Sauger testicular harvest eliminates sperm limitation during large‐scale saugeye (Walleye × Sauger) production

Abstract

ObjectivePoor milt yield via strip‐spawning in male Sauger Sander canadensis limits the production of saugeye (female Walleye S. vitreus × male Sauger) by the Ohio Division of Wildlife. Compared to strip‐spawning, collecting sperm via testicular harvest offers several advantages that increase production efficiency through enhanced sperm yield (e.g., requires fewer broodfish, allows higher sperm application rates, and increases fertilization rates). The benefits of testicular harvest have been demonstrated experimentally in Sauger but not at a production scale. In this study, I validated the large‐scale efficacy of testicular harvest in Sauger for saugeye production.MethodsI collected sperm from male Sauger by using either testicular harvest (42 fish) or strip‐spawning (222 fish), diluted samples with extender, and combined samples to create 9‐mL sperm pools (n = 21 for testicular harvest; n = 39 for strip‐spawning). I compared sperm quantity, sperm motility, and production attributes (broodstock requirements, sperm application rates, and expected fertilization) between testicular harvest and strip‐spawning collection methods.ResultBoth collection methods resulted in high‐quality sperm. Testicular harvest doubled the sperm yield (total number of sperm) per 9‐mL pool despite using only 2 fish/pool, while strip‐spawning required 5–7 fish/pool. Through this enhanced yield, testicular harvest produced enough sperm to fertilize 317 L of eggs (1.06 mL/L) by using 80% fewer males than strip‐spawning. Further, sperm application increased fourfold using testicular harvest (4.23 mL/L) while still requiring 30–40% fewer fish than are currently used to meet production. Adopting testicular harvest for saugeye production in 2023 increased broodstock sperm yield, allowed greater sperm application rates, reduced Sauger broodstock needs, and increased saugeye hatching rates (15–20% increase).ConclusionTesticular harvest provides an efficient approach for sperm collection during large‐scale production in fish species that produce small quantities of sperm.