Thermally Induced Larval Mortality in Hybrid Clarias Catfish: A Bio-Economic Modelling Framework for Climate-Resilient Aquaculture

Hybrid Clarias catfish account for more than 90% of farmed catfish production in Thailand, making hatchery resilience relevant to the continuity of freshwater fish supply. This secondary-data modelling study evaluated how early-life thermal stress may propagate from biological performance to hatchery production and longer-term economic outcomes. Previously published developmental data for hybrid Clarias catfish (Clarias gariepinus × C. macrocephalus) reared at 29 °C and 32 °C were used as empirical inputs to a coupled biological and bio-economic framework comprising temperature-dependent developmental functions, deterministic hatchery calculations, and 10-year scenario projections. In the source experiment, fertilization declined from 67.7% to 59.0%, hatching from 43.4% to 26.6%, and 72 h survival from 44.9% to 0% between 29 °C and 32 °C. The model represents the 32 °C condition as a developmental mismatch in which yolk reserves approach a near-depletion threshold before the assumed functional feeding threshold is attained. Under the illustrative hatchery assumptions, the unmitigated 32 °C scenario produced no viable fry at 72 h, whereas active cooling to 29 °C preserved modelled production but added energy cost. Ten-year projections further suggest that the relative economic performance of cooling and genomic adaptation depends strongly on assumed energy-cost escalation, thermal thresholds, and annual genetic gain. These projections should therefore be interpreted as scenario analyses rather than validated forecasts. The framework identifies parameters requiring empirical calibration and provides a basis for evaluating engineering, breeding, and combined adaptation strategies for climate-resilient hatchery management.