Post-stocking fate of June sucker in Utah Lake 2013 Annual Report

June sucker (Chasmistes liorus) is an endangered species endemic to Utah Lake UT. The lake historically supported 13 native fish species, but due to human interactions it now supports a suite of non-native species and only two natives, June sucker and Utah sucker Catostomus ardens. June sucker once were numerous throughout the lake but numbers declined in the late 1990s to as few as 300 wild individuals. Many factors contributed to their decline including overharvest, habitat degradation, and predation and competition by non-native species. Repatriation of hatchery produced fish is a primary recovery strategy for June sucker, but fate of stocked fish is not well known. The purpose of this study is to detail immediate post-stocking survival and dispersal of hatchery reared June sucker in Utah Lake. In the first year of this study, 20 June sucker were surgically implanted with sonic tags and 10 fish were implanted with “dummy” tags. The acoustic tagged fish along with 1117 PIT tagged fish were released from the shoreline in two separate stocking events. A directional hydrophone and receiver were used to actively track fish and multiple submersible ultrasonic receivers that continuously scanned for tags were placed throughout the study area for passive tracking. Remote PIT scanners were utilized in the lake to scan PIT tagged fish. Kaplan-Meier survival estimates for each telemetry study were calculated based on the final fate of each acoustic tagged June sucker. Patterns of dispersal were assessed for individual fish by mapping active and passive tracking records in ArcView®. Kaplan-Meier survival estimates were 0.58, 0.42, and 0.90 for late summer fish, early autumn fish, and dummy tagged fish respectively. In both stockings, fish dispersed into the pelagic (open water) zone of the lake proper. Mean daily movement was 1.73 km for late summer fish and 1.27 km for early autumn fish. A total of 69 PIT tag contacts representing 58 unique fish were recorded over the four month study period using remote PIT scanners. Overall, fish stocked in late summer exhibited the greatest movement, highest survival, and fewest fish lost to the study. Predation, particularly bird predation, appeared to be a major factor in the poststocking survival of fish as evidenced by presence and documentation of California gulls consuming immediate post-stocked fish. This was most apparent in the early autumn stocking in which five fish were lost to the study and at least a portion of these were likely consumed by California gulls. With 2 continued efforts these data coupled with PIT scanning will help to support stocking decisions and ultimately ensure the long term persistence and conservation of the species. Introduction June sucker Chasmistes liorus is an endangered species endemic to Utah Lake UT (c

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