George T. Mccabe, Jr., Robert L. Emmett, and Susan A. Hinton
CoastaZoneand Estuarne Studes D v s on, Northwest
Fishenes
Sc enceCenter NatonalMarineFisheries
Servce,
Natona Oceanc and Atmospheric
Ad..in stralan 2725 MontlakeBouevardEast,Seatte Washngton98112-2097
FeedingEcofogy of JuvenileWhiteSturgeon(Acipensertransmontanus)
in the LowerColumbiaRiver
Abstract
L;ttl. ii kn,^\n dh,)!t th,j
Fron1.prilLhrorrgh()('trlhl'|l9B8.1llcliu1ing(o|og1oljirreni|eilhitest
R i r e r . O r e r a l l . t h t t L r b + d r c l l i r r g a n l r h i l \ \ l A t u p h i u n r o L t r o n i s\ ! a s t h e m o s t i m p o r r a n r p r e " - f o r t h e t w o s i z e c l a s s e so l j u v d i l .
{ h i t e i r u r g . , ) n s t , k l i ( ! 1 .H r * o c r - d r r i n g u I s r n p l i r s r y r i o d s e n d e r b o l h e r e a s i R i r e r K i l o m e r e r s [ n K m ] l 5 j l a n d 2 1 1 1 , S ; e C l a $
I {hii{' st,,rg.r,,, (1,1,1-:150
li,rk crsrhl pf(vdl more heurilr on al rdlmonis than did Size Class II white sturg.oo (jlsl Lo 721
nnl'0lh.lt{,dl1l,'!l|\iljl)0|tlnLI'r(]\lorSili]chssIvhil|5lurgeonnrcllrdedLilopJun
lrrrae. and ernach,r
bt\ ^l\ e c orbicul d tlu n i n
thatjrrrenileshitestrrrgeonnrhotliareascoltairled
a|r.t|l.l'|atirrn.hi1rsbetl'eenrlensitieslnbund!Dces)ofspecifcbenthi.orgaDisInsandwhitr:
l S j l a n r l 2 l l . l ) , s r ) i r . r h , i m p o r r u c . o l C o t u p h i u n t s o L m a n i tl n r h e r t i e t s o f i u r e n i l e w h i t e s t u r ! : e o n .i t $ a s n o t a b u r r l a n t i r L h r :
hrrh,,s 1n[an,lfrsit\.
<185 r,rganismstnr in {pril rnd Seprember).
Introduction
'Ihc
rrhitc sturgeon \Acipensel transn:,n:irn:4j'),tI:,e
lalgest North American sturgeon. is an anaclnrmous
speciesfrrLrrrrlahng thc r,".cstcoast of North Amclica
from the Aleutian l-.Lrnds, -{laska. to Monterev.
Caliiornia(Scottand Crossrnanl9i3). Somc poprr
lations in the (lolurnbia Rir,er Basin are essenliallv
lanrlbcked duc to darr construction(Cochnaucret
o / . l ' 1 8 5 . t s " J n r " - l " f t p rp / a / . l q t ) r .
and Oregon DeparLmenl ol Fish and Wildlife
1992). Based on the number of recreationalangler trips in 1991. Lhe white stur-geonis sccond
onlv to salmonicl spccics as the rnost popular
rccrcational lish in the lower (lolurnbia River
(S'ashingtonDeparLmentol Fisbcricsand Orcgon
Ilcpanmcnt of lish and Wildlife 1992).
Hi-.toricdl1",the population of r!hite sturge{)n
in the ColLrrnbiaRivcr (Orcgon and Washingtoni
supportcd an intense comrnercial lisherv. rvith
catchespeaking;r I892 at rnorc than 2.4 million
kg (Craig and Hacker t9.lo). Hou,eler. dLre to
orerfishing.catchcsclcclincd.and in lB99 the total crtch $,:1sless than i313.250Lg. During the earlv
1900s. arnLraicatr,hesl'ere lessthan l04.930 kg
(Craig and Hackcr 19401.
LiLtleis knorn about thr ecolo;ryofwhitc sturgcon. rnd the feeding ecologr ofjuveniles in par-ticuiar has receired only limited investigation.
Thc
diets oi small juvcnilc r,".hitc
sturgcon( { 800 mm
total length) have been described in Lhe
Sacramento-SanJoaquin River Basin. Ctlifcrrnia
(Sclrreiber 1962, Radtke 1966). and in the Colunbia River and its estuary(Muir ertrzl. l9BB). Hot'ever. most ofthe r,hite sturgeoncollectedbv llTuir
et ul- ll9tl9) were {rom thc cstudry; onlv a small
numbcr {N (5,1) were collected upstream from
the estuarv over a:J-month pefiod.
Since the earl,v1900,.. lhite stulgeonpopulations in thc ColrrmbiaRivcr. particularlv the one
dorrnstrearnliom BonnevilleDarn (the lowerrnost
, L ' r n r .r , , , , r , r , J . r r i f i ,i ' n t l t l u . l p f u r l i m l o r ' t . r n t
recreationaland comrnerciallisheries.PresenLlv.
LheLrwer ColLrmbiaRiver (from thc mouth to Bonnel'ille Danr) suppolts onc of thc largest popuhtions of lhite sturgeon. In 1991, the estirnaLed
fecrealionaland conmcrciul har-vcsts
in the lo$er
(lolumbia River were 22.700 and 3.{}00 fish.
respctiivclv (srashington Dcpartment of l'isheries
We eramined thc scasonalfccding charlcteristics ol tto size classesof juvenile white sturgcon
(144-350 mm lork lcngth and 351-724 mm lbrk
length) in two areas of the lorver Columbia Rivcr
in l9BB. Wc asscsscdboth the importanceof various prey eaten and the feeding intensiLy.Also, we
enamined the relationship betrveen thc fecding
cha|atteristicsofjuvenile $hitc sturgconanclben
thic inverlebratecommunitiesand the relaLionship
bctlr,ccn whitc sturgcon cdtches and benthic iDvertebrate abundance.
170
Nolthwest Science. \rol. 67. No. il. 199iJ
iCr l99lJ l,\ rl', \rdl,\!e.
S(Cn lil. A"rr
i i,)f. Al rishls rrqrf(l
r-r-r-r-r--
0
25 km
r-r-r------]
ru
Washington
0
15mi
1g3
Bonneville Dam
GXm 234)
RKm 46
uolrlrAf,.
\
J
A:-:.:t
R K m1 2 1
RKm 127
R K m1 4 3
R K m1 5 3
RKm 211
RKm 205
oi(d
^ ^$1'-
Figurc1.
['lup ol thr lotr
Colunbia Rner sho*irg the eight -.anrpling areas rhere jurenile white stLugeon end bcnthic intr
rebrarf srmrlli,s $.r. , oll(r'tdl i,, lq8fl. SLorra.hs \rere collected from iurenile white sturgeon captLrred at River Kilonreters
(RKm) l5il ltd 2l l
Methods
Juvenile t'hite sturgeon wele collectcd $ith a 7.9-m
(headrope length) semiballoon shrimp trawl" rvhich
'nastot'ed bv a 12.2-m boat. in cight alcas of the
lot'cr Columbia River between River Kilomeler
(RKrn) 16 and RKm 2II (Fig. 1). )lesh size in
the trawl net $,as 38 mnr (strctchcd mcasure) in
tlre bocl_,-la L0-mm mesh liner tas inserted in the
cod end ofthc nct. Trarrling elforts were nofmallv
5 min in duration in an upstreamdirection: boat
speed varied clepenclingupon $ater velocity. $ind,
and bottom topography. Distance traveled lras es-
timaled using a radar rangelinder ancl used t'ith
the estimatedfishing width of the net (5.3 m) to
calculatc the alea fisheci.Sturgeon density [or each
elfort ilas then calculated (number of sturgeon
caught/area fished) and expressed a-q number,&ectarc (ha).
'I'rawling
va,s done from latc March through October. At each of thc cight sampling arcas. tratling rvas done along tvo ol threc pdr-alicltrdnsccts;
one tra$,l $'as done along each transect. Trlnsect
I was clrsest to the Washinglon shore. Transect
2 t'as lhc middlc transecL.and Tfansect 3 llas
Feeding Ecology of Jur.enile White Stur;leon
171
closestto the Oregon shorc. In rilel seclions where
onlv l$o lransect-($,ere establisherl,Transcct 2 $,a.s
closestto the Oregon shorc.
of l ceding (IF) u'ascalculatcdusing the equalion
,{ll fishescaptulcd in thc trawl r,ere identified
and counlcd. Cenerally, all *lritc sturgcol lele
measured {ibr'k iength to thc nealest mrn) and
weighed (g). \\hen a large nrrnrberof whitc stur'geon itas colleclcd in a samplinge11brL.
a subsanrplc ofat least 50 iish ras nreasurcdand rreighed.
\rhcre \\'s : r,;eighLof storrach contentsof a fish
and Wf : weight of a Iish. Diilerencesamong l!'
\'alucs ircrc statisticallt tesLrd using the NlannWhihre,ytesL(Rvan et al. 1976).
Stornachswerc lakcn from a subs:rrnpleoI while
-qlurgeoncilplu[cd at two areas (RKrn 153 and
211; Fig. l) to determine their dict ancl its relationship to thc bcnthic invertehratecomrrurrilv.
srhitc sturgeon stornachs r,'er-ctakcn during three
lirne periorJs:{1) Nlal-June. (2) Julv-August,and
(3) Septernber-Octobcr'.
At cach area, t'e tried L(r
obtain 2.1>
stornachsfrom each of tlo sizr:tlasscs
of rrhitc sturgeon during each sarrpling period. The
two size cla-sses*ere (I) 144 to 350 mm lbrk length
and 1II) 35] to 724 mrn lork length. Stomachs
lcrc rcrnoveclIrom the whilc sturgeonat capture.
plLrcedin inclividual vials containing a 7{/n buffered
fonnaldehvcle solution, and ]atcl tr:rnsfarred to !ials
corrtaining70(/oethvl alcohr-,1.
Food itcms in each
slomach lere identified lr) thc loll.cst practical l:t-\onomic lerel. <rrrrntcd.and leighed (rooled bv
LR-\(rn)
lo lhc ncarest0.1 mg using a Mcttlcr H-80
lncchanical balen(er.
A contlition iictor. C (Flelhart und Youn€is
l ' , 8 1 , . " : , - , r ' r r r p r r t , [. ul r e r , l r r . l r i t - - t r r l B , , , r r
selettcd for ,.tomachanalrsis usirrgthc lbrmuh
c = (\\ /L,,)x 105.
therc W : tcight (g) nnd L : length (lrrr, fork
lcngth).(londition laclorslcrc comparedhetleen
lhe lhrcc time periods irr each sizc class usinpl
analvsisof rariancc (ANOVA).
Thc clictsof lhite stufge(rnat RKm 153 and
2l I rrere analvzed Lrsingtrro approaches.The relatire conLribllli()nof a prcv ta\on Lo Lhe diel t\'as
.lelcfmirlcclusing a modilication of thc Inder of
llelalive Imlrortancc (IRI.1clescribedbv Pinkas et
al. (197I1
I R I : ( \ + S ) l .
rrhcre N : pefcent nLrmbcrof 1l ple_yiten. W :
p c r , c n l t \ c i , r l r ,t ' f . r p r r r i t e m . n n d F
I ' r 1 1 1r l
fr-equert<rv
of occurlence of a prev itern. Tnrlcxoi
Rclative lnqroltance valucs for inclividual prev
ilernswcrc thcn converledt(r perccntagcs.lo determine lieding intcnsitv in each area. an Jndcr
Ii2
N'lcCabc.Emmett. and llinton
IF:
(Ws -
Wl) x l(X)90.
Bcnthic macroinvertebratesN.crc collectedin
April and Septcmbcr l98B at t*o statir)ns{long
each lrrttom trarrling transect al thc cight sampling
arcas (Fig. I). Five berrthicinr.crtebratesamples
t'ere collected al cach sampJing sLation Llsing a
0.1-mr Van Veen grab sarnplcr (Word 1976).
E a e h- a r n 1 , 1" ,. r - . i , r , J t h l o r r g ha o . 5 - m m - r ' n 1 n
and thc lcsidue pfeservccl in a bulfcred lbrrnalclehvde solution ()470) containing rosc br:ngal. lf
it appcared tlrat mosL of the matcrial \fould nol
quickl,v*ash LhroLrgh
thc sieve.the enLir-e
samplc
t'a-" prcscrlcd and sieved al Lhe laboratorr. 'fhe
samplcs lere later rvashccl $'ith lrater and
preservedin a 909/odcohol solution. Rcnthic in
\.cltcbrateswere identificd to thc lolest pracl;cal
ta)ionom;c ler.el and countcd. Eulachon
(Thaleichtbs Jttu:trt<:us\L'.ggst'ere also countcd.
When large nunrbcrs ol eulachon eggs occurred
in samplcs.their nurnberswere cstimatedbv subsamphng.
The relationsh\rsbeh\,eenwhiLestLrrgconden,
sities (Aplil and OcLobcr) and Corb|cuLaluninett
and Conphium salntonir densities (April and September) at the eight sampling areastere exarnincd
using sirnplcancJrnuitipleregressions.Bcnthic in,
verlcbratc data collected in Septcmber \r.ere used
t u l h r r r c t e l i z et l r - O r t , , b 'r f i r i o , l .S h i t . - t ' . r g . , ' n
densitieswcrc transformedto logr6of (clensit,v
+
1.| and benthic inle.tcblatc densities were transtorncd (lo916)prior to analvsis.
Results
Stomach
Contents
A total of292 stomilchst'ere taken from r,;hitc stul
gcon collectedat RKm I53ancl 2l I in 1988. Thc
arnphipod C'.salnroni! r'as the mosl important prev
item at both areas(Tablc 1). Durirrg all thrre timc
periorJsin both areas. percent Indcr of llelative
lmportalce (o/oIRI) for C solnronis t'as higher' frrr
the smaller Size Class I lhite sturgeon Lhanfor thc
larger Size Classll r,".hite
sturgeon.indicatingthat
thc smaller juveniles prcvccl more hearilv on C'.
solrnr-,zir.Thc inrporlance o[ C. nlmonis lor Size
Class I rhite slurgcon dt llKm t5lJ remained
T.{BLE
r.
Sunrnrrr o{ iihite sturgeon diets from ['lar through October lgi]ili numbers -rho\rn
the trble.re
percenri o{t al
I n d e r o f R e l a t i r e I m p o r t r n c e ( r l o l R l ) . D a t o a r e p r e s e n t e i ll b r u o s i z e c l a s s e s S i z e C l o s s l ( 1 . 1 , 1 3 ; 0 n n n I o r L l e n g t h )
fiom tro &so{
t h r C o l u m b i uR i r r . R i r e r K i l o m c r o s L 5 3 a n d 2 l l .
a f d S i ? eC h s s I l ( 3 5 | ? 2 l m m f o r k l c n $ h )
On v prr itcms lLilh o/olRlralu.s grcNl.r then I (l;f rl kasL oni, sirc (hss !n(l icrsonJ um sho$r.
l\I|i Jun
Sizc I
R , r ,r } . i l , , r ,1r , , 1 5 3
<l
\ntlthiunt
rtlnuttis
lt
0
82
Corcph)unt spnticonte
<t
2
ll
2
<l
l2
31
<l
.1
15
,I
3
o
l:l
lil
o
<t
it8
7
ll
75
5
<l
0
2l
;l
<l
20
< l
2
14
21
<1
I
18
o
:12
<l
o
1l
Rirer Kiloneter 211
<l
ln4thirn
sakut
"
Conphum
spin)conte
Heniiptera
Chirononirltc lrrue
Chirrrroo
Hele
ac pupar:
0
5.)
l)
0
<l
ae Larrae
25
20
0
0
12
<t
<l
< i
t-3
L
35
0
<l
21
< L
{)
< l
0
<l
;t
:l
0
I
0
l3
It
J5
2
<l
Fish tunidertifieill
rclatilclv firnsistcnt throughout thc snrdv. ranging
ftorrr 75 to f32 9oTRI during the three pcriods;
nhereas. at RKm 2II. the o/oIRI ol C. saLmonis
tas morc r.aricd. ranging lrom ,l,l (Scptcmbcrrrgust).
O(lober) to 75 0IIRI (Jrrl,v-A
Sizc Classll ttitc sturgcon dLsoprcvcd primarilr on C .v/nloar,r. but" on occasion. thcv also consurncd largc quantilics {)f thc bivallc CirDicala
flutninea, Chironomidae larrae. and eLLlachoneggs
(Table 1). At RKm I5.). o/olRl lctr Corophium sal
nronir rangcd fronr 38t/n in Jul,v-Augustto 5l7o
in Septembef-O(tober. AddiLionally. eulachon egg-"
(I2 0/ollll) and Corbicukt.lTuninea |II %Ifil) t ere
impoltant pre_yin Mav June. and C. fluminea ll9
?oIRI) ancl Corophium spinicome l7 ToIRI) r'ere
irnporlanlin Julv-August.At ltKm 211. Tolltl for
C'. solrnotis ranged frorn l29t in l\{av-Jurltl lo 24olo
in Julv-October.Other irnportantprev 1orthis size
class at RKrr 2ll indudcd culachon cggs (51
o/oIRI)and (hrbicuh
oiIRI) in I'larJluntirtea i20
oiIRI)
in Julv-,\ugust. and
Irne. C. Jltntinea (35
(ihironomidre lan'ae (18 o/olRl) in September0ctober.
I
<l
<t
<t
0
o
0
23
0
0
Thc lF anal,vsisindicatccl a rcduction in leecling ofjuvenile white sturgeonat ltKm 153 ancl 2l I
in September-October.At RKm 153, l!'values for
both size classes of 1r'hite stur€{eont'ere signilicantly lorer (Mann-Vhitnev test. I' ( 0.05) in
SepLernber-October
than in eithcr N{ay-Juneor
Jul.v-August(Table 2). At RKm 2ll, onlv Sizc
Class ll vhitc stur€icon had signilicantlv lol'el ll'
ralues in Septenber-Octoberthan in \Ial-June or
July-August (Table 2). Besides lor,'er IF r'alues. Lhe
number of emptr' slornachsfor both size classes
in each area was highest in SepLenber-October,
furthcr indicatingrcduccd fccding.Thcrc vcrc no
signilicant cliffcrcnccs in C bctrtccn the three time
periods for either size class of lhite -sturgeon
( A N o V Al,' > 0 . 0 5 ) .
\liltcr tcmpcruhllcs in arcas vhere t'hite
sturgcon lrcrc collctlcrl for skrmach analvsis
rangcd lrom l3 to lBoC in Mav-Junc, 1? to 2loc
in Julv August. and 16 to 1B0C in SepternberOctober'.
Feeding Ecologl of Juvenile White Sturgeon
173
TABl.fl 2. Comtarisohsol Inile\ of l(rrling (IF) forr$o sj,r
classesol iuorile whitc st!.gdrr collect.d ar Rirer
Kildnur..s l5ll .nd 211 in lhf Columl)i! Ri!o.
l 9 1 l l J . S i z r :C l o s s I n h i t . s t ! r g e o n s e r e 1 1 . 1 - 3 5 0
mni inrk l,J,grh und Size (lluss Il ithite srurgrrn
$ere :J5l-72.1 mm forl l.arsrh. lfean Il $!s (al
culated using onlr stoma.hs thll contaiird litrnj.
The ri)rrl number of sro,rrrchs collectcrl n|rl rhe
, , u m b , - f o l e D p t \ s t i ) n r r c h sd r e s h , $ n r o r e a . , h
Sizc Cluss
I\JrIJ
rL
Jul .Lug
Scp Oct
Rnlr Kilometer
I53
Sizc I
!l nrern IF
cl Du
bcr ,'mplt
0.3!)
2(t
0
0.11
21
o.22"
20
t.2,'
25
I
0.iJ5
25
0.08'
21
lLr
t).3|
2,_
o.23
25
0
0.20
21
6
0.:lll
23
2
tl,:lt
25
0.03.
21
l7
Size II
,I number etr,t)Lv
RirerKilou.r(ir21t
Si,e I
.) ntrDlx.f.nrpt1
Sizc ll
r) me.n tF
c) numlrr
crrptr
' N ' l e a rI F l i r S r p O c t w a s s i s , , i j i ,
{ r l l r l e s st h a n l I l l f b o t l i
l l a r J u r a r d . l u l , \ u g : \ f a r r r v h i r n e r r e s t ,l ' < 0 . 0 ; .
Benthc Invertebrates
\lajor benthic ;nveftebratct.ra collecreclat ltKrn
153 irrclLrdecl Oliplochaeta. CorbiaLla fluninea.
CorLryhiun salrnozis, Chironornidac larvae. and
Heleiclac larrae (Tablc 3). At RKrr 2ll. major
bcnthic inrertcbrate t:r-ra included Trrr.bellaria,
Oligochacta. Corbiudu, .fluninea. Ostracoda.
Corophiuntrnlnronir, (llrironornidaelar.vae,and
Heleidaclarrae (TaLrlc3). Eulachonctgs \rere rnclucled in the table br-'causethev rcrc collected
along tith thc bcnthic inrertcbratesand rvcrc imp(|tant in the dict oflhite sturgcon.l)ensiriesof
specific invcrtehratesoftcn vaded consider.ablr,
arnong transe(:Lswithin each arcaC)verall.thc rclationshipsbct$,eennhitc stur
geon dicts and specific benthic invcr-tcbratedensitiestere poorat RKm I53 and21I (Figs.2 ancl
i:i). Although C'.solnronis rvas bv fal ttre mosr rmI7 |
\ 1 , C r l , , . . [ - r n m ' t t . r r n d H i r r r ,. .
portant prcv fbr both size classesof lr.hite sturgcon
in Nlav'Juneand September-October
ar RKm 15ii.
it was not an abundant bcnthic invertcbrate (mcan
densitv. <185 organisms/rn2in both April and
Scptember').Eulachon eggs. t'hich llere abundanL
in the benthosat RKrn 153 during April. lere an
important food item lbr Sizc Class II rvhite sturpJeonduring X{av-Junc.Heleidae larvae. althoLrgh
rclativelr abunclantat RKm 153, parLicularlvduring April, t'ere insignificant in vhilr sturgeon di()ts.
Likct'ise. oligochactcs t,ere relativelv abundunt at
RKrn 1513dLrringSepLembcr.vet $crc not eaten
bv whitc sturgeon.
At RKm 211, C. salmonit was bv flr rhc most
importanl prcv in both Mar,,Juneand SeptembcrOctober fbr Sizc ClassI whitc sturgeon;ho.wever,
it wa-qnot abundanLin thc benthos in cither.Alrril
or--(eptcmber(rneandcnsity. ( 120 organisms/rn2
in cach nrontlr). Corbicukt fl.u.nr,ineat;as lhc mosl
abundant bcntlic invertebrate at RKm 2ll in April
and $as also an importanl plcl for Size Classll
whiLesturgeonin Mav-Jure. Eulachol eggs werc
abundant aL RKm 2Il dLrringApril and were an
important prev lor both size classcs of rvhite stLrrgoon, particularly Size Olass II fish, in \{ar'-June.
ln Septernbcr. oligor:hactcs. C. fluminea, ancl
Heleidac larrae $'erc the most abundant benthicr
invertebratesat RKm 2-tl, vet these taxa were
unimportant in the diet of r,ihitc sturgeon in
September-October.
The rclationships betvccn t'hite sturgeon densiLies and densities ol Corbitttla .flu.nineu aru)
Corophium salmonis at the eight sarnplirrg areas
(dataconbincd lbr all areas)r'ere poor (Table 4).
Sirnplc regressionanalysisindicatcd that ovrrall
(combining the data for April and ScptemherOctober).onl,v7(/o of the lariation in $,hitc sturgeon densiticsrr.aserytlai.rc.,J
by Otrbit:ukt.flurniteo
dcnsities;200i of the variarion r,as erplaincclbv
CorophiutrLsalmonis tlensities. Multiple rcgr.cssron
analrsis sho!r.edthat 2B{/n of the variation in u,hitt:
stu+icon densitieswas explained bv using both Corbicula lurninea anclCorophium salmonis densities
as prediclors. Thc data \rerc also analyzed
separatdv for the two t;ne perio.ls. For Aprit, 129o
ofthe \.aialion in l,".hitesturgcon densities r,as ex
plained bv Corbicula,/lrruinea densities, and I I o/o
oI Lhc valiation *as explained 6t Corophiun
ralmonis densitics. Multiple regrcssion analvsis in
dicated that 260/ool the variation in rvhrLtsLurl;eon
cJcnsitiesin April vas erplaincd bv using both Corbir:ula fluninea and CorophiunL salmonis tlensitir:s
TABLI
3 . ] I e a n r l c r s i r n , s( n r r m b e r / m r ) a n d s f u n l ! r l , l c ! i a t l r N ( S D l o f m a i o r b e n l h i c r ! \ a ( r , l l . c t , i d i n A p r i l a n r l S e p t e m b e r 1 r ) 8 8
!r Rir.r Kil)d.ters GKnl l5jl anrl 2l I in Llr. Columbia Rirer. The totul lor car:h ta.se.r includes borl, m.jof r!x!
an(l kss inporlant l$4 nol sho\r,,.
Ol+ochaer!
Heleidae lunur
Eulachon cggs
t33 2
Heleidoe larur:
Total
,st)
SI)
Iean
r;3-r
-seplenrber1988
April L98il
RKn,
405
1.L9rl
ar40
13,1.366
1.1x
t_15;
l_0.11
fos.22r)
l,il:1.9
213
,13|
0
6q7
153
:106
0
136_655
103.352
2.;07
956
530
515
39
198
36
I ir;
1.019
251
2n2
369
285
68
122
262
513
939
f,592
Corophiun salnunis
,t2il
389
Heleidae larue
IX6
t;a)
t.t11
r9B
1 5 33
7n
2tt-l
2l],3
625
,1,9.701
i18.979
1.12[]
l3
t.210
'112
8.87,1
2t
860
509
tl.262
7rl
,l7B
500
0
t0.930
14-02iJ
t_ 0
Corbrcula lltLminea
Heleidoe larvu
5,t,1
301
t3i)
90B
,l6i
7
244
,t40
Tolul
982
OLsoch!e1r
Can'it\11turq.nnfited
Tolrl
2tt 2
0
t5
'rurl*llaria
Oligoclrd.la
Co,buuh Jluninea
ContplLiutL saLnonis
,106
224
59
it09
3;?
l.l6t
50
370
281
0
55il
t2
253
3Ba)
542
I,212
2f ,l
2t6
':t4
627
70
6,1;
50
l,t3
221
8,1
4]t
55
:t9
19
52
5il
0
Total
I,135
325
I,016
Bl0
Entire area'
tL.f22
8.B50
95;
657
Eulachon eggs
' l h e a r e L a g eo f a l l s u r r p l , s L a [ ( i n ! t R K t n 1 ; : ] :
" The rreragr: ol ull sat4rl,s taker at RKm 2ll:
A p r i l . o n h 2 8 s a q r l c s u e r e a n a l , v z e df . r r r h c c n L i n i d i . a
i n n p r i l . o r l ' 2 9 s a m p l e s w e r e a n r l " r z c r ll i r r L L . . n t i r u a l e a
Fccding Ecoloplyol Juvenilc White Sturgeon
l?5
E w z
80
- 6 0
600 o
400 0
40
0?
..-.""
""$'-."..:$.
.".::::"o
t,0m
z
80
nft1
3
600 g
:
L,Nr
Y
d 4 0
20
0
cv
:s-
".."
..v
<.
2m 3-
-a-
-\- -s'
(,.\S
c
Size ClassI
(1,14-350mm fork lcngfi)
illNN Size Class II
I
(351-724
mm forklengfi)
Benthic organismdensity
Figuk2.t1](a]nl]nde\ofne]at\ljllnIlorlan(e(%IItI)forpr.r.l,|.|s!sizeclasse..o{itlcnilrll'|iresru
Jurc und Septemher-0.tob.r l98il .t Itirer Kil,rn.r(jr iRKml 153 m rhe Columbie Rjrer. Also sl!,\{n !(.ddNities ol
selected ldthn, orsrnisms cole.red ir Afril !nd Seplember l9BBr Lh(i Arril da|t are preselr.d ji,r rl,c ltrr June peri,,,l
bccausc no benthic salnphrg was (lone n llla! or Juh.. llullchon eggs are shorn bccause rher were rollqrrrl
alons
irith the benthn in!crL(ibfltes and $ere inportanL i{hiLe sturseon pre}.
I ,n
\ l c C a L , . .t . m m e t t a. n d l l i n t , , n
2.143
I,0{0
t
z
8 m 3
80
600
400
I
2 m >
20-
-o-
..-l:l-l"
.."$"
,"*
"-$ "",.."$
8ff)
80
z
3
c
600 s
400
a'
2 c 0 3
3
20
0
c" s'r
Size Class I
NN
(144-350
mm fork length)
"""$ ".,."$
..,.:,.
$"9
Size Class II
I
(351-?24
rnmfork leng6)
Benthic organism density
Figure 3. Percent Index of Itelarire lnportaDce (0,6IHll fo. pr(i\ o I tr o siz. rlassr:s ol juve n ile wh ire srurseon collected during \la]'
June and Seprember October 19BB aL R;r.. Kilon.rcr (RKm) 2l I in thi, Columbi! Riler. Also shoro are der-.ities ol
selerted lerthir organisrns q,ll( rc,l in April ud Sep(ember l9ll8r rhe April data are pre-.erted for th. ['l!y-Ju,. p(iri,xl
because no benthic srmpling ras done in Mar or Jure. Eulach,"r r:sgs erc shown bccrusc thev were collected along
rn.l w.nj imrDrtanL whit. sLur!:eon Drer.
$ith the benthi. inyfflehrltcs
Feeding Ecologv of Juvcnile White Sturgcon
Ii7
TABLE 1. Surrnari oI rhitt' sturgeondensities(nurnberrhaloid benthicnrrertebratedensitieslnunrber/m')at eightsanrplingareas
lRiler Kil.,merer [RKn]-trarsectl ni the lower (inumbia Rirer, 1988. tr'leandensitiesare showr for the irrertebrates
CorbicuLa
.fluninea (Cl ard Coroph;urnsalndir ics). rhich are important pre,vfor jurenile white sturgeon.
Sep Oct
ftKrn
:16 I
29
811
;63
;
\62
.163
21
tzt-t
121.2
0
0
t27.1
12i.2
12;,3
5
fla)
t2
59,1
365
20
534,
6i
357
.19
75
5t
71
6
316
t;;
2t9
231
IJ
t0
2t2
,[61
l?
5
I.t9u
ir13
124
2
2r)
:189
2r3
39
6rl
'1
5
5,15
1
108
:151
o
2:l
':'
r;31332
153-3
0
3
lt5
251
1B
B
t 1:J,1
1.132
;5
6.57,1
1.046
a)
0
33,f
1{J
l;l
103
2::|:1.
60.1
l-516
4.56i
1 8 3I
t 83-2
0
t)
201
176
I
0
8
292
661
]lJ
68
2t)3.2
20; 3
42
312
33
I2
2
56
686
6
5.1
1.210
311
26
5
309
198
763
17u
218
;0
2 tI I
2 t L 2
2| il
irJ
5jI
t)
B
22r
'Sturgrln rcrc,oll(rLdl in O,roh(if1988.
! B(irthic irlrrt.brat(s
rtr
rtlll:tcd
ni -q.ptember 1988.
as prcdictols. For thc Scptcmbcr-Octobcrpcriod.
ilo/o and 320/o of the variations in rvhrtc sturgcon
densitiesuer-eexplaineclby ArbicttLo Jluminea an J
Corophium sttlmonis clcnsities, rcspectively. llTultiple rcgrcssion analvsis of thc Scptcmbcr-October
clatashorvedthat 330/ool thc valiation in rlhitc sturgeon densities n'as cxplaincd by using both CortticukLJluninea and.CoropAirrmsalmonis densitics
as predictors.
for white sturgeonlessthan 800 mm (otal length)
captured in the lover Columbia River and its estuarv rvas Cbroplla m saL,laolis,In Mrrir et o/.'s
(1988) smd,v. neither Corbicula flrlniiea nor e:uh , h u n , g . s , r , . i r n p o r r r nIt' r F \ f u r r ^ h i t . . t r r r g - u n
less than 800 mm long; this t'as in contr{st to lvhat
we observed. Mrir et al. (1988) sampled in the
Columbia River only in Julv-Septernberwhen eulachon eggs rvould not be present. This time period
lras lr'cll past thc spaltning migrations ofeulachon.
Discussion
Although RKm 153 and 2Il are intensively
uscd by juvcnilc whitc sturgeonj these areas do nol
har.e high standing crops of C. salmonis. ln both
areas. C salnolrir had mean densities less than
I 25/m'] (averageof all samples taken in each area)
during April 1988. For comparison. the mean density of C salmonls at four stations (RKn 30-,10)
in CathlametBa_v,r'hich is prirnarily a lreshwater
l h , t i . ' l i r r g, , " L , p . r. , i l r r u n i 1 , s h i t r - t u r c - o n i r r
our studv" in gcncral, agrccs rrith findings from
thc lovcr Columbia Rivcr feeding studv of \{uir
et al. (l9BB). Although fewer t'hitc sturgcon
stonachs \!ere analvzed for content during their
- t r , l r . t h , r . r l - u i . , ' r n , lr h r l l h , p r e d , r m i n u rpr rr e r
l7B
NIcCabe.Emmett. and Hinton
flunineu. They rnay be pre;-ing primaril;- on
Corophium salmonis anclseconda lv on Corbrlcula
fluninea because these invertebratesarr more
availablc to thcm thtn othcr-bcnthic invcrtcbratcs.
Corophium saLmonisis a tube-dt'elJing amphipod
that migrates,rerticellvin the waler column in the
Columbia Itiver estuarl (Dar.is l97B). This amphipod has also bcen obserredcrawlingover the boltom in the Columbia River estuary'(C. 1'. McCabe.
Jr.. pcrsonal obscrvation).CorbiculaflunLineo is
primarilv a filter feeder (Wa_vet a1. 1990) t'ith
shofl siphons :rn.l apparenlly lives in close prox'
irritl' to the substrate surface. Iiulachon eggs,
rvhich l,".erean important vhite sturgeon prev during Mav-June,are found attachedlo the ,qubslrate
surlace. Oligochaetesand Heleidae larr.ae mav be
found dccpcr in thc substrdtc. and thcrcfolc bc
largelv unavailable to juvenile white sturgeon.
bay in thc Columbia Rivcr cstuary.rras 7,739/m'?
in April l9B4 (Fimrncuer al. 1986). Ar RKrn 46
(Lrpperesluarr-)jthe rnean densitv of C. salmonis
r.a-q2.420/m'? in April 1988.
(ionsidering the relatir.el,vlot densities of C
solnrozisin thc bcnthosat RKm 153 and 2l I and
t l r ,i r i r n p u r t r r r r 'i,n r r l r i t . . t r r l g . , , rdr i r l - - i l i - 1 , , - silrle Lhatjrn'enile white sturgeonare (1) feeding
on C'.riotlionis cafried to them bv the crrrlent driit.
(2) movinplto ne:rrby ueas with higher C salmonis
dcnsiticsand fccding thcrc" or (3) verv cfficientl,v
feeding rrrr C. so[nnnis, e!en \rhen n.rt abundant.
Cort'phitLntspp. are often important river drift org r n i - m - . r n Jh J u l t , ' , , ' b - n . , l i r rr ' l r i t . . t r r r y . u n
cgg and lan'al samplcs collcctcd r,;ith plankton nets
fished along the botlon at RKm l9il and 2iJ0
(l\{uir 1990). Daris (1978) obserred that C
salrnonir undergoes a lertical diel migration in the
latcr column in thc Columbia Rivcr rstuar-v.
(itrcphiun t'o[utator, a related Atlantic species.ha-s
a1-"obeen lbund to st'im above the bottom during
part of its life cycle (Hughes 19BB). Il C. salmonis
populations in frcshlratcr scctions of thc lolrcr
ColumbiaRiver cxhibit similarbehavior.thev could
bc clispersedbv rivcr currents. During the early
part oi the l9BB lield season! \!e tried to sample
in\.eltebratc drift just abovc thc bottorrr Lrsrrrgarr
epibenthicsled: hot'erer. the sled would ofien lill
with sand then toled along the bottom.
Juvcrilc white sturgconrnav frcd in shallor *ater. where C'.Jalrrdlri\ is sornetimesrnore ebundanl.
In 1990. rnonthlv mean densities ol C salmon].rar
inclir.iclualstations in shallov t'atcr (l-6 rn dccp)
al RKm 15:l ofierrerrreded 1,200 organisms/rn2,
r,;hereasmonthlv mean densities at the deeper n'ater stations(11-21 m dccpJ gcncr-allvt'crc lcss than
(fi'[cCabeand Hinton l99l).
105 organisms/m'?
IIot'clcr. al RKm 2l l. rnonlhlvmcan dcnsiticsof
were
C. saLnonls at the three shallow-watersL:Lrions
lon and usuallv did not erceed 76 organisrns/mt
'l
{NlcCabcand Hinton I 991). hc populationsof C
solnr;zis [ound at Lheshallow-$aler stationsat RKm
I53 mav represent a good lbod source 1orjuvenile
$,hite stur€ieonin the area. Although juvenile rvhite
stur€ieonin the lowcr Columbia River tvpicall,v favor dccpcr- watcr (-9.1
m) during da_vlight
r V , C . r l ' a r r J H i ' , 1 , , ' rI t r ' , O 1 t. l r r ! m r \ r n , ' \ Fi n r , '
- h a L l o r . "rr. e t e ra l r i e h l l o t i e J . S t r r d i e -r r - i n gj u vcnilc whitc sturgcon that halc bccn taggcd rtith
sonic or radio tags are needed 1()describe their diel
movements.
Jur.enile l,".hitesturgeon mav not be selectively
plevin€i on Corophiun saLmonis rntl Corbicula
Bcnthic invcrtcbratep()pulat;ons
$,erenot sarlpled rnonthlv. ancl it is likch thdt somc in\.crtcbratc
densitiesrlere highel or lower in Mav-June than
indicated by the April surlc,v. Also, mrmbcrs o{
inveflebralesin October nay have dillerecl lrorrr
those during the September survev. However,
based on bentbic data coller.teclmonthlv at RKm
153 and 211 in I 990 (McCabcand Hinton 1991),
it is unJikely that Corophium salnonis densities at
the clecJrerNater stations(typieailv where white
sturgeon are more abundant during daylight) er.er
rc chcd modcralc or high dcnsitics.McCabc anrl
Hinton (1991) obsen'ed that densities of C
i.rlrrola fluctuated frorn June throLrghSeptember
but remained lolr'; densities never exceeded 380
organisms/m2 and \!ere usually less than or equal
to 101/rn':.
In conclusion. resuhs liom our study highlight
thc importrurcc of bcnthic inr.crtebratcs, particululy
C. salmoris, in rhe diets ofjuvenilc $hite strrrgeon
in thc lo*'cr Columbil Rir.cr. Scrrsonalchangcs wcrc
obsened in the diets ol juvenile white sturgeon.with
recluc,ed
leedingoccLrrringin SepLemtrer-October.
l)cspitc thc importancc of bcnthic invcrtcbratcs in
the diets oljureniles, the relationshipsbetweendensities of specific benthic organisms and n'hite stlrr'
goon diets \!ere gcnerally poor.
Acknowledgements
tr'e thank Lat'rence Davis. llaurice Laird. :rnd
Roy Petlit ftrr-lheir assislancr in sarnpling.This
studv i!'as funded primarilv by the Bonner'ille
Powcr Administration undcr I'roject 86-50.
Feeding Ecologl of Juvenile Vhite Sturgeon
I79
Notes
'Rlli rcnt'to trade names does rnLinph clrIrrsrnrntbr
N ! t ; o , u l U r r i n . F i s h e r i e sS e r r i c e .
the
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ro tl.t.
A, n!
Cor|s ol Lnsineers icortra.t
D.{(iW 57-B 1-1 -031tJ1. f'orthnd. Oregon. ll p. plus
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F l .c r h u r t . \ i . H . . a n d \ { ' . l J . Y o u i ) g s . l 9 B l . P r i , r i I l i , s , , f l l s h
.N !, icn.c. Cornel trnirersin l\ess. hha(!. N.{ \ orklj19 p.
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i,.,r'! srin,n,ins Lehrriour ol die a,nthlr)d Ciro,r,nn,x
t.l.utukn. l. \I!r. Biol. .{sn'.
llnited Kjrrgrlonr
68:565-5t'r.
\lca-ih.. (;. 1...1r..{nl S. l. Hnrron. 1990. Iiepot D. 1nA.
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liom l\'lc\arr Dam. Anr. ll{. t,, B,r,noil,. Po{cr r\,1
m i n . t P r o j e ( r i l o 5 0 ) . P o r r l a D t l .( l r e g o n . t 1 J . 1 1 9 - 1 9 1 .
-.
l ! ) 9 I . R e p o r t D . / a A . { . N i s , o ( , r l . l S t a r u sa n d
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tl,rrlNnd.Ofeson. Pp. 1.1; lll0.
Receh'ed 7 June 1992
Auepted for publicotion 2I Der:ember1992
IB0
XIcCabe.[rnrnr-tt. and Hinton
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Colrmtri! Rilef md irs estuary. llalili,rnir |ish en(l
C.me 7.1111:19-51.
t l i , r l l s - 1 . . -V . S . O l i p h a n r . o D d L L . K . I r e n r , . I 9 7 l . I i a l
habits of all,aorc. bluclin tunu. and bonito il Califor,
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Radtke. L. D. 1966. I)istrib!rion ol sneit- lurerile sturgr!n.
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r1,.r r5 r2(1.
RIan. T. {., Jr.. B. 1.. Join r. urrl u. F. Rran. 197(,. I'lniiuh
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ri!- 3ll p.
-schreiher- \l
H. l9(,2. Ohs.ri.!lions on the {ood habits ofju!.ril,.
rLhire snrrgeon. California l.iih a,rl Grkl
. r 8 1l ) : 7 ! ) i l o .
S o r r . S . 8 . , a n d E . J . ( - - r o s s n r a r1r .. t 7 3 . f r e s h w a t e r l i s h e s o l
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0l\npia.
\\nshinsron. 22.1 p.
\ \ J ! r . C . U . . D . J . H o r n b ! . h . C . A . [ 1 ; l t , i rW ! r . B . S . p a l n e .
ard A. C. Nlillrr. 1990. Drnanics of filter feeding nr
Cotbiula
!n.niHi
llliralria:
Corbiculidaer. Carr. J.
z , n , t6. 8 1 t ) rrt5 1 2 0 .
\ \ o n l . . l . Q . 1 9 7 6 . I n e l r l u a d l o f b e n L h n i i r ! ( i r r ( i b f a r , .s l m
pllrg der n:es li, r inr csLigaringleednrg habits o | fiih. /a
C. A. Sinensrod ond -s. J. Liporskr
habits snrdies- lst l'!.inf
\l ashingt,', iia
\o
ldls.) Irish lbol
hw.sl tcchnical ivorkshop.
G.!nr \ISG X O 7; 2. Urn.rsirr
Wasl|irgton, Seottle- trashinston.
t't). 13-:',5.
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