8144

• UCREFRP Catalog Number: 8144
• Author: Valdez, R. A.
• Title: Evaluation of Habitat Utilization Curves for Endangered Colorado River Fishes.
• USFW Year: 1985.
• USFW - Doc Type: \
• Copyright Material: NO

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3. What criteria were used to select th~ 5U% frequency discharge range
for 1~80-1984 as optimum for staging? If t~is level is used, the optimum
velocity range for staging will certainly be ~ias€d by the high runoff years
of 19b2-83 and 19&3-84. 1-

4. The logic for not developing substrate utilization curves for adult
st2ging Coloraao squawfish appears to be re2s~n2ble.
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3.2.3 Adult Colorado squawfish oEposition depth, velocity end substrate.

"bel ipVE'OI' to bE= more definitive?
made ~etween radio observations and
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2. Constraints 1 ~nQ 2 (page 11), rcoardinq the deposition depths useG
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by scui:"rtish sl'ou1n bE' C'fT'p!1i1siz('ri. 1
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.:l. How do rhe mOdeled rz.r,~f' of rlf?en wn~er column ve-l;citieS (page 13)
ccrr;p~re ~'Jith iJctllal. field measunments? hO\IIiT'UCI1 tiplr vaiidi:tion has this
I~ydr.)~l ic morjel rF"ce;ve:d?

4. ~ihat criteria werE.' used to selE?ct I the overlcppin9 5C~s frequency
"-c.nqe at bJCI1 chs~rved discfrc:rgf' iiS optimuml for spa~ming ([ata Utilizeo,
pa9~ l~)? lhlS conc~pt nepds to be further etpl~ine~.
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5. r-~Pf7ardins: crposition substr2tf?, only the prcdC'8incte substrate is
recognized. is it dC(1';n;:nce that ~p.ys ? fis~ to (! pr;rticular substrate for
s!J('l',:nirrg or is it ttlf' percentaqe of finels (sl1t)? This analysis r:ay
prov; riP a c1 u€' to gr:nerC1l substl~a te use but I not to tIll? speC" ifi C substrate
fff!tur~ t.hat ~ni'!t'li!:'s c1 fish to spC.~m Anr. its IC99S Jnct youn'] to survivE in i'!
given arra (Lamarra et al. lS~4).

1. How ",ere radio observations
5tatistical data ccmpftrisons should be
traciticnal capture deta.

~.2.'~ VUY Colcranc sr:ua~Jfislr repth, '.tel city r;nd substriite.

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1. 1t appears from t11€ ('!ocUIp.E::ntctiorl of UctiJ Utilizer. fc.'r Ct.-ptil,
velocity and substrate h.U. curves for past-Ilarval VGV that nC'~r1y all the
~veilable HiS data .'I!€rE userl. It is not IICE:'ftain if the "intEnsive YUY
collections (1979-1921) ponled~ (p~gc 17) are at the exclusion of the
b (i 1 en ceo! the "s t.8 n d ii r d; ~ e a 5 a Iii p 1 i n 9 p r ~ 0 r ? f'1 :' . ( ~ c: 9!" ;::0, ~ 3) for t h p
Colorado R1VCf. ThlS dRt~ oase needs furthe~ deflnltlon.
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,. lhe reasons for excllldino ~c;lllst'orr:linf' i'<r.d othEr habitat
collections excE'pt backwaters" (pilges- 17, L4) arr' not cleer. It the fish
r:!cr.lonstrated a strong preferpncl' for back,,"'a~t::rs, shou1rl thp ottH'r Ircbitnts
bf: exrluced, even tr.olJ~h fistl Wf'fe fauno ir these oth~~r habitnts? This
pArtitioning is biast:-d tO~/(UO r-eckwatersl (see subspcticr. L.5 of this
rloCll~e"t). I
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J. It is probably trup tnat catch per u~it pftort is a true reflpction
of h~bltat preferred. I

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