Aquaculture America 2024

February 18 - 21, 2024

San Antonio, Texas

ACUTE THERMAL STRESS IMPACTS SPERM QUALITY IN BLUE CATFISH Ictalurus furcatus

Kaylan A. Martin* , Jason W. Abernathy, Sepideh Barzegar-Fallah, Rex A. Dunham, Samitha Liyange, Luke A. Roy, V. Mackenzie Tackett, Kyle R. Wood, Ian A.E. Butts

 

 School of Fisheries, Aquaculture and Aquatic Sciences

203 Swingle Hall, Auburn University

Auburn, AL, 36849

kam0247@auburn.edu

 



Sperm of many aquaculture species are often inadequate in quality/quantity and result in low fertility and offspring viability. This is particularly true for fish that do not release milt via manual-stripping, such as with the commercially important blue catfish (Ictalurus furcatus),  which, is mated with  female channel catfish (I. punctatus )  to produce a hybrid that accounts for more than 50% of US catfish production. Pond aquaculture systems are prevalent in the catfish industry, where temperatures can reach upwards of 36o C  in warmer  months, and daily fluctuations of 3-6o C are common . These extreme conditions will likely be intensified by  the effects of global climate change. In fishes, most studies have focused on how environmental factors influence sires before mating. However, sperm themselves experience fluctuating environments, and potential  environmentally and genetically induced changes to sperm have implications on offspring traits. T his study  investigated how thermal stress impacts sperm quality and whether thermal stress-induced changes in sperm negatively impact offspring performance.

 Blue catfish sperm from 8 males were placed into temperature blocks at 4oC (control), 32o C (pond temperature towards  the end of spawning), and 36oC (pond heatwave). After 0- 90 min of temperature exposure,  sperm cell health (viability) was assessed. Sperm were activated  and kinematics analyzed using Computer Assisted Sperm Analyses software.  Sperm  exposed to the thermal environments were then used for in vitro fertilization trials, where  eggs from three females were fertilized with 9 males (3 females × 3 males each nested in female × 3 temperature exposures × 3 replicates = 81 experimental units). Hatching success was determined. Additionally, fry deformity rate, body weight, and survival  were  recorded at 30 days post-hatch.

 Sperm viability decreased over the thermal gradient, with  the lowest viability at 36oC after 30, 60, and 90 min of exposure (Fig. 1A). Sperm motility also declined over the thermal gradient (Fig. 1B). Offspring performance data from fertilization trials are currently being  analyzed. Data will help predict paternity  outcomes in response to environmental  thermal stressors.

 Fig 1. Impact of acute  thermal stress on sperm viability and motility in blue catfish .