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<br />SENT' BY: <br /> <br />1-12-96 <br /> <br />3:13PM <br /> <br />UTAH WILDLIFE RES. 4 <br /> <br />303-236-0027;# 3/12 <br /> <br />~ho following ~gguroptio~"z <br /> <br />~p Rlparl~n ~land8 constitute critioal rearing habitat for <br />na.tive fish; <br /> <br />~~ The current lo~ popUlat1ona Of ~hQGe fish are related to a <br />d8CraaBft tn the ~v~ilability of thw&9 babitats; and, <br /> <br />3. Flood<>d bottOmland" "an be ....n.lpulat.d and l1IAnA9"d (L... vi... <br />leve9 rerrava..l) in. weh . way.. to lncrsaJilCI rsa.:t"lng hab1.ta'l: at.td <br />~~imlme ourvivorBhLp oE young native fish. <br /> <br />.Because the levgg rlimlOV"al and land aequ.iait!on proqrara reprQQAJlt~ .a <br />Bubstantial c~twent of financial resources, it ia prudant to <br />comprehenaively ev~lu4te ~he8e 4B~umptiQn&. <br /> <br />Ill. gtud~ coala, abjBotive"r End Product, <br /> <br />BackgrOUnd <br /> <br />PreviOUB re8earch has dooumented. thQ ~rtllnc9 of low velocity habitats <br />(backwaterB) within the ~ln Cbannal 55 habit.t for nativs fish. The <br />formation and malntQnanCQ at tb9BQ nursery habitatB are currently undar <br />investigation (Sohmidt.) aa :L. the iCl'lpOrtance ot 'thes" areas to ~quawfi.Bh <br />populmtion dynamic. (Lent.ch) and ra~orbeok euckera (Vernal, CRFP). <br />F1OOdplaL~ watland. reprQaont ~n additional level Qf habitat and <br />biological CQmplexity and ara potentially very important for endangered <br />fish reoovQry~ Thair functio~l rQ~conn8ctioD in ths U~~ colorado <br />River 8agi~ ~ay bQ QQpoci~lly ~rtant given a gener.l rQduction in <br />chmtulel and fl.OOdplain complexity over the last 100 ye""". Thi.. <br />reduction can geO-erally be aaBociated with dam construction and flOOd <br />managarngnt actlvit~Q8. <br /> <br />Floodplain wetland. are generally area. of hiqh primary productivity. <br />They poBse8s elevated te~peratures, nutrientB, and light intenaitiaa. <br />Deoay of plant material (QmOrgent and floodsd terre.trial vegetation) <br />euppcrtu a large decOlllpo.itionAl p&t~ay within the overall foodweb. <br />The ~roduction of food orqanlmae for fish i. oorreopondlngly hiqh <br />bacauoo of . large food base (phytoplapkton, eto.), a structur.lly <br />complex environment (structure 9~ovided by emergent plants, flooded <br />vaqetation, and Algal m&ts), and W~r water temperaturQQ relative tc <br />the rlvQr~ rheg~ fAotocs takQrt in aggregate PU99Qgt that flood9d bottom <br />Landa are GxtraMaly prod~ctive areaa. <br /> <br />BBcaUBe or enhanced productiv~ty of food organisms, floodplain wetlanda <br />facilitAte rapld fish growtb and .urvival within the BreaD (rBsults of <br />OamundBQo) and enhance fish SUrvivorship and growth ~ithin the river <br />sYBtem. NativB young-of-the-ysAr (YOY) fisb th.t leave the river and <br />utl1i.e floodplain wetland. should be 8 larger s1.. than 1f they WOuld <br />have ramainad In the rivo~. Larger nu~lve ror fL~b 8hould be 1888 <br />Bu.captibla to predation by mogt dortnative fish in the main channel. <br />~hQ increase in 8iEB, tberetore. should erthanCQ aurvlvorship. These <br />potential benetitB co~ld be offset, however, if ~po~tant no~native fieh <br />specieB also utili.e theee habitats and enhance their gro~th and <br />6urv~vo~~hip~ The potential exists for nonnatlTQ flah to ba enhanced to <br />