Effects of Exploitation Pressures and River Damming on the Population Structure of Elephant Snout Fish (Mormyrus Kannume) Forsskal 1775: A Case Study on the Upper Victoria Nile

Abstract

The Elephant snout fish (Mormyrus kannume) Forsskal (1775) is one of the riverine fish species that was previously important for the River Nile riparian people as food and income. The fish is currently exploited mainly as bait for the Nile perch. This study was conducted from 2008 to 2016 and focused on catch rates, value, size structure, maturity status, and feeding habits of M. kannume. Annual catch estimates were made in order to evaluate the exploitation rate of the fish. Results revealed clear fluctuations in catches with a general increase in revenue from 1,200 (000) US$ to 8,600 (000) US$. With comparison to available literature, the fish exhibited a smaller size at maturity and smaller mean focal length (L50 for males and females were 25.2 and 28.2 cm; mean fork length of (25.9±0.32 cm). The observed changes could be due to increased fishing effort along with gear changes from gillnets to basket traps. Therefore the exploitation rate of the Elephant snout fish in the upper Victoria Nile may be unsustainable. Keywords: Bait; exploitation; Nile perch