Study On The Salinity And PH Preference Of The Rockfish Sebastiscus Marmoratus Yolk Sac Larvae

Based on the ecological theory that the extension of one abiotic factor for survival will shrink with another abiotic factor deviating from its optimum, the study is emphasis on the oil sac absorption, first ingestion rate, point of no return(PNR) and survival activity index(SAI) of the unfed rockfish yolk sac larvae. The results indicated that at the salinity of 22, the best overall performance exhibited: the highest first ingestion rate, SAI and the latest PNR. And the reason for the best survival at the salinity was the preferable absorption and conversion of the yolk and oil sac, the lesser energy cost for activity with the sufficient buoyancy and the better hormone level to stimulate the best ingestion.According to the same theory, the temperature upper limit of the larvae at different salinity, and the survival activity index at high temperature (SAIht) with various salinity and pH were measured. The results were: at 4 and 28 salinity, larvae showed a lower temperature upper limit, while highest SAIht were obtained at pH8..The optimal salinity and pH for these rockfish larvae from the study were 22 (psu) and pH8, which is consistent with former reports studied by different authors. So these methods mentioned above were practicable for measuring the salinity and pH preference of fish larvae.