Tricaine (MS‐222) is the most widely used anesthetic for fishes, but induction and recovery times are rather long. Studies on salmonids have shown that electroanesthesia is a good alternative to MS‐222 for short term (<1 min) immobilization. However, data on longer‐duration (3–5‐min) immobilization needed for surgical procedures are lacking. We analyzed induction and recovery times for 20 adult (52–81‐cm) striped bass Morone saxatilis immobilized with electroanesthesia and MS‐222. We defined induction time as the interval from the onset of each treatment until the fish was immobilized (i.e., did not respond to tactile stimuli) and recovery time as the interval from the fish's return to the water to its resumption of normal swimming. Surgical procedures similar to those necessary to implant a radio transmitter were performed on each fish. Induction time for fish immobilized with electroanesthesia (geometric mean, 8 s; 95% confidence interval [CI], 3–21 s) was much shorter than that for fish immobilized with MS‐222 (geometric mean, 47 s; 95% CI, 38–58 s) (P = 0.0006). Additionally, fish immobilized with electroanesthesia recovered much faster (geometric mean, 9 s; 95% CI, 4–19 s) than fish immobilized with MS‐222 (geometric mean, 206 s; 95% CI, 156–272 s) (P ⩽ 0.0001). Faster induction and recovery times of fish immobilized with electroanesthesia and the ability to process more fish per unit time are major benefits of this technique.

We sought to develop sperm cryopreservation methods for the pallid sturgeon Scaphirhynchus albus, a federally listed endangered species. Males were injected with synthetic luteinizing hormone releasing hormone at 50 μg/kg of body weight. After 24 h, sperm were collected, diluted at a ratio of 1:4 (sperm : extender) with Hanks' balanced salt solution (HBSS; diluted to 100 milliosmoles/kg), and kept refrigerated until use. Methanol was used as a cryoprotectant at concentrations of 5, 10, and 15% (volume per volume) and was mixed 1:1 with HBSS before the experiment to reduce effects of initial mixing. Sperm were mixed with the cryoprotectant, loaded into 0.5‐mL straws, packed into goblets (5 straws/goblet), and placed in the lower position on aluminum canes. Motility was estimated before freezing to determine the effects of cryoprotectant toxicity; there was no significant difference in motility at the concentrations tested (P = 0.4828). After a 2‐min equilibration period, the canes were lowered into a nitrogen vapor shipping dewar. The cooling rate of −22°C/min was recorded by thermocouples inserted into 0.5‐mL straws filled with extender and cryoprotectant. After 1 year of storage in liquid nitrogen, straws were thawed in a 40°C water bath for 9 s and motility was estimated. Postthaw motility did not differ among the cryoprotectants tested (P = 0.4880). Each sample was used to fertilize approximately 150 eggs, which were incubated at 21°C. Sperm that was cryopreserved with 5% or 10% methanol produced eggs with significantly higher hatch rates did sperm cryopreserved with 15% methanol (P < 0.0001). The development of techniques for cryopreserved sperm of pallid sturgeon allows for the creation of germplasm repositories that will aid in the recovery of this endangered species.