6010 - Laserfiche WebLink

Home Browse Search

- 22 - of all species and sizes were salvaged along the entire river by the public for use as bait or food. At no time did a buildup of fish produce a nzisance problem . Post-Treatment Investigations In the six mohths following treatment, an attempt was made to determine the exact extent of fish reduction. Fish population checks were made with gill nets and rotenone as long as weather and ice conditions permitted. Subsequent winter investigations were made with dynamite. Over- night gill net sets were made in the numerous locations yielding fish prior to treatment. After treatment no fish were taken in the sets below Big Piney, and whitefish were the only species caught above that point. The whitefish were probably downstream migrants from untreated waters. In October small unidentified fish, probably cyprinids, were seen approximately six miles below Green River Station 1. In November, additional unidentified fish were seen in the New Fork River between Stations 1 and 2, and two redside shiners were captured with a handnet in a backwater below Station 2. Tn addition, rotenone spot checks in the upper treatment area revealed the presence of numerous suckers and cyprinid fry and fingerling in some of the small backwaters. In October rotenone spot checks were made on the disconnected sloughs and backwaters along the New Fork drainage where small carp were found prior to treatment. Numerous fish, including trout and carp, were still present in some of the sloughs sampled. A single brown trout and a few dozen sucker fry were found in a small, side-channel dam about ten miles below New Fork Station 1. The fry were probably newly hatched and the larger fish may well 'nave been downstream migrants. Water temperatures in the sloughs were in the low forties when the fish were: discovered and retreatment at that time was deferred until the spring of 1.963. ti-~ Sampling by underwater dynamite detonation was initiated in late November when ice conditions precluded the effective use of gill nets. As of April 1, 1963 a comprehensive dynamite sampling program on all main stream waters has produced only a few whitefish in the upper treated area. From September 20, 1962 to November 28, 1962 Petroleum Geophysical Company of Denver, Colorado carried on intensive seismographic survey operations on the Green River. From the town of Green River, Wyoming to a point about three miles down- stream from the Utah-Wyoming state line, 275 underwater detonations at one-fourth mile intervals, using high velocity 40-60 percent nitroglycerine explosive, were made. All "shots" were made in the Green River proper at water depths of from two to six feet. During the period of these seismographic operations, the river water was clear and visibility was excellent. Petroleum Geophysical Corporation reported that no fish were observed in this section of the river. Comparative observations, before and after treatment, indicate almost total destruction of the aquatic invertebrate fauna present in the river prior to treatment. The pretreatment aquatic invertebrate fauna included the follow- ing forms: Hydracarina, Gastropoda, Annelida, Nematoda, Diptera, Ephemeroptera, Plecoptera, Trichoptera, Coleoptera, Hemiptera, Odonata, and Lepidoptera. Representatives of all of these groups, except Lepidoptera, have been found in invertebrate collections made since the treatment, but as of March 1 none of the forms had regained their former distribution in the river. It is planned to continue fish and invertebrate population studies in order to establish the rate and degree of reccvery of river fauna. -~ . .. `'ram;"