EVALUATION OF SEXUAL MATURATION AND REPRODUCTIVE ABILITY OF TRIPLOID YELLOW PERCH Perca flavescens AND VIABILITY OF PROGENY

Mackenzie Miller*, Thomas Delomas, and Konrad Dabrowski
 
School of Environment and Natural Resources, The Ohio State University
2021 Coffey Road, Columbus, OH, 43210 U.S.A
miller.5039@osu.edu
 

The sexual maturation and reproductive ability of triploid Yellow perch was evaluated. Triploid (3n) and diploid (2n, control) siblings were produced in the spring of 2014.  Triploidy was induced using heat shocks (29°C) applied at 5 minutes post fertilization for 25 min duration.  Ploidy was then determined using flow cytometry and triploidy was induced at a rate of 87% in the heat-shocked group, while control siblings were 100% diploid.  Fish were grown to sexual maturation and sexed based on morphological characteristics during the 2017 spawning season (April-June). Spermiation was observed in all diploid control males. Triploid males were non-spermiating; however, mature testes were observed upon dissection. Male and female triploid and control fish were then sampled and gonads were dissected for histological analyses (results are forthcoming).  

Eggs from both triploid (n=3) and diploid (n=2) females were stripped and in vitro fertilization was performed using a single unrelated diploid male during spring 2017.  Difference in average GSI between triploid (16.4±2.9%) and diploid (20.9 ±3.7%) females was not significantly different (p=0.3115). Fertilization rate was determined at the 2-4 cell stage.  Fertilization rate from the 2nx2n control cross (91.6±3.9%) was not significantly higher (p=0.1665) than the 3nx2n cross (67.9±18.3%).  Embryos from each female were isolated during incubation (16-18°C).   

Eyed-stage embryos from each female's progeny were randomly sampled for ploidy determination by flow cytometry.  Triploid-diploid crosses yielded 80-100% aneuploid progeny and all sampled embryos were deformed to various degrees. The control crosses yielded 100% diploid progeny.  Embryos were force-hatched and post-hatch larval survival was counted.  Post-hatch survival of control progeny (15.0±1.4%) was significantly higher (p=0.0023) than that of aneuploid progeny (4.6±1.1%).   In order to quantify the deformities within the aneuploid groups, progeny from each female were separated into swimming and non-swimming.  Non-swimming individuals made-up 20-100% of the aneuploid groups.  We attempted to raise the aneuploid progeny; however, high mortality was observed within the first 10 days of larval rearing in the aneuploid groups (94-100%), while control larvae only experienced 32-38% mortality.