What’s up with the Devils Hole Pupfish: spring and autumn counts highest in over 20 years

Authors: Kevin Wilson, Jeffrey Goldstein, John Wullschleger, Ambre Chaudoin, Olin Feuerbacher, Jennifer Gumm, Daniel Villanueva, Michael Schwemm, John Umek, Mark Hausner

Year: 2024

Abstract

The Devils Hole Pupfish Cyprinodon diabolis continues to inspire managing agencies of this critically endangered fish. Spring and autumn population counts in 2022 and 2023 have been at 22 and 20-year highs, respectively. Spring counts in 2023 and 2024 were the same with 175 observable pupfish. The highest spring counts since 2001. Autumn counts in 2022 and 2023 were also the same with 263 observable pupfish. The highest autumn counts in 20 years. Spring and autumn counts in 2024 were more variable with the spring increasing to 191 and the autumn count declining to 212 observable pupfish. The three managing agencies the National Park Service (NPS), the US Fish and Wildlife Service (FWS), and the Nevada Department of Wildlife (NDOW) continue to implement conservation and recovery actions outlined in a Strategic Plan for Devils Hole and the Devils Hole Pupfish (DHP). These include systematic monitoring of biotic and abiotic ecosystem processes, as well as developing specific research projects that investigate potential reasons for the recent fluctuations in population numbers. Two recent projects include a data synthesis project and a food web study. The data synthesis project used random forest modeling, a form of machine learning, to examine nine years of ecosystem monitoring data for causal relationships between abiotic and biotic parameters within the ecosystem and pupfish population dynamics. The food web project will incorporate the use of amino acid stable isotope analyses to better understand the role of autochthonous and allochthonous carbon contributions to the diet of the DHP, as well as the role of supplemental feeding. Initiated in January 2007, the supplemental feeding program is believed to have saved the DHP from extinction. Results from the random forest modeling suggest that the energy supplement continues to significantly influence DHP population dynamics. The food web study is designed in part to quantify this influence. This ongoing research is funded by the managing agencies to ensure that the best available science informs the adaptive management of Devils Hole.