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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3-5

4. Assumptions 2 end 3 on poge 171, regarding "No significant
di fference in depth preferences between Green land Colorado Ri vers", caul d be
more approprietely addressed ~ith Stcndara stjt;st;cel analyses.

5. The constraints of these curves I(pa~e 17) are accurate, but
constraint 2 (curves eprly only to backwater$) could severely limit use of
these oppth, velocity and substratE' ti.U. curv~s. StrEam channEl model s not
containing backwater h?bitats ';Jould ex.elucte trEir lISE. There do not appear
to b~ many Phl1.BSlh (Physical H(joHClt Simulatipn t.~ode1) cross-sE'ction models
thdt i ncl uae backwater habi tats. Tni s poi nTs! out a stlortcomi n9 of the IFIM
(lnstrE-am Flow Increrr.entel tv;ethoc1). If ~OY souawfish use backwaters
extensively, tne PHA8SIf~ should be modified tq consicer backwater h?bitats.
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3.2.5 Juvenile (60-249 nrn) Coloriluo SqU~\Jfish rlepth fine velocity.
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1. In Dati:. Utilized, (r~gc 25) !.rp l.r,qth intervcl :<61-2iL9 r.un TL
Jpr~ars to be a typo error -- should be bl - 449 mm TL.

2. I.alat is the criteria for dividiT19 Ithe juveniles ir.to t\"JO length
grNlps (b(l - 249 and ~5l) - 44~ mm TL)? BClsad on the H.Li. curves on pages
~b, ~(< ano jU, end 3(:, the p?rtiticr,illf! ~J(lS bds€c on some prior knm-vledge of
diite sepcr~tion or a statistical analysis. Tlhf' cepth H.U.cw"ves (pcges 26
,"nd ju) slimJ perticularly good Si:par2'':ion, r. ut thE.' Cl'rVt'S on pr:ges 28 aM
j, st:ow considerable: overlap. A statistical I dt'1?lysis is nceded to confirm
i: his per t; : i en i n 9 .1

w. Hahitat aata for juvenile Coloraaosou?wfish h~s always been
difticult to obtain because of the peucitv 6f fish CcptureCl in this size
ran~e. wI
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~.(:.f Juvf'ni1f' (250 - ~1jS' pn) Cr>lIJT"(l(!O ou?\lfish cwrtr nnf: velocit.y.

1. F.ssumpticns '- ef;d 3 rr-tlEct e g?p it thE:' r!"til biiSr- that tl?S been
ditti cul t to fi 11 . SC~t- depth ann vel oci ty 1C'!i':ta croP. prE'sentrd in hi stori c
dnc state (ColorcJoo Oi\'is;on of Idldlife)1 data trct cOI.;1(1 be uSt:d to
SlJpplpment the FWS data. 1

2. If the velocity H.U. curves apply nly to hydraulic r-!otif'lswhose
out~ut.is m~~n coluMn velocity, have these m01els b~f..'n thoroughly testec Clnd
vall0ated atl~ld? I

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,j.2.i Juvl'1nilF' (60 - dSI.l mm) Coloraco S~\Jc.,-.Jtish substrate.
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1. Tre dccurT'~'nt(Jtion c.prf'~rs to be r~,:;sonilblC' for the substrate
para~etpr for all juvenilps.

3.2.0 Adult (>2UfJ IP'" lL) hulT'poi'!cY. chuh Icpth, vplccity. and substrate.

1. lJcflrly (111 of tile dati1 tI~cd in (icv~loping I1.U. curvp.s for depth,
vel oci ty ane suhstrClti: were call f.ctcd trom ~lUlrnpb()ck. chub. jp Bl eck f\ocks and
~€>stwiitcr. ~;tatistical tests should be conliLJcL:cJ to dE.termine if a