Use of Optimised Conventional and Advanced Sperm Quality Diagnostic Tools to Establish Reproductive Data in Wild-Caught Redclaw Crayfish (Cherax Quadricarinatus)

Abstract

The Australian redclaw crayfish has great potential for aquaculture intensification and global market expansion. However, traditional production methods, subfertility, and high embryo mortality could curtail industry growth. Successful embryonic and post-embryonic development also depend on the paternal genetic contribution. Direct assessment of sperm quality can potentially determine the status of male fertility in decapod crustaceans. This study evaluated redclaw crayfish sperm quality using optimised conventional and advanced functional tools. Sexually mature male redclaw (n = 33) were collected from Ross River Dam, North Queensland, Australia and subjected to electroejaculation to yield spermatophores for sperm quality assessment. Sperm concentration and count (haemocytometer), morphology (phase contrast), viability (Hoechst 33342/PI), DNA fragmentation (TUNEL), and total potential fertile sperm concentration (TPFSC) were determined. Spermatozoa had an elliptical shape of varying sizes and a presumptive tail-like structure. The mean ± SEM sperm viability, DNA fragmentation, concentration, and TPFSC were 65.2 ± 3.9%, 17.2 ± 2.5%, 42.5 ± 5.1 x 104 cells/mL, and 23.6 ± 3.4 x 104 cells/mL, respectively. Sperm concentration (p = 0.001) and TPFSC (p < 0.001) were positively associated, sperm DNA fragmentation (p = 0.022) was negatively associated, and sperm viability (p = 0.188) was not associated with spermatophore weight. Sperm viability was also negatively associated with body mass (p = 0.010). In conclusion, this study reported the first quantitative data on sperm morphometry and functional traits, validated species-specific diagnostic tools for sperm quality assessment, and provided information on the relationships between sperm quality parameters and body or spermatophore weights. Our approach may inform the selection of fertile male broodstock and enhanced strategies for sperm harvesting in order to facilitate selective breeding programs for commercial redclaw aquaculture.

Keywords: Fertility marker, crustacean, DNA damage, electroejaculation, sperm viability