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<br />. 38 <br /> <br />~ ~ ( <br />. <br /> <br />. . <br /> <br />of popu.la~io.c... ::;8:;.: 1'.'.:..tio and disLributioLl, feCi.lI.ldity i.cwestie.-:atio.clS, <br /> <br />and forJbroodsLock.recovery progra8s. <br /> <br />Durir"g- the <br /> <br />, . <br />b,reec.i.clg <br /> <br />season, <br /> <br />male ill~ female Xyrauchen are easily distinguished on the basis of <br /> <br />differential coloration aad tubercula~ton. Throughout the year, <br /> <br />sexes are most easily distinguished by differences in the relative <br /> <br />size and morphology of the urogenital papilla. <br /> <br />.r'ecu.!ldi ty is lc.nO';.;n to inCl'ease v.; ieil length 8.!ld/ or weight j but, <br /> <br />in many species, feCUtlJi ty incl'eases ,'i1 t.h age, then decreases in <br /> <br />very old fish irregardless of size increments (ji~olski, 1969). <br /> <br />In ordez" to form a complete picture of XYTCl,ucnen fecund.ity: it ltdll <br /> <br />tl; necessary to fir"st olJtain mature individu:3.1s from. a size class <br /> <br />other than that e{iCO:l.c1tereu thus [al' in Lake Ivlohave, and second to <br /> <br />relate these size classes to age. <br /> <br />. , <br /> <br />DISCUSSIOl\J <br /> <br />i\.d.vcrse 'factors efi E:C ting the Lake Nohave Xyrauchen population <br /> <br />, . <br />ill&Y be roughly divided into thr~e categories: (1) ecological ef~. <br /> <br />fects, (2) patnuldbical factors and (J) gen~tic competition.. <br /> <br />'l'he loweriilg of mean ~vat.er 'vern"peratures and desil tatioi1 ot the <br /> <br />" (;010r:.:luo tii vel' belo.-: Hoover Darn, in cornbi{lation with the introduc- <br /> <br />'~l ..' . , <br />