Swiinming performances of four California stream fishes: temperature effects
Christopher A. Myrick"
Joscph J. Cech, Jr.
Lklx-rrniretlt of Wilcilifr, Fish, arm' Cor~senntionBiology Utliversit? of Cdiforttio, l h i s . CA 95616, U.S.A.
(e-mail:J J ~ ~ c ~ I @ L I C ~ ~ ~ L ' .'~C11r1.e11t
S . P ~ ~ LdLd )r :e s s : D~-pt~rtlirt'nt
of FixI~et-ym d bVildljfe l?inloLyy Colorado Store
Univcrsi@, Fort Collins. CO 80523-1474, U.S.A.
K l ~ ywet-ds: Cyprinidae, Cntostomidae. hardhead. h/\ lophat-odon cotlocephallis. hitch, Laviniil e,~ilic.auda,
Sacrarnento pikeminnow, P1~chocheil1rs
glartdis, Sacramento suckcr, Cclto.rtorrw occidenttrlis,
critical swimming velocity, water diversion
Synopsis
'The critical swimming velocity (U,,,) of four California stream fishes, hardhead, Mylopharodon cor~ocephnlus.
hitch, Luvinitr crilicrr~rrlu,Sacramento pikeminnmv, Ptychodleil~rsgrandis, and Sacramento sucker, Catostontr~s
uccirlt.rrtulis was measured at 10, 15, and 20'C. Hardliead, Sacramento sucker, and Sacramento pikeminnow swim~ n i n gperformances tended to be lowest at 10'C, higher at 15'C, and then decreased or remained constant at 20'C.
Hitch swimming perfonnance was lower at 1C)"Cthan at 20"C, There were no significant differences among species
nt 10 or 15'C, although pikerninnow and hitch \vere ca. 20% slower than hardhead or sucker. At 20°C hardhead,
Sacrarnento sucker, and Sacramento pikerninnon had remarkably similar U,,,, but hitch were significantly (by 1 I '%)
Faster. Wc I-ecommendthat water diversion approach velacities should not exceed 0.3 ms-I for hitch (20-30 cm total
length) and 0.4 ms ' for liardhzad, Sacra~i-lcntopibzminnow, and Sacramento sucker (2G30 cm TL).
Introduction
The endemic fish fauna of the SacramenteSan Joaquin
river systcm (California) includcs a number of uniquz
cyprinids and catostomids (Brown & Moyle 1993.
Moyle 1976), many of which have uxpcricnced declines
in abundance and distribution. Sornr: spccies, such
as the thicktail chub, Gila crassica~rdcr,Sacramento
perch, ,4rthplites inlet-I-riptu,r,
and Clcnr Lake splittnil,
Po'o~otlichthysciscoides, are either extinct or extreme1y
rare throughout their historical ranges. Na~ivc fish
population declines are the result of the combined
e f f m s of exotic species introductions (Brown Rr
Muylc 1993), impoundment construction (Moylc et
A , ' ) , large scale water diversion (McEwan & Jackson
1996), and historical fisheries management practices
'Moyle, P. B., R. M. Yushiyimi~,J. E. Williarns R: E.D.
Wikrarnnnayake. 1995. Fish species of special concern in
California. Final Report, 212XIR Dcpnrtmcnt of Wildlifc Rr
Fishcries Biology, University of California, Davis. 272 pp.
(Moyle et al. 1983). Fortunately, habitat alterations due
to d a y construction, intentional species introduction,
and dcstructivc management practices have largely
ceased. Perhaps the gravest threat still facing native
fishes are the r 1000 scr~cnedand unscreened water
diversion intakes along the remaining free-flowing sections of the Sacramento and San Joaquin river systems
(McEwan & Jackson 1996). Unlike velocity barriers,
which fish like the Sacramento sucker, Cntosrotn~fs
ouciderttalis, attempt to negotiate with high-velocity,
short duration bursts of anaerobic swimming (Wales
1950), fish may try to negotiate approach velocities of
water diversion intakes at aerobic speeds. Indeed, the
largest diversions are powerful enough LO reverse flows
in s i ~ a b l po~tions
c
of the Sacramentc-San Joaquin system, making it vcry hard for fish to avoid displacement
andlor entrainnicnt (Millcr".
' Millcr, P.E. 1993. The delta: overview of the Sacnmcnto-Sun
Jonquin Dclta. Report tu the California Urban Wntcr Agencies.
49 PP.
The risk of entrainment and severe injury or death
at an intake may be exacerbated by the drastic alteration of the natural flow and thermal cycles in the
Sxr3mcnto-San Joaquin system's impounded streams
(McEwnn 9r Jackson 1996, Pvlillcr'). Central Vdlcy
rivers historically carried large volumes of cold water in
winter and carly spring and smaller volumes of warmer
water at other rirncs. Howcvcr. flow patterns arc now
dctermincd by thc ;~gizultural.UI-han.and industrial
dcniands. Curruntly, flows are grncrnlly ~reduceriduring the winter monrhs, inurzascd flows of cold water
are provided in late spring and surnrncr, and reduced
Rows of war111water are provided in fall and early winter. Because fishes' aerobic swimming perfomanucs
can be affected by water temperature (Johnston & Ball
1997) and scnson (Kolok 1991), it is possible that the
risk of eritrainmclnl is incrcascd by thcse unnatural flow
regimes.
LJntil recently, most rescarch on California's native
fishes' tompcraturt: cfrccts focused on the economically valuable chinook salmon, Clr~cnrhpnchirs
t s h a ~ ~ ~ y t s c and
l ~ a , steclhcnd, Oncorhynchi~s ntjkiss
iiideus (Castlebcrry ct al.', McEwan &Jackson 1996).
Increased awareness of the critical status of native nungame delta smelt, Hyponwsus trmspncijcus, find splittail, P. maurolt.pirloti~s,and the magnitude of the thrcath
f -almg ihom led to their proteztioii under fidctill ~ndaiigered species legislation. These species' environmental
tolerances and swimming performance under different
conditions have been investigated recently (Swanson
et al. 1998, Young & Cech 1996). Native tishes that are
not currently protected undB state or federal endangered species legislation de~nandmore study because
they often dominate the fish fauna in both biomass and
ahsolutc n~umbers(Moyle et al. 1983).
Our objectives were: (1) to measure swirnniing performance of wild-caught, endemic hardhead, &lophnmdotl cnnouephalw, hitch, Lavitlia
~.~ilicaurla,Sacramento pikeminnow, Ptychocheil~/s
grandis, and Sacramento sucker, Catos~otnusoccidetlt a l k at 10. 15. and 20°C. and (2) compare their swirnming ahility with that of the sympatric rainbow trout.
These temperatures are seasonally found in the altered
parts of the Sacramento-San Joaquin system where
retnnant populations remnin.
'
Casllrhsrry D. T., J. J. Ccch, Jr., M. K. Saiki & U. A. Martin.
1993. Groibth, condition, irnrl physiological perfomlance o f j u ~ c nilc snltnonids frorn the lower American River: February thruugh
June, 1991. Rcpon to the East Bay Municipal Utilities District.
U. S. Fish ;~ndWildlife Scrvicc. 128 pp.
bhterikd and methods
Fish ccrpture, trririsporr, a m f holding
Fish wcrc collected frorn Cache Creek (Yolo and Lake
Co.), Putah Creek (Yolo and Solano Co.), and the Pit
River (Shasta Co.), all tributaries of the Sacramento
River. Sacramcnto suckcrs wcre collectcd via seining
or electrofishing. whilc all other fishes w r e line fished
using artificial lures \\ith harbluss hooks. Seasonal,
woathcr, and Row-dri~znfluctuntions in fish distribution and abunt-lance pre\entzd use of large. eqi~alsample sizes for each specie.; x temperature treatment. Fish
were transported to the University of Califomin, Davis,
in insulated. oxygcnatcd 120 to 250 lirrr containers.
Sodium chloride (3 g I-') and MS-222 (25 tng I-') were
added to the water to minimile transport and handling
stresses (Car~nichaelet al. 1984).
Species were segregated in insulated. shaded, round
500-litcr fiberglass tanks receiving a constant supply
of air-equilibrated, active carbon-dcchlorinated well
water. Dissolved oxygcn levels always exceeded 90%
of air saturation. Angled spray bars created a 0.3 to
0.3 m s-I orientation current. Fish were initially held
at the collection'site temperature (7 to 23'C) for 1 to
1 days before being acclimated at 1°Cd-I to test temperalures of 10, 15, ;LIIJ
'O'C. Fi.41 were acc1in1att.d
to the test tel-nperature closest to their collection temperature to avoid acclimation to unseasonal temperatures. Fish were never held for > 4 weeks. Hardhead,
hitch, and Sacramcnto suckers wcre fed commercial
trout pellets and frozen adult Artemia, and Sacramento
pikeminnows were fed li\-e goldfish, Cnrossius oumtus, and mosquitofish, Ccrthrsin ufinis. Individual fish
were randotnly selected and transferred to a separate
flow-through holding tank and fasted for 48 h prior to
swimming experiments.
We measured the four species' maximum sustainable
aerobic swirnrning velocity (critical swimming velocity; U,,,) (Rearnish 1973) in n 120-liter Brett-type
swinlrning tlumc (Brett 1964) with u velocity range of
0.1 to 0.8 m s-'. Fish were transferred to the swimming
chamber after bcing lightly anesthetized (25 mg I-'
MS-222; 3 g I-' NnC1). F:ish were exposed to the anesthetic trcatnient for < 3 min to reduce stress associated with capture and handling and never exceeded the
first stage of anesthesia (Iwama & Ackerman 1994).
Fish ~recovcrcdfor I h in a 0.1 ni 5 - ' orientation current.
Fish that did not orient to the current within 5 rnin were
rernovod and not tested (3 hardhead, 7 hitch). After
recovery. watcr vclocity was i n c r e a s d in 0.1 nis-I
stops every 30 rnin imtil thc fish fatigued. ?We defined
fatigue as the point when a fish bccanic impinged on
the rear swimming chamber screen and refuscd further swimming despite t e m p o r ~ u yflow reductions and
gentlz prodding with a rod. Fatigued Gsh wcrc lightly
anzsthzti~cd,weighed to the nearest gram. ~neasured
(total length, TL, in c m ) and markod nrith a dorsal
fin clip. Fish wcl-c h<ld for I week to moniror postexperimental mortalily (no mm-tality occurred) and
wcre thsn released at thz collection sites.
Critical swimming volocitics (ni s-') were calculated
(Brett 1964) for cach fish. Differences among treatment mean morphomctric and swimming performance
data were tested for using t-tests and ANOVA. StudentNewman-Keuls and Dunn's post-hoc tests were used.
We used backward stepwise regrzssion analyses to test
for relationships bctwccn each species' U,,,. T L and
water temperature,
angled, possibly creating downward-oriented lift to
resist downstrcam displacement. Suckers transitioned
to intermittent swimming at moderate velocities and
only used steady swimming at velocitics approaching
thcir impingement velocity. The maximum velocity at
which suckers could avoid impingement was defined
as the critical holding velocity and is held to be functionally sirnilx to [he U,,,,
(Kimmer et al. 1985).
Fishes used in the experi~~ient
were gcncrally similar in
size (Tahle I), possibly resulting from the size-selective
collecting techniques. However, the 10'C hardhead and
hitch wcrc significantly longer than the 10°C suckers
and pikeminnows, and thc pikcminnows were in turn
significantly longer than the 1O"C suckers. The 10°C
hardhead were similar in size to the 15 'C hardhead, but
were significantly longer t h m the 2 0 C hardhead. Hitch
used at 20°C were significantly sholter than those used
at I0'C. Because of the small range of sizes used, the
only species for which s i x was a significant independent variable in the regression equations was the hitch.
Curiously, larger hitch (albcit at the cooler temperature)
swam more slowly:
+
U, = 1.85 TL(-0.055). Body weight variation
generally followed the T L pattern.
Results
Hardhead, hitch, and Sacran~entopikeminnow swam
steadily over the tcstud vclacity and temperature
rangcs but Sacramento suokcr did not. A t low velocitits, the sucker remained stfi~iona-y on the bottom
of the swi~nrnirig chamber with their paired fins
The relatively nnrrow temperature range ( A T = 10°C)
did not GignificantIy affect U,,,,with the exception of
Trrhle I . Nulive non-garncfish mcnn (ASE) rotnl lengths. w r i g h t ~and
, critical swimming velocitics when acclirnnted to different temperillurcs. The snmc superscripted letters in one column dcnotc statistical rimilanty between species at the same ternpermre (p > 0.05).
ldenriunl wprrscriptcd numbers in o n s column dcnotc statistical similarity within a species a[ he different temperatures.
Tzrnpcrature
('C)
Species
hardhend
hitch
S;lcrarnento pikcminnow
Sacramento sucker
hnrdhcad
s,.~cr~rmento
..
pikcminnow
Sacramento s u c h
hnrdhcnd
hitch
Sacramento piktminnow
Sacramento ~ u c k e r
11
Total length
(cm)
Weight
(2)
Critical swimrriing
vclocity (m s-I)
hitch, where those swimming at 10 C were ca. 0.8 111s '
slowtr than hitch swimming at 20'C. This difference
may have resulted rroni the size difference (equation
above). The other specks' swimming performances
tcnded to he lowest at 1 0 2 C ,higher at 15:C, and then
dwreased or the same at 202C, but perhaps due of the
small sample sizes and high variability, these were not
significant trends,
a. hardhead
T h m wcrc no significant perforniancc differences
anzong thc species at 10 or 15'C, although the
pikeminnow and hitch were approxirnately 20% slowcr
than hardhead and suukcr. At 20 C, hardhead, Sacratnento pikerninnow and S:lcramento sucker swam at
remarkably similar vclocities. but hitch were significantly (by 11%) Easter.
b. Sacramento pikeminnow
Discussion
Despite differcnccs in microhabitat use (Brown 8
bloyle 199 l ) , hardhcad, hitch, Sacramento pikeminnow.
and Sacramento sucker showed siniilar levels of
station-holdins (i.e., swimming) performance ovcr the
10 to 20'C range. Although hardhead swimming pertnrtmnce clicl not significantly vary with tzmperaturc,
thc highest mean U,,,,
occurrcd at 15 C (Figure l a ) .
'She 17 tn 26% larger hardhcad at 1 O T (slowest mean
U,,,)
may h:lve been restricted by thc swimming chamber, i ~ l t h o ~their
~ ~ lcross-sectjonal
l
arcas did not exceed
the recommended maximum of 10% of the swirnming
chamber's cr-oss-sectional area (Webb 1993). Alternatively, the smaller hardhead could have derived some
hydrcldynamic advantage from occupying the boundary layer, though hardhead tended to swim in the middle
of the swimming chaniher. Cech et al. (1990) reportcd
that h x d h e a d resting routine oxygen consumptio~lrates
only increased by 33% over the 10 to 20'C range, far
less than the 2 to 3-fold increase typically seen in poikilothermic vertebrates (Schmidt-Nielsen 1990). Recent
studies h a w reported that fish show decrcnscd physiological thzmial sensitivity at temperatures approaching their optimum, which may explain our hardheads'
15:C swimniing optimum (Jobling 1997, Taylor et al.
1997). Thc lack of a significant relationship between
hardhead size and swimming performance may have
resulted from the narrow range of sizes used.
Although hardhead often occur syrnpatrically with
rainbow trout in I-elatively cool ( I 0 to 15'C) reaches
c. Sacramento sucker
Temperature
I.Ig~trtI . Effects of temperature on the critical swimming velocities of hardhead. Sacramento pikerninnow, nnd Sncramcnto
sucker.
of the Sacrament@San Joaquin system, they are also
found at temperatures of 26 to 28 C (Cooper 1983).
higher than the incipient lethal limit for rainbow trout
(Cherry et al. 1977). Future measurements of hardhead
swimming performance at these higher temperatures
would be of intcrcst.
Hitch were the only tested species that showed a
significant difference between UCd,at different temperatures, although, this differcncc may have been influenced by the larger size of thc 10'C fish (seeequation).
This relationship between U,,,and 'I'L wrt.~uncxpccted.
because Ui,, (cm s - ' ) gentrally increases with TL
(reviewed by Beamish 1978. Yxes 1993 ). We suspect
that our observation rcsults fro111a negative effect of
the swimming chamber on the larger hitch. though their
swimming movements appeared to be unimpaired. We
can only draw tentative conclusions reprding our hitch
results because of the lack of statistical robustness conferred by the small sample sizt. The impressive swimming performance of hitch at 20'C would serve them
well in the wanm. low-elevation lakes. sloughs and
slou-moving river reaches where they art typically
found.
Sacrarnento pikeminnow enjoy the sccond largest
distribution of the species studied, being found
throughout the lob,- to mid-clevation rcnchcs of
rhz SacramcnttrSan Joaquin system. Although
Sacramento pikzminnow swimming pcrfomanoe was
not significantly affected by temperature (Figure I b),
the highest mean L;,, at 15-C may indicate an optirnal temperature. Ccch et d ' s (1990) findings regarding Sacramento pikzminnow metabolism support this
hypothesis. Cech et al. (op. cit.) found that their oxygen
consumption rates were generally independent of ternpcrature from 15 to 25 C , with a significant increase
between 10 and 15:C.
The most widely diytributed species in our study,
the Sacrarnento sucker also had the most temperaturtindependent swimming perfomanoc (Figure lc). We
observed no tcrnperaturc or size-related diffcrcnces in
U,,,,: the differencc between the 10 and 10'C treatments' mean U,,,, was a remakably low 0.04 rn s ".
This temperature-independent performance may result
from the intermittent swimming behavior and use of the
paired tins. This swimming mode may be energetically
more efficient than steady swimming (Johnson et al.
1994). r t s t r v i n more c n q y for use during steady
swimming at vclociti~sapproaching their impingement
velocity. Additionally, the suckers' dcmersal orientation could allow thzm to be~tcrexploit the flow
boundary layers than the other thrcc spccizs. which typically swam in the center of our swimming chamber.
Finally. of the spccics tested. Sacramento sucker are
found along the rnort extensive elevation and thermal
gradient (iMoyle 1976), including high-velocity microhabitats (Brown & 1Ioyle 1991). Presumably their consistent swimrnin performance across the 10 to 2 0 - C
range facilitates this distributional success.
Based on our data, water diversion approach velocities should not exceed 0.3 m s-I (hitch) to 0 . 4 m s - '
(hardhead. Sacrnrnsnto pikeminnow, Sacramento
sucktr). High levcls of swimming performance vanation have heen reported in other North American
cyprinids (Kolok & Farrell 1994) and may reflect the
functional and genetic diversity prtscnt in wild fish
populations. Because Sacramento sucker are so widely
distributed. they are more likely to encounter water
diversion intakes than the other tested species. To preserve as much of the genetic stock as possible, consenativu swimming perforn~anccustimates should he
used to avoid excluding significant fractions of their
populntions. Future studies should also measure the
swimming performance of juveniles and the semipelagic larvae of native cyprinids and catostomids.
With the exception of the hitch and hardhead at 10°C
and the 15'C Sacramento suckers, the fish used were
of similar size, which simplifies the task of comparing their swimming performnnces. For a given
temperature, the four species tested had statisticnlly
similar swimming performances, although the sample
sizes were rclntively small and the intra- and intertreatment variation mostly large. However. given these
qxcies' sympmy, their similar aerobic swimming performances are not an unexpected result. The three
cyprinids (hardhead, hitch, and pikeminnow) had similar swimming styles that responded to temperature in
a similar manner, possibly due to convergent selective
pressures or as traits inherited from a common cyprinid
ancestor.
The only resident, native, sympatric gamefish is
the rainbow trout (Brown & Moyle 1993). Rainbow
trout are less tolermt of high temperatures than the
four species studied here with reported incipient lethal
temperatures of ca. 26'C and upper critical thermal
maxima for California hatchery strains approaching
3 1'C at high acclimation temperatures (Myrick 1998).
Critical swimming velocity values for 20 to 30 cm rainbow trout range from a low of 0.34 to0.52 m s-' (Duthie
1987) to a high of 0.94ms-' (Mulchaey 1994). The
effects of size on rainbow trout swimming have been
well documented (Bainbridge 1958, Webb et al. 1984).
The rainbow trout's higher U,,,. for the same size fish,
argues for water diversion approuch vclocitits to be
based on thc native, non-game species' swimming abilities, rather than those of the gamefish, especially at
temperatures < 1 5 T ,
Wr: demonstrated that four. sympatric wild tishes
have similar swimming performances over a range
of temperatures nomially encountered (but see Ptake
et al. 1997). Despite the s i m i l ~swimming performances. these specits manage to avoid serious compt-titive interactions through rnicrohabitat partitioning
(Moyle Le Raltz 1995). We werf not able to determine
if these species' perforrnancc \-xiability resultzd from
inherent (genetic) functional diwrsity or from their differential responses to handling and the laboratory environment. Svmc of our rccrnt work with domesticated
strains of rainbow trout (Myrick 1998) suggests that the
high Icvrl of variability is commonplace even among
fish accustomed to frequent handling.
Other swimming-related research is urnanted on
wild California native fishes. Steady swimming is
affected by a number of f~ztors.Rmong them light
levels (Swanson et al. 1993). dissolved oxygen levels (Bushnell et al. 1984). xenobiotic toxins (Heath
ct al. 1997), and feeding state (Alsop & Wood 1997),
and these factors need to be investigated for these and
other California native non-gmefishes. Steady swimming only represents one component of normal fish
swimming behavior. and work needs to be donc on
unsteady and burst-swirnminz ability, especially since
many fishes usc these swimming modes to navigate barricr mitigation stnictures like fishways and fish ladders
(Clay 1995). Finally, physiologists have recognized the
limitations of extrapolating data from restrictive flumeexperiments to wild situations. Because of this, there
is a need for more studies integrating laboratory and
field telemetry and studies using large-scale swimming
flumes,
This research was financed in part by the United
States Department of the Interior, Geological Survey,
through the State Water Resources Research Institute. and the Uni\-ersity of California Water Resources
Center, Project UCAL-WRC-CV-826. Contents of this
manuscript do not necessxily reflect the tirws and
policies of the U.S. Department of the Interior, nor
does mention of trade names or commercial products
constitute thcir endorsement or recommendation for
use by thc U.S. Government. Additional support was
provided by a University of California, Davis, JustroShislds Graduate Fellowship and a Marin Rod and Gun
Club Graduate Scholarship to C.A.M., and grants from
thc Pacific G:ls and Electric Compuny and the U.C.
Agricultural Experiment Station (#3455-H) to J.J.C.
We thank our tish collection crews for their effons
undcr sometimes trying conditions and our colleagues
in the fish physiological ecology laboratory and at UC
Davis for useful discussion. G. M. Dethloff reviewed
early drafts of the manuscript and provided useful commcntb. Some of the data contained herein were presentzd at the 1st international Congress on the Biology
of Fishes, Applied Envirnnmentnl Physiology of Fishcs
Symposium, and are includcd in abstract form in the
sy~nposiumproceedings.
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