Table of Contents
Advances in Zoology
Volume 2014 (2014), Article ID 615908, 10 pages
http://dx.doi.org/10.1155/2014/615908
Research Article

Sublethal Effects of Methanolic Extract of Raphia hookeri on the Reproductive Capacity of Clarias gariepinus

1National Centre for Genetic Resources and Biotechnology, Moor Plantation, Oyo State, Ibadan 200001, Nigeria
2Department of Zoology, University of Ibadan, Oyo State, Ibadan 200001, Nigeria

Received 8 May 2014; Revised 8 September 2014; Accepted 13 October 2014; Published 5 November 2014

Academic Editor: Raine Kortet

Copyright © 2014 Adedotun O. Afolayan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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 10–12-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.