Enhancing the supply and self-sufficiency of animal protein for local population through artificial propagation of African sharptooth catfish Clarias gariepinus (Burchell, 1822)

Abstract

The African sharptooth catfish, Clarias gariepinus Burchell, 1822 is the second most farmed fish species in Senegal due to its high fecundity, good growth performance and tolerance of a wide range environmental condition. Despite its economic importance, much remains to be done to improve the production of the species under controlled conditions. The main objective of this study was to implement a suitable method for seed production to meet the increasing demand for fish through the induction of C. gariepinus spawning by hormonal injection using ovaprim and pituitary gland extracts of C. gariepinus. The experiments were independently conducted in three different locations in Senegal: National Aquaculture Agency (ANA) hatchery (Kolda, Kolda), the National Agency for Agricultural Integration and Development (ANIDA) fish farm (Maraye village, Dagana, Saint-Louis) and SENAQUA farm (Tille Bobou, Khombol, Thiès). The results of hormonal induction with ovaprim (dose: 0.5ml/kg of female body weight) stimulated evolution, with 122,500, 150,000 and 15,000 eggs for the ANA, ANIDA and SENAQUA experiments, respectively. The induction with pituitary gland extracts did not, however, provoke female ovulation, probably due to the low dose of hormone contained in these extracts. The hatching rate of the three localities was 60% (73,500 larvae), 30% (45,000 larvae) and 48% (72,000 larvae), respectively. An average growth of 0.25cm/d was recorded for the ANA larvae that were fed exclusively with zooplankton from the third day after hatching, with an alternation of artificial food and zooplankton on the sixth day and with artificial food only on the fourteenth day. However the larvae in this locality had a very high mortality rate of 95%. The mortality rate was also extremely high at ANIDA (96%) where larvae were fed with artemia the second day after hatching throughout the first week, and at SENAQUA farm (98%) where larvae were exclusively fed with dry artificial food (exogenous) from the third day, which corresponds to the resorption of the yolk sac. The high larval mortalities recorded in this study may be due the diet and/or poor water quality in the rearing tanks. These parameters are crucial for the success of larval breeding of C. gariepinus. Based on these results, we suggest increasing by 2 to 3 pituitaries/female and see the effect of this increase on C. gariepinus ovulation.We therefore recommend monitoring breeding conditions after hatching and feeding the larvae with an appropriate diet, preferentially with live food to obtain a better yield, which could help improve production and open other perspectives for the development of aquaculture in Senegal.