Effect of water temperature on reproductive tract condition of Penaeus setiferus adult males

This study was conducted to determine the effect of water temperature on ma le reproductive tract degenerative syndrome (MRTDS) and male reproductive s ystem melanization (MRSM) in Penaeus setiferus, and to evaluate the effect of water temperature on spermatophore regeneration time and sperm quality i n electrically ejaculated adult males. Variation in sperm quality, gonadoso matic index, and histological changes in the reproductive system were used to assess reproductive tract changes in the first experiment. Sperm quality and regeneration time were measured before and after successive regenerati ons in the second experiment. Sperm quality was stable when shrimp were hel d at 26 C for 30 d but was reduced when shrimp were held at 30 C. Reproduct ive tissues of 20% of the shrimp held at 30 C were melanized to some degree but tissue melanization was found in only 2.5% of the shrimp held at 26 C. Spermatophore regeneration time was also affected by temperature. Average times for first spermatophore regeneration were 192 h at 25 C, 152 h at 30 C, and 144 h at 33 C. Sperm quality of regenerated shrimp was not affected at 25 C but was reduced for regenerated animals held at 33 C. Based on thes e results, we recommend a water temperature between 25 and 27 C to obtain a dequate spermatophore regeneration and to maintain healthy male P. setiferu s broodstock for at least 30 d.