%0 Journal Article
%T Sublethal Effects of Methanolic Extract of Raphia hookeri on the Reproductive Capacity of Clarias gariepinus
%A Adedotun O. Afolayan
%A Temitope I. Borokini
%A Gloria O. Afolayan
%J Advances in Zoology
%D 2014
%R 10.1155/2014/615908
%X Raphia hookeri fruits are used for fishing in Nigeria due to their ichthyotoxic properties. This study investigated the toxic effects of R. hookeri on the reproductive capacity of Clarias gariepinus. The results from both short-term (96-hour test) and long-term (3-month sublethal test) bioassays revealed a linear relationship between R. hookeri extract dose and negative effects on the catfish. The percentage survival of both sexes of the catfish decreased with increasing extract concentration at short-term exposure, with LC50 values of 600£¿mg/L and 800£¿mg/L for male and female, respectively. At long-term exposure, the reproductive capacity of 10¨C12-month-old male and female brood-stocks diminished at relatively higher concentrations of R. hookeri fruit extract, with the gravid females producing fewer and mostly unviable eggs. The fruit extract also affected the eggs¡¯ hatchability and fry survival when the exposed gravid females were treated with pituitary hormone and sperms from unexposed males, while the exposed males were unable to sexually stimulate female brooders. Sperms and pituitary hormone from exposed males were infertile, leading to low percentage of hatched eggs and mortality of the few hatched fries within 24 hours. These results confirmed the ethnobotanical use of this fruit extract for fishing in Nigeria. 1. Introduction Fish is one of the cheapest protein sources in sub-Saharan Africa [1], and the importance of fish in developing countries increased greatly after the Sahelian drought of 1971 to 1974, which decimated the cattle population and hence shot up the prices of beef [2]. Clarias gariepinus (Burchell, 1822) belongs to the family Clariidae, and is widely distributed in Nigerian waters [3]. The fish is known for its high tolerance and high survivability [4] and resilience in harsh habitat conditions [5]. There is a huge market value for the fish in Nigerian markets due to its taste [6], which resulted in the proliferation of fish farming business in Nigeria using different fish production methods. However, wild catch still remains important. In order to increase catch yields in traditional fishing, different toxic plants that can stupefy fish have been exploited [7, 8]. Chopra et al. [9] reported at least 112 plants with poisonous effects on fish. Seigler [10] reported the piscicidal effect of some common plants of India that are frequently used in freshwater bodies against target organism while Neuwinger [11] also observed that there is a wide variety of wild and cultivated poisonous plants available to coastal fishermen for
%U http://www.hindawi.com/journals/az/2014/615908/