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<br /> <br />Figure 64 Colorado squawflshlcharalote. 360 cm In total length" The specimen is a <br />hatchery-reared offspring (1974 year.class) of brOOdllSh caplured In the Green River <br />basin 01 Utah" <br /> <br />Ilshes after hecomln~ longer than 75 to 100 mm <br />Adults eat IJ[hr-r fishes ,Ind thus prohe and .....ander <br />extenslH:ly In ~t"arch of food. A squa.....flsh III 90 cm <br />long Ilr more must have devoured .dmos[ ,!flY orher <br />(ish in the river. <br />Squ.l\dish spJ......n owr gravd bar!> m channels 1)( <br />rivers In spring or summer. afn:r water temper.ltures <br />exceed 20' to 21 C. They often move lonF <br />distances w (('proJuce. and remrn ~'e;lr after reM [0 <br />the s.lffie lH J simdJr spawnmg .Ired. ,\talor runs In <br />spring mto rhe Gila RI\.er. well Jocumentr-d In olJ <br />newspaper .ICCOUntS. must hdH' been related to <br />spawning. Brt"t'Jmg squJ.wtlso bt"tome slh'ery <br />JhllVt" and creamy yellow on the belly With an <br />Intt"nse arr.IY of brlt:h[ f:olden tlecks lln the upper <br />SIl:lt'S. <br />RazorbaC"k 'iuckers (Fig. (5) tt"nded t!1 occupy <br />strong. unlfllrm currents o\"er sandy honoms They <br />also lived In tJdles and backwJters lareLl1 en the <br />river chanOt.!>;. sometimes concemratlnt: in dt"ep <br />places near CUt banks or {,lllt-n trt"e~ Lar~e J.dults <br />approAched or eX((:t"JeJ "'5 cm m len~h and m\lre <br />than 5.0 kg In wtif:ht A remnant population of <br />larFe adults In Lake ~[oh,l\'e, ACllOna.:\"evJ.da. <br />spawns from iJ.[t' )anuJry rhrou!,h April oYer t:rJ'I't'lly <br />bottoms In rdatl\.ely shallow water (FIt:. 661. :\faJe~ <br />become dark bro.....n to black lm tht" h,lck ,Ind <br />develop a russet. to orAflFe"colored !.iterJI b.lnd .\Od <br />yellow belly. Coarse. slurp rubercles. which are horn. <br />iJke outgrowths of skm. Me dt'\"elopt'd on the .Inal. <br />caudal. Jnd pelVIC tIns. and un the caud.ll peduncle. <br /> <br />Tht"se funcuun to hold the female Jurln,g tht <br />spawning .1U h'males th.1t hA\T spawned repe.Hedly <br />mJ}" bt. scarrt-d J.od abrJJed from ((lmact~ with <br />malt"s and with rocky bottllrns. Tht" t'K":;S J.rt' adhesive <br />and Me depl1sHed In ~pJ.(t's between ~r;l\'els. They <br />h,ltch In ,\ few d,lYS and younF mo'l"t to the shoreline <br />for.1 tlme" <br />Dt'spJte successtul reproJuctlun. there IS no <br />('\.iden(e for suC"ct's~ful f('lrUHment llr yuun,!:: iish intO <br />the LJke ~l(lha'.t' pllpulJuon for more than twO <br />dt(,ldes. Laf\Je mystt'f1ously dlsappc.!r before <br />achll.vln.c 15 mm roral len,..:;th. TOt" same situation <br />apr{'us co exist In mht"r, t1\'t"rme pans of the <br />Color.ldo River baSin. .\nd the speCIes IS proposed <br />for listing .IS end,ln~ert"d. Under natural conditions <br />m sttt'Jms. youn.c fi~h must have occupied <br />shtlrehnes. then flllH'ed With ,.-;rov.-th into h.lbuats <br />slmtlar to those IUH dt'sct1bed fllr Yt1un.c squawfish. <br />Razorb'lcks ft'eJ mllstly from tht. bocmm. hut have <br />ellml"-ated, "fuzz~'" t:lllr.lhrs .lnd .1 suhtt:rminal <br />mllUth hl)th ch,H.lCtet1stic t)f planktonlC" or detrital <br />tt"t-din!:: habits. <br />Remark.lbl~. little IS known \If the ecoloFY of <br />bonyt.til (FIg.. 6"'1" ,wd they are almost Fone m <br />nJture A sm.dl ropulatLon perSists In Llkf' Moha\"e. <br />bur lmly .I few have been recorJt'd from che upper <br />Colorado River In recent years. :\$ with razorbacks. <br />there ;.Itt' no records of suC({'ssful recruitment tlf thiS <br />spt'ues lor many JeC"ades. speCImens caught m <br />nature J.U J.ppear to be old (.;5-40 yr) adults" <br />BlInytad art' Iar,..::e. srrt":l.mlmed Ilshes thJ( have lon.c <br /> <br />32 <br />