The instantaneous growth rate of maricultured Sparedentix hasta (Valenciennes, 1830) and Sparus aurata (Linnaeus, 1758)

Abstract

The growth rate of two seabream species, was monitored during 2017. Seabreams Sparedentix hasta and Sparus aurata, were collected at age of 26 to 159 days and at 47 to 173 days for S. hasta and S. aurata respectively. The data obtained for age groups 47 to 159 days were used for comparison between the two species given 600 and 510 individuals for each species. They were raised from eggs under controlled ambient environmental conditions at the National Mariculture in the Kingdom of Bahrain. Early larvae were fed on live food such as Artemia and the fingerlings were fed on commercial feed. Weekly abiotic monitoring indicated that these species could tolerate slight fluctuations in these factors. Dissolved oxygen concentrations, in particular, ranged between 3.4 and 6 mg/l indicating their tolerance of occasional lower oxygen availability. The growth rate was exponential during the monitoring time. The linear correlations between body mass and body length were significant. Although some data indicated that the European seabream, S. aurata, can grow significantly faster (P≤ 0.05) than S. hasta, at certain age. In general, S. hasta had a higher instantaneous growth rate (Specific Growth Rate, SGR%). For example, SGR% was 20.29 from 54 to 61 days, whereas S. aurta had a value of 4.48%. SGR% ranged from 0.1 to 20.3% for S. hasta and from 0.2 to 19 % for S. aurata. Morphologically, S. aurata appears to have a more rounded and shorter body, but the native species, S. hasta, grows significantly longer and heavier. The differences in the rates of growth decreased with time as their body masses increased. There is an inverse relationship between body mass and the specific growth rate in both species. Monitoring SGR% using body mass or body length is one of the most useful indicators of production in mariculture. Attention needs to be considered however, to the husbandry and wellbeing of the cultured species.