Evaluation of egg production and quality in the Mediterranean red porgy (Pagrus pagrus) during two consecutive spawning seasons

摘要

Egg production from two broodstocks of captive-reared red porgy (Pagrus pagrus) was monitored for two consecutive seasons (2001 and 2002). Spawning lasted from January to April-May under water temperature between 15.8 and 19.2 degreesC. Spawning was mostly daily, though over the course of the two spawning seasons, the mean interval was 1.5-1.2 days spawn(-1). There was a large variation in daily fecundity without a consistent trend, except for a slight peak in the middle of the spawning season. Mean (S.E.M.) annual relative fecundity ranged between 408,300 (95,800) and 442,500 (180,800) eggs kg(-1) year(-1). Mean fertilization success increased significantly from 36.9 (2.0)% in 2001 to 68.9 (2.5)% in 2002, resulting in mean annual viable egg production of 174,800 (87,600) and 301,500 (99,800) eggs kg(-1), respectively. There were no significant differences between the 2 years in other egg quality parameters, which ranged between 74.5 and 79.3% 1-day embryo survival, 81.6-85.5% hatching success and 76.7-78.8% 5-day larval survival. Of the relations examined, fertilization % had a significantly positive correlation with 1-day embryo survival, which in turn was significantly correlated with hatching %. Larval survival was further correlated with hatching %. These data suggest that decisions on whether to proceed with the incubation of a batch of eggs and rearing of the larvae can be made within 1 day from egg collection, before much effort is invested by the hatchery. The present study presents further information on the spawning kinetics, and egg production and quality characteristics of the Mediterranean red porgy in culture, and demonstrates the suitability of this species for reproduction in captivity