The Recruitment Window for June Sucker: Thermal and Temporal Characteristics for Spawning, Embryo Development, and Larval Recruitment

June sucker is an endangered, lacustrine-adfluvial sucker, endemic to Utah Lake. Municipal and agrarian water use has altered the ecohydrology of Utah Lake tributaries. These changes have decoupled June sucker’s life history strategies from its contemporary environment. Actions to recover June sucker include hydrological management of tributaries. We designed laboratory experiments to determine the thermal conditions necessary to promote embryo survival and estimate the effect of temperature on embryo and larval developmental rate. We determined that the thermal niche for embryos was 12-22°C. We determined time to larval swim-up at various temperatures and paired our data with field observations of time needed for adult spawning and larval out-migration to predict the recruitment window of June sucker in the Provo River. The number of days needed to provide a recruitment window, from spawning in the Provo River to larvae entering Utah Lake, ranged from 43 to 16 d, at 12 and 19°C, respectively. We estimated the recruitment window available to June sucker under hydrological regimes present in the Provo River in 2010, 2009, and 2008. Integration of June sucker’s ontogeny, specifically its recruitment window and thermal niche, with relationships between temperature and discharge, could be used to promote natural recruitment.