Climate change is one of the main anthropogenic perturbations, in addition to destruction of habitats, introduction of alien species, pollution, and overexploitation, that have contributed to the erosion of biodiversity over the past century (Jeppesen et al., 2012). Mean global temperatures have increased by 0.85°C since 1850 (IPCC, 2014), which have partly contributed to the changes in fish fauna observed both in marine (Cheung et al., 2010) and freshwater ecosystems (Jeppesen et al., 2012). According to the latest report of the Intergovernmental Panel on Climate Change (IPCC, 2014), the average temperatures on the Earth’s surface could rise between 0.5°C and 5.5°C by the end of this century (2100) (IPCC, 2014) with strong local variations. This warming trend could continue to affect fish populations, as most fish species have no physiological ability to regulate their body temperature (Angilletta et al., 2002).
Freshwater fish species could be even more vulnerable to global climate change as they have limited dispersal ability within hydrographic networks in which they currently live (Buisson et al., 2008). In this context, an important scientific issue is to predict how fish populations will cope with future temperature changes (Comte et al., 2013).
World aquaculture has grown tremendously during the past two decades to becoming an economically important industry (Subasinghe et al., 2009). According to (FAO, 2007), aquaculture continues to grow more rapidly than all other animal food-producing sectors, with an average global annual growth rate of 8.8% per year since 1970, compared to only 1.2% for capture fisheries. Globally, aquaculture is expanding into two new directions, intensifying and diversifying. Intensive fish culture has the capacity to produce large quantity of fish per unit space but seldom exists without an efficient fish seed production (Adekoya et al., 2004). Fish seed production is an important aspect of aquaculture that has witnessed continuous research and innovation for increased fish production.
As the world population increases, the demand for fish in the world also grow, in spite of high preference for fish and fisheries products in Africa, the per capita consumption of fish in this part of the world is still very low FAO (2000).Clarias gariepinus and Heterobranchus species are the two commonly cultured Clariid fish (Ojutiku, 2008). They are reared all-over the country especially in the south and have very good commercial value in Nigeria markets (Owodeinde and Ndimele, 2011). Methods of artificial seed propagation of African catfish (Clarias gariepinus) are very expensive in Nigeria and hatchery operators are usually scared of big size of brood stock not just because of the large quantities of spawning hormone that will be required for induced breeding exercise, but also because of their high price Sule and Adikwu (2004).
1.3 AIM AND OBJECTIVE
Therefore, this project write up is aimed to determine or evaluate or assess the Effect of water temperature in the fertilization and hatchability of African catfish based on the following objectives:-
- To establish the optimal temperature range suitable for fertilization and hatchability of Clarias gariepinus eggs.