7025 - Laserfiche WebLink

Home Browse Search

27 Disease Fathead minnow was specifically identified as a possible disease source for native fishes by one respondent. Another identified Asiatic tapeworm as a disease problem. Habitat Alteration The common carp was listed by two respondents as having an impact upon native fishes through habitat alteration. Question 5: Are you aware of any documented evidence, published or not, in the Colorado River Basin demonstrating: -predation upon endangered fishes, in genera~ selectively, or as a threat to population survival? -a competitive advantage of an introduced fish species over an endangered or other native fish species? -a beneficial effect of an introduced species upon the native fish fauna? If the answer is yes to any of the above, please summarize below and cite the appropriate literature reference, or, if possible, please provide us with copies of unpublished reports. If the evidence exists as unpublished raw data, please specify as such. Sixty-two percent of the 26 respondents answered yes to the predation segment of the question. Apart from the eight references cited by numerous respondents, references were also made in two instances to unpublished file data in Utah DWR and at Arizona State University. Personal communication was cited several times regarding predation upon razorback sucker larvae or humpback chub. One respondent was confused by what defined "documented evidence" and two indicated they did not have time to adequately answer this question. Northern pike were listed as a possible "undocumented" threat to T&E species in the Green, White, and possibly Duchesne rivers. Smallmouth bass, flathead catfish and channel catfish were listed as predation problems for all native fish species in the Gila River basin. Two respondents indicated predation problems occurring primarily in impoundments. One respondent indicated predation by Colorado squawfish on channel catfish was a threat. I ! I 1 I Fifty percent of 20 respondents answered yes to the competition segment of the question, though few sources of evidence were cited One respondent indicated northern pike were dominating clear backwater habitat in the upper Yampa. Several respondents referred to the competitive impact of red shiner upon spikedace and loach minnow documented in draft'recovery plans for the two species in the lower Colorado River Basin. One respondent cited the increased catch/unit effort index for nonnative species relative to, native species as circumstantial evidence. One respondent felt red shiner undoubtedly had