International Journal of Aquaculture, 2017, Vol.7, No.20, 126-133
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nematodes, fish, fish eggs and fish scales in Lake Koka. In the present study also the cyprinid fish
V. beso
feeds
mainly on diatoms and green algae along with detritus of diverse origin in the Debbis River.
2.5 Fishery activities
Majority of the fishers in the study area (61.2%) have involved in fishing for 6-15 and there are seasonal
fishermen who fish from the river only for consumption. Fishing in the study area is mainly artisanal and sold at
the local market. The commercially important species are
L. forskalii
,
V. beso
and
L. intermedius
. The fisher folk
use locally available gears such as single hook and line and cast net (8-10 cm mesh size). Besides, Birbira
(
Milletia ferruginea
) seed powder is also used to anesthetize and collect the fishes.
3 Materials and Methods
The study area is located between 09°00’149’N latitude and 37°49’783’E longitude and altitude between
1886-1919 m.a.s.l in the West Shoa Zone in Ambo and Tokke kutaye districts, Ethiopia. The river bank is covered
with dense vegetation and rocky hills and agricultural lands. Livestock rearing is an important activity besides
crop production by the people. Fishing is practiced along Debbis River by fishermen to meet subsistence needs as
an additional source of income. Fishing is carried out during December to April when the water level becomes
less. The three representative sampling sites were selected on Debbis River and designated as (Deb
1
, Deb
2
and
Deb
3
) based on nature of bottom and the surroundings (Figure 4). Fish samples were collected from each site
(pools/riffles) during the dry season from January to March, 2017 by Electrofishing. Immediately after capture,
total length and total weight of all fishes were measured. Identification of the fish species was carried out
following Fish Base (2006) software.
Figure 4 Map of the study area showing the sampling sites along the Debbis River
Diversity Index was used to evaluate diversity of fish species. The Shannon index (H’) is a measure of species
weighted by the relative abundance of the species of fish (Begon et al., 1990).
Where the proportion (n/N) of individuals of one particular species; (n) = the total number of a particular species;
N = the total number of all the species; ln is the natural log; Σ is the sum of the calculations.
The relationship between total length and total weight of the most dominant species was calculated using power
functions as in Bagenal and Tesch (1978) as follows:
