Laserfiche WebLink
<br />2 <br />Abstract <br />Since their introduction in the mid-1970's, fathead minnows Pimephales promelas <br />rose to numerical dominance of the fish community in Upper Klamath Lake, Oregon, <br />occupying nursery habitats of the endangered Lost River and shortnose suckers (Del=es <br />luxatus and Chasmistes brevirostris) in great numbers. This study, in which laboratory <br />experiments assessed the predatory capability of fathead minnows on sucker larvae, is a <br />first attempt at assessing potential predatory impacts of introduced fathead minnows on <br />the endangered suckers. Despite lack of literature accounts of fathead minnow piscivory, <br />fathead minnows readily consumed sucker larvae in this study. Fathead minnow <br />piscivory appeared to be related to group behavior, no predation on sucker larvae <br />occurred unless at least three fathead minnows were present. Fathead minnows were not <br />gape limited when consuming sucker larvae because groups of minnows tore larvae apart <br />and ate them piecemeal. Presence of Daphnia and artificial dry food as alternate prey <br />reduced but did not eliminate predation on sucker larvae. Provision of cover in the form <br />of Scirpus stems reduced mean predation rates to 63 % relative to 97% in tanks without <br />cover. Potential significance of these results is discussed relative to sucker year class <br />formation and water management practices in Upper Klamath Lake.