Early Development of Pacific Surf Smelt (Hypomesus pretiosus)

We observed development in surf smelt (Hypomesus pretiosus) embryos from 24 hours post fertilization through hatch, at water temperatures of 12.52 oC (SD = 0.22) to 22.37 oC (SD = 1.14). Our system mimicked the tidal cycle by draining incubation chambers of water for 12 hours a day in concert with a photoperiod that mimicked a seasonal light/dark cycle of 16 hours of light and eight hours of darkness. The first detected heartbeat was documented at 62 degree days, partial hatch occurred by 187 degree days, and all remaining live eggs had hatched by 225 degree days. Developmental milestones were documented with micro photography and videography. Various developmental stages were illustrated in pen and ink for documentation. This work was used to gather developmental baseline data for the species. Key Points: We documented in photos, video, and illustrations, the embryological development of surf smelt. This lays the groundwork for future studies, including ecotoxicology, ocean acidification, and effects of shoreline modification.