IDENTIFYING SUB-TROPICAL EAST COAST COPEPODS FOR LARVICULTURE OF DUSKY KOB, ARGYROSOMUS JAPONICUS (TEMMINCK & SCHLEGEL, 1843)

Ameen, R; Moodley, G.K.; Robertson-Andersson, D.V.

University of KwaZulu-Natal; College of Agriculture, Engineering and Science, School of Life Sciences; Durban, KwaZulu-Natal, South Africa; Private Bag X 54001, 4000

Abstract

Since South African fin fish larviculture facilities rely on an imported source of live feed for larvae, it is important that we identify potential local live feeds. Pelagic copepods are a desired feed due to their high nutritional value, their predator-elicitation response, their size variability, and their small size which is ideal as a first feed for small mouth-gape larvae. Many production systems use alternate zooplankton sources such as Artemia naupilii and rotifers as they are much easier to grow on large scales. The disadvantage of these other live food sources is the lack of highly unsaturated fatty acids and polyunsaturated fatty acids, hence enrichment is required thereby increasing the cost of feed. The Mlalazi estuary, located along the sub-tropical east coast of South Africa, is in close proximity to the Mtunzini fish farm, thus facilitating the pumping of water from the estuary to maintain Argyrosomus japonicus (Temminck & Schlegel, 1843) larvae production. The study identified the most robust sub-tropical pelagic copepod species in the Mlalazi estuary by determining their temperature and salinity ranges. Copepods were subjected to temperatures from 10-40 ⁰C and salinities of 10-40 PSU and their survival recorded. Thereafter, the copepods were subjected to a combination of three temperatures and salinities over a 48 hour period. This study is the first step in identifying suitable sub-tropical copepod species for fin fish culture to increase the production rate and nutritional value of marine larvae, whilst decreasing production costs.

Keywords

East coast, sub-tropical, live feed, copepod, aquaculture, temperature, salinity