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others have young that drift into the lake, predation is believed to eliminate young native fish from the reservoir and precludes their survival/recruitment. The biggest sport fisheries management challenge is trying to stabilize a striped bass population that reproduces without limits and decimates pelagic stocks of threadfin shad upon which they depend. Elimination of shad results in striped bass starvation. Reduction of striped bass numbers allow shad to rebound from adult stocks residing in turbid, thermal refuges where they are less vulnerable to striped bass predation. As shad reenter the pelagic zone in large numbers, they are eaten by young stripers who grow rapidly, mature, and then, once again, eliminate shad from the pelagic zone. This classic predator-prey cycle fluctuated wildly during the 1980's and still occurs at present but within narrower parameters. Threadfin shad in Lake Powell exist in the northern most portion of their range. Lower lethal temperatures for shad are reported as 4.5-5° C. Shad currently survive winters where water temperatures consistently range near the lethal limit by seeking deep strata where temperature is stable without sudden changes that could trigger massive shad mortality. A reduction of even 1° C. may remove the shad thermal refuge and result in loss of shad over winter. Any proposal to alter dam operations, such as a multilevel intake structure that could alter the lake heat budget, must be evaluated with the potential loss of shad in mind. The absence of a pelagic forage fish would be devastating to Lake Powell sport fisheries. The absence of shad would not eliminate striped bass which now reproduce without limit and subsist on plankton for the first year or two of life. The end result would be a permanently stunted striped bass population without quality sport fishing value that may exert extreme predatory pressure on plankton abundance and thereby negatively impact other Lake Powell fishes. Results of recent NPS and USFWS surveys indicate some biocontaminants show an increasing trend in aquatic organisms nearing the dam. Selenium in plankton from Wahweap Bay and Warm Creek ranged 5.3 to 14.6 ug/g dry weight. Striped bass filets taken in Warm Creek and near the dam contained 12.7 to 19.9 ug/g dry weight selenium. Although there has been no apparent negative impacts on reproduction or survival of striped bass themselves, selenium at these levels could pose potential problems to anglers. Removal of angler catch limits of striped bass as a means of reducing that species has increased the opportunity for anglers to take and consume large quantities of fish filets containing selenium. Educating anglers and involving public health officials in risk assessment for developing consumption advisories is recommended, if determined that they are needed. 2. Lake Powell Goal: Maintain a stable, balanced sport fishery. 3. Lake Powell Management Objectives a. Provide sport fisheries with an average catch rate of 0.5 fish/hour for all species combined. 20