Environmental correlates for abundance, temporary emigration, and detection of Ash Meadows Amargosa Pupfish

Authors: Joshua Perkin, Jacob Wolff, Michael Schwemm, Ambre Chaudoin, Michael Bower, Kevin Guadalupe

Year: 2024

Abstract

The Ash Meadows Amargosa pupfish Cyprinodon nevadensis mionectes is a federally endangered pupfish endemic to Ash Meadows National Wildlife Refuge in the Mojave Desert of Nevada. This subspecies is threatened by non-native species introductions and alteration of habitats for agriculture, including diversion of spring outflows through irrigation canals. Conservation implementation strategies have included return of water flow to natural channels coupled with channel restoration and non-native species removal. Although pupfish have responded positively to restoration actions, additional research is needed to quantitatively link environmental correlates with abundance (i.e., number of fish at a site), temporary emigration (i.e., probability of movement in or out of a site), and detection (i.e., probability of trapping a fish when present at a site). We used a robust design repeated trapping experiment at 36 locations distributed across four spring systems to fit generalized N-mixture models to unmarked pupfish to test a series of ecological hypotheses. We found that pupfish abundance was positively correlated with warmer water temperatures and open canopies at thermal springheads, temporary emigration (measured as availability) was most likely for large stream channels, and detection was negatively correlated with increasing current velocity. These findings can be used to inform channel restoration designs to facilitate greater abundance and site fidelity as well as long-term monitoring designs to assess imperfect detection of individuals where current velocities are swift.