A modified egg water (EW) technique for in vitro induction of sperm activation was applied to Trachypenaeus byrdi, Xiphopenaeus riveti (closed thelycum shrimps), and Litopenaeus occidentalis (open thelycum) from a tropical estuary, Golfo de Nicoya, Costa Rica. The study was designed to investigate the changes that occur in the sperm following contact with egg water, and to determine the potential of the technique for the assessment of differences in quality between sperm from spermatophores and sperm taken from the seminal receptacles. The modified technique induced activation of sperm removed from females' seminal receptacles, and demonstrated that sperm from males of T byrdi and X riveti do not react against conspecific EW, indicating that further maturation is required in seminal receptacles. Sperm from wild males of L. occidentalis reacted against conspecific EW, but at a low rate, suggesting that further maturation may be required in the external surface of the thelycum. Activation rates were low or variable between individuals in each species despite the expected high sperm quality from wild shrimp, indicating that the technique is not yet an useful sperm quality assay for the captive reproduction industry. The interspecific interaction between T byrdi sperm (seminal receptacles) and EW from X riveti and L. occidentalis generated no acrosome reaction, which may be an indication that molecular recognition is missing. (C) 2003 Elsevier Science B.V. All rights reserved.
- marine shrimp