Habitat Use and Characterization of Young-of-the-Year (YOY) Labeobarbus Spp. in Gumara River, Lake Tana Sub-Basin, Ethiopia
No Thumbnail Available
Date
2020-01-01
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Information regarding habitat requirements of different fish species at early life stages plays
important roles for monitoring, protecting or managing fish populations and their habitats.
Although spawning migration of Labeobarbus species to Gumara River has been reported by
various studies, organized information on abundance, distribution, habitat use and preference of
young-of-the-year were not available. Such information is very important for the management of
the declining endemic Labeobarbus species of Lake Tana. So, the aim of this study was to
investigate abundance, habitat use and characterization of young-of-the-year of the
Labeobarbus species. Habitat use and characterization of young-of-the-year of the migratory
riverine spawning Labeobarbus species of Lake Tana were studied in Gumara River and its
tributaries from November 2018 to April 2019. Physico-chemical parameters were measured
using probes and there were significant variation (p<0.05) among sampling sites. Fish sampling
was conducted using point abundance sampling by electrofishing across banks and mid-channel
to cover all habitat types. A total of 3,880 fish specimens were collected from all sampling sites.
Out of the total catch, about 24.36% of the contributions were from young-of-the-year of the
Labeobarbus species. The abundance of fishes varied between sampling months and sites and
this might be attributed to the differences in physico-chemical parameters, substrate type,
altitude, depth and velocity of the water. The Shannon’s index (H'=1.21) and evenness value
(J'=0.53) in Gumara River indicate moderate pollution and uniform distribution of individuals.
Among the six sampling sites, the highest (H' = 1.30) and lowest (H' =0.94) diversity index were
recorded at sites in the upstream near to Wanzaye hot spring and below the bridge, respectively.
In terms of mesohabitat, the species diversity and evenness were higher in riffle (H' = 1.25, J' =
0.57) than run (H' = 1.15, J' = 0.55) and the pool (H' = 1.11, J' = 0.50). The result showed that
the species prefer at a mesohabitat scale riffles and later pools in Gumara River and this is
mainly due to the drying of riffle habitats during the dry season and hence forced to shift to pool
habitats. At a microhabitat scale also juveniles prefer sites with moderate water depth, low to
medium water velocity; gravel substrate type and vegetation cover. Pool habitat served as the
only option until the next rainfall comes. Therefore, emphasis should be given to the factors
which may lead to the collapse of the pool habitats, especially water abstraction through
pumping for small scale irrigation. The detailed study on the habitat modeling and the habitat
suitability index should be done for proper management of the Lake Tana fishery.
Description
Keywords
Abundance, Electrofishing, Habitat Preferences, Lake Tana, Young-of-the-Year