Seasonal movements & demographics of a critically endangered desert spring fish

Authors: Summer Burdick, James Harter, Mark Beckstrand, Rachael Paul-Wilson, Brian Hayes, Collin Smith, Russell Perry

Year: 2023

Abstract

Range and abundance of White River spinedace contracted over the 20th century from a known range that included at least seven springs in the White River Valley and part of the White River to only the Flag Springs complex in central Nevada. By 1991 and 1992 it was suspected that the species was limited to only 37 spinedace, nearing their maximum lifespan, that were captured in a 25 m long pool at the headwaters of north Flag Springs. Following removal of largemouth bass from the Flag Springs complex in Central Nevada and reintroduction of 20 spinedace to bass-free waters, reproduction ensued and the population rebounded. Emboldened by this success, a second reintroduction into Indian Springs was attempted in 2004 and 2005. This translocation failed to produce a reproductive population and it was suspected that lack of spawning habitat was the cause. To inform future reintroduction attempts, information is needed on spawning habitat use and demographic parameters for the species. We PIT tagged and released White River spinedace during four biannual events from November 2020 to June 2022. Fish were recaptured in minnow traps or detected on six passive PIT tag detection antennas placed throughout Flag Springs complex. Movement data were evaluated to understand seasonal habitat use. We used data on recaptured and redetected fish in a Barker mark-recapture model to estimate monthly survival rates between recapture events. Survival was greater between June and November than between November and June. The estimated recapture probability from these models was multiplied by the number of captured fish to estimate population size. We estimated there were from 322 to 874 White River spinedace in the Flag Springs complex. White River spinedace were active during spawning season but did not select habitat based on water temperature.