AN ABSTRACT OF THE THESIS OF
Nicola L.Swets for the degree of Master of Science in
Fisheries Science presented on June 24, 1996.
Title: Age, Growth, and Diet of Fish in the Waldo Lake
Natural-Cultural S
Redacted for Privacy
Abstract approved
priam J.Liss
Waldo Lake, located in the Oregon Cascades, is
considered to be one of the most dilute lakes in the
Even with very low nutrient concentrations and
sparse populations of zooplankton, introduced fish in the
world.
lake are large in size and in good condition when compared
to fish from other lakes. Fish were originally stocked in
Waldo Lake in the late 1800's. The Oregon Department of
Fish and Wildlife began stocking in the late 1930's and
Species existing in Waldo
Lake today include brook trout, rainbow trout, and kokanee
continued stocking until 1991.
salmon.
The overall objective of this thesis was to increase
the understanding of the interrelationships that affect
the age, growth, and diet of fish in Waldo Lake. The
specific objectives were to summarize and synthesize
available information on the substrate, climate, water,
and biota of the Waldo Lake Basin; describe the cultural
history and current cultural values of the Waldo Lake
Basin; determine the age, growth, length, weight,
condition, diet, and reproduction of introduced fish
species in Waldo Lake; interrelate the above information
to show how these components of the natural-cultural
system are related.
Fish were collected one week per month from early
June through mid-October in 1992 and 1993.
Variable mesh
experimental gillnets set in nearshore areas were used to
capture fish in 1992. During the 1993 sampling period,
experimental gillnets and trapnets were set in the
nearshore areas of the lake.
Relative age specific growth rates of brook trout in
Waldo Lake are comparable to brook trout growth rates in
other lakes.
Brook trout growth rates generally decreased
with age, however, there were no significant differences
in the growth rate of each age class between 1991 and
1993.
The condition of brook trout in Waldo Lake is also
comparable to brook trout in other lakes. The same is
true for rainbow trout and kokanee salmon.
Fish in Waldo Lake are large in size and in good
condition due, in part, to the availability of benthic
macroinvertebrates.
Taxa found in stomach contents of
fish captured in Waldo Lake consisted primarily of aquatic
benthic macroinvertebrates, but terrestrial vertebrates
and vertebrates, although infrequently consumed, were also
part of the total diet.
Rainbow trout in Waldo Lake
consumed primarily chironomidae larvae and pupae although
odonata larvae, ephemeroptera larvae, and amphipods were
also consumed. Kokanee salmon fed almost exclusively on
chironomid larvae although small numbers of ephemeroptera
larvae, odonata larvae, and coleoptera were also consumed.
The most important macroinvertebrate taxon consumed by
Waldo Lake brook trout was chironomid larvae and pupae,
although other species also were important.
The diet of
Waldo Lake brook trout varied in a complex way that
appeared to be related to the relative abundance of
macroinvertebrate taxa, feeding location in the lake, and
time of year. Brook trout diet also varied by size class.
The components of the Waldo Lake natural-cultural
system are complexly interrelated and the nature of these
relationships are constantly changing. Each component in
some way affects and is, in turn, affected by each of the
other components.
Changes in some components, such as
substrate, affect other components along geologic time
scales.
Other components, such human culture and biota,
may change rapidly within a decade. The capacity of
natural-cultural systems, such as Waldo Lake, to change
over time makes it possible to view the present state of
the system only as a snapshot in time. This dynamic
nature of the Waldo Lake natural-cultural system is not
unique to Waldo Lake, but is expressed in all natural-
cultural systems.
Age, Growth, and Diet of Fish
In the Waldo Lake Natural-Cultural System
by
Nicola L. Swets
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Master of Science
Presented June 24, 1996
Commencement June, 1997
Master of Science thesis of Nicola Lyn Swets presented on
June 24, 1996
APPROVED:
Redacted for Privacy
sor, representing Fisheries Science
Redacted for Privacy
Fisheries and Wildlife
Chair of Depar
Redacted for Privacy
Dean of G
ate School
I understand that my thesis will become part of the
permanent collection of Oregon State University libraries.
My signature below authorizes release of my thesis to any
reader upon request.
Redacted for Privacy
Nicol Lyn
Swets
ACKNOWLEDGEMENTS
I wish to express my sincere appreciation to Dr. Gary
Larson and Dr. Courtland Smith for serving on my graduate
committee and providing insight throughout this process.
Special thanks go to Dr. William Liss for his help in the
various iterations of the preparation of the thesis and
for the encouragement to stay on course, even when others
did not see things in the same way that I did.
I also wish to thank the employees of the Willamette
National Forest who were patient with me as I juggled
working full time and completing this thesis. Without
these individuals, this accomplishment would not have been
possible.
Finally, I am most indebted to my family, to my
parents Roger and Ellen Swets who always told me that
anything is possible with hard work (an idiom that is
perhaps idealistic, but which I still, and forever will
believe), and to my husband Brian, who provided unending
support and the encouragement necessary for me to fulfill
this dream.
TABLE OF CONTENTS
Page
INTRODUCTION
1
COMPONENTS OF THE WALDO LAKE NATURAL-CULTURAL SYSTEM
9
Substrate
Geologic History
Basin and Lake Morphometry
Basin Substrate
Lake Substrate
Climate
Precipitation
Air Temperature and Solar Radiation
Wind Speed and Direction
Water
9
9
11
11
13
13
14
14
14
14
Water Chemistry
Other Limnological Information
Biota
15
16
17
Phytoplankton
Zooplankton
Benthic Macroinvertebrates
Terrestrial Macroinvertebrates
Amphibians
Allochthonous Input
Autochthonous Organic Material
Human Culture
History of human Culture Component
The Introduction of Fish to Waldo Lake
Fishing Pressure
Conflicting Values
The Values
Protectionists and Naturalists
Multiple Use Advocates
17
18
19
23
26
26
29
30
30
34
34
36
37
37
38
TABLE OF CONTENTS (Continued)
AGE, GROWTH, AND DIET OF FISH IN WALDO LAKE
Methods
Fish Capture
Age and Growth
Condition
Diet
Reproduction
Results
Fish Capture
Age and Growth
Condition
Diet
Reproduction
Discussion
Waldo Lake: A Complex, Dynamic Natural-
Cultural System
Age, Growth, and Condition of Fish in
Waldo Lake
Diet of Fish in Waldo Lake
Reproduction of Fish in Waldo Lake
BIBLIOGRAPHY
40
40
40
41
42
43
44
45
45
45
49
53
63
66
66
72
73
76
78
LIST OF FIGURES
Figure,
1.
2.
3.
Page
A natural-cultural system symbolized in terms
of its primary and secondary subsystems
6
The Waldo Lake Basin and the Waldo Lake
Wilderness boundary
7
The natural-cultural system entailing
compositional hierarchy of human culture,
climate, biota, water, and substrate. The
environment of the natural-cultural system
8
4.
A bathymetric map of Waldo Lake
10
5.
Fish sampling locations in Waldo Lake and its
tributaries and outlet
12
Comparison of growth rates from recaptured
fish of known age and from back-calculated
age from otoliths of brook trout captured
between 1991 and 1993
48
Average relative growth rate by year for Waldo
Lake brook trout
50
Mean relative growth rates as determined from
otolith analysis for Waldo Lake brook trout
(1991-1993) compared to relative growth rates
of brook trout from other lakes
51
6.
7.
8.
9.
Percent occurrence of taxa observed in the stomach
contents of fish captured from Waldo Lake
(1991-1993)
54
10.
Location of prey items of Waldo Lake
brook trout, rainbow trout, and kokanee salmon
11.
12.
.
.
Percent of taxa observed in Waldo Lake
brook trout stomach contents (1991-1993)
Location of prey items of Waldo Lake brook trout
57
58
.
59
LIST OF FIGURES CONTINUED
Figure
Page
13. The relative abundance of aquatic
macroinvertebrate taxa collected from nearshore
and offshore areas (1992-1993)
61,62
14.
The percentage of taxa observed in the stomach
contents of two size classes of brook trout
(1991-1993)
64
15. Location of prey items of two sizes of Waldo
Lake brook trout
65
16. A food web focusing on the biotic component
of the Waldo Lake natural-cultural system
70
LIST OF TABLES
Table
1.
2.
3.
Page
Macroinvertebrate taxa collected from nearshore
microhabitats and offshore areas of Waldo Lake,
1992-1993
21
The number of taxa and the percent of the
total taxa collected in the nearshore
microhabitats, 1992 and 1993
22
The presence of nearshore macroinvertebrates
from late May through early October)
24,25
Visitor use days at Waldo Lake Campgrounds
from 1969 to 1992
32
5.
Waldo Lake recreation use data
33
6.
Number of fish stocked by the Oregon
Department of Fish and Wildlife in Waldo Lake,
Oregon
35
Number of fish captured and the number of
otoliths examined by species and year
46
Comparison of average growth rates and average
relative growth rates between the marked 1988
cohort and the backcalculated length of fish
captured in 1991-1993
47
4.
7.
8.
9.
Mean Fulton-type condition factor of fish
in Waldo Lake compared to fish in other lakes .... 52
10.
Taxa found in the stomach contents of fish
collected from Waldo Lake in 1992 and 1993
11.
A matrix for the Waldo Lake Basin showing the
interrelationships between the components
of the natural-cultural system
55
67,68
Age, Growth, and Diet of Fish
in the Waldo Lake Natural-Cultural System
INTRODUCTION
"The lake stretches away to the north; crags and
peaks tower above us.
It is a splendid scene - this
source of rivers and cities, hid away, like pure
trains of thought from vulgar observation - in the
bosom of the wilderness buried."
Judge John Beckenridge Waldo(1890)
Waldo Lake is considered to be one of the most dilute
(ultraoligotrophic) lakes in the world based on chemical
and biological characteristics of the pelagic zone (Larson
and Donaldson 1970, Larson 1972, Maleug et al. 1972).
Oligotrophy implies that biological production in the lake
is restricted by relatively low concentrations of
dissolved nutrients (Goldman and Horne 1983). The
concentrations of ions, conductivity, and alkalinity in
the lake are within the range of those measured from snow
samples taken from the basin (Maleug et al. 1972) and are
similar in composition to rainwater in a pristine
environment (Johnson et al. 1985).
Larson (1970) compared
the water chemistry of Waldo Lake to distilled water
because of the low concentrations of nitrogen,
phosphorous, and carbon. Inorganic nitrogen
concentrations reported by Larson and Salinas (1995) were
below the level of detection(1.0 p./1) during most sampling
efforts. Ammonia concentrations were more variable (,1.0
to 19 11/1)(Larson and Salinas 1995).
Both total and
organic phosphorous concentrations are very low (<5
11/1)(Larson and Salinas 1995).
Total carbon
2
concentrations range from 0.95 to 5.41 mg/1 (Larson and
Salinas 1995). Maleug et al. (1972) reported total carbon
In addition, both
concentrations to be less than 1 mg/l.
phytoplankton (Larson et al. 1991; Powers et al. 1975,
Larson 1972) and zooplankton occur in low densities in
Waldo Lake (Powers et al. 1975, Maleug et al. 1972, Malick
et al. 1971.)
Given the ultraoligotrophic nature of Waldo Lake, it
is surprising that introduced fish in the lake are
The
relatively large in size and in good condition.
productive capacity of lakes is often determined based on
physical, chemical, and biological characteristics within
the pelagic zone. Benthic productivity is not usually
considered when determining the trophic status of lakes,
but benthic organisms have been shown to be important
components in the diet of fish in many oligotrophic lakes
in the Cascade Mountains (Liss et al. 1995, Buktenica
1989).
Due to the diverse values and changing expectations
of society, there is a growing concern about the
management of public lands. Because Waldo Lake is located
on the Willamette National Forest, the United States
Forest Service is responsible for the management of the
Waldo Lake Basin, although other agencies such as the
Department of Environmental Quality, the Oregon Department
of Fish and Wildlife, the Environmental Protection Agency,
and the State Parks and Recreation Department are also
involved in decision-making processes. The U.S. Forest
Service has responded to public concerns about resource
management by adopting goals and objectives that recognize
the importance of studying entire ecosystems, rather than
focusing solely on one resource. Ecosystem management
strategies have been adopted at regional and local levels.
In 1993, the Willamette National Forest adopted an
3
Ecosystem Management Strategy to incorporate the
principles of ecosystem management in its daily operations
(Willamette National Forest, 1993).
The goal of the
ecosystem strategy is to manage using a holistic approach
that takes into account people, natural resources and
their interactions.
A natural-cultural system conceptual framework is one
example of an ecosystem management perspective.
The
natural-cultural system, as described by Gregor (1982) and
Warren and Liss (1983), is broken into five components:
water, substrate, climate, biota, and human culture
(Figure 1).
The basic premise is that all components are
related and a change in one will affect others.
Individual components can be studied in detail but cannot
be removed completely from the context of the system as a
whole.
This contextualistic idea can be related to a
tapestry.
If one is interested in a particular thread
within a tapestry, this thread can be raised in relief and
studied closely, but if the thread is pulled out of the
tapestry, not only does the tapestry unravel but the
context within which the thread was woven is lost. All
components of the natural-cultural system are interrelated
and inseparable.
To understand the interrelationships that affect the
age, growth, and diet of fish in Waldo Lake, it is
necessary to examine each of the components that
contribute to the overall functioning of the Waldo Lake
natural-cultural system.
Fish ecology can be raised in
relief, but cannot be removed from the context of the
other components of the Waldo Lake natural-cultural
system.
The substrate and local climate of an aquatic
system affects water chemistry and water temperature
which, in turn, affects nutrient availability and nutrient
mixing (Lomnicky, 1996).
The availability of nutrients
4
determines the types of biota as well as their abundances
(Liss et al. 1995).
The cultural component, depending
upon the values held for the particular resource,
determine the overall management of the system.
Natural-cultural systems can be described at
different levels depending upon the question of interest.
For purposes of this research, the ecology of fish in
Waldo Lake, the natural-cultural system will be described
However, the
at the Waldo Lake Basin level (Figure 2).
relationships between the Waldo Lake Basin and adjoining
natural-cultural systems should not be forgotten because
at a higher level of resolution, adjoining natural-
cultural systems affect one another (Figure 3).
The primary goal of this research is to increase the
understanding of the ecological conditions that sustain
fish growth and condition in Waldo Lake. Although there
are emerging controversies in the basin, such as the
effects of fish stocking and motor boat use on water
quality, there have been very few attempts to review and
synthesize the available data on Waldo Lake so that it
exists in a single document. This is another goal of this
thesis.
The specific objectives are to:
1)summarize and synthesize available information on
substrate, climate, water (water chemistry and other
limnological information), and biota (phytoplankton,
zooplankton, macroinvertebrates, amphibians,
allochthonous and autochthonous input).
2)describe the cultural history and the current
cultural values of the Waldo Lake Basin.
5
3)determine the age, growth, length, weight,
condition, diet, and reproduction of introduced fish
species in Waldo Lake.
4)interrelate the above information to show how these
components of the natural-cultural system are
related.
NATURAL-CULTURAL SYSTEM
.....
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WATER
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CLIMATE
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CULTURE
BIOTA
SUBSTRATE
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articles
Gases
Water
Figure 1. A natural-cultural system symbolized in terms of
its primary (1°) and secondary subsystems (2°).
After Gregor (1982).
7
a
a
:4
MILES
0
as
0
2
2
3
4,
4
KILOMETERS
6
5
i
8
Rigdon Butte (1706 m)
.:-tfit5W1
Charlton Butte (2134 m)
N
C
The Twins (2244 rn)
alaa
- 13azixt Boundary
cam; Waldo Lake Wilderness
Mt Ray (2134 m)
Figure 2. The Waldo Lake Basin and the Waldo Lake
Wilderness boundary.
(B)
(A)
NATURAL-CULTURAL
SYSTEM
Figure 3.
(A) The natural-cultural system entailing
compositional hierarchy of human culture (C),
climate (C1), biota (B), water (W), and
(B) The environment of the
substrate (S).
natural-cultural system. After Gregor (1982).
03
9
COMPONENTS OF THE WALDO LAKE NATURAL-CULTURAL SYSTEM
SUBSTRATE
The substrate of a natural-cultural system depends
upon the geologic history of the basin of interest. The
geologic events that form the basin determine the
These
substrate types of the basin and the lake.
substrate types are an important factor in determining
nutrient availability in the lake environment.
Geologic History
The geologic history of the Waldo Lake Basin is in
part responsible for the ultra-oligotrophic nature of
Basin formation is commonly attributed to
Waldo Lake.
glaciation (Larson and Donaldson 1970) yet after study of
the geology of the basin and the bathymetry of Waldo Lake,
Woller and Black (1982) suggest that the lake was formed
by volcanic activity. The bathymetric map of Waldo Lake
depicts a steeply sloping western shoreline and a more
gradually sloping eastern shoreline (Figure 4). Glaciers
typically form lake basins that are longest in the
direction that the glacier is moving and steepest towards
the source of the ice (Woller and Black, 1982). Glaciers
are thought to have moved westward through this region, a
direction opposite of that which would have been necessary
to create a lake that is deepest on the western shoreline
Carbon dating
and longest along the north-south axis.
suggests that the western shoreline is the result of an
10
Figure 4.
A bathymetric map of Waldo Lake.
11
older basaltic andesite flow estimated to be between
300,500 and 500,000 years old.
The gently sloping
bathymetry of the eastern shoreline is attributed to lava
formation by an ancient volcano, now known as The Twins,
The age of
located 5 km east of Waldo Lake (Figure 5).
this flow is estimated to be between 10,000 and 250,000
The presence of glacial drift on the southern
years old.
shore of the lake suggests that glacial activity did occur
in this area, but it is not thought to have been the major
factor forming the Waldo Lake Basin.
Basin and Lake Morihometr'
Waldo Lake, located at an elevation of 1650 meters in
the central Oregon Cascade Range, is the second largest
natural body of water in Oregon. The area of the Waldo
The lake encompasses an area nearly
Lake Basin is 79 km2.
The lake
one third of the total basin area (25.12 km2).
has a volume of 0.95 km3, an mean depth of 38.0 meters,
and a maximum depth of 128 meters (Larson and Donaldson
1970).
Basin Substrate
The regolith of the basin consists of moderately
weathered light colored pumice and rounded rock boulders
up to 1.5 meters in diameter (Larson and Donaldson 1970,
Malueg et al. 1972). According to Larson (1972) the depth
of the soil mantle is no greater than 2 meters and the
underlying fractured, hard basaltic bedrock is exposed in
many places, especially at the north end of the lake. The
soil mantle of the basin is porous and allows for rapid
percolation of groundwater (Larson and Donaldson 1970,
Davis and Larson 1976).
12
a
2
4
2
0
HILES
1
4
6
5
8
KILOriETERS
tr
Rigdon Butte (1706 m)
:41V.447­
'Vi1,22
North Fork of the Middle Fork X
4.1-17
Charlton Butte (2134 m)
of the Willamette River ?Mni
Dam Camp
Outlet Cove
X Brookic Slide
Islet Campground
*V.
Waldo Lake (1650 m)
1111
The Twins (2244 ni)
Shadow Bay
6'
- - -13aain Boundary
Brifige East of South Waldo Shelter
'
South Waldo Shelter Tributary
alxvi
,0440
Mat- Waldo Lake Wilderness
Mt Ray (2134 in)
Figure 5. Fish sampling locations in Waldo Lake and its
tributaries and outlet (North Fork of the Middle
Fork of the Willamette River) (designated by an
X on the map).
13
Lake Substrate
The lake substrate is similar to that of the
surrounding basin. The irregularly shaped shoreline is
composed of bedrock, boulders, cobble, gravel, sand and
silt (Robert Hoffman, Department of Fisheries and
Wildlife, Oregon State University, unpublished data).
Sandy beaches are common on the eastern and northern
shores but are rare along the western shore. The lake
bottom is comprised primarily of silt.
Studies on
sedimentation rates by Davis and Larson (1976) suggest
that the lake has always been ultra-oligotrophic and that
the sedimentation rate is low (approximately 1.5
The organic contents of these sediments also
gr/m2/yr).
Sediments
suggest that Waldo Lake is ultraoligotrophic.
taken from the deepest part of the lake (127 m) contained
0.2 percent total phosphorous, 0.9 percent total nitrogen,
and 5.1 percent total carbon (Malueg et al. 1972).
CLIMATE
Climatic conditions are important components of
natural cultural systems. Climate determines the amount,
timing, and form of precipitation entering a basin as well
as the solar radiation, air temperature, and wind speed
Climatic conditions determine the
and direction.
In addition,
environment in which the basin is situated.
climate may play a role in basin formation through glacial
activities.
14
Precipitation
The major sources of water entering the lake come
from direct precipitation and snow melt runoff (Johnson et
al. 1985).
The average precipitation is between 154 and
180 cm (Larson and Donaldson 1970, Powers et al. 1975,
Lidder et al. 1980). Precipitation falls as snow during
the winter months with a reported mean of 8 1/3 m (Larson
and Donaldson 1970). Summer months typically experience
less precipitation than occurs during the rest of the
year.
Air Temperature and Solar Radiation
The mean annual air temperature is 5° C (Larson and
Yearly average monthly temperatures
Donaldson 1970).
The
range from -5.2° to 18° C (Lidder et al. 1980).
entire lake surface freezes during the winter of some
Larson (1970) reported that the average incident
radiation for the Waldo Lake area was 266 g cal/cm2/4 hrs.
years.
This was measured in 1969 from 1000 to 1400 hours.
Wind Speed and Direction
Winds in the basin are typically from the west and
may reach 12 to 20 knots.
WATER
The water component of a natural-cultural system
describes the chemical and physical attributes of the
environment in which aquatic organisms live. This
component is extremely important as these attributes
influence the colonization of species and their abundance.
15
Water Chemistry
Waldo Lake is thought to be one of the most dilute
lakes in the world based on comparing water chemistry and
biological standards to those of other lakes that are
classified as being oligotrophic (Larson and Donaldson
1970, Larson 1972, Maleug et al. 1972)
Powers et al.
(1975) supported this conclusion by reporting that the
specific conductance and total dissolved solids in Waldo
Lake are an order of magnitude less than those in other
lakes in North America that are classified as
oligotrophic, such as Lake Tahoe and Crater Lake.
Nutrient concentrations in Waldo Lake are very low. The
concentrations of ions, conductivity, and alkalinity in
the lake are within the range of those concentrations
measured in snow samples taken from the basin (Maleug et
al. 1972) and are similar in composition to rainwater in a
pristine environment (Johnson et al. 1985).
Larson (1970)
compared the water chemistry of Waldo Lake to that of
distilled water.
Inorganic nitrogen concentrations
reported by Larson and Salinas (1995) were below the level
of detection(1.0 p/1) on most sampling dates.
Ammonia
concentrations were more variable (1.0 to 19 g/1)(Larson
and Salinas 1995). Both total and organic phosphorous
concentrations are very low (<5 g/1)(Larson and Salinas
1995).
Total carbon concentrations range from 0.95 to
5.41 mg/1 (Larson and Salinas 1995).
Maleug et al (1972)
reported total carbon concentrations to be less than 1
Larson and Donaldson (1970) reported that samples
taken from the water surface and from deep within the lake
had nearly identical chemical characteristics.
mg/l.
16
Other Limnological Information
Aside from water chemistry there are other physical
limnological characteristics that describe the
oligotrophic nature of Waldo Lake such as Secchi disk
readings, pH values, and temperature and dissolved oxygen
Summer Secchi disk readings, which describe the
transparency of a lake, ranged from 23.0 to 35.4 m (Larson
profiles.
and Donaldson 1970, Maleug et al. 1972, Powers et al.
1975, Lidder et al. 1980).
Secchi disk readings may vary
depending upon climatic conditions or due to coniferous
pollen suspended in the water column (Powers et al. 1975).
The pH of Waldo Lake, taken from both the surface and
the water column, varies from a range of 5.3 to 5.9
(Maleug et al. 1972, Lidder et al. 1980) to a range of 6.0
to 6.6 (Carter et al. 1966, Larson and Donaldson 1970).
More recent research (1989 to 1993) found pH values
ranging from 5.4 to 7.6 (Larson and Salinas 1995). The
alkalinity of Waldo Lake is very low at <4 mg/1 as
CaCO3(Carter et al. 1966, Maleug et al. 1972).
Larson and
Salinas (1995)observed a range in alkalinity from 1.6 to
2.9 mg/liter as CaCO3
This low alkalinity suggests an
extremely low buffering potential to resist changes in pH.
The summer water temperature ranges from 18.3° C at
the surface to 3.3° C at a depth of 100 m (Larson and
Salinas 1995). The lake is thermally stratified from June
through October (Larson 1970).
Thermal stratification
occurs every year and the epilimnion ranges in depth from
5 to 10 m (Powers et al. 1975).
The thermocline occurs
between 14 and 20 m (Lidder et al. 1980).
Dissolved
oxygen was reported to be near saturation levels at all
lake depths by Carter et al. (1966). Lidder et al. (1980)
reported dissolved oxygen concentrations of 9.0 mg/1 in
the epilimnion and 11.5 mg/1 in the hypolimnion. These
results were similar to those found by Ziesenhenne in
17
1938.
Powers et al. (1975) estimated the annual
evaporation from the lake to be 109 cm and the lake water
retention time to be 21.2 years.
BIOTA
The biota in a natural-cultural system can be
described as the living organisms found within the system
In the Waldo Lake natural-cultural system
the biotic components that will be described include those
of interest.
inhabiting the lake environment such as phytoplankton,
zooplankton, autochthonous input, benthic
macroinvertebrates, amphibians, and fish as well as the
terrestrial components which include plant communities
which provide allochthonous input to the lake as well as
Research on
terrestrial invertebrates and vertebrates.
age, growth, and diet of fish in Waldo Lake was performed
The methods used
during the 1992 and 1993 field seasons.
and results obtained from this research are discussed in
the following chapters. The remainder of this chapter
summarizes the information that is currently known about
the biotic components of the Waldo Lake natural-cultural
system.
Phytoplankton
Phytoplankton primary production and chlorophyll a
concentrations in Waldo Lake are considered to be the
lowest ever reported for freshwater lakes (Larson 1991).
Primary production is thought to be controlled by
temperature, light and nutrient availability (Larson
Powers et al. (1975) found that primary
1970).
productivity and phytoplankton densities in Waldo Lake
18
were significantly less than those found in Crater Lake or
Larson (1972) reported barely measurable
concentrations of chlorophyll a (2.9 mg chl a/ m2). More
Lake Tahoe.
recent studies indicate that primary production (mg
Carbon/m2/hr) has increased from a mean of 6.79 in 1989 to
a mean of 69.97 in 1993 (Larson and Salinas 1995).
Previous to 1989 the primary production in Waldo Lake was
Dinoflagellates are the predominant
phytoplankton taxa. The most common dinoflagellate
fairly constant.
belongs to the genus Glenodium (Johnson et al. 1985).
Green flagellates and diatoms occurred in low densities
(Maleug et al. 1972).
The most common diatom is the genus Eunotia although
Asterionella formosa, Melosira sp., and Synedra sp. are
also present (Johnson et al. 1985) Cymbela and Tabellaria
sp. have also been identified in Waldo Lake (Carter et al.
1966).
Davis and Larson (1976) added Peronia sp.,
Frustulia sp., Navicula sp., Achnanhtes sp., and
Fragilaria sp., to the list of diatoms present in Waldo
Lake after conducting sediment core tests.
They concluded
that most of the diatoms were periphytic and very few were
They also found that oligotrophic diatoms
were present throughout the core sample suggesting no
planktonic.
changes in the water quality of the lake prior to the 1976
study.
Zooplankton
Zooplankton populations in Waldo Lake are sparse
throughout the water column but are thought to be more
abundant near the lake bottom (Aquatic Analysts 1990).
Powers et al. (1975) and Maleug et al. (1972) found no
zooplankton in Waldo Lake plankton tows. Malick et al.
(1971) collected between 0.27 and 1.40 zooplankton/ m3
19
while performing vertical tows using a no. 6 mesh net
(intake diameter = 0.5 meters). These numbers were
significantly lower than those Malick et al. (1971)
obtained in Crater Lake (260 to 575 zooplankton/ m3).
Larson and Donaldson (1970) and Lidder et al. (1980) were
more successful at collecting zooplankton. Zooplankton
taxa captured included Diaptomus, Daphnia, Polyphemus,
Senecella, Calonoides, and two rotifers.
There has been an apparent change in both zooplankton
density and species composition since zooplankton studies
were first initiated in the late 1960's (Larson and
Zooplankton densities increased from 2
Salinas 1995).
individuals/m3 in 1966 to over 4,000 individuals/m3 in
1991.
The dominant taxa also changed during this time
period from Daphnia to Bosmina.
Benthic Macroinvertebrates
Macroinvertebrates are integral members of high
mountain lake ecosystems. One group of
macroinvertebrates, aquatic insects, comprise a major
proportion of the secondary productivity in freshwater
systems (Benke 1984). In addition, Merritt et al. (1984)
described aquatic insects as performing important roles in
the processing, cycling, and storing of nutrients in
lentic and lotic ecosystems. Larkin (1979) labelled
freshwater invertebrate species as "fish food", and
according to Healey (1984) fish production can be
influenced by aquatic insects that provide a substantial
forage base for many freshwater fish populations.
A total of 41 taxa were collected from Waldo Lake
nearshore and offshore samples (Table 1) using sweep nets
and benthic core samples in the nearshore and an Eckman
dredge in the offshore.
Taxa is used in this context to
20
identify
organisms at a particular level of taxonomic
resolution (e.g., order, family, genus).
Aquatic insects
comprised the majority of taxa (80%) collected in benthic
samples (Robert Hoffman, Department of Fisheries and
Wildlife, Oregon State University, unpublished data).
The
nearshore area, or littoral zone, of Waldo Lake had the
highest diversity of taxa with 98% of all taxa present in
nearshore microhabitats. The number of taxa collected
from offshore sites, or pelagic zone, was considerably
less (27% of all taxa).
Differences in distribution, diversity, and abundance
of macroinvertebrates in nearshore microhabitats can, in
part, be related to concordance between habitat conditions
and the habitat requirements of organisms (Liss and Warren
1980, Gilinsky 1984, Hoffman et al. 1996). Many
differences observed during a season may be due to
perennial localized conditions associated with benthic
substrates and habitat complexity.
The distribution of
nearshore macroinvertebrates in Waldo Lake varied by taxa
and microhabitat. Table 2 shows the number of taxa found
in each of the microhabitat types during the 1992 and 1993
nearshore benthic surveys. Taxa diversities were lowest
in the sand and massive rock/bedrock microhabitats and
highest in sand/silt, gravel/cobble, small boulder, large
boulder, and aquatic vegetation microhabitats (Robert
Hoffman, Department of Fisheries and Wildlife, Oregon
State University, unpublished data).
21
Table 1. Macroinvertebrate taxa collected from nearshore
microhabitats (littoral zone) and offshore areas
(pelagic zone) of Waldo Lake, 1992-1993) (Robert
Hoffman, Department of Fisheries and Wildlife
Oregon State University, unpublished data).
Nearshore
Taxa
Hydra
aamatoda
Atari
Oligochaeta
Mirudinea
Anphipoda
Pelecypoda
Ephemeroptera
Cdonata
Plecoptera
Trichoptera
Talitridae
Gamnaridae
Sphaeriidae
Baetidae
Siphlonuridae
Leptophlebifdae
Aeshnidae
Cordulfidae
Lestidae
Libellulidae
Coenagrionidae
Chloroperlidae
Pteronarcyidae
Lepidostoaatidae
Leptoceridae
Liavvq3hilidae
Hyallela azteca
Gammarus sp.
Functional
Offshore
Feeding Group
)0a
SCAV
300(
DETR
SCAV
SCAV
SCAV
DETR
CODA
CODA
CODA
PRED
PREO
PRED
PRED
PRED
PRED
SHRD
SHRD
CODA
SHRD
SHRD
CODA
PRED
PRED
PRED
PRED
PRED
PRED
SHRD
PRED
PRED
PRED
PRED
PRED
SHRD
PRED
GERR
CODA
PRED/SHRD
MO(
xxx
MC<
Callibaetis
Ameletus
pareeptoohlebia
Aeshna
Sympetrum, Libellula
Sweltsa
Pteronarcella
Leoidbstoma
Mystacidks
Nesperophytax
Omneohilus
Megaloptera
Neaiptera
Coleoptera
Lepidoptera
Diptera
PRED
CODA
SCAV
SNRD
DETR
GENR
=
=
=
=
=
=
Polycentropodidae
Sialidae
Corixidae
Gerridae
Notonectidae
Saldidae
Curculionidie
Dytiscidae
Gyrinidae
Nydrophilidae
Pyralidae
Ceratopogonidae
Chfronmaidae
Culicidae
Tipulidae
Predator
Collector-Gatherer
Scavenger
Shredder
Detritivore
Generalist
Psychoelypha
Polycentroous
Sialis
Gerris. Treaobates
Notonecta
Hydaticus
Nydroporus
Oreodytes
irxrs
Hydrophilus
Crambus
Aedes
MO;
22
Table 2. The number of taxa and the percent of the total
number of taxa collected in the nearshore
microhabitats, 1992 and 1993 (Robert Hoffman,
Department of Fisheries and Wildlife, Oregon
State University, unpublished data).
Microhabitat
Sand
Sand/Silt
Gravel/Cobble
Small Boulder
Large Boulder
Massive Rock/Bedrock
Aquatic Vegetation
Number of
Taxa
16
26
29
27
26
17
23
Percent
(n = 40)
40.0
65.0
72.5
67.5
65.0
42.5
57.5
23
Differences in macroinvertebrate distribution were
Some macroinvertebrate taxa
such as Gammarus, Ameletus larvae (order Ephemerpotera),
also related to time-of-year.
and Chloroperlidae larvae (Order Odonata) were found
consistently throughout the ice-free season (June-October)
(Table 3) (Robert Hoffman, Department of Fisheries and
Wildlife, Oregon State University, unpublished data).
Other taxa such as Callibaetis larvae (order
Epmemeroptera) and Corduliidae larvae(order Odonata) were
most abundant during the early season, whereas
Paraleptophlebia larvae (order Ephemeroptera) and several
trichoptera taxa were most prevalent during mid-season.
Taxa most abundant during the late season were
Hesperophylax and Psychoglypha larvae and pupae (order
Trichoptera).
All nearshore macroinvertebrate taxa collected in
1992 and 1993 were assigned to functional feeding groups
The majority of taxa in Waldo
Lake were classified as predators (50%) although
(Merritt and Cummins 1984).
scavengers, shredders, and collector-gatherers were also
In general, functional feeding group
present (Table 1).
organization tended not to vary much between microhabitats
(Robert Hoffman, Department of Fisheries and Wildlife,
Oregon State University, unpublished data).
Terrestrial Invertebrates
Terrestrial invertebrates may be an important
component of fish diet in some lakes (Reimers et al. 1955,
Wales 1946, Smith 1961, Reimers 1979). Terrestrial
invertebrates were collected from the lake surface and
from onshore substrates along the lake perimeter during
the 1992 and 1993 field seasons. Most terrestrial
invertebrate taxa were observed during the first month of
24
Table 3. The presence of nearshore macroinvertebrates
Placement
from late May through early October.
into categories was based on the mean number of
microhabitats in which each taxon was present
(Robert Hoffman, Department
during each month.
of Fisheries and Wildlife, Oregon State
University, unpublished data).
25
Table 3.
Taxa
Nematoda
Atari
Oligochaeta
Hirudinea
Hyallela azteca
Gammarus
Sphaeriidae
Ameletus
Callibaetis
Paraleptophlebia
Aeshnidae
Coenagrionidae
Corduliidae
Lestidae
libellulidae
Chloroperlidae
Pteronarcyidae
Hesperophvlax
Leoidostoma
limnephilus
MVstacides
Polyeentropus
Psychoglvpha
Sialis
Corixidae
Gerris
Notonecta
Saldidae
Trepobates
Curculionidae
Gyrinus
Hydaticus
Hydrophilidae
Hydroporus.
Category Associated With Portion of Season
When Macroinvertebrates are Present
6a
6b
5
6c
3
4
1
2
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
tfembus
Ceratopogonidae
Chironomidae
Culicidae
Totals
Percent
X
X
qa24YTS1
X
X
X
X
7
6
11
2
17
15
27
5
5
12
8
1
1
19
2
2
Key to Categories:
Fairly consistent presence the entire season
Highest presence early-season
Highest presence mid-season
4. Highest presence late-season
Highest presence during the first month of season
S.
6a. Present during first month only
6b. Present during second, third, or fourth month only
6c. Present fifth month only
1.
2.
3.
1992 Season = late-May to early-October
1993 Season = late-June to early-October
26
the field season, decreasing to only one family
(Formicidae) by August (Robert Hoffman, Department of
Fisheries and Wildlife, Oregon State University,
Terrestrial vertebrates observed in
the Waldo Lake Basin include spiders (Arachnida),
unpublished data).
grasshoppers (Orthoptera), Homoptera, ground beetles and
lady bird beetles (Coleoptera), moths (Lepidoptera), and
several families of Hymenoptera.
Amphibians
Salamanders were secretive and difficult to locate.
Two species were identified in Waldo Lake: Ambystoma
gracile and Taricha granulosa.
Adults and neotenes of
these species were found in Waldo Lake, but no egg masses
were found in Waldo Lake. Several small ponds in the area
could be used for egg laying and early larval development
(Robert Hoffman, Department of Fisheries and Wildlife,
Oregon State University, unpublished data).
Frogs and toads were abundant in the nearshore areas
of Waldo Lake.
Species identified include Rana cascadae,
Adult H. regilla were seen
primarily in June, while adult R. cascadae and B.boreas
Bufo boreas, and Hyla regilla.
were present from June through early October. R.cascadae
tadpoles and recently metamorphosed individuals were found
in meadow areas and grass bordered coves along the south
shore of the lake near the South Waldo Shelter.
Allochthonous Input
A lake can be influenced by its watershed through
inputs of allochthonous organic material (Richey and
Wissmar 1979, Wetzel 1979). These materials are important
sources of nutrients and vary according to timing,
27
quantity, quality, and resistance to decomposition (Richey
and Wissmar 1979, Wetzel 1979, Ward 1984).
Allochthonous
inputs can be an important source of carbon in lakes that
have limited autochthonous primary production (Ho 1980).
In oligotrophic Mirror Lake, New Hampshire, USA, Cole et
al. (1989) found that 70% of the lake's carbon input was
derived from terrestrial inputs, while in Findley Lake,
Washington, USA, Wissmar et al. (1977) found that
allochthonous inputs provided enough carbon to be a
sufficient forage base for aquatic insects.
Aquatic
insects have adapted in many ways to exploit this source
of energy (Wetzel 1979, Ward 1984). Allochthonous inputs
can also potentially enhance periphyton production in
lakes and greatly influence biological activity on benthic
substrates and in the water column (Richey and Wissmar
1979).
The deposition of allochthonous organic matter
occurred both onshore and within Waldo Lake, especially in
coves and other sheltered areas along the lake shoreline
(Robert Hoffman, Department of Fisheries and Wildlife,
Oregon State University, unpublished data).
The
deposition of allochthonous organic material at onshore
locations along the shoreline of Waldo Lake was extensive
and contained a large amount of organic material.
The allochthonous organic matter in Waldo Lake is
composed predominantly of conifer needles, pollen, coarse
and fine wood, conifer cones, and grass.
Combinations of
these materials are deposited in large masses along the
shoreline or blown onto the lake surface, usually in the
nearshore area, where they sink to the substrate surface.
Inputs on the nearshore substrate are often re-suspended
and washed ashore by the action of wind and waves, while
organic material in onshore deposits are sloughed back
into the water where they again sink to the substrate.
28
This cyclical movement of allochthonous materials
continued throughout the ice-free season (approximately
June to mid-October) until the lake water level decreased
to a point where onshore deposits were no longer impacted
by shoreline wave activity (Robert Hoffman, Department of
Fisheries and Wildlife, Oregon State University,
unpublished data).
Pollen is a form of allochthonous input into many
lakes, but may not significantly contribute to the
nutrient cycle within a lake. Pollens tend to be
differentially resistant to decay (Sangster and Dale 1961,
Wetzel 1983, Faegri and Iverson 1989), especially in the
non-oxidizing sediments of most standing waters (Wetzel
Sangster and Dale (1961) found Pinus pollen to be
extraordinarily resistant to disintegration and was
1983).
therefore well represented in the sediment deposits of
four habitats (pond, lake, swamp, bog) in Ontario, Canada.
Pollen was sampled at nearshore and offshore
locations in Waldo Lake (Robert Hoffman, Department of
Fisheries and Wildlife, Oregon State University,
unpublished data). Two genera, Pinus and Abies, were
identified and appeared to be most prevalent in June and
Pollen tended to accumulate in large masses along
July.
the shoreline either on the substrate or suspended in the
water column. Samples of pollen collected by hand from
large clouds of suspended pollen grains contained 13,250
grains/ml to 19,800 grains/ml. Pollen did not appear to
accumulate in large masses offshore, although occasional
"slicks" of pollen on the lake surface could be seen.
Pollen grains were collected in offshore tows during June
and July with the greatest number of grains per tow
Grains
occurring in late-July (126 grains per 10 m tow).
of pollen were not found in August or September tows. It
appears that pollen input into Waldo Lake occurs primarily
29
from late-Spring (i.e., approximately June) to early
summer (i.e., approximately late-June through July) and is
concentrated in the nearshore area, where much of the
pollen accumulates on the lake substratum.
Autochthonous Organic Material
According to Wetzel (1983) the organic matter of
aquatic systems is often synthesized predominantly through
primary phytoplanktonic production.
Yet, in
ultraoligotrophic lentic systems, a large proportion of a
lake's primary production can be derived from other
autochthonous sources such as benthic plant production
(Kalff and Welch 1974, Welch and Kalff 1974).
Autochthonous materials have been identified as the
primary sources of particulate matter in many lakes
(Merritt et al. 1984).
Typical materials include
phytoplankton, moss, emergent/ submergent vegetation (such
as grasses and vascular hydrophytes and periphyton),
bacteria, fungi, fine detritus, and microscopic
invertebrate species (Lamberti and Moore 1984).
Autochthonous materials collected from Waldo Lake
include epibenthic algae, moss, submerged grasses,
emergent/submergent vascular hydrophytes, and periphyton
associated with cobble and small boulders (Robert Hoffman,
Department of Fisheries and Wildlife, Oregon State
University, unpublished data).
30
HUMAN CULTURE
Human influences have increased since the 19th
century making the human component a very dynamic and
integral part of the present day Waldo Lake Natural-
Cultural System. Table 1 shows how the cultural
components might interact with the natural components.
To
understand the role of human culture in the Waldo lake
natural-cultural system it is helpful to look at the
history of human activities and management in the basin.
This information gives insight to the development of human
values currently associated with Waldo Lake.
History of Human Culture Component
Waldo Lake was a natural system long before it became
a natural-cultural system. This change occurred about
5,000 years ago when Native Americans are thought to have
Before the
first inhabited the Waldo Lake Basin.
addition of the cultural sub-system, the natural sub­
system likely developed along a course different from that
seen today. When humans interact with a natural system,
the development of that system may be changed through the
direct and indirect effects of the interactions. This is
part of the evolution from a natural to a natural-cultural
system.
Archeological sites indicate that Native American
tribes such as the Klamath, Calapooyan, and Molallas used
the area surrounding Waldo Lake approximately five
thousand years before white settlers arrived. Information
on the Native Americans is limited, but it is probable
that the Waldo Lake Basin was used primarily as a summer
31
camp area for hunting and huckleberry picking (Carol
Winkler, archeologist, US Forest Service, personal
communication).
White settlers first explored this area in the
1800's. Judge John Beckenridge Waldo, the lake's
namesake, visited the area in the late 1800's (Williams
The Waldo Lake Basin and the surrounding areas
were used for camping, hunting, and fishing. During this
time, the basin could only be accessed by horseback.
Access to Waldo Lake was limited to jeep roads and
hiking trails prior to 1969. Since this time, paved roads
1989).
to the lake and three campgrounds on the eastern shore,
containing a total of 226 units, have been added. Since
the addition of the campgrounds, visitor use has increased
dramatically. The Forest Service reports that in 1971
there were 18,700 recorded visitor use days and by 1992
this number had increased to 144,002 (Table 4). Visitor
use is highest during the snow-free season, which is from
late May to early October in most years. The largest
percentage of human use occurs in the form of overnight
camping, with fishing, hiking, boating, viewing,
picnicking, swimming, hunting, and winter use also
Since the road into
occurring in the basin (Table 5).
Waldo Lake is not plowed, winter use consists primarily of
snowmobiling, cross country skiing, and snowshoeing.
In 1984, Congress passed the "Oregon Wilderness
Bill", which designated the western and northern portions
of the Waldo Lake Basin as wilderness (Figure 2). The
southern and eastern portion of the basin, as well as the
lake and its shoreline are not included in the wilderness
designation. Motor boats are allowed on the lake,
although there is a state regulation limiting speed to 10
miles per hour.
32
Table 4. Visitor use days at Waldo Lake Campgrounds from
1969 to 1992 (Chris Jensen, USFS, Willamette
National Forest, Oakridge Ranger District,
unpublished data).
Year
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
Number of Visitors
18,700
16,400
27,900
25,300
29,300
19,600
23,200
25,000
24,500
33,300
49,700
44,900
55,100
58,200
53,700
61,952
91,780
97,754
83,241
96,397
121,801
144,002
33
Table 5. Waldo Lake recreation use data (modified from
the Oregon Department of Transportation, State
Parks Division, 1986).
Activity
Camping
Fishing
Hiking
Boating
Winter Sports
Viewing/Driving
Picnicking/Swimming
Hunting
Visitor Days
61,800
8,500
7,600
6,500
6,200
5,000
3,000
1,800
Percent
62
9
7
6
6
5
3
2
34
The Introduction of Fish to Waldo Lake
Waldo Lake is a naturally fishless lake. The first
known stocking of fish was done by Judge John Beckenridge
Waldo in the late 1800's (Williams 1989). Files obtained
from the Oregon Department of Fish and Wildlife (ODFW)
report anglers catching brook trout as early as 1930
although ODFW has no records of stocking the lake until
It is possible that other anglers followed the role
of Judge Waldo and transported fish from nearby lakes and
1938.
planted them in Waldo Lake.
1938 until 1990 (Table 6).
ODFW stocking occurred from
Species stocked by ODFW
include rainbow trout (Oncorhynchus mykiss), brook trout
(Salvelinus fontinalis), cutthroat trout (Oncorhynchus
clarki), and kokanee salmon (Oncorhynchus nerka). Of these
species, all but cutthroat trout exist in the lake today.
Brook trout have been stocked nearly every year from 1939
to 1990. Rainbow have not been stocked since 1979 and
kokanee salmon were last stocked in 1970. In 1991,
stocking of the lake was discontinued due to a threatened
lawsuit by the Waldo Wilderness Council for violation of
the Clean Water Act of 1972. The basis of the lawsuit was
that fish stocking in this naturally fishless lake could
potentially increase the nutrient concentrations in the
lake and increase primary productivity therefore altering
the ultraoligotrophic nature of Waldo Lake.
Fishing Pressure
A fishing questionnaire was handed out to campground
hosts at North Waldo, Islet, and Shadow Bay Campgrounds to
assess the fishing activity on Waldo Lake.
From the
information gathered in the survey conducted by the
campground hosts, it appears that fishing effort on the
lake was low throughout most of the summer in 1993.
Very
35
Table 6.
Year
Number of fish stocked by the Oregon Department
of Fish and Wildlife (ODFW) in Waldo Lake,
Oregon (from ODFW files, Springfield, Oregon).
Rainbow
Trout
Brook
Trout
Kokanee
Salmon
Cutthroat
Trout
72,000
1938
98,130
1939
1,234,560
1940
44,330
1941
87,500
1948
417,169
583,391
1950
1951
151,240
247,900
329,270
1952
82,512
570,265
1953
401,499
322,327
1954
84,744
218,975
1955
120,922
297,811
1956
440,738
137,569
1957
175,785
100,000
1958
1959
133,020
240,351
290,240
258,706
1961
100,016
668,860
1962
380,919
300,170
174,980
1963
25,125
1964
343,760
213,867
337,080
1965
414,235
284,723
235,815
384,815
196,550
1966
253,977
361,920
1967
179,760
797,112
1968
338,550
1,444,866
207,440
1969
194,650
300,572
200,284
1970
267,462
1971
299,500
478,400
1972
17,226
172,000
11,830
1973
1974
55,154
1975
199,840
49,997
1976
147,000
1977
291,768
200,430
1978
2,400
264,701
76,683
100,485
1979
1980
110,625
222,273
1981
200,200
1982
249,945
1983
1984
200,705
1985
199,976
74,880
1987
106,864
1988
8,195
1989
109,300
1990
1991 Stocking of Waldo Lake was discontinued.
36
few people reported catching fish in July and August.
Primary methods of fishing include trolling, spin casting
with lures and fly fishing. Anglers fished both from
motorboats and from shore. Fish ranged in size from 8 to
20 inches in length and all were kept. It is possible
that other individuals who caught fish were not sampled,
but this survey gives the general impression that the lake
(It should be noted that the
is not heavily fished.
people who often fish Waldo Lake do so in the early spring
and late fall and therefore would not have been included
The results obtained from this
in this survey).
questionnaire are similar to those reported in 1986 (Table
While fishing is one activity that occurs in the
5).
basin, it does not appear to be the primary reason that
most people visit the area.
Conflicting Values
As is common with any resource, there are conflicting
ideas about the types and amounts of use that should occur
Conflicts over the use of Waldo Lake and
in a given area.
its surrounding basin occurred as early as the 1800's
between recreational users and sheep herders. Controversy
over the management of Waldo Lake and its surrounding
Concern over the management of Waldo
basin continues.
Lake has been increasing over the last several years.
During the Willamette National Forest Planning process,
management of the Waldo Lake Basin received 1,921
comments, making it one of the most commented on areas on
In addition to
the forest (USDA Forest Service, 1991).
the Forest Plan, a number of letters are received each
year regarding the development and allowable activities
within the Waldo Lake Basin.
37
There are many groups of people who use the lake
resulting in differing and sometimes conflicting sets of
As is often the problem with a multiple-use
values.
resource, there are many users who would like to see the
lake managed for their own uses and values.
The Values
Human values associated with the Waldo Lake Basin
were compiled from letters written to the Forest Service,
comments to the Willamette National Forest Plan,
editorials, magazine and newspaper articles and personal
communication with individuals concerned with the
management of Waldo Lake. Values that people hold about
Waldo Lake can be categorized into two broad categories,
protectionists and naturalists and multiple-use advocates.
PROTECTIONISTS AND NATURALISTS
Protectionists and naturalists generally believe that
long term solutions are the most important aspect of
management decisions. Exclusion from human use is
considered to be the best management method if it is
thought that the natural system cannot withstand the
pressures of human activities.
In response to management of Waldo Lake, those
fitting into the Protectionist/ Naturalist category
believe that the biggest threat to Waldo Lake are humans
and would support management decisions that would revert
the lake back to its natural condition or at least seek to
Intrinsic in
keep further degradation from occurring.
this belief is the thought that motors, which may
potentially pollute the lake with oil, gas and noise,
should be banned and that campgrounds should be removed if
38
it becomes evident that the number of visitors is
negatively impacting the lake. There is also the belief
that the stocking of non-native fish species should not be
The belief is that these fish are contributing
to the pollution of the lake and there are many less
The
unique lakes nearby where anglers can catch fish.
allowed.
management views of both protectionists and naturalists is
that Waldo Lake should be preserved so that this uniquely
wild place will be available for future generations.
MULTIPLE-USE ADVOCATES
Multiple-use advocates generally believe that
resources should be managed for multiple use, while
maintaining the integrity of the natural ecosystem so that
future generations may also enjoy the resource. Often
underlying this is the idea of sustainable use management,
that is, through proper management, resource systems can
be utilized in such a way so as to maximize the range of
human uses without sacrificing the natural system.
In regard to the management of the Waldo Lake Basin,
multipe-use advocates believe that multiple use of this
resource is possible and that it is not necessary to
Motors are
preclude certain user groups from the lake.
thought to be acceptable because of concerns of safety and
lake access. The ten mile per hour speed limit and the
few numbers of boats on the lake even during the peak
summer season lead this group to the conclusion that motor
boats are not posing a threat to the water quality of the
lake although some do propose using electric motors to
decrease noise pollution. Fish stocking in the lake is a
generally accepted activity. Fish were first stocked by
Judge Waldo in the late 1800's and ODFW stocked fish from
1938 to 1991.
The question that multiple-use advocates
39
pose is, "If fish were polluting the lake why has there
not been a detectable change in water quality during this
time?" The management view of conservationists is to
maintain the beauty and integrity of the Waldo Lake
ecosystem, while continuing current activities such as
boating, fishing, and camping, especially if there is no
available scientific evidence to prove that these
activities are harmful to Waldo Lake.
Although none of the letters within the U.S. Forest
Service files express the value, some members of the
public believe that non-wilderness areas such as the
eastern portion of the Waldo Lake Basin have an economic
value that is not currently being utilized to its full
potential as a timber resource and therefore is not being
managed properly as a multiple-use resource. There is
also the general belief that tourism to places such as
Waldo Lake is an economic venue that is not being utilized
to its fullest extent.
40
AGE, GROWTH, AND DIET OF FISH IN WALDO LAKE
Methods
Fish Capture
Fish were collected one week per month from early
June through mid-October (the ice-free season) in 1992 and
Variable mesh experimental gillnets set in
1993.
nearshore areas were used to capture fish in 1992. During
the 1993 sampling period, experimental gillnets and trap
nets were set in the nearshore areas of the lake. The
length of time that nets were set was variable. The
experimental gillnet was checked every few hours and left
set overnight in cases where few fish were captured during
The trap net was set and then checked between 12
and 24 hours later. During occasions when few fish were
captured, the trap net was left for an additional 12 to 24
A backpack
hours before being re-checked and pulled.
the day.
electroshocker was used in 1993 to capture fry in the
inlets and the outlet of the lake, although some fry were
also captured in the trap net in 1993. Figure 5 shows the
sampling locations.
Field measurements included species determination,
Fork length
sex, total length, fork length, and weight.
and total length were measured to the nearest millimeter.
Weight was measured to the nearest gram using a hand-held
Due to concerns about depleting current stocks of
fish, otoliths and stomach contents were removed from a
scale.
sample of fish representative of size classes for the
determination of age, growth, and diet.
41
Age and Growth
Otoliths are useful in determining the age and growth
in fish because of the patterns of bands that occur as
fish grow. When otoliths are viewed under a microscope
with reflected light, translucent and opaque bands are
Opaque bands are associated with the rapid
visible.
growth of spring and summer, while translucent bands are
A
associated with slower growth of fall and winter.
translucent and opaque band together represent one year of
growth (Jerald 1983) Otoliths obtained by the Oregon
Department of Fish and Wildlife (ODFW) in 1991 as well as
those obtained in the 1992 and 1993 field seasons were
analyzed to determine age and growth.
Otoliths were immersed in 75% alcohol for 24 hours,
and in 95% alcohol for 24 hours to remove any residue.
For each fish both otoliths were cleaned and the otolith
in best condition was chosen for examination. Otoliths
were air dried and then immersed in one-two drops of
Canadian Balsam for 24 hours. Following this procedure,
otoliths were viewed under a stereomicroscope to determine
the number of annular rings and the distance between
Fish captured after the formation of the first
rings.
annular ring but before the formation of the second
annular ring were designated as age I fish. The same
procedure was used to place fish in other age groups.
Growth of fish captured in Waldo Lake was determined
from otoliths by backcalculating length-at-age, and by
recapture of fish that had been marked and released as age
I fry by ODFW in 1988. Backcalculated length-at-age
provides information about the length of the fish at the
time of annular ring formation. Backcalculated length-at­
age was determined by using the direct proportion method
Only the last year of growth was used to
backcalculate length-at-age. Gutreuter (1987) noted that
(Ricker 1975).
42
using only the most recent annuli decreased risks of
temporal contamination of data for comparisons over time
when inevitably, growth information from prior years is
incorporated into the estimates for latter years of
growth.
Also, using only the last year of growth reduced
the confusion of size selective mortality (Lee's
phenomenon) with annual growth (Gutreuter 1987).
Average relative growth rate (GR) was calculated
according to Warren (1971) as GR = L2-L1/0.5(L1 +L2)(t2-t1)
where L2 is the length at the last annular ring formation
and L1 is the length at the previous annular ring
formation; t2 is the time at the last annular ring
formation and tl is the time at the previous annular ring
formation. The average relative growth rate relates
growth over a time interval to average size over the same
interval, whereas absolute growth [G = L2 - Ll] does not
relate to average size. All sexes were combined to
increase sample size and all otoliths were assumed to be
normal.
Length obtained from recapture of fish marked in
1988 provided information on growth of fish of known age.
ANOVA was used to analyze differences in age-specific
growth rates between years.
Condition
The condition of the fish in Waldo Lake was assessed
by using a Fulton-type condition factor. Length and
weight data was available from 1951 through 1991 from ODFW
files.
Using these data, as well as the data collected
during the 1992 and 1993 field seasons, a mean condition
factor was calculated for each fish species captured per
For brook trout analysis, only those sampling dates
occurring between September 21st and October 2nd were used
year.
in an attempt to eliminate the effect of time of year as a
43
confounding variable. This was not possible for rainbow
trout and kokanee salmon due to low sample numbers,
therefore all samples for these species were combined.
All sexes were also combined due to a lack of available
ANOVA was used to analyze
information in some years.
differences in mean condition between years.
Diet
To determine the diet of fish in Waldo Lake, stomach
contents were removed in the field and stored in 70%
Stomach contents were analyzed at Oregon State
ethanol.
Stomach content
University using a stereomicroscope.
components were identified to the lowest taxonomic level
possible using whole specimens or identifiable body parts
such as the thorax or head capsule when whole organisms
were not available. Taxa were identified using the key
developed by Merritt and Cummins (1984). When large
numbers of organisms were present in the stomach contents,
Counts obtained in the subsample
subsamples were taken.
were multiplied by the corresponding dilution factor to
obtain the total number of individuals of each taxon in
the stomach.
Taxa that made up greater than one percent of the
total number of consumed taxa were analyzed to determine
if there was seasonal variation in diet within fish
species and to what extent diet overlap occurred between
The percentage of a given taxon consumed,
fish species.
which consists of the total number of individuals of that
taxon divided by the total number of individuals of all
taxa consumed, describes the relative importance of each
taxon in fish diet (Bowen 1983). This method of
quantifying food types does not, however, reflect the food
This would require knowing the
preference of the fish.
44
amount of food consumed of a given type relative to the
amount available in the lake (Ivlev 1961). This method
also does not take into account the nutritional value of a
particular food item. For example an individual salamander
is larger and probably has a higher nutritional value than
an idividual chironomidae larvae, but each still only
counts as one food item.
To determine if there were differences in the feeding
location of the three fish species in Waldo Lake, taxa
consumed by fish were categorized based on the location in
which they were found during macroinvertebrate surveys.
Some benthic macroinvertebrates were found only in the
nearshore samples while others were found in both
nearshore and offshore samples. Therefore if a fish had
eaten an organism that belonged to the nearshore category,
the fish must have been feeding in the nearshore area,
while if it consumed a taxon that belonged to the
nearshore/offshore category it is impossible to know at
Taxa that were
which location the prey item was taken.
located on the surface during benthic macroinvertebrate
sampling were presumably consumed by fish at the water
surface or within the water column as the prey item became
water-saturated and sunk below the water surface.
Reproduction
Reproduction of fish species in Waldo Lake is of
special concern due to the discontinuation of the stocking
To determine if reproduction is
program in 1991.
occurring in Waldo lake, major inlets along the southern
end and the outlet (the North Fork of the Middle Fork of
the Willamette River), from Waldo Lake to the falls, were
Species
electroshocked during the 1993 ice-free season.
of fry caught in these areas were determined.
45
Results
Fish Capture
Overnight trap nets and gill nets were the most
effective methods of fish capture.
In 1992, 42 fish were
captured, and in 1993, 187 fish were captured (Table 7).
Fish ranged in size from 75 mm (total length) to 480 mm.
Brook trout were the most commonly caught species followed
by kokanee and rainbow trout.
Due to concerns about
depleting current stocks, otoliths and stomach contents
were removed from 32 of these fish for the determination
of age, growth, and diet.
Age and Growth
To validate otolith aging techniques, back-calculated
length at age from otoliths were compared to the measured
lengths from fish belonging to the brook trout cohort
marked and stocked as age I fish in 1988 by ODFW.
Comparisons of the growth curves shows that backcalculated
length-at-age has a similar slope to the length-at-age
determined from the capture of marked fish (Figure 6).
The confidence intervals of these two curves do not
overlap, however, indicating that there is a significant
difference between the curves. This could be due to
errors in back-calculation techniques, differences in
growth rates between the 1988 cohort and the 1991-1993
fish due do differing environmental conditions, or
different initial sizes of the fish.
Table 8 shows that
the growth rates and relative growth rates for the 1988
cohort are similar to those of the 1991-1993 fish which
suggests that differences observed may be due, in part, to
differences in initial lengths.
46
Table 7.
Number of fish captured and the number of
otoliths examined by species and year (data and
otoliths for 1991 fish were provided by the
Oregon Department of Fish and Wildlife,
Springfield, OR).
Number of
Fish Captured
Number of
Otoliths Examined
Year
Species
1991
Brook Trout
Rainbow Trout
Kokanee Salmon
136
79
5
0
0
0
Brook Trout
Rainbow Trout
Kokanee Salmon
55
15
4
9
4
6
Brook Trout
Rainbow Trout
Kokanee Salmon
75
23
2
1
6
1992
1993
44
47
Table 8. Comparison of average growth rates and average
relative growth rates between the marked 1988
cohort and the back-caculated lengths of the
fish captured in 1991-1993.
(Data and otoliths
for 1991 fish were provided by the Oregon
Department of Fish and Wildlife, Springfield,
OR).
Average Growth Rate (mm fish length/year)
Age
I to II
II to III
III to IV
IV to V
1988 fish
89.7
82.3
33.8
24.8
1991-1993 fish
89.0
72.9
36.3
Average Relative Growth Rate (mm/mm fish length/year)
Age
I to II
II to III
III to IV
IV to V
1988 fish
1991-1993 fish
0.454
0.290
0.099
0.067
0.503
0.283
0.116
48
500
-E- Captured Fish
450
Back-calculated
Captured Fish 95% CI
+ Back-calculated 95% CI
400
350
E
E
-c 300
co
cm
-I 250
200
150
100
III
IV
V
Age (years)
L
Figure 6. Comparison of growth rates from captured
fish of known age and from back-calculated age
from otoliths of brook trout captured between
1991 and 1993.
49
Using only data from the last year of growth as
suggested by Gutreuter (1987),
the average relative
growth rates for each age class of brook trout were
compared between years (Figure 7).
rate generally decreased with age.
Brook trout growth
However, there were no
significant differences in the growth rate of each age
class between 1991-1993 (1991-1993, ANOVA p>0.1).
Relative age specific growth rates of brook trout in
Waldo Lake are comparable to brook trout growth rates in
Due to the small sample sizes of
rainbow trout (n=5) and kokanee salmon (n=14), age and
other Lakes (Figure 8).
growth analysis were not conducted.
Condition
The Fulton-type condition factor is an index of well­
being and is useful in comparing conditions of fish in the
same lake over time or in comparing the condition of fish
in a particular lake to fish in other lakes. For Waldo
lake brook trout there were statistically significant
differences between years for mean condition factors
(Table 9; F-Statistic = 17.3 with 6 and 1044 degrees of
freedom; p-value < 0.01). Brook trout in 1969 and 1992
have slightly higher condition factors than those in other
years.
The condition of Waldo Lake brook trout is
comparable to brook trout in other lakes. The same is true
for kokanee salmon and rainbow trout (Table 9).
50
222 1991
I to II
II toils
III to IV
IV 0 v
1,77]
1992 ;11.21; 1993
V to VI
VI to VII
Age Class
Figure 7. Average relative growth rate for Waldo Lake
brook trout.
51
Hon
H to III
Waldo Lake (OR)
Pyramid Lake (CAN)
Ill to IV
IV to V V to VI
Age (Years)
Red Rock Lake (CAN)
Matamek Lake (CAN)
fa
Castle
Lake (CA)
Bunny Lake (CA)
Figure 8. Mean relative growth rate as determined from
otolith analysis for Waldo Lake brook trout
(1991-1993) compared to relative growth rates of
brook trout from other lakes (determined from
Data for Matamek Lake
length-at-age data).
(Canada), Red Rock Lake (Canada), and Pyramid
Lake (Canada) reported in Scott and Crossman,
Data for Bunny Lake (California), and
1979.
Castle Lake (California) were reported in
Carlander, 1969.
52
Table 9. Mean Fulton-type condition factor of fish in
Waldo Lake compared to fish in other lakes (the
number of fish from which the condition factor
was calculated is shown in parenthesis).
Condition.
Factor
Species
Location
Brook trout
Waldo Lake (1969)
Waldo Lake (1978)
Waldo Lake (1985)
Waldo Lake (1990)
Waldo Lake (1991)
Waldo Lake (1992)
Waldo Lake (1993)
8 California Lakesa
Castle Lake (CA)a
Mono Lake (CA)a
1.36(115)
1.21(377)
1.27(186)
1.25(107)
1.24(136)
1.32(55)
1.25(75)
0.96(many)
1.05-1.98(512)
1.34(661)
Rainbow trout
Waldo Lake (1991)
Waldo Lake (1992)
Waldo Lake (1993)
Castle Lake (CA)a
Convict Lake (CA)a
Dorothy Lake (CA)6
Mildred Lake (CA)a
Crater Lake (OR)b
1.19(5)
1.20(4)
1.06(2)
1.05(673)
1.02
0.88
1.15
1.11(124)
Kokanee salmon Waldo Lake (1992)
Waldo Lake (1993)
Crater Lake (OR)b
aCarlander 1969
bBuktenica and Larson 1992
1.20(9)
1.07(44)
0.97(188)
53
Diet
Taxa found in stomach contents of fish captured in
Waldo Lake consisted primarily of aquatic benthic
macroinvertebrates, but terrestrial invertebrates and
vertebrates were also part of the total diet (Table 10).
Of the three fish species present in Waldo Lake, brook
trout were the most opportunistic, consuming chironomidae
larvae and pupae, trichoptera larvae and pupae,
ceratopogonidae adults, amphipods, Hymenoptera
(formicidae) adults, as well as the larvae of
ephemeroptera, odonata, and megaloptera (sialidae) (Figure
Rainbow trout in Waldo Lake consumed primarily
9).
chironomidae larvae and pupae although odonata larvae,
ephemeroptera larvae, and amphipods were also consumed.
Kokanee salmon displayed the most specialized feeding
behavior. Kokanee salmon fed almost exclusively on
chironomidae larvae and pupae although small numbers of
ephemeroptera larvae, odonata larvae, and coleoptera were
also consumed. Vertebrates are not included in Figure 9
because they were generally of less importance by number
than the other categories of food items and did not make
up greater than one percent of the total diet.
Chironomidae larvae were the most common component of
the diet of all three fish species in Waldo Lake (Figure
Other taxa consumed by all three species of fish
included ephemeroptera larvae, odonata larvae, amphipoda,
9).
coleoptera larvae and chironomidae larvae and pupae.
Ceratapogonidae adults were consumed by brook trout and
kokanee salmon. Brook trout was the only species that
consumed trichoptera larvae and pupae, megaloptera larvae,
and hymenoptera adults in amounts large enough to comprise
greater than one percent of the total diet.
54
Food Organism
Ephemeroptera
Odonala I.
Amphipoda
MI=
Trichnidera 1.+11'
Megaloplera
Coleoptera I.
I
Chironomidae I.+P
'
\\\
\ \
%.%
Ceratapogottidhe
hymen Formienle A
0
10
20
30
40
50
60
70
no
90
100
%. of Total Diet
NE
Brook Trout
(n=67)
ESE Rainbow Trout
(n=5)
Kokanee Salmon
(n=14)
Figure 9. The percent of taxa observed in the
stomach contents of fish captured in Waldo
Lake (1991-1993). Only taxa comprising >1% of
the total diet are included. L = larvae, P =
pupae, A = adult).
55
Table 10. Taxa found in stomach contents of fish
collected from Waldo Lake in 1992 and 1993.
Taxa are grouped according to the location in
which they were collected during benthic
macroinvertebrate surveys.
AQUATIC
Nearshore
Hirudenia
Ephemeroptera larvae
Odonata larvae
Nearshore and Offshore
Oligochaeta
Amphipoda
Pelycypoda (Sphaeriidae)
Trichoptera larvae and pupae
Megaloptera larvae
Coleoptera larvae and adults
Ceratopogonidae larvae and pupae
Chironomidae larvae and pupae
Lake Surface (Aquatic Adults)
Trichoptera
Ephemeroptera
Coleoptera
Ceratopogonidae
Chironomidae
TERRESTRIAL
Lake Surface (Terrestrial Adults)
Arachinidae
Hemiptera
Coleoptera
Diptera
Lepidoptera
Hymenoptera
VERTEBRATES
Hyla regilla (adult)
Unknown salamander species
Taricha aranulosa (adult)
Trout fry
56
All three species of trout in Waldo Lake fed heavily
on taxa that inhabited both the nearshore and offshore
areas (Figure 10). Rainbow trout and brook trout tended
to feed more on organisms found only in the nearshore
areas than did kokanee salmon. Brook trout fed on surface
organisms while these organisms did not comprise greater
than one percent of the total diet of rainbow trout and
kokanee salmon.
Brook trout diet in Waldo Lake varied throughout the
In June, brook trout fed nearly
exclusively on trichoptera larvae and pupae and
ice-free season.
ephemeroptera larvae (Figure 11).
In July, brook trout
diet was the most diverse of all months. Trichoptera
larvae and pupae were still important components of the
diet as were trichoptera adults but brook trout also
consumed larvae of odonata and megaloptera and terrestrial
coleoptera adults, ephemeroptera adults, oligochaetes, and
Brook trout diet shifted primarily to
chironomidae larvae in August. The larvae of odonata and
hirudinea.
coleoptera, as well as amphipoda, and hymenoptera
(formicidae) were also consumed in August. Chironomidae
larvae and amphipods dominated the diet in September.
Odonata larvae, terrestrial diptera adults and vertebrates
were also consumed in September.
In October, brook trout
diet shifted primarily to amphipods and ceratopogonidae
Trichoptera larvae and pupae and megaloptera
larvae were also consumed.
adults.
To determine if the feeding areas of brook trout
shifted throughout the ice-free season, taxa consumed by
brook trout were again grouped according to their location
during macroinvertebrate surveys (Figure 12).
Taxa
located only in the nearshore area were consumed less
often as the season progressed.
Taxa located in both
nearshore and offshore areaswere consumed consistently
57
100
80
0)
o
60
-a
20
0
Brook Trout (n=67)
Nearshore
Rainbow Trout (n=5)
Nearshore and Offshore
Kokanee Salmon (n=14)
Lake Surface
Figure 10.Location of prey items of Waldo Lake brook
trout, rainbow trout, and kokanee salmon.
Locations were determined from benthic
macroinvertebrate surveys conducted during 1992
and 1993 (Table 10; Robert Hoffman, Department
of Fisheries and Wildlife, Oregon State
University, unpublished data). Only taxa
comprising >1% of the total diet of each species
of fish are included.
58
June (n = 5)
July (n = 11)
Odonata (L)
Ephcmcroptcre (L)
(38.4%)
Oligochctae
Mcgaloptcra (L) (4.4%)
Colcoptcra (TA) (22 %)
Ephcmcroptcra (AA) (22%)
Ihrudenea (2.2%)
Trichoptera (AA)
(44.4%)
Trichoptera (L+P)
(61.0%)
August (n
= 14)
September (n = 12)
Chironomidac (L +P)
(62.1%)
Odonata (L) (23%)
Colcoptcra (L) (2.8%)
Amphipoda (4.6%)
Amphipoda
(273%)
Hymeneptera (Formicidac) (TA)
(6.5%)
Odonata (L) (6.1%)
Chironomidac (1.+P)
(82.0%)
Vertebrates (3.0%)
Di ptcra (TA) (13%)
October (n = 25)
Amphipoda
(38.2%)
Ceratapogonidac (AA)
(522 %)
LEGEND
Mcgaloptcra (L+P) (4.4%)
Trichoptera (L+P) (2.7%)
= aquatic insect larvae
P = aquatic insect pupae
AA = aquatic insect adult
TA = terrestrial insect adult
Figure 11.Percent of taxa observed in Waldo Lake brook
Only taxa
trout stomach contents (1991-1993).
comprising >1% of the total diet are included.
59
100
80
60
40
20
Nearshore and Offshore
Nearshore
Lake Surface
Location of Prey Item
June (n=5)
July (n=11)
September (n=12)
October (n=25)
August (n=14)
Figure 12.Location of prey items of Waldo Lake brook
trout. Only taxa comprising >1% of the total
diet are included.
60
throughout the ice-free season although the relative
importance of individual taxa in the diet varied by month.
Taxa located at the water surface were consumed
sporadically throughout the season, probably depending
upon the wind drift and hatches of aquatic adults.
Brook trout diet does not appear to be consistently
related to the relative abundance of benthic
macroinvertebratescollected in nearshore and offshore
areas. Months when the nearshore or offshore
macroinvertebrates were most abundant in nearshore and
offshore areas were not necessarily the same months when
those taxa were the most frequently consumed (Figure 13).
In June, chironomids were the most abundant taxon in the
benthic surveys, but constituted less than one percent of
brook trout diet. However, trichoptera larvae and pupae
were the second most abundant taxon in benthic surveys in
June and were a significant component of brook trout diet
Ephemeroptera, although not as abundant as
other taxa, were also an important component of brook
(Figure 11).
trout diet in June. In July, trichoptera larvae, pupae,
and adults, and odonata larvae were the most consumed taxa
in brook trout diets (Figure 11), yet chironomids were
much more abundant throughout the lake and amphipods were
In August, chironomids
more abundant in nearshore areas.
were the most common taxon consumed by brook trout (Figure
In
11) and were the most common taxon in benthic surveys.
September, trout continued to consume large quantities of
chironomids even though the abundance of this taxon in the
Finally, in
nearshore area had declined significantly.
October, amphipods were the most common taxon consumed by
brook trout. Amphipods were abundant only in the
nearshore area in October.
61
Figure 13.The relative abundance of aquatic
macroinvertebrate taxa collected from nearshore
and offshore areas (1992-1993) (Robert Hoffman,
Department of Fisheries and Wildlife, Oregon
State University, unpublished data) and the
percent occurrence of these taxa in brook trout
stomach contents.
Figure 13.
% of TnIni Wet
I Indy, m 2
100
Odonata Larvae
00
80
P
40
20
infivs./m
July
August
September
no
400
00
300
00
10
200
40
20
100
20
Trichoptera
Larvae and Pupae
7. of Total Wet
N Indvs./m 2
Amphipoda
300
August
July
June
October
350
100
500
0
June
7. of Tolul Diel
2
100
00
7. of Total Dlet
IncIrs./m 2
100
5.000
00
4.(WA)
\ `4,
October
September
Chironomidae
Larvae and Pupae
250
100
00
80
80
200
40
150
40
2.000
100
20
1.000
20
50
0
June
July
August
September
June
October
August
July
7. of Total Wet
N Intivs./m 2
50
Ephemeroptera
Larvae
40
September
100
DD
- 00
30
KM Offshore Abundance
-, 40
20
- 20
10
0
June
July
August
September
October
= Henoshore Abundance
I of Total Fish Diet
October
63
Small brook trout (101-250mm) tended to be more
opportunistic in both taxa consumed (Figure 14) and
location of feeding (Figure 15) than did large brook trout
(251-450mm).
Ceratopoginid adults and amphipods were the
major taxa composing the diet of the small brook trout,
while larger brook trout tended to consume primarily
chironomids larvae and pupae, trichoptera larvae and
pupae, ephemeroptera larvae, and amphipods (Figure 14).
Small brook trout fed on taxa located in a wider variety
of areas than did large brook trout, which tended to
concentrate feeding on taxa located in the nearshore and
offshore areas (Figure 15). Smaller brook trout also
consumed more surface organisms that did larger brook
trout.
Reproduction
Rainbow trout, brook trout, and kokanee salmon appear
to reproducing in the Waldo Lake Basin.
Fry of all three
species were captured in the bay near the outlet during
the 1993 ice-free season. Brook trout fry were also
located in the in several of the intermittent tributaries
along the southern end of the lake (Figure 5). In the
small tributary that flows past the South Waldo Shelter, 3
brook trout fry ranging in size from 75 to 125 mm were
Similar-sized brook trout were also found below
the first bridge crossing east of the South Waldo Shelter.
captured.
No fish were sighted upstream of this bridge. Kokanee
salmon and rainbow trout fry were captured in the North
Fork of the Middle Fork of the Willamette River between
Waldo Lake and the falls. Although other tributaries
along the southern shore were shocked, no fish were
observed.
64
Food Organism
Ephemeroptera °I.
Odonata °I.
Araphip oda
Trichoptera L+P
Mega. sialidae °I.
Coleoptera 'L
Chironomidae °I.+P
Trichoptera °A
Ceratapagonidae °A
Hyrnen.Forraicidac 'TA
0
10
20
40
30
50
70
60
80
BO
100
2; of Total Diet
IN 101-250 mm En 251-450 mm
(n
36)
(n - 30)
Figure 14.The percentage of taxa observed in the stomach
contents of two size classes of brook trout
(L = larvae, P = pupae, A =
(1991-1993).
adult).
65
100
80
60 t
40
20
0
Nearshore
Nearshore and Offshore
Lake Surface
Location of Prey Item
101-250mm (n=36)
251-450mm (n=30) I
Figure 15.Location of prey items of two size classes of
Waldo Lake brook trout. Only taxa comprising
>1% of the total diet are included.
66
Discussion
Waldo Lake: A Complex, Dynamic, Natural-Cultural System
The components of the Waldo Lake natural-cultural
system are complexly interrelated. A change in one
component has the potential to affect other components
(Figure 1 and Figure 3). This complexity is observed in
all natural-cultural systems, of which the Waldo Lake
natural-cultural system is but one example. Table 11 shows
how each component of the Waldo Lake natural-cultural
For
system is related to each of the other components.
example, climatic conditions are an important component of
the Waldo Lake natural-cultural system. Climate
determines the amount, timing, and form of precipitation
entering the basin as well as the solar radiation, air
Climatic
temperature, and wind speed and direction.
conditions determine the environment in which the Waldo
In addition, climate has had a
Lake Basin is situated.
role in basin formation through glacial activities.
Climate has the potential to affect the human culture
component as visitor use days tend to fluctuate depending
upon weather conditions and seasonal patterns. Air
temperatures and seasonal changes may also affect the
biotic component.
The substrate of the Waldo Lake natural-cultural
system depends upon the geologic history of the basin.
These substrate types are an important factor in
determining nutrient availability in the lake environment.
The water component of the Waldo Lake natural-
cultural system describes the chemical and physical
attributes of the environment in which aquatic organisms
67
Table 11. A matrix for the Waldo Lake Basin showing the
interrelationships between the components of the
The matrix
Waldo Lake natural-cultural system.
depicts how the components shown in rows along
the top of the matrix effect those components
listed along the left side.
Table 11.
Climate
Water
Substrate
Human Culture
Human Culture
Pollution and the addition
Due to a low lake to basin
and/or redistribution of
ratio and the volcanic
substrate of the basin, Waldo nutrients are possible
depending upon the
Lake has low nutrient
concentrations. There are no management of the basin.
Roads, trails, and
permanent inlets.
campgrounds may change
runoff patterns.
Biotic communities are
Nutrient
availability
determine
Precipitation timing, forM and Water quality In Waldo Lake See Figure 16 (Waldo Lake
affected
by the management
species
composition
and
Food
Web)
for
greater
detail
determines species
amount as well as air
of the basin. Fish were
abundance.
of
the
interrelationships
of
the
composition
and
abundance.
temperature may effect
introduced into the Waldo
Macroinvertebrate diversity
Low nutrient concentrations biota in the Waldo Lake
species composition and
Lake Basin. Fire
and
density
vary
depending
Basin.
result
in
low
primary
abundance. Wind and
suppression activities in the
on
the
substrate
of
different
productivity and sparse
wave action form
basin have the potential to
habitats.
zooplankton populations in
accumulations of
affect allochthonous input.
Waldo
Lake.
allochthonous and
autochthonous input
Sedimentation patterns may
Decomposition of biota and
The Waldo Lake basin was
be
affected by roads,
allochthonous and
formed, in part, by glacial
campground, and trails.
autochthonous
input
is
a
activity. Wind and wave
source of sedimentation.
action cause erosion and
effect sedimentation rates
Solar radiation and wind
effect water temperature, lake
mixing and evaporation rates.
Biota
Substrate
Air pollution may lead to acid
rain which could effect the
pH of Waldo Lake
Evaporation from the lake
surface results in future
sources of precipitation.
Climate
Water
Biota
Visitor use days and types of The water is used for
use fluctuate depending upon activities such as boating,
swimming, and fishing.
weather conditions and
seasonal changes.
Redistribution of available
nutrients through uptake and
excretion by the biota.
Nutrient addition through
allochthonous and
autochthonous input as well
as from decomposing biota.
Wildlife viewing, as well as
hunting and fishing are
common activities in the
basin
The basin defines the setting Human values determine the
management of the Waldo
of the lake.
Lake Basin. Values in the
Waldo Lake Basin have
changed over the last few
decades.
0
oo
69
live.
This component is extremely important as these
attributes influence the colonization of species and their
abundance.
In addition, evaporation from the lake surface
results in future sources of precipitation.
The biota in the Waldo Lake natural-cultural system
can be described as the living organisms found within the
system of interest. Figure 16 shows the
interrelationships between the biotic populations
inhabiting the lake environment and other components of
the Waldo Lake natural-cultural system that are closely
related to the biotic component. The biota may affect the
water component as activities such as feeding and
excretion redistribute available nutrients.
The
decomposition of biota is a source of sediment input.
the human component, the biota is often considered a
For
source of recreational activities such as hunting,
fishing, and wildlife viewing.
Waldo Lake was originally a natural system and did
not become a natural-cultural system until approximately
5,000 years ago when native Americans are thought to have
first used the Waldo Lake Basin. Human influences have
increased since the 19th century making the human
component a very dynamic and integral part of the present
day Waldo Lake natural-cultural system. To understand the
role of human culture in the Waldo Lake natural-cultural
system it is helpful to look at the history of human
activities and management in the basin. This information
gives insight to the development of human values currently
associated with Waldo Lake.
Changes in human values associated with the Waldo
Lake natural-cultural system have occurred over the last
Fish were originally stocked into Waldo Lake
during a period of time when human values focused on
few decades.
development, making Waldo Lake a better, more accessable
70
Terrestrial
tight
Energy
Energy
Autochthonous
Input
Alloch honous
Input
Nutrients
Terrestrial
Insects
Detritus
IDecomposition &
Sedimentation
Benthic
Mocrolnwrfebralss
Brook Trout
KoKanee
Rainbow Trout
Aquatic
e
Humans
Figure 16.A food web focusing on the biotic component of
the Waldo Lake natural-cultural system.
71
place for humans to recreate.
This is exemplified not
only by the stocking of fish, but also the addition roads,
campgrounds, and boat ramps into the Waldo Lake Basin. In
the last few decades a shift of values has occurred. Now
instead of requesting that more amenities be added to the
Waldo Lake Basin, many people are looking for more of a
It also remains to
pre-developmental type of experience.
be seen how this trend will change in the future.
Changes in the biotic component of the Waldo Lake
natural-cultural system have also occurred in the last few
decades.
Recent studies of Waldo Lake suggest that
primary production has increased by a factor of ten from
1989 to 1993 (Larson and Salinas 1995). The cause for
this change is unknown and it has yet to be seen if this
trend will continue into the future.
The components of the natural-cultural system are
constantly changing. Some components such as climate and
substrate, may change slowly, over thousands of years,
while other components such as biota and human culture may
change rapidly within a centuary, or even a decade.
This capacity of the natural-cultural system to
change makes it possible to understand the
interrelationships only as they exist at a given time, for
at some later time the interrelationships may have changed
Therefore, although it is possible to
significantly.
devise a view of the Waldo Lake natural-cultural system,
This
it is only a snapshot in time of a dynamic system.
capacity of the Waldo Lake natural-cultural system to be
dynamic is not unique to Waldo Lake, but is expressed in
all natural-cultural systems.
72
Age, Growth and Condition of Fish in Waldo Lake
Relative growth rates of Waldo Lake brook trout
suggest that they are growing well in this
ultraoligotrophic system when compared to other lakes in
which brook trout are present. The oldest brook trout
captured from Waldo Lake during the course of our research
(1991-1993) was eight years old and 470mm in length.
Fish
in Castle Lake, California reportedly lived as long as the
fish in Waldo Lake but were not as large (Wales 1946,
1947).
At eight years old, brook trout in Waldo Lake are
not the oldest brook trout recorded. A stunted population
of brook trout in Bunny Lake, California contained
individuals that lived to be 24 years old (Reimers 1979).
These fish only reached a length of 238 mm.
The dominant
factor influencing the length of life and the stunted
growth of the Bunny Lake brook trout was shortage of food
and low water temperatures that were more conducive to
torpor than to activity.
In contrast to Bunny Lake brook
trout, brook trout in Waldo Lake are large for their age,
although fish from Red Rock Lake and Pyramid Lake, both in
Canada, reached a larger size at an earlier age (Scott and
Crossman 1979) than did Waldo Lake brook trout.
Fish in Waldo Lake are in relatively good condition
when compared to fish in other lakes.
Table 9 shows that
Waldo Lake brook trout have relatively high condition
factors compared to brook trout in ten lakes in California
(Carlander 1969). Kokanee salmon in Waldo Lake are also
in good condition when compared to kokanee salmon in
Crater Lake (Buktenica and Larson 1992). Rainbow trout in
Waldo Lake appear to be in good condition, although the
sample sizes are too small to be conclusive.
73
Diet of Fish in Waldo Lake
Large fish exist in Waldo Lake, despite its
ultraoligotrophic nature, in part because the definition
of lake trophic status is based upon physical, chemical,
and biological characteristics within the pelagic zone of
Benthic productivity is not normally considered
when classifying the trophic status of lakes although
the lake.
benthic organisms have been shown to be important
components of fish diet in lakes (Larkin 1979, Healey
1984, Benke 1984, Buktenica 1989, Liss et al. 1995).
Benthic invertebrates are important in the diet of
The most important food items for
kokanee salmon, rainbow trout and brook trout were
fish in Waldo Lake.
chironomidae larvae and pupae although ephemeroptera
larvae, odonata larvae, amphipods, trichoptera larvae and
pupae, megaloptera larvae, coloeptera larvae and
ceratapogonid and hymenoptera (formicidae) adults also
constituted greater than one percent of the total diet.
The feeding behavior of salmonids is often
characterized as being opportunistic (Muttkowski 1925,
Prey items
Allen 1941, Elliot 1967, and Metz 1974).
include a wide diversity of life forms depending upon
available food sources.
Large-bodied prey items are
thought to be preferred with smaller food items becoming
important as they become available and as large prey
decline in abundance. Studies of salmonids in lake
environments have shown that prey size, visibility, and
relative abundance effect the types of prey that are
consumed (Bisson 1978, Zaret 1980, Allan 1981).
Waldo Lake brook trout diet does not appear to be
directly related to the relative abundance of nearshore or
Instead, a more
offshore benthic macroinvertebrate taxa.
complex relationship between the relative abundance of
macroinvertebrates, feeding location, and time of year
74
appear to determine which taxa are consumed by brook
Brook trout tended to feed on macroinvertebrate
taxa that were found only in the nearshore area early in
trout.
the ice-free season (Figure 12). In June brook trout fed
on ephemeroptera (which had a relatively low abundance but
were found only in the nearshore area) and trichoptera
larvae and pupae (abundant in the nearshore area, but
scarce in the offshore area). Chironomids were the most
abundant taxa in June, but were not consumed by brook
In July, brook trout diet shifted to odonata
larvae (located in the nearshore area) and trichoptera
trout.
larvae, pupae, and adults (not as abundant in the
nearshore area as in June, but more abundant in the
During August and September, chironomidae
larvae and pupae were an important component of brook
offshore area).
Chironomidae larvae and pupae were abundant
in the offshore area throughout the ice-free season, and
trout diet.
abundant in the nearshore area through August.
In
addition to chironomid larvae and pupae, amphipods
(abundant in both nearshore and offshore areas) and
odonata larvae (available only in the nearshore area) were
also consumed by brook trout in September.
In October,
when the brook trout were spawning, amphipods (abundant in
the nearshore areas) were consumed frequently.
Specialization by specific individuals within a
population also occurs, but it is not thought that the
degree of specialization has any affect on growth rates
Different types of specialists
tend to grow equally well. The degree of specialization
(Bryan and Larkin 1972).
varied both between and within fish species located in
Waldo Lake. Kokanee salmon displayed the most specialized
feeding behavior.
Brook trout consumed a wider variety of
75
taxa than did kokanee salmon.
Brook trout feeding
behavior also varied depending on fish size.
Small brook
trout (100-250mm) were more opportunistic than were large
brook trout (251-450mm).
These findings tend to be consistent with the feeding
behavior of brook trout in other lakes. Ricker (1932)
found brook trout to be opportunistic, feeding on
amphipods, ephemeroptera larvae, trichoptera larvae and
pupae, chironomidae larvae and pupae, as well as a variety
of aquatic and terrestrial adults.
In general the diet of
brook trout in lakes tends to be made up mostly of insects
and aquatic invertebrates (Reimers 1979, Smith 1961, Wales
1946, Reimers et al. 1955, Allen 1960, Royer 1960).
Like brook trout, aquatic and terrestrial insects are
the primary food for rainbow trout (Reimers et al. 1955,
Bisbee 1961, Wales 1946, Hasler and Farner 1942, Atkinson
1932).
Amphipods are also important in rainbow trout diet
(Reimers et al. 1955, Atkinson 1932, Hazzard 1932).
Efford and Tsumura (1973) found that in Marion Lake
Canada, rainbow trout fed specifically on trichoptera
larvae and pupae and odonata larvae. Wurtsbaugh and
Brocksen (1975) found that the rainbow trout in Castle
Lake, California were primarily consuming ephemeroptera
larvae and chironomidae larvae and pupae. Rainbow trout
in Waldo Lake displayed feeding behavior similar to that
found in other lakes. Taxa comprising greater than one
percent of rainbow trout total diet included chironomidae
larvae and pupae, odonata larvae and amphipods.
Kokanee salmon typically feed on zooplankton in lakes
where this food item is available, although they may also
feed to a lesser extent on aquatic insects (Beacham and
McDonald 1982, Graynoth et al. 1986, Platts 1958, Lewis
1970 and 1971). Chironomids are usually considered to be
a minor component of the diet of kokanee salmon (Clemmens
76
et al. 1939), but in Nicola Lake, Canada, chironomids
constituted a major portion of the overall summer diet
(Northcote and Lorz 1966).
This is also the case in
zooplankton-sparse Waldo Lake where chironomid larvae and
pupae are the most commonly consumed taxa.
Ephemeroptera
larvae, odonata larvae, and coleoptera larvae were
consumed to a lesser extent than chironomids.
In lakes
where zooplankton are not available it appears that
kokanee salmon are able to feed on chironomids and other
aquatic insects (Efford and Tsumura 1973, Graynoth et al.
1986).
Vertebrates such as frogs, salamanders, and other
fish were found infrequently in brook trout and rainbow
trout stomachs in Waldo Lake and made up less than one
percent of the total diet. This is probably due to the
low abundance of these vertebrate species currently in
Waldo Lake.
Reproduction of Fish in Waldo Lake
There is evidence that all three species of fish in
Waldo Lake are reproducing, but the extent of reproduction
is unknown. Fry of all three species of fish were
captured during the course of this study.
In addition
kokanee salmon and rainbow trout populations existing in
Waldo Lake during this study must be derived from natural
reproduction since, according to ODFW records, rainbow
trout have not been stocked since 1979 and kokanee salmon
were last stocked in 1970 (Table 7).
Kokanee salmon and
rainbow trout fry were captured in the bay near the
outlet, as well as in the outlet itself.
77
Several brook trout fry were collected in the lake as
well as some of the small ephemeral tributaries entering
Brook trout juveniles were found in the small
the lake.
tributary that flows past the South Waldo Shelter. This
tributary becomes intermittent during the summer making it
unlikely that the fall spawning brook trout spawn in this
stream during most years.
Spawning for all three species of fish is apparently
possible in Waldo Lake even though there are no permanent
inlets entering the lake. Ricker(1932) and Wurtsbaugh and
Brocksen (1975) found that brook trout were able to spawn
in the shallows of lakes if underwater springs are
available to oxygenate the eggs. Kokanee salmon are also
thought to be able to spawn near springs or on gravel
where there is significant wave action (Chapman and
Fortune 1963). There are thought to be underwater springs
located at the southern end of Waldo Lake where the
majority of spawning activity for brook trout and kokanee
salmon occurs in the late fall (ODFW, personal
Smith (1959) reported that in Lake
communication).
Rotokawan and Blue Lake, New Zealand, rainbow trout were
able to successfully spawn along sand and gravel areas
that were sufficiently oxygenated due to wave action.
Shoreline spawning may also be possible in Waldo Lake due
to the cool water temperatures and the often present wave
action along the eastern and western shorelines.
78
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