A review on the cultivation potential of Solea senegalensis in Spain and in Portugal

The sole, Solea senegalensis, is a common high-value flatfish in Southern Europe, commonly reared in extensive aquacultural production in Portugal and Spain. Research in recent years has focused on the production of larvae and juveniles of good quality. Natural spawning of broodstock in captivity has been accomplished, and is the only way viable eggs have been obtained to date. The broodstock feeding regime is based on squid (Loligo vulgaris), being supplemented with polychaetes (Hediste diversicolor) during final maturation. Temperature plays a very important role in the onset and duration of the spawning period, with egg emission stopping below 16 degrees C. Observed duration of the spawning period has ranged from 4 to 6 months. The total daily egg collection during the spawning season ranged from 0 to 180 g for a broodstock of 15 fish. Egg fertilization rates varied between 20% and 100%, and the percentage of viable eggs had a mean of 72.1 +/- 26.5%. Variations in egg size between batches were detected, with egg size tending to decline during the spawning season. Larvae hatch with an average size of 2.4 +/- 0.1 mm total length, but this varies widely by batch. Larvae accept Artemia nauplii as first prey and reach a size of 8 mm by day 15. Metamorphosis starts on 11 days after hatching (DAH) and is completed by 19 DAH. Survival at 19 DAH range from 29% to 87%. From 19 DAH onwards fish are fed live Artemia metanauplii, and reach 16 +/- 0.8 mm on 40 DAH. Ponds stocked with unweaned juveniles produced after one year fish with 16.6 +/- 2.1 cm total length and 40.3 +/- 2.5 g wet weight, with a survival of 20%. Unweaned juveniles stocked together with Sparus aurata reached a size of 35.3 +/- 1.8 cm total length and 456.1 +/- 3.6 g wet weight after one year fish, with a survival of 8%. Epizootic mortalities due to pasteurellosis have been observed in juvenile S. senegalensis. As in other flatfish, pigmentation abnormalities as well as some malformations associated with the migration of the eye have also been observed. The optimization of the weaning and growout procedures, including the development of appropriate feeding regimes, and further studies into the causes of pigmentation abnormalities are necessary before this species can be reared intensively on a large scale. (C) 1999 Elsevier Science B.V. All rights reserved.