Determining post-stocking fate of June sucker, Chasmistes liorus, in Utah Lake, UT

Authors: Chase Ehlo, Jamie Wisenall, Brian R. Kesner, Paul C. Marsh

Year: 2013 (xlv)

Abstract

June sucker, Chasmistes liorus is an endangered fish endemic to Utah Lake, Utah. Its decline is attributed to overharvest, habitat degradation, and predation and competition by non-native species. A major component of the June Sucker Recovery Implementation Program (JSRIP) is augmentation of the remnant wild population with hatchery reared fish. Acoustic telemetry techniques were employed at Utah Lake to determine post-stocking survival and dispersion of hatchery reared June sucker. Twenty fish (10 in late July and 10 in mid-September 2013) longer than 200 mm were implanted with model PT-4 tags (Sonotronics, Inc., Tucson, Arizona) and tracked using a combination of active and passive methods for 60 days post stocking. Twenty submersible ultrasonic receivers (SURs) were placed in permanent stations throughout the lake and an additional 4-5 SURs were placed for ~24 hour periods at random locations. In addition, up to 300 manual tracking points were systematically visited weekly to pinpoint fish locations. Survival was calculated using the Kaplan-Meier estimator, and movement was analyzed using ArcGIS. Initial trials gave tag detection ranges of ~500 meters with SURs and ~200 meters with an omni-directional hydrophone. Sixty day post stocking survival of tagged fish was estimated at 58.3 %. They were generally associated with the pelagic zone of the lake and could move large distances (>10 km/day) between contacts. Cause of mortality is unknown for the fish, but large predators (i.e., brown trout Salmo trutta) were observed in the Provo River where two fish were determined dead, and many species of piscivorous birds are present on the lake (e.g., American white pelican, Pelecanus erythrorhynchos). In a lake that can be difficult to sample with traditional methods, such as netting, we have shown acoustic telemetry to be successful in providing post-stocking survival and general dispersion of June sucker. With continued efforts these data will help to support management recommendations for the long term persistence and recovery of the species.