A generalized approach for sperm cryopreservation in the genus Pomoxis: Sperm cryopreservation and fertilization efficiency of black‐stripe black crappie, Pomoxis nigromaculatus

Abstract

Abstract Approaches for white crappie, Pomoxis annularis sperm cryopreservation have led to interest in applying similar methods to black‐stripe black crappie, Pomoxis nigromaculatus. Their rarity in wild populations makes them a preferred phenotype for hatchery use. Sperm cryopreservation procedures were compared between black‐stripe black crappie and white crappie for sperm motility and egg fertilization rate. There was no difference in black‐stripe black crappie sperm motility after thawing between 5% dimethyl sulfoxide (DMSO, 45% motility) and 10% methanol (50% motility). However, fertilization rates were higher (p < .001) for sperm cryoprotected with 5% DMSO (38 ± 8%) than 10% methanol (22 ± 7%). Hatchery use requires sperm‐to‐egg ratios and fertilizing potential of single doses (i.e., 0.5 ml straw). Using black‐stripe black crappie sperm (2.5 × 108 sperm/ml; 5% DMSO), the highest fertilization (27%) was found using single straws with 785 eggs (0.25 ml); total sperm:egg ratio: 159,000:1; motile sperm:egg ratio: 71,700:1. Therefore, sperm of two Pomoxis species could be cryopreserved using 350 mOsmol/kg Hanks' balanced salt solution as an extender, 5% DMSO as a cryoprotectant, cooling at 40°C/min, and thawing for 8 s at 40°C to maintain sperm motility and fertility. Basic protocols can be generalized within a genus if variables such as sperm concentration, process timing, and sample volumes are controlled.

Keywords

• black‐nose
• Centrarchidae
• crappie
• cryopreservation
• fertilization
• Pomoxis