The Effect of Birbira, Milletia Ferruginea (Hochst.) Baker on Some Barbus Spp. (Cyprinidae, Teleostei) in Gumara River (Lake Tana), Ethiopia
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Date
2004-02
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Addis Ababa University
Abstract
To assess the possible effect(s) of birbira, Milletia ferruginea (Leguminosae) on the barbs,
Barbus spp. (Cyprinidae) from Gumara River (Ethiopia), aquarium and field study was
conducted during August to September, 2002. The effects of birbira at concentrations of 0.02,
0.04, 0.1, 0.2, 0.3 and 0.4 g/l were studied to conduct experiments on different species, sizes
and sexes of fish. The amount of crude powders of birbira seeds actually applied by the
fishermen at Dukalit stream (a tributary of Gumara River) was estimated to be about 0.4 g
per liter of water. This amount was found to be excessive as only 0.02 g/l (a 5% dilution) was
enough to bring about total fish kills in about an hour. It was observed that the amount of
oxygen in the birbira solution remained almost intact after all of the fish died, supporting the
idea that rotenone does not deplete oxygen dissolved in the water but affects mechanism of
oxygen uptake by fish. The findings of the study revealed that when using birbira
concentrations of 0.02 to 0.4 g/l, all of the fish died in about 30 to 60 minutes. Comparison of
different species showed that B. brevicephalus and juvenile ‘large’ barbs (weighing < 50 g)
had relatively better tolerance than had another close relative, Varicorhinus beso of similar
weight. Female B. brevicephalus (usually ≥ 100 g) with running (ripe) gonads of tolerated the
poison better than their male (usually < 100 g) counterparts. Fertilized eggs, presumed to
have been spawned by B. brevicephalus, were collected from Dukalit stream and poisoned
with 0.4 g/l birbira for 15 minutes, and then incubated in clean water. None of these eggs
hatched while all of the controls (unpoisoned eggs) did after 3 days of collection from the
river. The findings of this study are believed to lay a basis for further research and
consequently to solve problems related to poisoning fish with birbira and/or other herbs on Gumara River and other waters.
Key words/phrases: birbira (Milletia ferruginea); Gumara River (Lake Tana); ‘large’ Barbus
spp.; survival time.
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Keywords
birbira (Milletia ferruginea); Gumara River (Lake Tana); ‘large’ Barbusspp.; survival time.