Shielding Endangered Lineages via Strategic Biobanking: Evaluating Extenders and Thaw Rates for Optimizing Viability of Cryopreserved Milt from Golden Mahseer (Tor putitora)

Abstract

Background: The Golden Mahseer (Tor putitora) is a coldwater fish species of paramount ecological, economic and cultural importance in India, now facing endangerment. In response to the urgency of conservation, this study focuses on the cryopreservation of Golden Mahseer milt, aiming to contribute valuable insights to conservation efforts. Methods: To evaluate cryopreservation protocols, we tested four extender solutions (E1-E4) and applied three thawing temperatures (37, 40, 45°C). The primary indicators of sperm quality were motility rate and duration. The study employed statistical analyses to assess the significance of the results. Result: Extender E1 (modified Ringer’s solution) demonstrated remarkable performance, achieving a 42% motility rate at 37°C, surpassing E2 (31%) and significantly outperforming E3/E4 (3-5%) (P≤0.05). However, within E1, increasing thawing temperatures led to a progressive decline in motility, from 42% at 37°C to approximately 12% at 40°C and 11% at 45°C (P≤0.05), attributed to thermal shock. The success of cryopreservation was found to depend significantly on both extender formulation and controlled thawing rates (P≤0.05). These findings offer crucial insights to strategically enhance post-thaw viability, paving the way for indefinite biobanking and potential species resurrection, aligning with critical conservation goals for the endangered Golden Mahseer.