was the largest run in the 1800s before the access to the Upper Klamath River Basin (above first Copco Dam in 1917 and now Iron Gate Dam (Snyder, 1931)) was restricted. The spring run once had an estimated population of at least 5,000 in each of the (in the Upper Basin), the Williamson River (in the Upper Basin), the Shasta River, and the Scott River (Moyle, 2002). In the Lower Basin, the construction of Dwinnell Dam in 1926 caused habitat degradation that ultimately resulted in the disappearance of the Shasta River spring run. The smaller Scott River spring run is estimated to have vanished by the early 1970s (Moyle, 2002). It is believed that the spring run suffered more than the fall run from the reduction in accessible spawning area because the spring run used to take advantage of the more challenging upstream habitats before the blockages were built. The upstream habitats were more challenging to the chinook in that they were inaccessible during the summer (because of high temperatures and low flows in the lower basin), and hard to spawn in during snowmelt high flows (as the holding pools are scoured) (Moyle, 2002). Today the spring run remains in the Salmon River Basin and the Trinity River Basin and has numbered between 200 to 1500 in the last 25 years (Figure 9).

Page 12 of 21 J. C. M. Andersson May 5, 2003

Spawning Escapement lnriver Recreational catch Indian Net catch Non-landed Fishing and Mortality Fish Die-off 2002

250000

200000

150000 s t l u ad f o r e mb Nu 100000

50000

0 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 Figure 8. Estimates of the distribution of the Klamath River adult chinook fall run (data from PFMC, 2003). Trihey & Associates (1996) indicates that the minimum natural spawner escapement goal is 35,000 (dotted line). This escapement data, however, includes hatchery fish as well. Moyle (2002) notes that the natural spawner escapement in this period was probably between 20,000 and 40,000.

1600

1500

1400

1300

1200

1100 e 1000 siz

900

800

700 estimated population l a 600 Tot

500

400

300

200

100

0 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 Figure 9. The estimated total population size of the Salmon River chinook salmon spring run between 1980 and 2002 (data from SRRC, 2003).

Page 13 of 21 J. C. M. Andersson May 5, 2003

The total in-river chinook salmon fall run was estimated to be 169,297 in 2002 (KRTAT, 2003). The highest proportion of the run was made up of natural spawners (42%), and the fall fish die-off constituted about 19% (32,553) of the total population (Figure 10). The two most prominent age classes in 2002 were 3 and 4-year-old adults. Furthermore, there was a greater proportion of age 3 natural spawners compared with the proportion of hatchery spawners that year (Figure 11). Looking specifically at the Shasta River, a marked decline in the fall run chinook salmon population size has been documented (Figure 12).

Hatchery Spawners Natural Spawners Total In-river Harvest Fish Die-Off

19% 17%

Total In-river fall run 169,297

22%

42%

Figure 10. The distribution of the total in-river chinook salmon fall run in 2002 (data from KRTAT, 2003).

Hatchery Spawners Natural Spawners Total In-river Harvest Fish Die-Off 100000

2 90000 0 0 80000

inook 2 70000 h

60000 run C ll a 50000 of f r 40000

30000 d numbe e t a 20000 tim

Es 10000

0 2345 Age

Figure 11. The distribution of the total in-river chinook salmon fall run per age class in 2002 (data from KRTAT, 2003).

Page 14 of 21 J. C. M. Andersson May 5, 2003

90000

Commercial fishing in lower 80000 Klamath River closed by the state

70000 Gillnetting resumed in lower 20 miles of Klamath River by Hoopa Valley Indian Reservation fishers.

60000 s ack j d n 50000 a s t

adul 40000 of r e b m u 30000 N

20000

10000

0

0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 4 6 8 0 2 3 3 4 4 4 5 5 6 6 6 7 7 8 8 9 9 93 93 94 95 95 96 97 97 98 98 99 99 00 19 19 193 1 1 19 19 19 194 1 1 19 19 195 1 1 19 19 19 196 1 1 19 19 197 1 1 19 19 198 199 1 1 19 19 200 2 Figure 12. The total number of adults and jacks in the Shasta River between 1930 and 2002. The lowest recorded population estimate (37 adults and jacks) is from 1948. Between 1938 and 1955, spawning escapement was estimated 6.5 miles above the confluence with the Klamath River and considerable spawning occurred below this point (PFMC, 2003).

Figure 13 outlines the threats to chinook salmon that the Humboldt Chapter of the American Fisheries Society concluded upon in 1992 (Higgins et al., 1992). Figure 14 compares the trends of chinook salmon populations in the Lower Klamath Basin established by Myers et al. (1998) with the recent population changes since 1997. Significantly, it shows that both the Salmon River fall and spring run population trends have been reversed (from increasing to decreasing) in the last five years. Furthermore, the Scott River fall run population has begun to decrease, while the Shasta River population has turned the previously negative trend into a positive one. However, the data for the Scott and Shasta Rivers is only based on the 2002 population information and is thus less reliable than the data for the Salmon River. Figure 15 displays the spatial distribution of the chinook salmon fall run and spring run populations for each tributary and the mainstem above the Trinity River confluence categorised according to population size. It is evident from the figure that the fall run population is much larger and occupies a much greater spawning area compared with the spring run population that, apart from the in Trinity River, only spawns in the Salmon River

Page 15 of 21 J. C. M. Andersson May 5, 2003

(including ). Furthermore, the fall run chinook is most abundant in the upper part of the Lower Basin in the mainstem and in Bogus Creek near the Iron Gate Dam, suggesting that it may also have spawned in the rivers of the Upper Basin before the dam constructions were completed (Figure 15).

P

a Shasta River c

i Fall Chinook f i

c (A)

O c e a n

Scott River Fall Chinook (C) Coho (A)

Lower Klamath Fall Chinook (B) Salmon River Spring Chinook (A)

Trinity River Fall Chinook (C)

South Fork Trinity River Spring Chinook (A) Fall Chinook (C)

Figure 13. The relative threat to different salmon populations in the Lower Klamath Basin (Higgins et al., 1992). Category A, stocks at high risk of extinction, "showed continuing spawner declines with fewer than 200 adults". Category B stocks, at moderate risk of extinction, "have declined substantially from historical levels". Category C, stocks of concern, "are low and unstable but specific information may be lacking on true population numbers, or may have higher spawner escapements but some specific threat is known that could cause severe population decline or loss" (Not to scale).

Page 16 of 21 J. C. M. Andersson May 5, 2003

Bogus Cr. Fall run: +20%

Shasta R. Fall run: +23% Klamath R.

ean Scott R. c Fall run: - 6%

Pacific O Salmon R. Fall run: - 9% Trinity R. Spring run: -21%

(a) (b)

Figure 14. Chinook salmon population trends (percent annual change). (a) Fall-run trends based on data between 1950 and 1997 (Myers et al., 1998). (b) Spring and fall run trends based on a comparison between Myers' et al. (1998) most recent 5-year geometric mean population size and, for the Salmon River, the 5-year geometric mean population up until 2002 (SRRC, 2003); and for the Scott River, Shasta River and Bogus Creek, the population size of 2002 (KRTAT, 2003). (Not to scale.)

Page 17 of 21 J. C. M. Andersson May 5, 2003

Legend

<100 100-499 500-1,999 2,000-4,999 5,000-15,000 >15 000 (a) (b) Figure 15. The spatial distribution of the chinook salmon fall run (a) and spring run (b) according to population size in the Lower Klamath River Basin above the confluence with the Trinity River (map modified from Barnhart, 1994 based on data from KRTAT (2003)).

Page 18 of 21 J. C. M. Andersson May 5, 2003

CONCLUSIONS

The anadromous chinook salmon gravel spawning beds need to have good throughflow of water, low temperatures and low degrees of siltation if they are to qualify as suitable sites for embryo incubation. In addition, alevins have low tolerance for redd dewatering. Spring run fry rear more in the mainstem Klamath River and pursue their nocturnal outmigration later in the year compared with the fall run fry that tend to rear in the estuary. Small-scale habitat diversity - such as varying water velocities, presence of boulders, large woody debris and aquatic vegetation - is important for the survival of the fry. Chinook salmon reach their adult size in the ocean at the age of 3 to 6-years-old. Spring run chinook disperse more in the ocean compared with fall run chinook that tend to stay close to the river mouth. Spring run chinook enter the Klamath River between March and July whereas the fall run chinook upward migration peaks in September. During the upward migration, adult chinook change physical appearance and stop feeding. Spring run chinook hold during the summer in deep, relatively cool pools before they begin spawning, whereas the fall run tend to start spawning immediately after choosing a suitable redd site. Elevated temperatures cause multiple problems for the spawners such as migration blockage, elevated chance of disease and higher egg and juvenile mortality. Therefore, they need cold refuges - such as that provided by riparian vegetation lining the stream channels - during their last migration upstream. They further need adequate dissolved oxygen for survival. The 2002 chinook salmon total in-river fall run was estimated to be 169,297. In the long term, the fall run populations of the Scott, Salmon and Shasta rivers have declined significantly. The 2002 chinook salmon spring run was estimated to be just over 1,000, which is two orders of magnitude lower than their potential historic abundance. The spring run shows evidence of a much-reduced distribution, now only remaining in the Salmon River and the Trinity River basins, and there is evidence of a declining population in the Salmon River.

Page 19 of 21 J. C. M. Andersson May 5, 2003

REFERENCES

Allen, M.A., and T.J. Hassler. 1986. "Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Pacific Southwest) - chinook salmon." U.S. Fish & Wildlife Service Biological Report 82 (11.49). U.S. Army Corps of Engineers, TR EL-82-4. Anderson, E. 2003. "Habitat and hydraulics: An overview of the impacts of , diversions and flow manipulation on Klamath River salmonids." Ecology and Geomorphology of the Lower Klamath Basin and its Tributaries. Eds. J. Mount, P. Moyle and S. Yarnell. Davis, CA. Barnhart, R. A. 1994. "Salmon and steelhead populations of the Klamath-Trinity Basin, California." pp. 73-97 In: T. J. Hassler (ed.) Klamath Basin Fisheries Symposium. Humboldt State University. Arcata, CA Chambers, G. 2003. "Impacts of on surface water flows in the lower Klamath Basin: historic vs. current interactions." Ecology and Geomorphology of the Lower Klamath Basin and its Tributaries. Eds. J. Mount, P. Moyle and S. Yarnell. Davis, CA. Chesney, W. R. 2002. Annual Report: Shasta and Scott River juvenile outmigrant study, 2000-2001, Project 2a1. California Department of Fish and Game Steelhead Research Monitoring Program. Everest, F. H., and D. W. Chapman. 1972. "Habitat selection and spatial interaction by juvenile chinook salmon and steelhead trout in two Idaho streams." J. Fish. Res. Board Can. 29:91-100 Gangmark, H. A., and R. G. Bakkala. 1960. "A comparative study of unstable and stable (artifical channel) spawning streams for incubating king salmon at Mill Creek. California Department of Fish and Game 46:151-164 Healey, M. C. 1991. "Life history of chinook salmon." pp. 311-349 In: C. Groot and L. Margolis (eds.) Pacific Salmon Life Histories. University of British Columbia Press. Vancouver, BC, Canada. Higgins, P.T., S. Dobush, and D. Fuller. 1992. Factors in Threatening Stocks with Extinction. Humboldt Chapter of American Fisheries Society. Arcata, CA. Kelsey, D. A., C. B. Schreck, J.L. Congleton, and L.E. Davis. 2002. "Effects of juvenile steelhead on juvenile chinook salmon behaviour and physiology." Transactions of the American Fisheries Society 131: 676-689. KRTAT (Klamath River Technical Advisory Team) 2003. Klamath River Fall Chinook Age- Specific Escapement, 2002 Run, 4 March 2003. U.S. Fish & Wildlife Service, Yreka, CA. Lister, D. B., and H. S. Genoe. 1970."Stream habitat utilization by cohabiting underyearlings of chinook (Oncorhynchus tshawytscha) and coho (O. kisutchk) salmon in the Big Qualicum River, British Columbia. J. Fish. Res. Board. Can. 27:1215-1224 McCullough, D.A. 1999. A Review and Synthesis of Effects of Alterations to the Water Temperature Regime on Freshwater Life Stages of Salmonids, with Special Reference to Chinook Salmon. Prepared for the U.S. Environmental Protection Agency (EPA), Region 10, Seattle, Washington. Published as EPA 910-R-99-010. Moughamian, R. 2003. "Impact of temperature and flow changes on Lower Klamath River (and associated tributaries) water quality and aquatic habitat." Ecology and Geomorphology of the Lower Klamath Basin and its Tributaries. Eds. J. Mount, P. Moyle and S. Yarnell. Davis, CA. Mount, J. and Moyle, P. 2003. Ecology and Geomorphology of Streams: Class Reader. Spring Quarter, 2003. University of California, Davis. Moyle, P. B. 2002. Inland Fishes of California. Revised and expanded. University of California Press. Berkley, CA.

Page 20 of 21 J. C. M. Andersson May 5, 2003

Myers, J.M., R.G. Kope, G.J. Bryant, et al. 1998. Status Review of Chinook Salmon from Washington, Idaho, Oregon, and California. U.S. Department of Commerce, National Oceanic & Atmospheric Administration Technical Memorandum. NMFS-NWFSC-35 Nawa, R.K. and C.A. Frissell. 1993. "Measuring scour and fill of gravel stream beds with scour chains and sliding bead monitors." North American Journal of Fisheries Management. 13: 634-639. Newcombe, C.P. and D.D. MacDonald. 1991. "Effects of Suspended Sediments on Aquatic Ecosystems." North American Journal of Fisheries Management. 11: 72-82. PFMC (Pacific Fishery Management Council) 2003. Review of 2002 Ocean Salmon Fisheries. Pacific Fishery Management Council, Portland, Oregon. Sanchez, J. 2003. "An overview of the geomorphology of Lower Klamath basin rivers and streams (Shasta vs. Scott Rivers). Ecology and Geomorphology of the Lower Klamath Basin and its Tributaries. Eds. J. Mount, P. Moyle and S. Yarnell. Davis, CA. Silver, S.J., C. E. Warren, and P. Doudoroff. 1963 "Dissolved oxygen requirements of developing steelhead trout and chinook salmon embryos at different water velocities." Transactions of the American Fisheries Society 92:327-343 Snyder, J. O. 1931. "Salmon of the Klamath River, California." California Department of Fish and Game 10(4) SRRC (Salmon River Restoration Council) 2003. 'Fisheries'. http://www.srrc.org/. Date accessed: 2003-05-04 Trihey & Associates, Inc. 1996. Instream Flow Requirements for Tribal Trust Species in the Klamath River. Prepared for the Tribe. Concord, CA. Wallace, M. 2000. Length of residency of juvenile chinook salmon in the Klamath River estuary. California Department of Fish and Game Final Performance Report. Federal Aid in Sport Fish Restoration Act. Project No. F-51-R; Subproject 32. California Department of Fish and Game. Arcata, CA. Weitkamp D. E. (2001) Chinook Capacity to Adapt to Saltwater. Parametrix Inc. Kirkland, Washington, USA. USFWS (U.S. Fish & Wildlife Service). 1998. Klamath River (Iron Gate Dam to Seiad Creek) Life Stage Periodicities for Chinook, Coho, and Steelhead. Unpublished report 42 pp.

Page 21 of 21