The qualitative and quantitative description of growth and condition of silver kob, A. inodorus
Date
2006-03
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
The development of basic husbandry techniques and determining basic performance
parameters are among the first steps towards culturing a new species. Silver kob,
Argyrosomus inodorus, is a large Sciaenid and endemic to South Africa and Namibia and
has been selected as a candidate aquaculture species. However, the proposed culture raises
many questions, with two of them being the adaptability to captive conditions and product
quality in the captive raised fish. To address these, trials were set up with eighty-three
silver kob, divided into three ponds and fed three different diets. The effects of the diet on
performance and quality were determined over a nine month trial period. The fish fed the
pilchard diet adapted faster to the captive conditions than the fish fed the artificial diets.
The growth of these fish were also markedly better than that of the fish fed the artificial
diets, although after the adaptation period, the growth rate of the fish fed the artificial diets
surpassed that of the fish fed the pilchards. Fifteen fish, five from each treatment were
sacrificed and compared on a chemical and sensory level to wild-caught fish (control,
n=6). Differences (p≤0.05) were noted in the total lipid content and fatty acid composition
between the fish fed the different diets and the control. Sensory analysis revealed that the
fish fed pilchards differed (p≤0.05) from the other groups by having an undesirable odour
and flavour. The body partitioning and the proximate chemical composition of silver kob
were determined. The length-weight relationship for silver kob raised in captivity was
determined and a b-value of 3.32 was obtained, which indicates allometric growth with the
fish becoming more rotund as their length increases. The results of these trials indicates
that silver kob, A. inodorus adapts in captive conditions. The final product also compares
favourably to wild-caught fish. The use of digital image analysis as a method of
determining fish condition was also assessed with promising results for future application
in research and production systems.
Description
Thesis (MscAgric (Animal Sciences))--University of Stellenbosch, 2006.
Keywords
Dissertations -- Agriculture, Theses -- Agriculture, Dissertations -- Animal sciences, Theses -- Animal sciences, Argyrosomus -- Growth, Argyrosomus -- Condition scoring, Fish culture, Aquaculture