Enhancing Thermal Resilience in Delta Smelt: A Comparative Study of Temperature Regimes During Embryonic Development

This dataset contains larval heart rate measurements from hatchery-reared Delta Smelt (Hypomesus transpacificus), a critically endangered species native to the San Francisco Bay-Delta. The data were collected at the UC Davis Fish Conservation Physiology Lab as part of an experiment investigating how early-life exposure to different thermal environments influences cardiac performance and thermal tolerance. Embryos were incubated under three temperature regimes: constant (16°C), controlled diurnal fluctuation (16–20°C), and natural outdoor pond conditions with variable temperatures. Larval heart rate was recorded during an acute thermal ramp using a microscope-mounted camera system to track cardiac activity in real time. These data were collected to assess the physiological plasticity of Delta Smelt and to inform conservation hatchery strategies aimed at enhancing resilience to thermal stress.