The hatching of common carp ( Cyprinus carpio L.) embryos in response to exposure to different concentrations of cryoprotectant at low temperatures

Abstract

The hatching performance of embryos of the common carp ( Cyprinus carpio L.) was examined after 1, 7, 14, 21, or 28 days of storage at −8, −6, −4, −2, 0, 2, or 4 °C with different concentrations of methanol (0.5–7.0 M in 0.5 M steps) or varying concentrations of methanol in 0.1 M sucrose or trehalose. Preserved embryos failed to hatch after storage at −8 and −6 °C, regardless of the duration of storage or the concentrations tested. Likewise, there was no hatching out above 5.0 M concentration of methanol, even with the addition of sucrose or trehalose. After storage at 2 or 4 °C, the hatching rate was higher with mixtures of methanol (1.5 M) and trehalose (0.1 M) than with methanol plus sucrose or methanol alone. At 4 °C, the solution containing 1.5 M methanol supplemented with trehalose gave the highest hatching response of embryos stored for 14 days. Comparison of hatching after 24 h of storage at the effective temperatures (−4, −2, 0, 2, and 4 °C) revealed that low concentrations of methanol were effective at high temperatures and high concentrations at sub-zero temperatures. The combination of 0.1 M trehalose with 1.5 M methanol gave the highest percentage hatching out both at 4 and 2 °C. At 0 °C, the highest percentage hatching occurred with 0.1 M trehalose plus 2.5 M methanol and at −2 and 4 °C, the best results were with 0.1 M trehalose plus 3.0 M methanol.