Using temperature-dependent embryonic growth models to predict time of hatch of American lobster (Homarus americanus) in nature

Hatch time of American lobster (Homarus americanus) varies between years and regions, which affects temperature experienced by the developing larvae and hence the time and distance these drift before settling. Hatch time can be assessed by working with fishermen and inspecting the brood of gravid females caught in their traps. However, this would require frequent sampling as the hatch period is protracted (approximate to 7-12 weeks) and would require dedicated sampling in many regions where hatching occurs outside of the fishing season. To address these limitations, we tested the accuracy with which hatch time can be predicted by taking egg samples during the fishing season and estimating embryo development using embryonic eye size (Perkins eye index) and lab-derived, temperature-dependent development functions. Using a linear development function and observed variability in Perkins eye index at hatch, we successfully predicted 100% of the observed 50-day hatch period, and 96% of predicted hatch dates fell within this period. Our results suggest that samples can be obtained in collaboration with fishermen to predict the timing and progression of hatch of American lobster.