Numerical dominance and origin of. exotic fathead minnows
(Pimephales promelas) in Upper Klamath Lake, Qregon
Douglas F. Markle
and
David C. ·Simon
Department of Fisheries and Wildlife
104 Nash Hall
Oregon State University .
Corvallis, Oregon 97331-3803
Running head: Klamath fathead ·minnows
1 2
Abstract.-Since its introduction less than 20 years ago, the
fathead minnow (Pimephales promelas) has become the dominant
fish in Upper Klamath Lake, Oregon. In 143 beach seine
samples collected in 1991, fathead minnows greater than 20
mm made up 33-86% of the fish at a site, 69% of the fish
2 biomass, and had an average density of 7.4/m • The density
of native blue chubs (Gi.l.a. coerulea), the second most
abundant species, was 1.1/m2 • In 45 trap net samples
collected in 1992, fathead minnows greater than 40 mm made
up 59% of the fishes in the Agency Lake subbasin, 27% in
Upper Klamath Lake, and 17% in river mouths entering the
lake. Tui chubs, Gi.l.a. bicolor, appear to be the only native
species to have declined relative to other fishes of the
pre-fathead minnow fish fauna.
Probable sources of fathead minnows are bait bucket
introduction and laboratory release. Their introduction to the
Klamath Basin was coincident with the U. S. Environmental
Protection Agency Environmental Research Laboratory-Duluth (EPA
ERL-Duluth) promotion of fathead minnows as bioassay test subjects. Upper Klamath Lake fathead minnows shared diagnostic 3 morphological features with those from EPA ERL-Duluth, but more
closely resembled those from the southwestern U.S. in body shape. The possibility of. laboratory release suggests prudent modification of EPA bioassay protocols to include destruction of all test or excess subjects. 4 INTRODUCTION
Fathead minnows, Pimephales promelas, are broadly
distributed east of the Rocky Mountains with a native range from
Great Slave Lake, Canada to Chihuahua, Mexico and eastward to
the Appalachians (Vandermeer 1966; Lee and Shute 1980). Their morphology is variable and several characters show strong geographic trends such that as many as ·five subspecies might be recognized according to Vandermeer (1966). Typically, either no or two subspecies have· been recognized: E. p. promelas, a mid western to northeastern form with an incomplete lateral line and nuptial tubercles on the lower jaw; and E. p. confertus, the southwestern form with a complete lateral line and no nuptial tubercles on the lower jaw (Hubbs and Black 1947) .
Fathead minnows were first collected in Oregon in the
Klamath River on May 13, 1974 (Andreasen 1975). Further upstream expansion into the Klamath Basin was documented in Lake Ewauna below Klamath Falls by 1979 and in Upper Klamath Lake above
Klamath Falls by 1.982, where fathead minnows constituted more than 18% of the catch in an October 1983 trap net (Ziller 1991;
J. Ziller, fisheries biologist, Oregon Department of Fish and 5 Wildlife, personal communication) . By 1993 we captured them in
the Klamath Marsh National Wildlife Refuge (50 km northeast of
Upper Klamath Lake) and Gerber Reservoir (50 km southeast of
Upper Klamath Lake) (unpublished data) .
Fathead minnows are a popular bait fish and have been intentionally or accidentally introduced for that purpose in many western states. For example, state-sanctioned propagation and distribution began in Idaho about 1945 (Simpson and Wallace
1978) and in California in 1953 (Shapovalov .e.t. .al. 1959) . Many early introductions to western states were of western or southwestern forms of fathead minnows. Earliest introductions to the lower Colorado River were of southwestern fathead minnows,
{£. ~· confertus), imported from Truth or Consequences, New
Mexico (Miller 1952), and Minckley (1973) reported that most
Arizona fathead minnows are referable to the southwestern form.
However, in addition to its value as a baitfish, the fathead minnow has also been promoted as a bioassay .test subject by the U. S. Environmental Protection Agency (EPA) beginning in the late 1960's and early 1970's (EPA 1972; Brauhn and
Schoettger 1975) . Stocks of fathead minnows have been maintained 6
by the EPA Environmental Research Laboratory-Duluth (EPA ERL
Duluth) and widely distributed for bioassay work by EPA as well
as private companies. The EPA promotion was coincident with
their first occurrence in Oregon and a comparison of original
Klamath fathead minnow data reported by Andreasen (1975) with
the trends reported by Vandermeer (1966) shows that the Klamath
fish are more similar to fathead minnows from the Great Lakes
region in their incomplete lateral lines than to southwestern
populations.
Our efforts to identify possible sources for fathead
minnows in the Klamath drainage did not add clarity to the
picture. State stocking records are reliable but there are no
records tracking use of bioassay test subjects. For example,
California Department of Fish and Game stocked fathead minnows
in a downstream reservoir (Copco Reservoir) in 1975 after noting
that a 1974 survey of J. C. Boyle Reservoir in Oregon showed large baitfish (fathead minnows) and gamefish populations
{Dennis Maria, fishery biologist, California Department of Fish and Game, personal cormnunication) . California and Oregon fishery biologists active at the time knew of bioassay work at 7 regional universities and agencies but no documentation could be
found.
The source of exotic fathead minnows might be of minor
concern except that their impact on native faunas and ecosystems
could differ depending on origin. Strong morphological
differences as documented by Vandermeer (1966) suggest the
possibility of ecological differences as well. For example, in
• ) '.'"' - . • .. . ,.. ~ l'f - ._. •.,,\.· ; ·: ~:...... :.. .- ,~ l..t_1y.-: ...... ,_,. , c ..-.- ,.:1 •· ...... "small ~ ': 'muddy 'sf reams . and ponds" I . ·an:a. -'Eliey /· have··-n:of' s\icceeded 'in
reservoirs where fluctuating ' waEer ~ · Tev.el.s - ·presuinab1y· interfere
·with thefr-·reproduclfve "·association ·· with 'aquatic· ve~J°etation
(Moyle 1976) . Pflieger (1971) pointed out that fathead minnows are relatively tolerant of conditions found in stagnant pools
(high temperatures, low dissolved oxygen, high turbidity), but apparently intolerant of competitors. Upper Klamath Lake is a natural lake regulated as a reservoir to control the timing of water release. It is hypereutrophic (Miller and Tash .1967) with an annual fluctuation of about 1 m and summer conditions of high temperature, widely fluctuating dissolved oxygen levels, and high pH (Castleberry and Cech 1993). 8
In this paper we document the relative abundance of exotic
fathead minnows in Upper Klamath Lake, make a first-order
comparison with the fish fauna before their introduction, and
discuss the impact on the fish fauna. We also compare diagnostic
morphological characters of Upper Klamath Lake fathead minnows
with Great Lakes and southwestern forms, as well as with the
geographic trends reported by Vandermeer (1966) .
MATERIALS AND METHODS
Description of Area
Upper Klamath Lake is located in Klamath County in southern
Oregon and is the largest lake in Oregon. The northern subbasin
2 is Agency Lake. The total drainage basin is 9415 km , of which
603 km2 drain into Agency Lake (Johnson .et. .a.l. 1985) . The
Williamson River and its tributary the Sprague River account for
46% of the inflow to Upper Klamath Lake and the Wood River accounts for most of the inflow to Agency Lake (Fig. 1).
Agency Lake has about 41 km of shoreline, a mean summer surface area of 3,554 ha (8,781 acres), an average depth of 0.9 m and a maximum depth of 2.1 m (Johnson .et. al. 1985; U. S. Army
Corps of Engineers 1978) . Upper Klamath Lake has 141 km of . 9
shoreline, a mean summer surface area of 27,811 ha (68,719
acres), an average depth of 2.4 m and a maximum depth of 15.2 m.
(Johnson et. .al. 1985; U. S. Army Corps of Engineers 1978).
Johnson et. .al. (1985) erroneously reported greater average depths (4.2 m) and a total shoal area (< 3.3 m) of only 14% of the lake's surface area. From a digitized map, we estimated 73% of the summer surf ace area of Upper Klamath Lake is less than 2 m deep.
Water quality in Upper Klamath Lake is heavily influenced by its eutrophic state and summertime blooms of the blue-green algae Aphanizomenon flos-a
(Scoppettone and Vinyard 1991) .
Distribution and Relative Abundance
Sampling was conducted in 1991 and 1992 to determine the accessibility of juvenile endangered suckers to different 10 sampling gears. Data on fathead minnows and other fishes were
collected incidental to this work. In 1991, ten sites in Upper
Klamath Lake and four sites in Agency Lake were seined from 18
July to 26 September (Fig. 1). The seine was 6.1 m long with 4.8 mm bar mesh and a 2 X 2 X 2 m bag. A sampling unit was a single
2 1/4 circle arc that sampled approximately 30 m • Sites were sampled approximately weekly but some sites became inaccessible as lake levels dropped during summer. Four sites (Al, A3, A4 and
UlO) were sampled 3-7 times whereas the remainder were sampled
9-15 times.
In 1992, trap net sites were located in Agency Lake, the northern half of Upper Klamath Lake, and lacustrine river mouth habitats (lower Williamson River, Thomason Creek, Crystal Creek, and Recreation Creek) (Fig. 1). Sampling was conducted from
April 21 to October 22. The trap nets had a single 2.4 x 23 m lead, two 2.4 x 10.7 m wings, a 1.2- by 1.2-m square frame with two 10-cm throats and were constructed with 6.5-mm-bar mesh.
Trap nets in lake habitats were set in offshore open water areas. Trap nets in lacustrine river mouth habitats were set in mid-channel. All sites were fished approximately 24 h per set. 11
Lengths of all fish, except suckers, were measured to the
nearest millimeter in the field. Fork length was measured for
all species except for sculpins and lampreys, for which total
lengths were measured, and suckers, for which standard lengths
were measured from preserved specimens in the laboratory.
Weights of all species except suckers were measured in the field
to the nearest 0.1 g with an Ohaus model CT1200 electronic
scale. Weights of suckers were measured from preserved specimens
in the laboratory . Weight-length regressions were calculated
using Statgraphics version 5 (Manguistics 1993) and fitted to
the model W=aLh, where W= weight in grams, L= length in millimeters, and a and b are calculated coefficients
Morphology
Using characters identified by Vandermeer (1966) as indicative of regional origin, we measured predorsal length, eye diameter, caudal peduncle length, and caudal peduncle depth, and counted numbers of pored and total lateral line scales. We also recorded standard length, head length, and nuptial tubercle patterns on ripe males. The four nominally diagnostic measurements were analyzed using Vandermeer's (1966) adjusted 12
mean calculations. A simple view of overall shape was created
using principal components of the normalized value of each
variable (Marcus 1990) . All six morphometric variables were
normalized using z-scores, the transformation the variable would have in a standard normal distribution with mean of o and variance of 1.
Specimens examined for morphology are deposited in collections at Oregon State University (OS) and the Museum of
Southwestern Biology, University of New Mexico (MSB) and include representatives of Great Lakes EPA populations and southwestern source populations originally introduced into California.
Collection locality and related information, museum catalog numbers, and size and numbers of specimens are as follows:
Oregon - Klamath Drainage: OS 4944, 11 of 19 spec., 45.5-51.2 mm
SL, Spencer Cr., Klamath River, 13 May 1974; OS 7955, 6 of
35 spec., 41.5-49.9 mm SL, Spencer Cr., Klamath River, 25
August 1979; OS 7953, 2 spec., 41.4-60.8 mm SL, .Jenny Cr.
above Iron Gate Reservoir, Klamath River, 20 August 1979;
OS 12506, 2 of 3 spec., 40.4-45.6 mm SL, Upper Klamath
Lake, 24 October ·1988; OS 14116, 6 spec., 42.0-52.3 mm SL, 13
Klamath Marsh, Upper Klamath Lake, 9 June 1993; OS 14326, 1
spec., 45.4 mm SL, Upper Klamath Lake, 5 June 1989; OS
14327, 10 spec., 46.3-53.5 mm SL, Upper Klamath Lake, 25
July 1989.
Oregon - Willamette Drainage: OS 5408, 3 spec. 52.0-61.3 mm SL,
St. Louis Ponds introduced with largemouth bass, 12 June
1976.
Minnesota - Great Lakes Drainage: OS 14274, 13 of 19 spec.,
41.9-56.3 mm SL, from stocks maintained by EPA ERL-Duluth,
13 January 1994.
New Mexico - Rio Grande Drainage: MSB 735, 12 of 69 spec., 56.3-
62.9 mm SL, Truth or Consequences 12 January 1958.
RESULTS
Beach Seine
One hundred and forty three beach seine samples were
collected: 118 from Upper Klamath Lake and 25 from Agency Lake.
Mean fathead minnow percentages per site ranged from 33 to 86%
of the fishes collected (Table 1) . Those sites east of a
longitudinal line through site US (Ul, U2, U3, U4 and UlO) had 14
mean fathead compositions less than 60% whereas those sites to
the west (including site US) had more than 60%, except Al (Table
1). Further, mean fathead minnow densities were 4.S/m2 east of
the line through site US and 9.S/m2 west of the line through
(and including) site US. Representative length frequency
distributions for fathead minnows indicate that this gear was
ineffective on fish smaller than about 20-2S mm (Fig. 3).
Beach seine samples contained ten species of fish. Mean
densities of the five most common species were as follows:
2 fathead minnows (7.373/m ); blue chubs, Gil.a coerulea,
2 2 (l.066/m ); tui chubs, Gil.a bjcolor, (0.3S6/m ); shortnose
2 suckers, Chasmistes breyjrostris, (0.088/m ); and marbled
2 sculpins, Cottus klamathensjs, (0.07S/m ). Five less common
species present at densit~es one to three orders of magnitude
less were slender sculpins, Cottus tenuis, Lost River suckers,
Deltistes luxatus, Klamath Lake sculpins, Cottus princeps, bluegills, Lepomjs macrochirus, and yellow perch, Perea
flayescens. Catch per unit effort (number per seine haul)
(Table 2) and species composition (Table 3) was highest for
fathead minnows in both Upper Klamath and Agency lakes. Beach 15
seine samples in Agency Lake captured fewer species (5 verses
10) and had higher catch rates of all fish than Upper Klamath
Lake.
There was a highly significant (P<0.001), but noisy
(R2 =.20), positive relationship between the abundance of fathead
minnows and the abundance of native fishes: ln(FHM+l)=l.96
+0.62(ln NF+l), where FHM is the abundance of fathead minnows
and NF is the abundance of all native fishes. Thtfff,"'"'-' :faE:head
minnows seem t6"' readily ·as.sociate 'with common native . fishes~ -:" •
Weight-length regressions were calculated for 12 species,
using the model, W=aLb (Table 4). Dispersion was low (R2 values
greater than 0.90), but fathead minnows showed the greatest
variation. The sources of fathead minnow variation were not
examined, but male-female dimorphism, possible multiple origins,
different reproductive states, and greater relative measurement
error associated with field measurements of small fish are all I 1 • factors that contribute to greater variation in the weight-
length regression of fathead minnows.
we ·estimated that f~thead minnows represented 69% (14,665
g) of the total fish biomass : (21,260 g) in 1991 beach seine 16
samples when all samples were colnbiried. Other important species
were blue chubs 17% (3,550 g), tui chubs 9% (1,932 g), and
shortnose suckers 2% (345 g) . All other species combined
represented less than 3% of the total beach seine biomass.
Thus, fa the ad minnows dominate
·Upper Klamath · ·an·d - Agency · '- lakes;:tp.··-~aen-s' it~-y~ ;::~relative .abundance,
·species composit~on, ·- <:u~q_ . :tJiomass ~~:-
Trap Net
Forty five trap · net samples were collected: 11 from Upper
Klamath Lake, 13 from Agency Lake, and 21 from lacustrine river mouth habitats. There was no significant (AOV, F=0.059,
P=0.809, R2 =0.14) relationship between number of hours fished and In-transformed number of fish caught. However, we have chosen to standardize all catch rate data as fish/hour.
Fathead minnows were the most abundant species in trap net samples in Agency Lake; however, blue chubs were most abundant in Upper Klamath Lake and lacustrine river mouth habitats (Table
5). With comparable effort, Agency Lake trap nets caught fewer species (10) than in Upper Klamath Lake (13) or lacustrine river mouth habitats (14), but had higher total catch rates (Table 6). 17
Although total catch rates were lowest in lacustrine river mouth habitats, species diversity was greatest. Trap nets appeared ineffective on fathead minnows less than 40-45 mm (Fig. 2).
Depth appeared to be a primary environmental factor contributing to the f aunal differences between trap net samples from Agency Lake and those from Upper Klamath Lake and lacustrine river mouth habitats. Most Agency Lake trap net samples came from depths less than 2 m whereas most Upper
Klamath Lake and lacustrine river mouth samples came from depths greater than 2 m. Fathead minnows were -strongly -oriented to · -· shallow water; very few were caught in depths greater than 2 m
(Fig. 3). In contrast, blue chubs were dominant in the 3 to 4 m depths of Upper Klamath Lake and lacustrine river mouth habitats. Agency Lake has little total surface area that is deeper than 2 m.
Morphology
Hubbs and Black (1947) considered a complete la~eral line as a diagnostic feature of £. ~- confertus and Vandermeer (1966) considered that it showed a strong regional trend being lowest in the northeast and highest in the southwest. Average 18
completeness of lateral lines in specimens we examined was 45%
(6-90%) in Klamath, 44% (12-98%) in Great Lakes and 95% (81-
100%) in western fathead minnows and reflects the number of
pored lateral line scales (Fig. 4). Hubbs and Black (1947) also
considered absence of nuptial tubercles on the mandible as a
diagnostic feature of the subspecies£. ~- confertus. Breeding males from uppe:f".ifiamatil"-·Eake ·· had an average .of ~ 4 ~3 tubercles on
the ··chin, "'·in close .agreement with,- an -_ ~ye~.~g~~.of~ _3_,.,.3 ~~ - , tubercles ; found on -the Great Lakes specimenf.3_ -: ·wef ~examIIiecL ~-~~ .. ·• ·. . . . ------. - -·.
Three characters that Vandermeer (1966) considered as showing moderate regional trends were total lateral line scales, predorsal length and eye diameter. In Klamath fathead minnows total lateral line scales were high as in western fish (Fig. 4).
Adjusted mean values for predorsal length were intermediate in
Klamath fathead minnows (25.4 in Klamath, 27.1 in Great Lakes and 24.8 in western fathead minnows examined), whereas, adjusted mean values for eye diameter were similar in Klamath .and western fathead minnows (2.84 in Klamath, 3.33 in Great Lakes and 2.80 in western fathead minnows examined) . The overall morphological similarity of Klamath and western fathead minnows and their 19 variability is shown in the second and third principal
components of the Z scores of the six morphological measurements
(Fig. 5) .
DISCUSSION
Fathead minnows were the most abundant species in beach
seine samples from Upper Klamath and Agency lakes in 1991. They
were 8.6 times more abundant than the next most abundant
species, blue chubs, in Upper Klamath Lake and 3.6 times more
abundant than blue chubs in Agency Lake (Table 2). Fathead
minnow biomass was 69% of the total beach seine fish biomass in
Upper Klamath and Agency lakes--more than four times the biomass
represented by the next most abundant species, blue chubs. On a
spatial scale, fathead minnow densities were slightly higher in
2 2 Agency Lake than Upper Klamath Lake (7.5/m versus 7.3/m ), and appeared more abundant along the western shorelines of Upper
Klamath Lake (Fig. 1 and Table 1) . ~~~ - ~2 - uap- net-samples; filtheaa · nuru16ws " 'were~·sg% ' ·of ··"Ehe .. ~fish ·"'in ·Agency·-Lake', _ :t7%'"cff ···the... fish c-in ··Upper ·Klamath '"Lake, arid "l?t·····of the fish in lacustrine river mouths (Table 5) . The highest catch rates of fathead minnows were in Agency Lake (Table 6) . 20
Assuming an average fathead minnow density of 7.5/m2 in
Agency Lake and 7.3/m2 in Upper Klamath Lake, the area within
lOm of shore contained 3.1 million and 10.3 million fathead
minnows greater than 20 mm, respectively. If these densities
were constant out to 2 m depth, a first order estimate of the population of 20mm+ fathead minnows is 2.6 billion in Agency
Lake and 15 billion in Upper Klamath Lake.
The only available data for evaluating the impact of fathead minnows are 1964 and 1965 surveys in Upper Klamath Lake by Vincent (1968). Vincent's data and analyses are difficult to interpret and compare. His standard unit of effort was a gang of three gill nets and a single hoop net, and his data were reported as pooled results from all four nets. His gill nets had stretched mesh sizes 32, 45, 57, and 152 mm and he gave no mesh size for the hoop nets. With one exception, he reported results as various percentages rather than in terms of effort.
Thus, we can only make crude comparisons of changes in species composition and not relative abundance. In Table 7, we compare our trap net results with Vincent's data to provide a first order glimpse of the qualitative changes that have taken place. 21 Noteworthy is that fathead minnows were not present in 1964· and
1965. We found fathead minnows made up 17% of the trap net fish
fauna in river mouths, 27% in Upper Klamath Lake and 59% in
Agency Lake. In our Upper Klamath Lake samples, blue chubs more
closely resemble the f aunal proportions that Vincent found
{Table 7) I whereas ~:µ1 ·~_-_chubs ., appe·a.:r· .to have declined by ' a factor
·o·f .. '.three -to five;·. Agency Lake has presumably changed greatly ·
from the-pre_;fathead minnow .. fatina.'
Have fathead minnows displaced other fishes, such as tui chubs? Castleberry and Cech {1993) stated that workers in the
Upper Klamath basin have speculated that blue chubs have declined coincident with the increase in fathead minnows. They claimed that increased temperatures and decreased dissolved oxygen levels in the basin have favored fathead minnows and tui chubs over blue chubs. Vincent {1968) mentioned that tui chubs were caught at a maximum rate of about five per hour in July and
December at Shoalwater Marsh. Based on Vincent's rel~tive species composition {Table 7), his maximum rate for blue chubs must have been about 8.3/h. Our lake trap net catch rates were
1.1-2.5 tui chubs/hand 5.6-18.9 blue chubs/h (Table 6), and 22
suggest that tui chubs, not blue chubs, have declined.
The apparent decline in tui chubs suggests that they might
experience greater interannual variation in abundance than other
species or that there might be a direct or indirect interaction
between fathead minnows and tui chubs. Dunsmoor (1993) has
experimental evidence that laboratory fathead minnows are
predators on sucker larvae. Gil.a spp. larvae are available in
the same near-shore habitats as fathead minnows and are smaller
than sucker larvae (unpublished data), thus potentially more
vulnerable. At present we know of no early life history
characteristics that might make larvae of blue chubs (Gil.a
coerulea) more resistant than tui chubs (Gil.a bicolor) to the
presence of fathead minnows. A substantial area of Agency Lake
and Upper Klamath Lake has been usurped by fathead minnows,
which now make up at least 69% of the biomass in the nearshore
area. The impacts of this change in biomass are unknown, but may include decline of tui chubs, as well as an impediment to
recovery of endangered suckers.
Our preliminary analysis of the origin of Klamath fathead minnows suggests that most are the broadly distributed 23
eastern/mid-western form, £. p. promelas, and not the
southwestern subspecies, £. p. confertus. Only in body shape
characters that Vandermeer (1966) considered locally variable,
are Klamath fathead minnows more like £. p. confertus (Fig. 5).
Unfortunately, there is no active work on fathead minnow
systematics and the number of species or subspecies has not been
critically examined since Vandermeer's work. This taxonomic
ignorance is relevant to the current debate on aquatic nuisance
species. Moyle and Li {1994) have suggested that fathead minnows be exempt from their proposed prohibition on interstate
transport of baitfish because they are already widely distributed. If this recommendation was enacted, we would need a clear understanding of the taxon's constituents, which of the many fathead minnow constituents had been widely introduced, and which have the potential to dominate particular habitats.
The variability in Klamath fathead minnows suggests the possibility of multiple origins, possibly including the Great
Lakes region where EPA began the promotion of fathead minnows as a standard bioassay subject. Governmental and other labs using fathead minnows in bioassay work, as well as baitshops, obtain 24
supplies from multiple sources, often the lowest bidder. Thus,
it is not known whether laboratory releases of fathead minnows
have occurred and, if so, whether these could be distinguished
from baitfish release. However, their detection in Oregon was
coincident with the promotion of fathead minnows by EPA and 21 to 29 years after their introduction as baitfish in neighboring
Idaho and California (Simpson and Wallace 1978; Shapovalov
1959) .
The potential for· exotic bioassay subjects to be released and the irony that it might happen in the furtherance of environmental protection, suggest a prudent countermeasure.
EPA's published protocols specify initial quarantine of incoming fish, but do not specify disposition of excess or test fathead minnows except in some larval assays where specimen fixation in formalin is part of the assay (Brauhn and Schoettger 19.75;
Norberg and Mount 1985; DeGraeve ~.al. 1991). It can be argued that the states govern access, distribution and handling of fishes within their borders and that the evidence presented here is equivocal. However, a laboratory's record for following EPA protocols may be a greater incentive than poorly enforced state 25
regulations and the costs of disastrous introductions far
outweighs the minimal costs associated with destruction of test
organisms. All protocols for bioassay of exotic organisms should
specify destruction of all test and all excess individuals at
the end of the bioassay.
Acknowledgments
This work was supported, in part, by contracts from the
Klamath Falls Office of U.S. Bureau of Reclamation (USER), the
Denver Office of USER, the Portland Office of U. S. Fish and
Wildlife Service, and the Oregon State University Agriculture
Experiment Station. We are grateful to Mark Beuttner and Sharon
Campbell (USER) for logistics support and information, and Larry
Dunsmoor, Klamath Tribe, for discussions of Klamath fathead minnows. We thank D. Logan, E. Lesko, and M. Beck for field assistance. Fathead minnows from EPA ERL-Duluth were provided by Vince Matson. This is Oregon State University Agriculture
Experiment Station Contribution No. 0000. 26
Literature Cited
Andreason, J.K. 1975. Occurrence of the fathead minnow,
Pimephales promelas, in Oregon. California Fish and Game
61 ( 3) : 15 5 -15 6.
Bartleson, G.C. and M.O. Fretwell. 1993. A review of possible
causes of nutrient enrichment and decline of endangered
sucker populations in Upper Klamath Lake, Oregon. U.S.
Geological Survey, Water-Resources Investigations Report
93-4087, Portland~ Oregon.
Brauhn, J. L. and R. A. Schoettger. 1975. Acquisition and
culture of research fish: rainbow trout, fathead minnows,
channel catfish, and bluegills. Ecological Research
Reports, EPA-660/3-75-011.
Castleberry, D. T. and J. J. Cech Jr. 1993. Critical thermal
maxima and oxygen minima of five fishes from the Upper
Klamath Basin. California Fish and Game 78:145-152. 27
DeGraeve, G. M., and six coauthors. 1991. Variability in the
performance of the seven-day fathead minnow (Pimephales
pramelas) larval survival and growth test: an intra- and
interlaboratory study. Environmental Toxicology and
Chemistry 10:1189-1203.
Dunsmoor, L. 1993. Laboratory studies of fathead minnow
predation on catostomid larvae. Klamath Tribes Research
Report: KT-93-01. Chiloquin, Oregon.
EPA (U. S. Environmental Protection Agency). 1972. Recommended
bioassay procedure for fathead minnows, Pimephales promelas
Rafinesque -- chronic tests. National Water Quality
Laboratory, Duluth, Minnesota.
Hubbs, C. L. and J. D. Black. 1947. Revision of Ceratichthys, a
genus of American cyprinid fishes. Miscellaneous
Publications of the Museum of Zoololgy, University of
Michigan No. 66.
Johnson, D . M. , R . R . Petersen, D. R. Lycan, J. W. S~eet, M. E.
Neuhaus and A. L. Schaedel. 1985. Atlas of Oregon Lakes.
Oregon State University Press, Corvallis. 28
Lee, D. S. and J. R. Shute. 1980. Pimephales promelas
Rafinesque, fathead minnow. Page 341 in D. S. Lee, C. R.
Gilbert, C. H. Hocutt, R. E. Jenkins, D. E. McAllister and
J. R. Stauffer, Jr., editors. Atlas of North American
freshwater fishes. North Carolina Biological Survey
Publication No. 1980-12, North Carolina State Museum of
Natural History.
Manugistics, Inc. 1993-. Statgraphics, version 7. Rockville, Md.
Marcus, L. F. 1990. Traditional morphometrics. Pages 77-122 in
F. J. Rohlf and F. L. Bookstein, editors. Proceedings of
the Michigan Morphometrics Workshop, Special Publication
No. 2, University of Michigan Museum of Zoology, Ann Arbor.
Miller, R. R. 1952. Bait fishes of the lower Colorado River from
Lake Mead, Nevada, to Yuma Arizona, with a key for their
identification. California Fish Game 38:7-42.
Miller, W. E. and J. C. Tash. 1967. Interim report, Upper
Klamath Lake studies, Oregon. Pacific Northwest Water
Laboratory, Federal Water Pollution Control Administration.
Water Pollution Control Research Series No. WP-20-8. 29
Minckley, W. L. 1973. Fishes of Arizona. Sims Printing Co.,
Inc., Phoenix, Arizona.
Moyle, P. B. 1976. Inland fishes of California. University of
California Press, Berkeley.
Moyle, P. B. and H. W. Li 1994. Good report but should go much
further. Fisheries 19:22-23.
Norberg, T. J. and D. I. Mount. 1985. A new fathead minnow
(Pimephales promelas) subchronic toxicity test.
Environmental Toxicology and Chemistry 4:711-718.
Pflieger, W. L. 1971. A distributional study of Missouri fishes.
University of Kansas Publication of the Museum of Natural
History 20:225-570.
Scoppettone, G.G. and G. Vinyard. 1991. Life history and
management of four endangered lacustrine suckers. Pages
359-377 in W.L. Minckley and J.E. Deacon, editors. Battle
Against Extinction: Native Fish Management in the American
West. University of Arizona Press, Tuscon and London. 30
Shapovalov, L., W. A. Dill and A. J. Cordone 1959. A revised
check li$t of the freshwater and anadromous fishes of
California. California Fish and Game 45:159-180.
Simpson, J. C. and R. L. Wallace 1978. Fishes of Idaho.
University Press of Idaho, Moscow.
U. S. Army Corps of Engineers. 1978. Klamath River Basin,
Oregon, Reconnaissance Report. San Francisco District.
Vandermeer, J. H. 1966. Statistical analysis of geographic
variation of the fathead minnow, Pimephales promelas.
Copeia 1966, 457-466.
Vincent, D.T. 1968. The influence of some environmental
factors on the distribution of fishes in Upper Klamath
Lake. Masters thesis, Department of Fisheries and
Wildlife, Oregon State University, Corvallis.
Ziller, J. S. 1991. Factors that limit survival and production
of largemouth bass in Upper Klamath and Agency lakes,
Oregon. Information report No. 91-6, Fish Division, Oregon
Department of Fish and Wildlife, Portland.
------31 Table 1. Percent of fauna and mean density (number per square
meter) of fathead minnows in 1991 beach seine samples from Upper
Klamath Lake and Agency Lake. Sites are shown in Fig. 1. N is number of samples taken at a site, percent is the mean fathead composition expressed as a percentage of all fish at a site, mean is mean density per m2 of fathead minnows at that site, CV is the coefficient of variation of densities, and range is the range of densities.
Upper Klamath Lake
Per Density
Site N Cent Mean CV Range Ul 15 43 0.9 135.4 0 - 4.6 U2 13 56 8.8 131.6 0 - 37.0 U3 12 33 1.5 254.4 0.0+ - 13.4 U4 15 54 8.4 208.2 0.0+ - 63.7 us 9 77 16.4 116.6 0.3 - 57.5 U6 10 62 3.6 136.7 0 - 13.8 U7 12 76 3.8 121.3 0.2 - 13.1
UB 14 62 5.2 162.4 0 - 27.1 U9 12 86 24.0 216.7 0.1 - 166.8 UlO 6 51 0.7 134.8 0 - 2.0 32
Table 1. Continued.
Agency Lake
Al 6 54 1.8 87.7 0.5 - 4.9 A2 9 83 9.2 133.8 0.4 - 39.4 A3 3 85 21.6 147.2 0.3 - 58.0 A4 7 82 4.3 153.9 0.1 - 19.0 33
Table · 2. Mean catch per unit effort (CPUE) (number/seine haul) values of fishes from beach seine samples collected from Upper Klamath and Agency lakes in 1991. N is the total number of that species caught, CV is the coefficient of variation, and range is the minimum and maximum CPUE for that species.
Species N CPUE CV Range
Upper Klamath Lake
Fathead minnow 25294 214.36 270 0 - 4872
Blue chub 2935 24.87 190 0 - 282
Tui chub 1132 9.59 266 0 - 229
Shortnose sucker 388 3.29 520 0 - 175
Marbled sculpin 312 2.64 240 0 - 46
Klamath Lake sculpin 39 0.33 356 0 - 8 34
Table 2. Continued
Cottus spp. 28 0.24 580 0 - 13
Slender sculpin 14 0.12 429 0 - 4
Lost River sucker 12 0.10 452 0 - 3
Bluegill 3 0. 03. 807 0 - 2
Yellow perch 2 0.02 765 0 - 1
All species 30159 255.58 233 0 - 4896
Agency Lake
Fathead minnow 5491 219.64 179 3 - 1695
Blue chub 1518 60.72 359 0 - 1104
Tui chub 355 14.20 361 0 - 256 35 Table 2. Continued.
Marbled sculpin 2 0.08 346 0 - 1
Shortnose sucker 1 0.04 500 0 - 1
All species 7367 294.68 197 9 2512 36
Table 3. Mean percent composition of fishes from beach seine
samples in Upper Klamath and Agency lakes in 1991. CV is the
coefficient of variation and range is the minimum and maximum percent of that species in a sample
Species Percent CV Range
Upper Klamath Lake
Fathead minnow . 59. 2 50.5 0 - 100.0
Blue chub 20.4 103.2 0 - 78.5
Tui chub 8.3 123.3 0 - 40.2
Marbled Sculpin 6.4 189.7 0 - 55.6
Shortnose sucker 2.7 396.4 0 - 100.0
Slender sculpin 1.5 658.6 0 - 100.0
Klamath Lake sculpin 0.9 447.9 0 - 33.3
Cottus spp. 0.5 556.2 0 - 21.4
Lost River sucker 0.1 561.9 0 - 4.9
Yellow perch <0.1 1039.6 0 - 1.8
Bluegill <0.1 818.8 0 - 1.1
Agenc~ Lake 37
Table 3 . Continued
Fathead minnow 76.4 30.7 15.8 - 100.0
Blue chub 20.1 105.6 0 - 84.2
Tui chub 3.2 184.1 0 - 21.7
Marbled sculpin 0.3 346.8 0 - 3.3
Shortnose sucker 0.1 500.0 0 - 1.4 38
Table 4. Statistics for weight-length relationships (W=aLb) in
Upper Klamath Lake fishes, where W is weight in g, L is length
in mm (total for lamprey, standard for suckers and fork for
others), a and bare calculated coefficients, N is sample size,
and lOO.xR2 is the coefficient of determination. The coefficient
a is expressed as a natural logarithm to facilitate calculation
of weights.
Species ln a b N 100.xR2
Pacific lamprey -15.61 3.41 27 98.2 fathead -12.04 3.19 243 88.7 tui chub -11. 95 3.18 88 99.2 blue chub -12.35 3.23 680 99.4 yellow perch -11.92 3.12 211 99.1 pumpkinseed -10.78 3.01 15 89.2 brown bullhead -11.54 3.05 152 99.? marbled sculpin -11. 97 3.17 33 96.3 slender sculpin -11.86 3.12 68 92.9
Klamath Lake sculpin -10.32 2.71 11 97.6 39
Table 4. Continued shortnose sucker -11.17 3.06 245 99.9
Lost River sucker -11.70 3 . 14 226 100.0 40
Table 5. Mean percent composition of fishes from trap net
samples in Upper Klamath Lake, Agency Lake, and lacustrine river
mouth habitats (Williamson River, Thomason Creek, Crystal Creek,
and Recreation Creek) in 1992. CV is the coefficient of variation and range is the minimum and maximum percent in a sample.
Species Percent CV Range
Upper Klamath Lake
Blue chub 62.1 38.2 22.9 - 93.0
Fathead minnow 26.8 67.8 1.4 - 65.1
Tui chub 6.9 116.4 0 - 28.8
Marbled sculpin 2.1 163.0 0 - 10.2
Klamath Lake sculpin 1. 7 134.3 0 - 6.3
Slender sculpin 0.2 272.5 0 - 2.1
Bluegill 0.1 331. 7 0 - 0.6
Brown bullhead <0.1 331. 7 0 - 0.2
Pacific lamprey <0.1 239.7 0 - 0.2
Pumpkinseed <0.1 331. 7 0 - 0.2 41
Table 5. Continued
Shortnose sucker <0.1 331. 7 0 - 0.2
Lost River sucker <0.1 222.5 0 - 0.1
Yellow perch <0.1 331. 7 0 - 0.1
Agency Lake
Fathead minnow 59.2 38.7 26.4 - 97.0
Blue chub 20.0 82.5 1.3 - 47.8
Tui chub 9.4 92.0 0 - 32.6
Yellow perch 9.0 237.6 0 66.6
Marbled sculpin 1.2 227.4 0 - 9.5
Pacific lamprey 0.5 217.1 0 - 3.9
Klamath Lake sculpin 0.3 190.8 0 - 2.0
Brown bullhead 0.2 301.5 0 - 2.0
Lost River sucker <0.1 360.6 0 - 0.3
Slender sculpin <0.1 360.6 0 - 0.1
Lacustrine river mouths
Blue chub 35.9 91. 9 0 - 87.7
Fathead minnow 16.8 153.4 0 -100.0
Brown bullhead 12.6 232.7 0 - 94.6
Tui chub 9.5 110.8 0 - 33.9 42
Table 5. Continued
Yellow perch 7.6 175.5 0 - 40.0
Klamath Lake sculpin 7.3 253.1 0 - 75.0
Marbled sculpin 5.4 169.6 0 - 40.0
Pumpkin seed 2.0 362.2 0 - 33.3
Pacific lamprey 1.7 359.1 0 - 27.3
Shortnose sucker 0.7 145.9 0 - 2.8
Lost River sucker 0.6 198.4 0 - 4.5
Slender sculpin "<0.1 458.3 0 - 0.9
Klamath largescale
sucker <0.1 458.3 0 - 0.8
Bluegill <0.1 458.3 0 - 0.3 ~ J
43
Table 6. Catch per unit effort (CPUE) (number/hour) values of fishes from trap net
samples collected from Upper Klamath Lake, Agency Lake, and lacustrine river mouth
habitats (lower Williamson River, Thomason Creek, Crystal Creek, and Recreation Creek) in
1992. N is the total number of that species caught·, CV is the coefficient of variation,
and range is the minimum and maximum CPUE for that. species.
Species N CPUE CV Range
Upper Klamath Lake
Blue chub 5325 18.86 113 0.21 - 74.40
Fathead minnow 1927 4.89 92 0.16 - 13.89
Tui chub 451 1. 06 88 0 - 2.94
Klamath Lake sculpin 71 0.33 195 0 - 2.17
Marbled sculpin 63 0.19 170 0 - 1. 09 44
Table 6. Continued
Slender sculpin 15 0.05 258 0 - 0.44
Pacific lamprey 5 0.02 293 0 - 0.17
Lost River sucker 3 <0.01 232 0 - 0.04
Shortnose sucker 1 <0.01. 332 0 - 0.05
Brown bullhead 1 <0.01 332 0 - 0.04
Pumpkinseed 1 <0.01 332 0 - 0.04
Bluegill 1 <0.01 332 0 - 0.04
Yellow perch . 1 <0.01 332 0 - 0.04
All species 7865 25.42 86 0.62 - 80.00
Agency Lake
Fathead minnow 7277 23.86 109 1.17 - 76.00
Blue chub 1760 5.64 100 0.07 - 16.04
Tui chub 770 2.52 78 0 - 5.71 45 Table 6. Continued.
Yellow perch 284 1. 05 277 0 - 10.65
Marbled sculpin 31 0.10 149 0 - 0.44
Klamath Lake sculpin 17 0.05 196 0 - 0.34
Pacific lamprey 14 0.04 . 165 0 - 0.25
Brown bullhead 4 0.01 208 0 - 0.09
Lost River sucker 1 <0.01 361 0 - 0.05
Slender sculpin 1 <0.01 361 0 - 0.04
All species 10160 33.29 80 2.13 - 78.38
Lacustrine river mouths
Blue chub · 2221 4.31 243 0 - 46.08
Brown bullhead 819 1. 60 309 0 - 16.90
Tui chub 366 0.72 207 0 - 6.71
Fathead minnow 201 0.36 158 0 - 2.33 46
Table 6. Continued.
Yellow perch 97 0.17 136 0 - 0.78
Marbled sculpin 80 0.14 165 0 0.87
Klamath Lake sculpin 53 0.09 183 0 - 0.52
Shortnose sucker 33 0. 06. 210 0 - 0.58
Lost River sucker 24 0.05 244 0 - 0.50
Pumpkin seed 22 0.04 219 0 - 0.30
Pacific lamprey 15 0.02 173 0 - 0.14
Klamath largescale sucker 1 <0.01 458 0 - 0.05
Bluegill 1 <0.01 458 0 - 0.04
Slender sculpin 1 <0.01 458 0 - 0.01
All species 3934 7.57 174 0.05 - 57.42 47
Table 7. Comparison of relative species composition for 1992
trap net samples from this study with data reported from Upper
Klamath Lake by Vincent (1968). UKL is Upper Klamath Lake, AL
is Agency Lake, and LRM is lacustrine river mouth habitats.
Species
or species group LRM AL UKL Vincent (1968)
lampreys 2 <1 <1 <1 trouts <1 brown bullhead 13 <1 <1 5 tui chub 10 9 7 35 blue chub 36 20 62 58 fathead minnow 17 59 27 suckers 1 <1 <1 <1 sculpins 13 2 4 <1 yellow perch 8 9 <1 2 sunfish <1 <1 <1 48
List of Figures
Figure 1. Map showing Upper Klamath Lake and Agency Lake,
Oregon. Shoreline beach seine sites are indicated by an "A" or
"U" and trap net sites are indicated by a "T".
Figure 2. Relationship between number of fathead minnows caught
per hour in trap nets and depth of trap net: l=Upper Klamath
Lake, 2=Agency Lake, and 3=lacustrine river mouths.
Figure 3. Length frequency distribution of fathead minnows in
Upper Klamath Lake and Agency Lake showing 31 trap net samples from summer 1992 (upper} and 21 beach seine samples from 8-14
September 1991 (lower} .
Figure 4. Means and confidence intervals (95%} for scale counts of Klamath Basin (K}, Great Lakes (G}, and western (W} fathead minnows: pored lateral line scales (upper) and total lateral line scales (lower) . 49
Figure 5. Overall shape of Klamath Basin (K), Great Lakes (G),
and western (W) fathead minnows as expressed by second and third principal components of Z scores of six morphological measurements. WA
Crystal Creek
Upper Klamath Lake
Figure 1. Markle and Simon Number per hour ...,.~ I\) ~ ~ m Q) '°11 0 0 ([) 0 0 0 I\) 0
3: Pl 11 ~ 1--' ([) Pl ::s 0.
CJ) __, ...,. NSO a 0 ::s I\) ~ I\) I\) I\) ~ 0 CD ~ "C ::r..+ ~ ~ (,.) ...._...3 c. !! I
.'6J
('.@ ~ U> __,
CJ1 800 Summer 1992 31 trapnet samples
600
400
L- ~ 200 E ::s z 0 0 20 40 60 80
240 September 1991 21 beach seine samples 160 80 0 0 20 40 60 Fork length (mm)
Figure 3. Markle and Simon N=13 N=38 N=14 50 t m 40 m0 UJ ·-~ 30 ~ jg 20 ~ t "'C ~ 0 10 a.. 0
51.
UJ CD 49 ~ UJ CD .E- 47 ~ t jg 45 I ~ 1U j2 43 ·41 t 39 G K w Locality
Figure 4. Markle and Simon 1.1
+""c 0.6 Klamath Cl) c a.0 E w 0 0.1 K W 0 m K a. ·c:; c -0.4 ·c: a. Q 9E ·-..r::. • I- -0.9 Great Lakes -1.4
-1.9 -2.1 -1.1 -0.1 0.9 1.9 2.0 Second principal component
Figure 5. Markle and Simon