Publication Abstract

The effects of exposing the eggs of Pacific threadfin and amberjack eggs to different concentrations of hydrogen peroxide for 5 min on hatch rate and survival were assessed in a series of experiments using a petri dish model rearing system. Despite significant inter-batch variation in hatch rate, it was shown that eggs of both species could be safely exposed to up to 11340 mg L^-1 H₂O₂ for 5 min.

Exposure to 34230 mg L^-1 H₂O₂ for 5 min was shown to be lethal to amberjack eggs at a late stage of development. In two further experiments, it was demonstrated that Pacific threadfin eggs were resistant to all tested concentrations of a range of polyvinylpovidone iodine (PVPI) concentrations and contact times (up to 1000 mg L^-1 PVPI for 10 min).

The level of bacteria adhering to the eggs of both species was highly variable. Where eggs were heavily colonised (> 10⁴ cfu egg^-1), hydrogen peroxide concentrations of at least 11340 mg L^-1, or PVPI concentrations higher than 500 mg L^-1 for 10 min, were required for effective sterilisation. In less colonised batches, rinsing in sterile seawater or exposure to lower (550 mg L^-1) concentrations of H₂O₂ was sufficient to result in high apparent levels of surface sterility (< 1 cfu egg^-1).