Cold storage of the sperm of the endemic trout Oncorhynchus mykiss nelsoni: a strategy for short-term germplasm conservation of endemic species

Abstract

Aiming to determine an appropriate protocol for short-term storage of the sperm of San Pedro Mártir trout,Oncorhynchus mykiss nelsoni, wild fish previously matured in captivity were anesthetized and the semen, obtainedby abdominal pressure, was suspended in Erdhal and Graham extender at 1:3, 1:6 and 1:9 dilution ratios and kept at4° C for 9 days with an undiluted sample as control. The percentages of sperm motility and membrane integrity wereassessed daily. The results indicated that sperm suspended at a dilution of 1:9 can be stored at 4° C with ≥ 80% motilityand ≥ 65% membrane integrity for 7 and 6 days respectively. In addition, the results show that membrane integritydecreased more rapidly than motility, which suggests that it may be used as an early indicator of sperm damage duringshort-term cold storage. The results obtained are important to support future conservation programs of this trout.