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OCR for page 214
6
Causes of Decline and Strategies for
Recovery of I(lamath Basin Suckers
When the Lost River anti shortnose suckers were listecI uncler the En-
ciangerecI Species Act (ESA), the U.S. Fish anti WilcIlife Service (USFWS)
anti others iclentifiecI numerous factors that couicI explain their clecline anti
their failure to recover after elimination of the sucker fishery (Chapter 5,
Scoppettone anti VinyarcI 19911. Since the listing, many of these factors
have been stucliecI. As a result, unclerstancling of the biology of Klamath
suckers anti of requirements for their recovery has improved. Information
on suckers is founcI in over 500 articles, reports, memoranda, anti critiques,
although most are unpublishecI anti so have not benefited from scientific
peer review. The number of persons working on the suckers has grown
from a few ichthyologists to several clozen scientists, resource managers,
policy clevelopers, consultants, anti informed citizens. New information
clerivecI from the increased pace of documentation anti research supports
increasingly firm judgments on the current status of the species, probable
causes of their clecline, priorities for further study, anti actions that shouicI
anti can be taken to move the species toward the ultimate goal of recovery,
as clescribecI in this chapter.
CRITERIA FOR JUDGING STATUS AND
RECOVERY OF SUCKER POPULATIONS
Criteria for the assessment of status anti recovery provide a useful point
of departure for the causal analysis of clecline of the enciangerecI suckers
anti for evaluating proposals for their restoration. Criteria presented here
214
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DECLINE AND RECOVERY OF KLAMATH BASIN SUCKERS
215
are intenclecI as a too! of convenience for present purposes; other criteria
might be useful for other purposes.
Because each life-history stage of a population is linkecI to all other
stages, unusual suppression of any life-history stage may be reflectecI ulti-
mately in the suppression of the population as a whole. Thus, trencis in the
abundance of any stage can be chosen arbitrarily as an inclex of the status of
a population. For the enciangerecI suckers, the most convenient life stage to
use as an inclex of status is the aclult. As explainecI in Chapter 5, other
stages are clifficult to observe or sample, especially in large lakes, although
attempts to clo so are essential to the diagnosis of mechanisms that affect
specific life-history stages.
If aclults are used as an inclex of the status of the populations, three
criteria, taken together, wouicI indicate recovery: diversity in the age clistri-
bution of aclults, annual entry of at least some inclivicluals into the aclult
stage in most years from the younger life stages couplecI with entry of large
numbers of such recruits in some especially favorable years, ancI a popula-
tion size that reflects carrying capacity for an environment that is generally
well suited, although not necessarily optimal, for the suckers. The presence
of multiple age classes of aclults wouicI indicate past recruitment to the
aclult stage ancI persistence of conditions suitable for the maintenance of
aclults. The combination of new recruitment in most years ancI very high
recruitment in some years wouicI indicate the general welfare of younger
stages ancI successful spawning. The maintenance of populations at a clen-
sity that approaches expected carrying capacity wouicI indicate that growth
ancI reproduction occur at sufficient rates to offset mortality through the
life cycle as a whole.
As inclicatecI in Chapter 5, the status of geographically clefinecI sub-
populations of the two enciangerecI suckers varies cirastically. Table 6-1
summarizes the status of various geographic subpopulations on the basis of
the aclults. As shown in Table 6-1, Clear Lake ancI Gerber Reservoir sup-
port apparently stable subpopulations ancI therefore provide a basis for
comparison with other subpopulations. The Upper I(lamath Lake subpopu-
lations, in contrast, clo not meet the criteria for recovery, nor clo they
indicate recovery in progress. These subpopulations took an important
positive turn after elimination of fishing in 1987, through the entry of new
fish into the subaclult ancI aclult populations each year ancI through the
production of one very strong year class (1991) ancI several moclerately
strong year classes cluring the clecacle of the l990s (Chapter 51. Indications
of no recovery without further environmental change, however, inclucle the
failure of aclults to show an upward turn in overall abundances ancI the lack
of a cliversifiecI age structure among oicler age classes, presumably because
of repeated mass mortality of large fish.
OCR for page 216
Endangered and Threatened Fishes in the Klamath River Basin
Table 7-2. Nonnative Fishes of the Lower Klamath and Trinity Rivers
Name
American shad, Alosa sapidissima
Life
History Status
A
Comments
Goldfish, Carassius auratus
Fathead minnow, Pimephales prom elas
Golden shiner, Notemigonus
chrysoleucas
Brown bullhead, Ameiurus nebulosus
Wakasagi, Hypomesus nipponensis
Kokanee, Oncorhynchus nerka
Brown trout, Salmo trutta
Brook trout, Salvelinus fontinalis
Brook stick l aback, Culea incons tans
Green sunfish, Lepomis cyanellus
Bluegill, L. macrochirus
Pumpkinseed, L. gibbosus
Largemouth bass, Micropterus
salmoides
Spotted bass, M. punctulatus
Smallmouth bass, M. dolomieui
Yellow perch, Percaflavescens
N
N
N
N
N
N
N. A
N
N
N
N
N
N
N
N
N
Uncommon
Uncommon
Uncommon
Uncommon
Locally abundant
Locally abundant
Locally abundant
Common in some
streams
Common
Locally abundant,
spreading
Common
Common
Uncommon
Common
Locally common
Locally common
Locally common
Small annual run in lowermost reach
r ~
Or river
Ponds and reservoirs
Invading from upper basin where
extremely abundant
Important bait fish in California
Ponds and reservoirs, especially
Shasta River; some in mainstem
In Shastina Reservoir but a few
downstream records
Reservoirs
Sea-run adults rare
Only in headwater streams and lakes
Recent introduction into Scott River
Warm streams, ditches, and ponds
Ponds and reservoirs
Abundant in upper basin
Ponds and reservoirs
Only in Trinity River reservoirs
Only in Trinity River reservoirs
Abundant in upper basin, including
Iron Gate Reservoir
Abbreviations: A, anadromous; N. non-migratory.
COHO SALMON
The coho salmon (Figure 7- ~ ~ once was an abundant and widely distributed species in the
Klamath River and its tributaries, although its historical numbers are poorly known because of
the dominance of Chinook salmon. Snyder (1931) reported that coho were abundant in the
Klamath River but also indicated that reports of the salmon catch probably lumped coho and
Chinook. Historically, coho saImon occurred throughout the Klamath River and its tributaries, at
least to a point as high up in the system as the California-Oregon border. It is possible that they
once migrated well into the upper Klamath basin (above Klamath FalIs), as did Chinook and
steelhead, but there are no records of this, perhaps because most people are unable to distinguish
them (Snyder 1 93 1 1.
Today coho salmon occupy remnants of their original range wherever suitable habitat
exists and wherever access is not prevented by dams and diversions (Brown et al. ~ 994, Moyle
2002~. Because the coho salmon is clearly in a long-term severe decline throughout its range in
California, all populations in the state have been listed as threatened under both state and federal
endangered species acts (CDFG 20021.
216
OCR for page 217
DECLINE AND RECOVERY OF KLAMATH BASIN SUCKERS
217
Fishes of Tule Lake (ancI of the associated Lost River) show no signs
whatsoever of recovery according to the criteria shown in Table 6-1. Lack
of recruitment of young fish into the subaclult ancI aclult stages indicates
lack of reproduction or negligible survival of young fish. Two aciclitional
locations, Lower I(lamath Lake ancI Lake of the Woods, are listecI even
though they lack enciangerecI suckers. These are locations where sucker
populations conceivably couicI be establishecI in the future. The main-stem
reservoirs also are listecI but belong to a somewhat different category be-
cause, as explainecI in Chapter 5 ancI further in this chapter, the potential
for creation of suitable conditions for the entire life cycle is probably lower
for these waters than for Upper I(lamath Lake or the other waters where
the suckers originally thrived.
REQUIREMENTS FOR PROTECTION AND RECOVERY
The ESA requires both protection ancI recovery of listecI species (Chap-
ter 91. Protection is accomplishecI by prohibitions of take ancI preserva-
tion of habitat. Protection alone is insufficient, however, in that the popu-
lations as a whole have shown a drastic clecline over the last several
clecacles, ancI there is no evidence that the populations are recovering. At
the subpopulation level, as inclicatecI in Chapter 5, the balance between
protection ancI remecliation clepencis on location. Because the subpopula-
tions of Clear Lake ancI Gerber Reservoir are the only ones in the upper
I(lamath basin that meet the criteria for recovery as outlinecI above, their
protection is of utmost importance for the long-term survival of the two
enciangerecI sucker species in the upper I(lamath basin as a whole. These
subpopulations appear to clepencI entirely on tributary spawning. There-
fore, maintenance of tributary conditions suitable for spawning is an
essential element of their protection. It is important that neither of the
reservoirs be drawn clown to extremes that wouicI produce summer or
winter mortality. Given the historical experience of the l990s, the re-
quirements of the 2002 biological opinion appear to be aclequately pro-
tective in this respect, but it is critical for these subpopulations that no
errors in judgment leacI to extremes in cirawclown beyond that observed in
the l990s.
The subpopulations of Upper I(lamath Lake also have high priority but
have different status. As explainecI in Chapter 5, they showed some encour-
aging responses to the curtailment of the snag fishery, but the numerical
abundance of aclults ancI the continuing attrition of oicI fish appears to be
hoicling the population clown ancI may even be driving it closer to extirpa-
tion. The pathway to recovery for this population is not clear. A great clear
of the analysis of cause ancI effect in the remaining part of this chapter is
clevotecI to the Upper I(lamath Lake subpopulations because of their his-
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218
FISHES IN THE KLAMATH RIVER BASIN
torical numerical importance anti the lack of clarity about the means of
achieving their recovery.
The Tule Lake subpopulations consist of a very small number of appar-
ently healthy aclults, but they fail to meet all three of the criteria outlinecI
above for recovery: there is no evidence of recruitment into the aclult stage,
there is no diversification of age structure for aclults, anti abundances per
unit area are low. Because the suckers are long-livecI, the aclults of the Tule
Lake population are of high value, anti also couicI be supplementecI with
salvagecI inclivicluals from other locations. The first step toward recovery of
the Tule Lake subpopulations wouicI be to establish spawning capability,
which wouicI require intensive work with tributary waters. Acquisition of
water rights anti steps toward the creation of (potentially artificial) physical
habitat suitable for spawning anti for larvae wouicI be necessary initial steps
toward recovery of these subpopulations. The Tule Lake subpopulations,
although small, neecI not be written off as unrecoverable.
Listed fifth in Table 6-1 is Lake of the Woods. As explainecI in Chapter
5, this was the location of a population probably consisting of shortnose
suckers, but the population was eliminatecI. The present fish populations of
Lake of the Woocis shouicI be eliminate cI, anti aclult shortno se suckers anti
other native fishes shouicI then be reintroclucecI. If the suckers meet the
recovery criteria outlinecI above after a number of years, fish biologists
couicI consider the reintroduction of game fish (fish other than suckers
probably will have colonizecI the lake by that time in any event).
Lower I(lamath Lake lacks suckers anti is probably unsuitable for them
(Chapters 3 anti 5), but alteration of these conditions couicI be feasible.
Steps shouicI be taken toward acquisition of water rights suitable for main-
tenance of higher water levels in Lower I(lamath Lake if feasibility studies
support this approach. Aclult suckers from salvage (as clescribecI later in this
chapter) shouicI then be transferred to Lower I(lamath Lake. Water quality
anti habitat conditions may be unsuitable, but suitability can be cleterminecI
most effectively by monitoring of trial reintroductions. To the extent that
maintenance of higher water levels wouicI interfere with agricultural use of
lancI, its establishment wouicI require negotiations anti compensation for
. . . . . .
acquisition ot private rig nts.
The last subpopulations mentioned in Table 6-1 are the ones in main-
stem reservoirs. These reservoirs have value primarily for long-term storage
of large suckers. They clo not have high priority for recovery, because they
are not part of the original habitat complex of the suckers anti probably are
inherently unsuitable for completion of life cycles by the suckers. Mainte-
nance of aclults in these locations cloes, however, provide some insurance
against loss of other subpopulations.
Construction of fish laciclers for suckers at the clams might facilitate
return of fish from main-stem reservoirs to Upper I(lamath Lake. A fish
OCR for page 219
DECLINE AND RECOVERY OF KLAMATH BASIN SUCKERS
219
lacicler at Link River Dam, which is scheclulecI for completion in lanuary
2006, shouicI receive high priority; movements of fish through the lacicler
shouicI be monitored.
SUPPRESSION OF ENDANGERED SUCKERS
IN UPPER KLAMATH LAKE:
CAUSAL ANALYSIS AND REMEDIES
For several reasons, causal analysis of the suppression of enciangerecI
suckers deserves more attention for the Upper Klamath Lake subpopula-
tions than for other subpopulations. First, despite severe suppression of
enciangerecI suckers in Upper Klamath Lake, these subpopulations still con-
tain many fish. Second, the subpopulations in Upper Klamath Lake were
large as recently as 50 yr ago, so it seems reasonable, lacking evidence to the
contrary, that they couicI be restored by a reversal of one or more critical
human-inclucecI impairments that have occurred over the last 50 yr. Third,
water management involving Upper Klamath Lake is the responsibility of
the fecleral government through the U.S. Bureau of Reclamation (USBR),
which has access to substantial resources anti also has legal responsibility
for reversing or moderating any adverse effects of its management of Upper
Klamath Lake if causal linkages between management anti harm to the
suckers can be establishecI. Fourth, even though the subpopulations of
enciangerecI suckers are suppressed in Upper Klamath Lake, all life stages
are present anti some recruitment appears to be occurring from one life
stage to another every year; recovery seems feasible if some key factors can
be iclentifiecI anti changed.
Actual or potential cause-ancI-effect relationships that explain the sta-
tus of a population are hierarchical. For present purposes, immediate causes
can be explainecI in terms of suppression of one or more stages of the life
cycle. For example, suppression of the entire population couicI be explainecI
entirely or in part by exceptionally high mortality of larvae. Suppression of
more than one component of a population couicI prevent it from recover-
ing. There can be more than one immediate cause of suppression of a
population.
Proximate causes are environmental factors. An example is poor water
quality that leacis to mass mortality of aclult fish. A single proximate cause
may be linkecI to more than one immediate cause. For example, poor water
quality may suppress not only aclults but also other life-history stages.
Ultimate causes, in the present context, are clirect or indirect results of
human actions. For example, operation of unscreened canals is an ultimate
cause of mortality of fish in various life stages. Human actions that have lecI
to changes in the water quality of Upper Klamath Lake are ultimate causes
of mass mortality of large fish.
OCR for page 220
220
FISHES IN THE KLAMATH RIVER BASIN
Recovery of the populations of enciangerecI suckers can be approached
most efficiently through analysis of the three levels of causation that ex-
plain failure of the fish to recover. Because the possible combinations of
cause ancI effect are numerous, remeclial actions, which are expensive, must
focus on chains of cause ancI effect that are most likely to produce recovery.
Winnowing the importance of cause-ancI-effect relationships requires infor-
mation, some of which must be quantitative to be useful. The task of the
researcher or the monitoring team is to produce information, typically over
a period of years, that can be used to support estimates of the suppression
of the population by chains of causation involving specific life-history stages
(immecliate causes), specific environmental factors (proximate causes), ancI
specific human actions (ultimate causes). I(nowlecige of causation can pro-
cluce estimates of the beneficial effect of remecliating the effects of human
actions.
Intensive research on the enciangerecI suckers has been uncler way for a
relatively short time, especially in view of the complicating effects of natu-
ral variation caused by climate ancI other factors that are not uncler human
control. Only a few causal relationships are known well enough to support
remeclial action with confidence, but some of these are among the most
important because they explain notable mortality of one or more stages of
the population. Eventually, some of the more subtle but still important
types of impairment ancI their causes must be clarifiecI, as inclicatecI in the
following overview ancI analysis of cause ancI effect.
The analysis of causal connectivity is summarized in Figure 6-1. The
figure shows the life stages of the enciangerecI suckers as presented in Chap-
ter 5 ancI identifies potential proximate causes of suppression of each life
stage. Because the life stages are interconnected clevelopmentally, the un-
clerlying premises of the diagram are that suppression of any life stage
contributes at least potentially to suppression of the overall population ancI
that a potential remedy for the suppression of the population lies in the
identification ancI reversal of the suppression of incliviclual life stages. It is
not a foregone conclusion, however, that reversal of a particular type of
suppression on a specific life stage will move a population notably toward
recovery.
Figure 6-1 shows connections between immediate, proximate, ancI ulti-
mate causes as solicI or ciashecI lines. SolicI lines indicate causal connections
that are well establishecI scientifically; typically these connections involve
phenomena that are easily observed or clocumentecI (such as mass mortality
of aclults or cleath clue to entrainment). Dashed lines indicate causal connec-
tions that are uncler stucly ancI for which there is insufficient evidence to
show them as unimportant, moclerately important, or important.
The figure shows convergence of multiple lines on incliviclual immecli-
ate causes in some cases. Thus, the diagram indicates the likelihoocI that
OCR for page 221
221
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OCR for page 222
222
FISHES IN THE KLAMATH RIVER BASIN
some immediate causes of clecline are explainecI by multiple factors ancI that
the factors might interact in their effects on a specific life-history stage. In
aciclition, the diagram indicates that some environmental factors (proxi-
mate causes) have multiple connections with immediate causes; that is, they
can affect more than one life stage. This is also expected from the literature
on fish populations. The last column in the diagram lists remeclial mea-
sures; the clegree of certainty in their effectiveness is cliscussecI below. Even
though the life-history stages are interclepenclent ancI so must be consiclerecI
together in the final prescriptions for recovery, it is useful to consider
them incliviclually first because each stage is affected by a distinctive suite of
environmental factors. The discussion therefore follows the life-history
sequence.
Production ant! Viability of Eggs
The production of eggs is usually cliscussecI in terms of spawning fish,
which are much more easily observed than eggs. The eggs themselves are
the concern, however, ancI successful spawning is only one element of their
final value to the population. Low viability of eggs, for example, couicI
undermine the effectiveness of successful spawning. No researchers have
attempted to make a case that the viability of eggs differs in Upper I(lamath
Lake or its tributaries from what wouicI be expected in an unimpaired
environment. Thus, the present discussion focuses on spawning, but it
shouicI be noted that lack of discussion of the fate of eggs after spawning is
clue partly to lack of information.
Dams
Small clams are found in the tributaries of Upper I(lamath Lake. Where
it can be shown that the clams clo not allow passage of fish attempting to
spawn, they shouicI be removed or, if a clam must be retained, it shouicI be
fitted with a functional bypass.
The only moclerately large clam on a tributary to Upper I(lamath Lake
is Chiloquin Dam, which blocks the Sprague River near its confluence with
the Williamson River (Figure 1-31. Construction of Chiloquin Dam in the
early 1900s (1918-1924 the exact ciate is unclear) may have eliminatecI
more than 95°/O of the historical spawning habitat in the Sprague River (53
FecI. Reg. 61744 F19881, p. 51. This possibility is basecI on total river miles
above the clam ancI cloes not take into account unusable portions of the
river or the ascent of the clam by at least a few spawning fish via the fish
lacicler each year. There are more fish below than above the clam, however,
ancI few fish enter the fish lacicler (e.g., Janney et al. 2002), although the
actual number is unknown. Improved access to the upper Sprague River
OCR for page 223
DECLINE AND RECOVERY OF KLAMATH BASIN SUCKERS
223
wouicI increase the extent of spawning habitat ancI expand the range of
times ancI the conditions uncler which larvae enter Upper I(lamath Lake.
Proposals for improving access of suckers to spawning grouncis on the
upper Sprague River involve two possibilities: removal of the clam ancI
improved fish passage at the clam. Scoppettone ancI VinyarcI (1991) recom-
menclecI removal of the clam, as have others since then (e.g., I(lamath Water
Users Association 20011. Stern (1990) estimated the cost of removing the
clam at about $500,000 ancI of fish passage improvements at $560,000.
CH2M HILL (1996) presented cletailecI plans for improvement of passage
ancI estimated the cost at $1.445 million but gave no estimate for removal
of the clam. The plan of CH2M HILL inclucles construction of a new
vertical-slot lacicler on the left bank (looking upstream) that wouicI replace
the present lacicler, which is ineffective. The new lacicler wouicI be basecI on
fish passage structures through which cui-ui (Chasmistes cujus) move up
the Truckee River ancI into Pyramid Lake.
CH2M HILL (1996, p. 2) clismissecI removal of Chiloquin Dam be-
cause of "too many environmental concerns . . . as well as a lack of local
support." The environmental concerns were not enumerated; presumably
they are relatecI to release of sediment ancI the clifficulty of predicting how
fish wouicI responcI to the new hyciraulic conditions (e.g., Stern 19901.
Issues relatecI to sediments arise with virtually any clam-removal project,
but often they can be resolvecI (Heinz Center 20021. The response of the
fish is unknown, but removal of the clam is likely to result in a natural
migratory response, at least by young spawners that have not aireacly clevel-
opecI the habit of spawning downstream of the clam.
Lack of local support for removal of Chiloquin Dam is explainecI in
part by water clelivery via the clam to the Mocloc Point Irrigation District
(MPID). MPID involves about 60 farms ancI irrigates 3,000-5,300 acres
annually, or less than 3°/O of the irrigable acreage in the basin. The MPID
apparently has "acloptecI a Resolution indicating its willingness to partici-
pate in a project to restore fish passage" (I(lamath Water Users Association,
unciatecI memo, about 2001) ancI is willing to consider moving its point of
diversion away from Chiloquin Dam (E. Bartell, The Resource Conser-
vancy, Inc., Fort I(lamath, Oregon, unpublishecI report, 20021. Coopera-
tion with MPID is important to the removal of Chiloquin Dam.
Removal of Chiloquin Dam has high priority ancI shouicI be pursued
aggressively. In the interim, spawning fish couicI be captured at the base of
the fish lacicler anti releasecI immecliately above it; some of the releasecI fish
shouicI be fitted with transmitters. Such a program wouicI immecliately give
more fish access to the Sprague River ancI wouicI show what upstream areas
are favored by the fish. Continued monitoring below the clam also wouicI
provide information on numbers of aclults returning downstream anti num-
bers of larval fish reaching the lake. A summer sampling program couicI
OCR for page 224
224
FISHES IN THE KLAMATH RIVER BASIN
determine whether juveniles are in the river anti wouicI demonstrate the
status of other native fishes in the river.
Water Level in Upper Klamath Lake
Spawning occurs at shoreline sites around Upper I(lamath Lake from
late February to May; maximum spawning activity occurs in March anti
April. More than 60% of spawning occurs in water more than 2 ft creep at
locations with inflowing stream water (e.g., Reiser et al. 2001; see also
Chapter 51. Inundation to a depth of at least 2 ft may be necessary for
successful use of spawning substrate. At Sucker anti Ouxy springs, two of
the most frequently used sites (Hayes et al. 2002~' lake elevations below
4~142.5 ft place 55°/0 anti 67%' respectively, of the spawning area in water
shallower than 2 ft. Reiser et al. (2001' p. 7-2~' in a separate analysis,
concluclecI that lake elevations below 4~142.0 ft "severely diminish avail-
able spawning habitat"; they recommencI that Upper I(lamath Lake be kept
at full pool elevation (4~143.3 ft) from micI-March to as late as micI-May to
provide adequate water depth for spawning. Uncler recent operating re-
gimes, water levels have remained above 4~143 ft for extenclecI intervals in
wet years but have fallen well below 4~143 ft in ciry years (Figure 6-2~.
Figure 6-2 shows the effect of water-level regulation in Upper I(lamath
Lake on spawning area according to the criteria proposed by Reiser et al.
(2001~. Uncler natural conditions, spring water levels wouicI have been at or
near full pool (4~143.3 ft). Uncler conditions prevailing in 1990-2001' full
pool elevation was achieved cluring the spawning interval in 6 of 10 yr; in
4,143.5
4,143.0
Upper Klamath Lake Water Level, March - May
au
au
` 4,142.5
au
1
5-
au
4,142.0
4,141.0
4,140.5
, , , , , , , , , , ,
MAM MAM MAM MAM MAM MAM MAM MAM MAM MAM MAM MAM
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Undiminished
Somewhat
Diminished
Diminished
Severely
Diminished
au
5-
. -
I
con
FIGURE 6-2 Water levels for 5-day intervals in Upper I(lamath Lake over months
of most vigorous spawning by suckers (March, April, and May MAM), shown in
context with spawning habitat designations given by Reiser et al. (2001~.
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DECLINE AND RECOVERY OF KLAMATH BASIN SUCKERS
TABLE 6-3 Incidence (HO) of Various Indicators of Stress in Suckers of
Upper I(lamath Lake Based on Visual Inspection
Incidence, %
239
Lampreys Copepods
Wounds Infections
Eye
Damage Emaciation Wounds
Lost River Suckers, Live Fish, 2001
Lake spawning 40 22 4 0 1
River spawning 48 28 22 0 2
Lake non-spawning 51 18 8 1 2
Shortnose Suckers, Live Fish, 2001
Lake spawning 53 30 3 0 0
River spawning 38 51 16 0 1
Lake non-spawning 48 33 8 0 4
Fish Kill
1997 73a
allased on Foott 1997 and Holt 1997 in USFWS 2002; incidence of Columnaris disease was
92% and 80%, respectively, during the 1996 and 1997 fish kills (USFWS 2002).
Sources: Coen et al. 2002, Cunningham et al. 2002, Hayes et al. 2002.
Mortality of fish during routine sampling with trammel nets also increases
during the weeks preceding a fish kill (USFWS 20021.
Although USFWS (2002) went to considerable lengths to examine the
possible direct influence of high water levels in Upper I(lamath Lake on
sucker welfare, the data now on hand contradict the hypothesis that water
level is associated with fish kills (NRC 2002, Figure 3; Chapter 31. Fish kills
have occurred in years of low, average, and above-average median August
lake levels. Water level may affect the accessibility of refuges that are re-
portedly used by large fish during periods of poor water quality and fish
kills, but the data on this topic are largely anecdotal (see Buettner 1992
unpublished memo, USFWS 2002, Appendix C, and below).
High incidences of parasites, bacterial infections, and other anomalies
imply that stressful conditions exist in Upper I(lamath Lake for several
weeks before the appearance of dead fish. Loftus (2001, cited in USFWS
2002) developed a "stress-day" index that accounts for multiple stress
factors related to water quality. In 1990-1998, accumulated stress days
were maximal in luly and August during the fish-kill years of 1995 and
1997. The stress-day index approach is useful in that it involves regular,
coordinated monitoring focused on water quality, meteorology, fish condi-
tion (parasite frequency, body condition, and so on), and attention to in-
creased numbers of adults in the Link River or presumed refuges. When
conditions and early warning signs converge, whatever remedial actions are
. . . . . .
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240
FISHES IN THE KLAMATH RIVER BASIN
feasible should be taken, possibly including oxygen supplementation at spe-
cific locales where suckers aggregate (Chapter 31.
In some lakes, mass mortality of fish occurs under ice ("winterkill"),
usually in association with low concentrations of dissolved oxygen. Win-
terkill is not known to have occurred in Upper I(lamath Lake or in any
other lakes occupied by endangered suckers. Thus, the relevance of win-
terkill to Upper I(lamath Lake remains hypothetical, as do management
actions that would minimize its likelihood or effect.
Winter mortality (but not necessarily winterkill) has been postulated as
the cause of a 90°/O reduction of first-year juvenile suckers in Upper I(la-
math Lake from late fall to early spring and population reductions in other
species (Simon and Markle 20011. Comparable data are needed on winter
mortality in surrounding water bodies with better water quality (such as
Clear Lake) to determine whether the 90°/O mortality figure is extreme.
Concern over winterkill is justified, especially if water quality deterio-
rates further or if an exceptionally cold winter results in an unusually long
period of ice cover. Improvement in water quality in the lake probably
would reduce the likelihood of winterkill, but may be infeasible over the
short term. Winter monitoring of oxygen should be undertaken in any
event (Chapter 31.
Loss of Habitat
Adult Lost River suckers and shortnose suckers prefer open water; they
use flowing waters chiefly for spawning. Total lake habitat available to
suckers throughout the I(lamath basin is a fraction of its original extent
because of drainage and other water-management practices (Chapter 21.
Even where it persists, habitat for adults may be compromised during late
summer. Adult suckers appear to prefer water that is deep and turbid, and
thus dark (USFWS 2002), but degraded water quality in summer appar-
ently forces fish to use specific areas of shallow, clear water, such as the
mouth of Pelican Bay in Upper I(lamath Lake.
Factors Relevant to All Life-History Stages
A number of factors, some of which have already been mentioned, are
potentially relevant to all life-history stages, although further research may
show them to be more relevant to some stages than to others. Most promi-
nent is poor water quality, which is linked not only to mass mortality of
adults but potentially to undocumented mortality of other stages and to
stress, which in turn may be a cause of anomalies, parasitism, and disease in
multiple life-history stages. A second complex of factors that may apply
broadly across stages, but still in unknown ways, falls under the heading of
OCR for page 241
DECLINE AND RECOVERY OF KLAMATH BASIN SUCKERS
24
predation ancI competition, primarily from nonnative fishes. A final factor
that cannot yet be attached to any particular life-history stage is hybricliza-
tion, which may change populations genetically.
Water Quality
Suckers of Upper I(lamath Lake suffer from varied deformities, para-
sites, lesions, cysts, ancI infections. The afflictions of aclult suckers inclucle
eroclecI, cleformecI, ancI missing fins; lorclosis; pugheacI; multiple water-
moicI infections; reciclening of the fins ancI body clue to hemorrhaging;
cloucliness of the skin caused by low mucus production; loss of pigmenta-
tion; external parasitic infection by copepocis ancI leeches; lamprey wounds;
ulcers; gas emboli in the eyes; exophthalmia; cataracts; ancI a high incidence
of gill, heart, ancI kiciney abnormalities after fish kills. Plunkett ancI Snycler-
Conn (2000) reported bocly-anomaly rates of 8-16% in larval ancI juvenile
suckers. luvenile suckers suffered infestation with copepocis ancI trema-
todes of O-7% in 1994-1996 and 9-40% in 1997-2000; shortnose suckers
generally show higher rates of infestation than Lost River suckers (USFWS
2002 basecI on Carison et al. 20021. Data on both species in Upper I(lamath
Lake ancI at river spawning sites also indicate relatively high frequencies of
abnormalities in aclults (Table 6-31. Spawning ancI nonspawning fish clo not
show substantial differences in the incidence of such indicators, except that
copepocI infestations appear to be higher in shortnose suckers ancI eye
ciamage is higher in river-spawning fish of both species. The latter finding
might reflect crowding of fish downstream of Chiloquin Dam or injuries to
the fish as they attempted to negotiate the unsuitable fish lacicler at the clam.
The wiclely used Inclex of Biotic Integrity (I(arr et al. 1986) incorpo-
rates 1% as a threshoicI criterion for anomalies; sites with fish above this
threshoicI receive the lowest metric scores for their ability to support a
diverse biota. The appropriate threshoicI may vary geographically ancI by
taxa, however. For the Willamette River, Hughes ancI Gammon (1987)
iclentifiecI 6% as a threshoicI. Hughes et al. (1998) proposed a more general
threshoicI of 2%. Most collections from all size classes of Upper I(lamath
Lake suckers exceed these threshoicis. It is not known why Clear Lake, with
its better water quality ancI apparently stable population, also is character-
izecI by "heavy parasite loacis on suckers ancI other fish" (Snycler-Conn,
personal communication cited in USFWS 2002' Appendix E, p. 381.
Even if infections ancI afflictions clo not leacI clirectly or even inclirectly
to cleath, they are likely to inhibit growth (e.g., M.R. Terwilliger et al.,
Oregon State University, Corvallis, Oregon, unpublishecI material, 2000)
ancI reproduction ancI may compromise an incliviclual's ability to resist
other sources of stress. Without better baseline ancI reference values for
suckers in other water bodies in ancI out of the I(lamath basin, it is clifficult
OCR for page 242
242
FISHES IN THE KLAMATH RIVER BASIN
to state categorically that the incidence of anomalies is extraordinary, but
fielcI researchers who work with fish selclom observe affliction rates ap-
proaching those founcI in Upper I(lamath Lake.
Nonincligenous Species as Predators ant! Competitors
Eighteen of the 33 fish taxa in the upper I(lamath basin are nonnative
(Chapter 51. The nonnatives dominate numerically in many habitats ancI
probably influence native species, inclucling the enciangerecI suckers, through
predation ancI competition. Competition is particularly clifficult to quantify
in nature (Fausch 1988, 19981. Thus, it is not often possible to invoke
competition as a major cause of problems in a population, ancI it also is
clifficult to moderate competition even where it can be clemonstratecI. In
contrast, predation on native fishes by nonnative fishes is easily clemon-
stratecI; it can have devastating effects on native fishes (e.g., Fuller et al.
19991. In Upper I(lamath Lake, introclucecI fathead minnows may prey on
larval suckers, as shown in laboratory enclosures (Dunsmoor 1993, cf.
Ruppert et al. 1993), although the applicability of the laboratory studies to
conditions in nature is uncertain. luvenile ancI aclult yellow perch ancI
juvenile largemouth bass consume larvae, as may Sacramento perch, most
other centrarchicI sunfishes, ancI the two buliheacI species present in Upper
I(lamath Lake. luvenile ancI aclult largemouth bass also couicI feecI on juve-
nile suckers, although aclult suckers reach a body size that provides them
refuge from fish predators. Comparisons of Upper I(lamath Lake with
other lakes in this regard couicI be useful. With the exception of Sacramento
perch, Clear Lake apparently has been spared significant introductions of
nonnative fishes, ancI its populations appear to be stable. A species list for
Gerber Reservoir is not reaclily available.
The presence of numerous ancI diverse nonnative fishes in the I(lamath
system complicates recovery efforts. Nonnative species typically clo well in
clisturbecI systems (Moyle ancI Leicly 19921. Given that attempts to recluce
abundances of nonnative fishes usually are unsuccessful, the best tactics for
decreasing the success of these invaders are to discourage future introcluc-
tions (especially of preciators), to restore water quality if possible, ancI to
prevent movement of nonnative fishes within the basin. Selective control of
nonnative species has been pursued in some environments (Ruzycki et al.
2003), however, ancI shouicI not be rulecI out entirely for Upper I(lamath
Lake.
Hybridization ant! Introgression
Hybridization results in wasted spawning ancI loss of genetic diversity
through elimination of rare alleles. Introgression (backcrossing of hybrids
OCR for page 243
DECLINE AND RECOVERY OF KLAMATH BASIN SUCKERS
243
with parental species) can harm a rare species, as apparently has hap-
penecI to the enciangerecI lune sucker, Chasmistes liorus liorus, which
hybridizes readily with the more abundant Utah sucker, Catostomus
ardlens (Echelle 19911. The original ESA listing document for I(lamath
suckers (53 FecI. Reg. 27130 f19881) cited apparently high rates of hy-
briclization among the three Upper I(lamath Lake sucker species, espe-
cially between shortnose suckers ancI I(lamath largescale suckers, ancI
cited hybridization as a potential contributor to loss of genetic integrity
ancI clecline of species. Apparent hybrids, as inclicatecI by morphological
intermediacy, are commonly found in the Williamson River downstream
of Chiloquin Dam ancI in sucker populations of Clear Lake, where crosses
between Lost River suckers ancI I(lamath largescale suckers are most fre-
quently suspected (e.g., Cunningham et al. 2002; Moyle 2002; D. Markle,
Oregon State University, Corvallis, Oregon, personal communication,
20021. Recent anatomical studies of hybridization, however, imply that it
is a rare occurrence. Among spawning fish captured in Upper I(lamath
Lake in 2001' 0.2% of fish from shoreline spawning sites, 4°/O from the
lower Williamson River, ancI 6% occupying the area below Chiloquin
Dam were apparent hybrids (Cunningham et al. 2002' Hayes et al. 2002'
lanney et al. 20021. In contrast, one-thircI of fish caught at Chiloquin
Dam in 2000 appeared to be anatomically intermediate. Morphological
studies may overestimate hybridization; allozyme frequency ancI nuclear
genetic ciata indicate that recent hybridization is rare, that nominal spe-
cies are all valid, ancI that little genetic divergence has occurred among
populations within species (D. Buth, University of California at Los Ange-
les, Los Angeles, California, personal communication, 2002; Dowling
2000; T. Dowling, Arizona State University, Tempe, Arizona, personal
communication, 20021. Microsatellite ciata indicate, however, that the
three species present in the Lost River (largescale, shortnose, ancI Lost
River suckers) are significantly different from suckers in Upper I(lamath
Lake ancI the upper Williamson River (G. Tranah, Harvard School of
Public Health, Boston, Massachusetts, personal communication, 20021.
Overall, morphological ciata indicate that hybridization has occurred,
but current genetic analyses reveal that Lost River suckers ancI shortnose
suckers are distinct ancI that the identity of the species has not been eroclecI
by extensive hybridization. High priority should be attached to further
genetic analysis that will give more information on hybridization ancI on
the genetic structure of currently isolated populations.
Before the I(lamath Project was completed, all sucker habitats were
subject to interchange of fish (Chapter 21. Dams ancI irrigation canals
isolated populations to an extent that could ultimately affect the genetic
diversity of the species. None of the primary clams in the I(lamath basin
allow passage of suckers. Efforts to protect the species with regard to
OCR for page 244
244
FISHES IN THE KLAMATH RIVER BASIN
range fragmentation shouicI focus on habitat protection ancI improvement
of all subpopulations ancI on construction of laciclers of proven effective-
ness or removal of barriers to improve exchange among subpopulations.
Other Issues Relevant to Recovery
Other Natives ant! the Paraclox of Persistent Enclemics
Shortnose ancI Lost River suckers apparently are more susceptible to
clegraclecI habitat conditions or other factors, such as preciators, than any of
the 14 other native species. Blue chub ancI tui chub clo appear in some fish
kills, sometimes in large numbers, but their populations remain large in
Upper I(lamath Lake, as clo populations of I(lamath Lake scuipins ancI
recibancI trout. Even the I(lamath largescale suckers in the upper I(lamath
basin ancI I(lamath smaliscale suckers in the lower basin seem not as af-
fectecI by anthropogenic change as Lost River ancI shortnose suckers, al-
though the I(lamath largescale sucker is listecI as a species of special concern
in California (Moyle 20021. IntroclucecI species, such as yellow perch ancI
fathead minnow, appear to be unaffected by poor water quality. Sacra-
mento perch, which have been greatly reclucecI throughout their native
range (Moyle 2002), apparently are cloing well in the I(lamath basin. Ex-
planations for the exceptional vulnerability of shortnose ancI Lost River
suckers couicI be appliecI to recovery efforts.
One line of evidence is relatecI to physiological tolerances among
species, but this information is limitecI. Falter ancI Cech (1991) found that
shortnose suckers were less tolerant of elevatecI pH than were I(lamath tui
chub ancI I(lamath largescale suckers (Chapter 51. Aciclitional comparative
studies of physiological responses to water-quality clegraciation in the
I(lamath basin are neeclecI. Overall, more ancI better information is neeclecI
on the biology ancI population status of nonsucker species in the upper
basin (Chapter 51. Because all native I(lamath fishes are enclemics, any
significant cleclines in their populations couicI trigger ESA actions. Al-
though research efforts clirectecI specifically at native fishes other than the
listecI suckers wouicI be clesirable, information on them can be collectecI in
conjunction with studies of suckers. Some of the species can be used as
indicators of water quality ancI habitat conditions ancI wouicI provide
insight into the welfare of the enciangerecI suckers, especially where cliffer-
ences in physiological tolerance can be clemonstratecI. Comparisons be-
tween enciangerecI I(lamath suckers ancI other catostomicI species in the
I(lamath basin ancI between I(lamath suckers ancI lake suckers elsewhere
couicI provide aciclitional, invaluable insight into solutions to problems in
the I(lamath basin.
OCR for page 245
DECLINE AND RECOVERY OF KLAMATH BASIN SUCKERS
Captive Propagation
1 1 1
,_ ~ 1
245
Cantive Propagation is a controversial means of protecting enciangerec!
species. Successful propagation can leac! to complacency about the concli-
tion of natural populations anc! to clelay in the correction of the original
causes of clecline, but it also can serve as insurance against catastrophes.
Although I(lamath suckers have not reached the point where captive propa-
gatlon IS necessary, many conservation practitioners recommenc against
waiting until there is no alternative to captive Propagation. because bv then
.
1 1 1 ~ , ,
genetic resources are climinishec! anc! problems with rearing methods may
be disastrous.
The I(lamath Tribe has established a sucker hoicling anc! rearing facility
(the I(lamath Tribes Native Fish Hatchery) at Braymill near Chiloquin. The
facility has been used for physiological anc! behavioral studies anc! for
fertilization anc! larva-rearing trials (e.g., Dunsmoor 1993; L. I(. Dunsmoor,
I(lamath Tribes, Chiloquin, Oregon, personal communication, September
3,20021. The facility could serve as the core of a captive-propagation effort
if populations continue to clecline. Methods aireacly clevelopec! there can be
used, perhaps with advice based on successful propagation of cui-ui at the
David I(och Cui-ui Hatchery in Sutcliffe, Nevada, if captive propagation
proves necessary.
Critical Habitat
Critical habitat, as clefinec! by the ESA (Chapter 9), was not iclentifiec!
for the I(lamath suckers at the time of original listing, anc! has yet to be
completed for either enciangerec! species, although a ciraft proposal ap-
pearec! in 1994 (59 FecI. Reg. 61744 F199411. On the basis of established
ESA criteria (for example, water quantity anc! quality; physical habitat
appropriate for spawning, rearing, anc! feeding; anc! protection from precia-
tion anc! climatic stress), USFWS iclentifiec! six critical-habitat units (CHUB)
in the basin: Clear Lake anc! its watershed, Tule Lake, the I(lamath River,
Upper I(lamath Lake anc! its watershed, the Williamson anc! Sprague Riv-
ers, anc! Gerber Reservoir anc! its watershed. All except Gerber Reservoir
are habitat units for both sucker species; Gerber Reservoir contains only
shortnose suckers, but Lost River suckers presumably could live there.
The ciraft critical-habitat determination (59 FecI. Reg. 61744 F19941)
anc! its recommendations should be reviewed anc! revised in light of recent
finclings. The process of identifying critical habitat for both species needs to
receive higher priority anc! should be more specific. In designating Upper
I(lamath Lake a CHU, USFWS (59 FecI. Reg.61744 F19941) clic! not identify
specific areas of particular value. The CHU approach could be expanclec! to
inclucle the needs of specific life-history stages, for example, east coast
springs for spawning, Williamson River mouth anc! nearby shorelines as a
OCR for page 246
246
FISHES IN THE KLAMATH RIVER BASIN
nursery region, Mocloc Point anti Goose Bay as staging areas before spawn-
ing, anti west coast bays as postspawning aggregation areas (see Chapter 51.
Buettner (1992) identified sites that have the greatest potential as adult
refuges at low lake levels on the basis of their size, proximity to the main
lake, relative water quality, ancI density of submerged vegetation. The issue
of water-quality refuges neecis more stucly relative to critical habitat. If the
postulatecI patterns can be verified anti the location anti use of these appar-
ent water-quality refuges can be confirmed, they might be clesignatecI as
critical habitat anti consiclerecI for special protection.
Although there is only weak pressure for clevelopment in the I(lamath
basin, the human population of the area has grown, anti future growth is
likely (Chapter 21. Proposals for new construction or use of the lake should
take into account possible adverse effects on suckers. For example, an
article in SAIL magazine for luly 2002 iclentifiecI HowarcI Bay, Pelican Bay,
anti Harriman Springs as clesirable destinations for boaters. HowarcI Bay
apparently is a preferred aggregation area for postspawning shortnose suck-
ers (Coen et al. 20021; Pelican Bay was identified by Buettner (1992) as
a refuge for suckers cluring the fish kills of luly 1971 anti August 1986
anti was consiclerecI the best sucker refuge site on the west shoreline when
lake levels cirop; anti Harriman Springs is a former spawning site. Increased
boat traffic, clevelopment, grounc~water pumping, or other activities may
aciversely affect these sites.
LESSONS FROM COMPARATIVE BIOLOGY OF SUCKERS
Of the 63 species of suckers in the woricI, 61 are endemic to North
America. Among the few known extinctions of freshwater fishes in North
America, suckers figure prominently. Previously abundant, sometimes wicle-
spreacI species have clisappearecI, inclucling the harelip sucker (Lagochila
lacera) anti the Snake River sucker (Chasmistes muriei). Fully 35% of
sucker species are imperilecI (Warren anti Burr 1994), and eight have fed-
eral enciangerecI or threatened status (50 CFR 17.11 F199911.
Populations of large suckers in general anti lake suckers in particular
have cleclinecI largely because of anthropogenic factors. Although there is
an obvious neecI for concern about these very American fishes, comparative
ciata indicate that they can survive long periods of interrupted recruitment
anti can recover from these remarkable hiatuses in reproduction if factors
causing clecline are reclucecI. For example, clecline has occurred in other lake
suckers: cui-ui experienced no known recruitment from 1950 to 1969; lune
suckers hacI experienced at least 15 yrs without recruitment by the micicIle
1980s, anti that probably continued into the l990s; some populations of
razorback suckers (Xyrauchen texanus) experienced 20-30 yr without re-
cruitment; anti Utah suckers (Catostomus ardens) did not reproduce suc-
cessfully between the micicIle 1960s anti the early 1990s.
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DECLINE AND RECOVERY OF KLAMATH BASIN SUCKERS
247
Despite extenclecI interruptions in breeding, several species of suckers
have responclecI successfully to recovery programs. Cui-ui successfully spawn
in the Truckee River because of enhanced flows ancI are propagated in a
hatchery managed by the Paiute Tribe, from which they are regularly trans-
plantecI into Pyramid Lake, where they are abundant (USFWS 1992b). Ef-
forts to promote recovery of lune suckers have been uncler way since the early
l990s anti appear to have been successful; they inclucle water-allocation
agreements, refuge-population establishment, ancI captive breeding ancI re-
lease (USGS 19981. The robust rec~horse, Moxostoma robustum, a large
sucker thought to have undergone population cleclines in Atlantic slope cirain-
ages, is now propagated anti plantecI anti has shown successful recaptures in
three southeastern rivers (Jennings et al. 1998; C. lennings, U. S. Geological
Survey, Athens, Georgia, personal communication, 20021. An extensive re-
covery program for razorback suckers instituted in 1988 inclucles captive
rearing anti transplantation, habitat acquisition ancI protection, ancI control
of nonincligenous species; success has been mixed (Minckley et al. 1991,
Mueller ancI Marsh 19951. This general picture of clecline, public concern,
multifacetecI efforts at recovery, anti evidence of success can suggest actions
that might be successful with the I(lamath basin sucker species.
All four living lake suckers (shortnose sucker, Lost River sucker, cui-ui,
anti rune) are relatively large anti long-livecI (Chapter 51. High tolerance of
poor water quality implies that the fishes evolvecI in habitats that periocli-
cally experience extremes of water quality. Long life in these suckers may
reflect an evolutionary history that incluclecI harsh conditions that often
resultecI in reproductive failure, perhaps for many consecutive years. Excep-
tional longevity is a cause for optimism in that it allows the fish to recover
from population cleclines once conditions favorable to survival are restored
(Scoppettone anti VinyarcI 1991).
Age distributions in Upper I(lamath Lake suckers, as refiectecI in the fish-
kill data, show apparent resilience in I(lamath species (e.g., Cooperman anti
Markle 20031. Heavy fishing pressure resultecI in low numbers of oicI suckers
until 1987, when the fishery was eliminatecI. Numbers of aclults later increased
sharply (Figure 5-41. The rapicI increase demonstrates the positive effect of
closing the fishery. More important, the increase shows that even after pro-
longecI population cleclines brought about by overfishing, a relatively small
number of large, highly fecund inclivicluals can produce many young anti help
to restore a population (Cooperman ancI Markle 20031. Even slight improve-
ments in conditions favorable to suckers in Upper I(lamath Lake, its tributar-
ies, anti surrounding water bodies couicI contribute to recovery.
CONCLUSIONS
Despite elimination of fishing for the shortnose anti Lost River suckers
in 1987, these two listecI species have failecI to show an increase in overall
OCR for page 248
248
FISHES IN THE KLAMATH RIVER BASIN
abundance. Apparently stable populations with regular recruitment ancI the
presence of all life-history stages at appropriate abundance are found only
in Clear Lake ancI Gerber Reservoir. Thus, the listecI suckers at these two
locations require special degrees of protection, both in the lakes themselves
ancI in tributary waters where the suckers spawn.
The two listecI suckers are present in Upper I(lamath Lake, where they
reproduce ancI show the full spectrum of age classes indicating successful
maturation of at least some inclivicluals. This population has not increased
in abundance, however, because of episodes of mass mortality affecting
large fish ancI possibly other factors as well. Populations at other locations
(the main-stem reservoirs, the main stem of the Lost River, ancI Tule Lake)
are of very low abundance ancI consist primarily of aclults; no full represen-
tation of age classes is present at these locations. Suckers have been elimi-
natecI entirely from the micicIle portion of the main stem of the Lost River,
from Lower I(lamath Lake, ancI from Lake of the Woocis.
Small irrigation clams ancI the larger Chiloquin Dam across the main
stem of the Sprague River impede the movement of suckers attempting to
spawn in the tributaries to Upper I(lamath Lake. Elimination of Chiloquin
Dam couicI greatly expand any potential spawning area, although channel
ancI riparian improvements to the upper Sprague might be necessary to
achieve the full benefit of clam removal.
Spawning of suckers in tributaries to Upper I(lamath Lake is successful
in producing fry, but the spawning areas clo not receive special protection
ancI are poorly stucliecI. Physical restoration of tributary spawning areas is a
matter of high priority anti will involve exclusion of livestock anti other
measures clesignecI to promote conditions that favor spawning of the suck-
ers. Physical restoration near the mouth of the Williamson River as it enters
Upper I(lamath Lake is also important.
Water level in Upper I(lamath Lake shows no relationship to water-
quality conditions that result in mass mortality of aclult suckers or other
potentially adverse water-quality conditions. In aciclition, water level shows
no relationship to year-class strength or to abundance of fry or juveniles
over the years cluring which stanciarclizecI sampling is available. Thus, main-
tenance of water levels above recent historical levels in orcler to increase the
abundance of suckers by maximizing the area of habitat where young
suckers are founcI is not supported by the currently available evidence.
Water levels lower than recent historical levels couicI have unclocumentecI
adverse effects ancI therefore are inacivisable. Experimental maintenance of
specific water levels couicI be incorporated into a management plan, how-
ever, through agreements between USFWS ancI USER, if USFWS sees merit
in further studies of water-level control.
The two listecI suckers spawn in specific lakesicle areas of Upper I(la-
math Lake, typically in association with the presence of springs. Some
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DECLINE AND RECOVERY OF KLAMATH BASIN SUCKERS
249
spawning areas have been abanclonecI entirely, possibly because of the elimi-
nation, through fishing, of specific groups of fish that habitually used these
areas. Some spawning areas show signs of anthropogenic clegraciation. Se-
lective restoration of these areas anti manipulation of stocks to encourage
bonding of specific groups of suckers to the unused sites couicI be beneficial
in spreading the reproductive risk of the sucker populations.
Suckers of all ages in Upper I(lamath Lake historically have been en-
trainecI into the A Canal, which is the main supply conduit for USBR's
I(lamath Project. Screening of this source of mortality is scheclulecI for
summer of 2003, but it cannot be expected to prevent mortality of very
small fish. Refinement of the operation of the screens as recommenclecI by
USFWS (2002) might recluce the mortality of very young fish. The Link
River Dam intake units remain unscreened, ancI thus remain a source of
mortality for fish of all ages.
Suckers of Upper I(lamath Lake ancI at other locations where suckers
are present in the upper basins share their habitat to varying degrees with
nonincligenous species, some of which are known to prey upon or compete
with young suckers. Elimination of nonincligenous species over very large
systems such as Upper I(lamath Lake is beyond the current state of the art,
but programs clesignecI to prevent aciclitional introductions ancI prevent the
spreacI of presently nonincligenous species wouicI be highly acivisable. Be-
cause the actual effect of the nonincligenous species on the suckers is poorly
known, it is clifficult to jucige the importance of this factor basecI on current
. , .
Information.
Hybridization among sucker species was an original concern of consicI-
erable importance to the listing of the suckers. Subsequent studies have
reclucecI the level of this concern, but it wouicI be acivisable to have more
information on the genetic identities of suckers at various locations in the
upper basin.
Captive propagation is a possibility ancI couicI be concluctecI on a pat-
tern that has been clevelopecI for populations of relatecI suckers at other
locations. Captive propagation is probably clisacivantageous at present,
however, in that it tencis to undermine incentives for return of the popula-
tions to a self-sustaining basis, which may still be possible in the I(lamath
basin. Continued clecline of the population sizes or loss of any major sub-
populations wouicI indicate a neecI for captive propagation.
The long life-history of suckers requires extenclecI observation as a
means of judging population trencis. Benefits of restoration actions will not
necessarily be evident until the fish benefiting from these actions have
achieved spawning capability. Similarly, the negative effects of mortality
focused on large fish may become evident only graclually, but couicI extin-
guish entire subpopulations.
Representative terms from entire chapter:
water level
