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<br />sunfish, and carp. Studies of the bass population have been on~oinr. <br />for only the last few yearn. Completion of these stu(lies is nchedulcd <br />for 1977. <br /> <br />1. .0enera1. Hany factors affect larr.emouth ballS reproduction; <br />these include air and ",ater temperatures, ",ind and wave action, water <br />quality, ve~etative cover--terrestr1al and aquatic, water level <br />fluctuation, predation, and human activity. The effects of each factor <br />are interrelated and are presently being studied. Recent studies <br />suggest that water level fluctuation, and its resultant effect on both <br />terrestrial and aquatic vegetation may be the major controllable item in <br />the management of the bass fishery on Lake Mead. <br /> <br />2. Cover. The filling of Lake Powell has produced relatively <br />stable ",ater levels in Lake Mead, ",hich resulted in the establishment of <br />aquatic plants. Dense and open plant communities of pond",eed sp., <br />cattail, anrl spiny naiad were present in coves and shallow areas durIng <br />periods of extended stable lake levelR. <br /> <br />tJell establiRhed zoneR of lH]Unt1c plnntH Hl"(-' conduc1vfo. to r,ood <br />hnBR production. ^ rl1pid incrcnsc of wnter lcvcd H tluch nH occurred 111 <br />197J floods the aquatics to excessive depths which rerluceR their cover <br />value. Under these conditions, ho",ever, good bass productIon may c.tIll <br />occur due to inundation of terrestrial ver,etation which is established <br />In well-defined shoreline zones because of stable conrlitions. <br /> <br />TerrestriRl cover appears to lose considerable value after 1 year <br />of flooding. The loss of Tamarisk fronds and finer stem material <br />results in less desirable escape cover for fry and [in~erling, and <br />evidently offers nothing to enrich the zooplankton bloom of the shore- <br />lines and coves. Also, receding ",ater levels during bass spa"'" may <br />aggravate the effects of bank e:>cposure. Sloughing bank lines may cause <br />suffocation and burial of nests. <br /> <br />3. T<:!"]lera ture. Studies indica te that bass are tr ip.v.ered into <br />spawning activity as spring approaches and "'ater temperatures reach <br />60oF. or above. Bass in Lake Mead do not follow this accepted pattern <br />anti have been cbserved to spat.m in tempcraturcfi .l1S low as 540P. Thls <br />of course occurs only in the early months of sprinr" particularly '\arcll. <br /> <br />4. _T_emperature Variations. l!indy weather and r,encrally cool air <br />masses over the lake seem to be the major factors caus1nr, water <br />temperatures to vary. IHnd action results in the movement of colder <br />"'a ter from the lo",er lake levels, in the open basi ns, in to the lit terol <br /> <br />17 <br />