Evaluation of egg production
and quality in the Mediterranean red porgy (Pagrus pagrus) during two
consecutive spawning seasons
C.C. Mylonas, M. Papadaki, M. Pavlidis, P.
Divanach-2004
Aquaculture, 232: 637-649
Abstract:
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 °C. 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.
(Institute of Marine Biology of Crete, P.O. Box 2214,
Iraklion, Crete 71003, Greece, e-mail: mylonas@imbc.gr)