Thermal tolerance of allis shad (Alosa alosa) embryos and larvae: Modeling and potential applications

The objective of this study was to assess the potential effects of climate change on the survival of allis shad early life history stages. Embryos and larvae were exposed to temperatures ranging from 5 to 35 degrees C. No embryonic survival was recorded at extreme temperatures (<= 10 and >= 30 degrees C), and no larval survival was observed at 5 or 35 degrees C. Based on these experimental results, a survival model was developed to predict survival rates at different temperatures for embryos and larvae up to 14 days post hatch. The model confirmed that embryonic daily survival is more impacted by temperature than larval survival. The highest survival rates (greater than 80%) were found for temperatures between 15.7 and 25.6 degrees C for embryos and between 14.6 and 26.7 degrees C for larvae. This survival model can be used to explore the impact of temperature on recruitment of allis shad in southern France. Preliminary analysis from two different rivers suggests that cold temperatures may have a strong impact on embryonic and larval survival.