Optimization of shock conditions to induce gynogenesis in topmouth culter (Culter alburnus)

Standing duration (from fertilization to the beginning of cold shock), shocking temperature, and cold shock duration are critical factors for improving the fertility of the female parent and survivability of offspring in the gynogenesis of topmouth culter (Culter alburnus). A 3-factor quadratic-orthogonal-rotation combination design experiment was conducted to evaluate the main and interacting effects of these three factors on gynogenesis efficiency with the fewest experimental combinations. Two indices including gynogenesis and hatching rates were measured repeatedly for each experimental combination. Using quadratic regression equations of the two experimental indices for these factors, optimal factor combinations were screened within factorial-level intervals, such as a standing duration of 6 min, shock duration of 18 min, and shock temperature of 7 °C for the gynogenesis rate, while 6 min, 23 min, and 5 °C, respectively, were identified for the hatching rate. Response surface analysis showed that within factorial intervals, the single-factor curve and double-factor surface exhibited a convex shape. Among the three factors, standing duration showed the greatest contribution to both gynogenesis and hatching rates, while shocking duration showed the smallest contribution.