Research Article Population Aspects of Fishes in Geba and ...

Research ArticlePopulation Aspects of Fishes in Geba and Sor RiversWhite Nile System in Ethiopia East Africa

SimagegnewMelaku1 Abebe Getahun2 andMulugetaWakjira3

1Department of Biology Faculty of Natural and Computational Sciences Metu University PO Box 318 Metu Ethiopia2Department of Zoological Sciences College of Natural Sciences Addis Ababa University PO Box 1176 Addis Ababa Ethiopia3Department of Biology College of Natural Sciences Jimma University PO Box 387 Jimma Ethiopia

Correspondence should be addressed to Mulugeta Wakjira enku2005yahoocom

Received 28 February 2017 Accepted 12 April 2017 Published 11 May 2017

Academic Editor Stephan Koblmuller

Copyright copy 2017 Simagegnew Melaku et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

This study was carried out to assess the diversity condition factor length-weight relationship and sex ratio of fishes in Geba and SorRivers located in Baro-Akobo BasinWhite Nile systemwithin Ethiopia Fish samples were collected in one wet and one dry seasonThe length-weight relationships were fitted using power equation for the most abundant species A total of 348 fish specimens werecollected using gillnets and hooks These were identified into eight species and one Garra sp representing seven genera and fourfamilies Family Cyprinidae was the most dominant with six species (667) Labeobarbus intermedius Labeobarbus nedgia andLabeo cylindricus were the most abundant fish species respectively with 6072 1683 and 1466 index of relative importance(IRI) The diversity index was higher for Geba River (1198671015840 = 150) than for Sor River (1198671015840 = 110) All the three most abundant specieshad negative allometric growth Seasonal variations in the mean Fulton condition factor (FCF) were statistically significant for Lcylindricus (119901 lt 005) There was variation in the sex ratio with the females dominating in all the three most abundant speciesFurther investigation into the fish diversity food feeding and reproductive behaviors of fish species especially in the tributaries ofthese rivers and their socioeconomic aspects is recommended

1 Introduction

Ethiopia could be called the ldquowater tower of northeasternAfricardquo on a continent where aridity is the rule Ethiopiais rich in inland water bodies with diversified fish speciescomposed of Nilo-Sudanic East African and endemic forms[1 2] A review by Tedla [3] listed 93 fish species for theentire Ethiopian freshwater system A survey by Getahun andStiassny [4] identified 65 species belonging to 19 genera and9 families Later on reviews by Getahun [5 6] listed up to 153valid indigenous fish species and subspecies in 25 families forthe Ethiopian freshwater systems A more recent survey byGolubstov andDarkov [7] provided a basin-wide summary ofthe nationrsquos ichthyofaunal diversity According to this workthe nationrsquos major basins namely Baro-Akobo (White Nilewithin Ethiopia) Abay (Blue Nile within Ethiopia) Omo-Turkana Tekeze-Atbara Shebelle-Genale and Rift Valleybasins respectively have 113 77 76ndash79 34 33 and 28ndash31 fish

species Even so a study on the diversity of the Ethiopianfish fauna still remains far from complete largely owing to thelarge expanse of its geography (ie 11 million km2 total area)and limited surveys Many of the drainage basins especiallythe rivers are not exhaustively explored [6] Geba and SorRivers are among such rivers that lack exhaustive studies onthe diversity and associated biological characters of their fishfaunaThus the present study was undertaken to address thisgap and as such it represents a baseline study on the diversityrelative abundance and some biological characteristics offishes in the rivers addressed in the present study in an effortto contribute to any conservation attempts of their fish fauna

2 Materials and Methods

21 Description of the Study Area The study was conductedin Geba and Sor Rivers located in Yayu and Metu Districts

HindawiInternational Journal of BiodiversityVolume 2017 Article ID 1252604 7 pageshttpsdoiorg10115520171252604

2 International Journal of Biodiversity

Town

Geba and Sor sampling siteRivers

District boundary

36∘0㰀0㰀㰀E35

∘50

㰀0㰀㰀E35

∘40

㰀0㰀㰀E35

∘30

㰀0㰀㰀E35

∘20

㰀0㰀㰀E

36∘0㰀0㰀㰀E35

∘50

㰀0㰀㰀E35

∘40

㰀0㰀㰀E35

∘30

㰀0㰀㰀E35

∘20

㰀0㰀㰀E

8∘0㰀0㰀㰀N

8∘10

㰀0㰀㰀N

8∘20

㰀0㰀㰀N

8∘30

㰀0㰀㰀N

8∘0㰀0㰀㰀N

8∘10

㰀0㰀㰀N

8∘20

㰀0㰀㰀N

8∘30

㰀0㰀㰀N

Figure 1 Map of the study sites and rivers

of Ilu Aba-Bor Zone Oromia Regional State in southwesternEthiopia (Figure 1) The districts are located at 550 km and600 km southwest of the capital Addis Ababa respectivelyThe annual temperature ranges from 1413 to 2907∘C and1121 to 2733∘C for Yayu and Metu Districts respectively Themean annual rainfall is 1563mmyear for Yayu District and142717mmyear for Metu District with high variation fromyear to yearThe rainfall patterns of the districts are unimodalwith low rainfall during January and February and the highestrainfall between June and August [8] Ficus species Coffeaarabica Croton macrostachyus and Schefflera abyssinica areamong the frequently observed vegetation in the area

22 Sampling Sites Eight sampling sites were selected fromboth rivers based on flow nature and accessibility (Figure 1)The basic habitat characteristics and geographical locationsof the sampling sites are summarized in Table 1 The SorRiver sampling sites are located relatively at higher altitude(gt1500m above sea level) than the Geba River sites which arelocated below 1300m above sea level The channel diameterof the sampling sites ranged from 29 to 40m with a meanvalue of 3321mAll the sampling sites except theHora site onSor River (S1) had clear water with sandy gravel and rockybottom Hora site was turbid with largely muddy bottomMost parts of the Sor River were highly irrigated and had lessvegetation cover

23 Fish Sampling and Identification Fish samples werecollected during one wet season and one dry season between

October 2012 andMarch 2013 Fish specimens were collectedusing gillnets of various mesh sizes (12 16 20 and 24 cmstretched mesh) and hooks Gillnets were set late in theafternoon and collected early in themorning the next dayThesame extent of fishing effort was used across the seasons andsites Field-level identification of the fish specimenswasmadeto species level using relevant taxonomic literature [3 9ndash12]Total length (TL) and total weight (TW) measurements weretaken to the nearest 01 cm and 01 g respectively Ultimatelyvoucher specimens from each species were preserved in 10formalin solution and transported to the Department ofBiology Jimma University where they are deposited

24 Data Analysis Shannon diversity index (1198671015840) [13] wasused for assessing the diversity of fish species for eachsampling site and the rivers as follows

1198671015840 = minus119878

sum119894=1

ni119873 ln(ni119873) (1)

where sum is the sum from species 1 to 119878 ni is the number ofindividuals of species ldquo119894rdquo119873 is the total number of individualsof all species 119878 is species richness

Estimation of the relative abundance of fishes in thestudy rivers was made by comparing the relative catch innumber and weight in the total sampling An index ofrelative importance (IRI) which is a measure of the relativeabundance or commonness of the species based on number

International Journal of Biodiversity 3

Table 1 Summary of the sampling sites and rivers asl above sea level

River Site Habitat type Width (m) Altitude(m asl) Coordinates

Sor

Hora site (S1) Turbid water gravel andmuddy 32 1552 N 8∘2210158404510158401015840

E 35∘3210158404210158401015840

At the bridge fromMetu toHurumu (S2)

Clear water gravel sandyand rocky 30 1554 N 8∘2010158401310158401015840

E 35∘3510158404710158401015840

Lakata site (S3) Clear water gravel androcky 33 1554 N 8∘1810158402710158401015840

E 35∘3710158403810158401015840

Moges site (S4) Clear water gravel androcky 337 1556 N 8∘1310158403310158401015840

E 35∘3810158405510158401015840

Geba

Doko site (G1) Clear water gravel androcky 35 1241 N 8∘2310158404210158401015840

E 35∘4910158402310158401015840

At the bridge from Yayu toDoreni District (G2)

Clear water gravel androcky 33 1252 N 8∘2210158405910158401015840

E 35∘4610158402910158401015840

Down the bridge from Yayuto Doreni District (G3)

Clear water gravel sandyand rocky 40 1254m N 8∘2410158405810158401015840

E 35∘4210158405210158401015840

At the bridge fromMetu toAlge District (G4)

Clear water gravel androcky 29 1149m N 8∘3010158401610158401015840

E 35∘3810158405310158401015840

andweight of individuals in catches as well as their frequencyof occurrence [14 15] was computed as

IRI = ( 119882119894 + 119873119894) times 119865119894sum119878119895=1 ( 119882119895 + 119873119895) times 119865119895times 100 (2)

where 119895 is 1 to 119878 119882119894 and 119873119894 are percentage weightand number of each species of total catch respectively 119865119894is percentage frequency of occurrence of each species intotal samplings 119882119895 and 119873119895 are percentage weight andnumber of total species of total catch respectively 119865119895 ispercentage frequency of occurrence of total species in totalnumber of samplings and 119878 is the total number of species

The relationship between total length and total weight ofthe dominant fish species namely Labeobarbus intermediusLabeobarbus nedgia and Labeo cylindricus was fitted usingpower function [16] as

TW = 119886TL119887 (3)

where TW is total weight (g) TL is total length (cm) and ldquo119886rdquoand ldquo119887rdquo are the constant and power coefficients respectivelyof the regression line

The well-being of fishes of the study rivers was inves-tigated for the three most abundant species using Fultoncondition factor (FCF) [16 17] computed as

FCF = TWTL3times 100 (4)

where TW is total weight (g) and TL is total length (cm)The sex ratio for the three dominant species was deter-

mined using the equation

Sex ratio = number of femalesnumber of males

(5)

Significant variation in FCF between seasons was tested usingone-way analysis of variance (ANOVA) whereas significantvariation in sex ratio was tested using Chi-square at 5 levelof significance in SPSS for Windows (ver 16)

3 Results and Discussion

31 Fish Species Diversity and Distribution A total of eightspecies and oneGarra sp representing seven genera and fourfamilies were identified from Geba and Sor Rivers duringthe study period (Figure 2) The identity of a single Garraspecimen collected from Sor River could not be determinedusing the existing keys [3 9ndash12] This specimen has muchresemblance to the Garra specimens reported from thesame river by Golubtsov et al [18] and discussed as beingpotentially undescribed It thus calls for further collectionof sufficient samples for possible description in the futureLabeo forskalii Raiamas senegalensis Bagrus docmak andMormyrus hasselquistii were collected only from Geba Riverwhile Oreochromis niloticus and Garra sp were collectedonly from Sor River Labeobarbus intermedius Labeobarbusnedgia and Labeo cylindricuswere recorded from both riversThere was variation in diversity between the two rivers asthe Shannon diversity index was higher for Geba River (1198671015840= 150) and lower for Sor River (1198671015840 = 110)

The diversity of fish fauna identified from the studiedrivers contains a mixture of Nilo-Sudanic (L forskalii Lcylindricus B docmak andM hasselquistii) and East Africanforms (L intermedius L nedgia O niloticus and Garra sp)The Nilo-Sudanic forms were the dominant forms in termsof diversity and are represented by a large number of speciesfound in the Baro-Akobo Basin [6] This could be probablybecause of the connection between the White Nile and thetwo rivers [2 7 10] Only one species endemic to Ethiopia (Lnedgia) was recorded from the two rivers and it is the firstreport for Baro-Akobo Basin


(a) (b)

(c) (d)

(e) (f)

(g) (h)

(i)

Figure 2 Fish species identified fromGeba and Sor Rivers during the present study (a)Mormyrus hasselquistii (Mormyridae) (b)Garra sp(c) Labeo forskalii (d) Labeo cylindricus (e) Raiamas senegalensis (f) Labeobarbus intermedius (g) Labeobarbus nedgia (Cyprinidae bndashg)(h) Bagrus docmak (Bagridae) and (i) Oreochromis niloticus (Cichlidae)

32 Relative Abundance A total of 348 fish specimens werecollected from eight sampling sites during the study periodOf the total specimens collected 116 were caught duringthe wet season and 232 specimens were caught during thedry season Labeobarbus intermedius was the most abundantspecies in number (4713) during both the wet and the dryseasons followed respectively by L cylindricus (2184) Lforskalii (1236) and L nedgia (1236) Raiamas senegalen-sis M hasselquistii and Garra sp were the least abundantfish species in number represented by one specimen each(Table 2) Based on the index of relative importance (IRI)which more or less concurred with the numeric abundancethe most important species in the total catches were Lintermedius (4862) L nedgia (1681) and L cylindricus(1476) (Table 2)

In both rivers the weight and number of fish specimenswere higher in the dry season than in thewet season (Table 3)That fewer fish were caught during the wet season might bedue to high turbidity speedy run-off and low temperature[19] There is also higher water discharge during the wet

Table 2 Summary of the percent number ( 119873) percent weight( 119882) and index of relative abundance ( IRI) of fish species ofGeba and Sor Rivers Total number of specimens (119873) = 348

Species 119873 119882 IRILabeobarbus intermedius 4713 4862 6072Labeo cylindricus 2184 1515 1466Labeobarbus nedgia 1236 1594 1683Labeo forskalii 1236 1296 602Oreochromis niloticus 287 125 049Bagrus docmak 201 554 120Raiamas senegalensis 086 024 0043Garra sp 029 018 0018Mormyrus hasselquistii 029 012 0016

season so fishes could be highly dispersed in the large volumeof water than during the dry season and it thus becomesdifficult to catch them [20] In addition the variation in


Table 3 Summary of the weight (g) of fish species for each season

Fish species Wet season Dry season OverallGeba Sor Total Geba Sor Total Total

L intermedius 2430 600 3030 5025 3180 1760 4940 4748 7970 4862L cylindricus 320 430 750 1244 1045 695 1740 1672 2490 1515L nedgia 1240 320 1560 2587 715 345 1060 1019 2620 1594L forskalii 570 mdash 570 945 1560 mdash 1560 1499 2130 1296O niloticus mdash 070 070 116 mdash 135 135 130 205 125B docmak mdash mdash mdash mdash 910 mdash 910 875 910 554R senegalensis mdash mdash mdash mdash mdash mdash mdash mdash 040 024Garra sp mdash mdash mdash mdash mdash 030 030 029 030 018M hasselquistii mdash mdash mdash mdash 020 mdash 020 019 020 012

Table 4 Length-weight relationship of the most common fish species of Geba and Sor Rivers (ANOVA 119901 lt 005) 119873 = total number ofspecimens

Species Rivers TW = 119886TL119887 1198772 119901 Mean plusmn SE TL Mean plusmn SE TW 119873L intermedius Geba 0035TL270 097 000 3848 plusmn 140 81304 plusmn 8950 69

Sor 0013TL227 079 000 2668 plusmn 055 24947 plusmn 2136 95

L nedgia Geba 0049TL260 097 000 436 plusmn 232 9775 plusmn 12399 20Sor 0026TL270 079 000 2761 plusmn 124 28913 plusmn 5880 23

L cylindricus Geba 0051TL256 092 000 2852 plusmn 073 28437 plusmn 2090 48Sor 0236TL288 068 000 3121 plusmn 052 40178 plusmn 2204 28

gillnet efficiency might have contributed to variation in thecatches between wet and dry seasons Moreover leaves logsand roots that were brought by flooding could decrease theefficiency of gillnets during the wet season

The number and weight of fish specimens in Geba Riverare higher than in Sor River The difference in number andweight of fish specimens in these rivers might be attributedto the less vegetation cover and widespread irrigation devel-opment in most parts of Sor River This in turn may havecontributed to the lack of good habitats with diverse riparianvegetation

33 Length-Weight Relationship Length-weight relationshipof the three most abundant species L intermedius L nedgiaand L cylindricus showed negative allometric growth The119887-value for L cylindricus (272) is comparable with the value(276) reported from Angereb and Sanja Rivers Tekeze Basin[20] The 119887-values are relatively lower for L intermedius(250) and L nedgia (265) (Table 4) when compared withthe values reported for these species from Angereb River(L intermedius 296 L nedgia 294) [20] and from Arno-Garno River (L intermedius 295 L nedgia 298) [21] Thevariations in the results between the present study and thosestudies could be ascribed to the differences in the numberof samples the differences in food availability stage of fishgonad development and spawning period [16]

34 Fulton Condition Factor (FCF) Fish conditions dependon biological factors such as the age and environmental

or geographical and temporal factors such as the seasonof the year when samples are collected [22ndash24] Generallyhigher condition is associated with high energy content ade-quate food availability reproductive potential and favorableenvironmental conditions [25] The mean FCF value for Lintermedius (121) (Table 5) is comparable to the value (123)reported for Borkena River in Awash Basin [26] The meanFCF value for L nedgia (105) from Geba and Sor Rivers waslower than the value (148) reported for Angereb and SanjaRivers in Tekeze Basin [20] However the FCF values for Lintermedius were higher than the value (10) reported for thesame species from Beles and Gilgel-Beles Rivers [27] as wellas the value (112) reported from Guang Ayima Gendwuhaand Shinfa Rivers [28]Themean FCF value for L cylindricus(121) was higher than the value (118) reported for Angereband Sanja Rivers in Tekeze Basin [20]Themain reason for thedifferences observed in the mean FCF between the presentand past studies might relate to the variation in the extent ofsampling or variations in the factors such as food quantityand quality water level and flow rate feeding rate healthand reproductive activity of fishes in the study areas [29 30]Statistically significant seasonal variation was observed for Lcylindricus (Table 5)

35 Sex Ratio The sex ratio for the three most abundant fishspecies namelyL intermedius L nedgia andL cylindricus isprovided in Table 6 There was variation in sex ratio with thefemales dominating in all the three speciesHowever theChi-square test showed that there was no significant difference


Table 5 Summary of the Fulton condition factor for the most abundant species of Geba and Sor Rivers SE is the standard error of the mean119873 is the total number of the specimens lowast indicates statistically significant variation at 5

Species Wet season 119873 Dry season 119873 ANOVAMean plusmn SE Mean plusmn SE 119865 119901

L intermedius 120 plusmn 006 50 122 plusmn 003 114 0127 0722L cylindricus 110 plusmn 005 20 125 plusmn 002 56 9954 0002lowast

L nedgia 103 plusmn 003 25 109 plusmn 005 18 1109 0299

Table 6 Summary of sex ratio for the most abundant species ofGeba and Sor Rivers

Number Fish species Females (F) Males (M) F M ratio1 L intermedius 85 75 1 0882 L nedgia 26 17 1 0653 L cylindricus 44 32 1 072

between the numbers of males and females (1205942 119901 gt 005)Thedifference in sex ratiomight be due to variation in the twosexes in their vulnerability to the fishing gears used fishingsites habitat and segregation during spawning and feeding[31]

4 Conclusion

In the present collections eight species and one Garra sprepresenting seven genera and four families were identifiedfrom Geba and Sor Rivers Baro-Akobo Basin White Nilesystem within Ethiopia Fish diversity of the two riversappeared to be low as compared to the other most studiedrivers in Ethiopia The fish faunal diversity of both riverswas dominated by cyprinid fish species with L intermediusL nedgia and L cylindricus being the most abundant fishspecies respectively Studies are needed on food and feedingreproductive behaviors of fish species and fisheries socioeco-nomic aspects of the two rivers

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

The authors would like to thank Jimma University for thefinancial support

References

[1] R B Wood and J F Talling ldquoChemical and algal relationshipsin a salinity series of Ethiopian inland watersrdquo Hydrobiologiavol 158 no 1 pp 29ndash67 1988

[2] T R Roberts ldquoGeographical distribution of African freshwaterfishesrdquo Zoological Journal of the Linnean Society vol 57 no 4pp 249ndash319 1975

[3] S Tedla Freshwater Fishes of Ethiopia Department of BiologyAddis Ababa University Addis Ababa Ethiopia 1973

[4] A Getahun andM Stiassny ldquoThe freshwater biodiversity crisisthe case of the Ethiopian fish faunardquo SINET Ethiopian Journalof Science vol 21 no 2 pp 207ndash230 1998

[5] A Getahun ldquoThe nile in the Ethiopian territory Riverine fishand fisheriesrdquo in Proceedings of the Food and Water ChallengeInternational Workshop Addis Ababa Ethiopia 2003

[6] A Getahun ldquoAn overview of diversity and conservation statusof the Ethiopian freshwater fish faunardquo Journal of AfrotropicalZoology special volume pp 87ndash96 2007

[7] A Golubstov and A Darkov ldquoA review of Fish Diversity in themain Drainage systems of Ethiopiardquo in Ecological and FaunisticStudies in Ethiopia S Dmitry Pavlov Y Dgebuadge A Andreyand M Mina Eds JERBE 20 Years Scientific CooperationArtistic inc Addis Ababa Ethiopia 2008

[8] National Metrological Agency Jimma Branch Jimma 2013[9] G Boulenger Catalogue of the Freshwater Fishes of Africa

vol 1ndash4 British Museum of Natural History London UK1909ndash1916

[10] A Golubtsov A Darkov Y Y Dgebuadze and M Mina AnArtificial Key to Fish Species of the Gambela Region (The WhiteNile Basin in the Limits of Ethiopia) Joint Ethio-Russian Bio-logical Expedition Artistic Printing Enterprise Addis AbabaEthiopia 1995

[11] M L J Stiassny and A Getahun ldquoAn overview of labeoninrelationships and the phylogenetic placement of the Afro-Asiangenus Garra Hamilton 1922 (Teleostei Cyprinidae) with thedescription of five new species ofGarra fromEthiopia and a keyto all African speciesrdquo Zoological Journal of the Linnean Societyvol 150 no 1 pp 41ndash83 2007

[12] R Habteselassie Fishes of Ethiopia Annotated Checklist withPictorial Identification Guide Ethiopian Fisheries and AquaticScience Association Addis Ababa Ethiopia 2012

[13] M Begon J Harper and C Townsend Ecology IndividualsPopulations andCommunities Blackwell Scientific Publications2nd edition 1990

[14] J KoldingThe fish resource of Lake Turkana and their environ-ment [Cand Scient thesis] University of Bergen Norway 1989

[15] J Kolding PASGEAR A Data Base Package for Experimentalor Artisanal Fishery Data from Passive Gears An IntroductoryManual University of Bergen Department of Fisheries andMarine Biology 1999

[16] T Bagenal and F Tesch ldquoAge and growthrdquo in Methods forAssessment of Fish Production in Fresh Waters T B Bageal Edpp 101ndash136 Black well New York NY USA 1978

[17] G Lecren ldquoThe length-weight relationship and seasonal cyclein gonad weight and condition in the perch (Perca fluviatilis)rdquoJournal of Animal Ecology vol 20 pp 201ndash219 1951

[18] A S Golubtsov S E Cherenkov and F Tefera ldquoHigh morpho-logical diversity of the genusGarra in the Sore River (theWhiteNile Basin Ethiopia) onemore cyprinid species flockrdquo Journalof Ichthyology vol 52 no 11 pp 817ndash820 2012


[19] C A Nsor and E A Obodai ldquoEnvironmental determinants in-fluencing fish community structure and diversity in two distinctseasons among wetlands of northern region (Ghana)rdquo Interna-tional Journal of Ecology vol 2016 Article ID 1598701 10 pages2016

[20] G Tesfaye Diversity relative abundance and biology of fishes inAngereb and Sanja Rivers Tekeze basin Ethiopia [MS thesis]Addis Ababa University Addis Ababa Ethiopia 2006

[21] S Gebremedhin pawning migration of Labeobarbus species ofLake Tana to Arno-Garno River Blue Nile Basin Ethiopia [MSthesis] Bahir Dar University Bahir Dar Ethiopia 2011

[22] S Ferreira R Sousa J Delgado D Carvalho and T ChadaldquoWeight-length relationships for demersal fish species caughtoff the Madeira archipelago (eastern-central Atlantic)rdquo Journalof Applied Ichthyology vol 24 no 1 pp 93ndash95 2008

[23] A Vaslet Y Bouchon-Navaro M Louis and C BouchonldquoWeight-length relationships for 20 fish species collected in themangroves of Guadeloupe (Lesser Antilles)rdquo Journal of AppliedIchthyology vol 24 no 1 pp 99ndash100 2008

[24] M Nowak W Popek W Jagusiak et al ldquoWeight-length rela-tionships for three fishes (Leuciscus leuciscus Phoxinus phox-inus Salmo trutta) from the Strwiaz River (Dniester Riverdrainage)rdquoArchives of Polish Fisheries vol 17 no 4 pp 313ndash3162009

[25] C Paukert and R S Rogers ldquoFactors affecting condition offlannelmouth suckers in the Colorado River Grand CanyonArizonardquoNorth American Journal of FisheriesManagement vol24 no 2 pp 648ndash653 2004

[26] A Tessema M Mingist and E Dejen ldquoDiversity relativeabundance and biology of fishes in Borkena and Mille RiversAwash Basin Ethiopiardquo Journal of Fisheries International vol 7no 3ndash6 pp 70ndash76 2012

[27] Z Berie Diversity relative abundance and biology of fishes inBeles and Gilgel-Beles Rivers Abay basin Ethiopia [MS thesis]Addis Ababa University Addis Ababa Ethiopia 2007

[28] D Tewabe Diversity relative abundance and Biology of fishesin Gendwuha Guang Shinfa and Ayima Rivers North GonderEthiopia [MSc Thesis] Addis Ababa University Addis AbabaEthiopia 2008

[29] A Payne Ecology of Tropical Lakes and Rivers John Ailey ampSons Chichester UK 1986

[30] G Tefera Food nutrition and digestive efficiency in Oreochromisniloticus L (Pisces Cichlidae) in Lake Awassa Ethiopia [PhDthesis] University of Waterloo Ontario Canada 1987

[31] D Admassu ldquoMaturity fecundity brood size and sex ratioof Tilapia (Oreochromis niloticus) in Lake Awasa EthiopiardquoSINET Ethiopian Journal of Sciences vol 17 no 1 pp 53ndash691994

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Microbiology


Town

Geba and Sor sampling siteRivers

District boundary

36∘0㰀0㰀㰀E35

∘50

㰀0㰀㰀E35

∘40

㰀0㰀㰀E35

∘30

㰀0㰀㰀E35

∘20

㰀0㰀㰀E

36∘0㰀0㰀㰀E35

∘50

㰀0㰀㰀E35

∘40

㰀0㰀㰀E35

∘30

㰀0㰀㰀E35

∘20

㰀0㰀㰀E

8∘0㰀0㰀㰀N

8∘10

㰀0㰀㰀N

8∘20

㰀0㰀㰀N

8∘30

㰀0㰀㰀N

8∘0㰀0㰀㰀N

8∘10

㰀0㰀㰀N

8∘20

㰀0㰀㰀N

8∘30

㰀0㰀㰀N

Figure 1 Map of the study sites and rivers

of Ilu Aba-Bor Zone Oromia Regional State in southwesternEthiopia (Figure 1) The districts are located at 550 km and600 km southwest of the capital Addis Ababa respectivelyThe annual temperature ranges from 1413 to 2907∘C and1121 to 2733∘C for Yayu and Metu Districts respectively Themean annual rainfall is 1563mmyear for Yayu District and142717mmyear for Metu District with high variation fromyear to yearThe rainfall patterns of the districts are unimodalwith low rainfall during January and February and the highestrainfall between June and August [8] Ficus species Coffeaarabica Croton macrostachyus and Schefflera abyssinica areamong the frequently observed vegetation in the area

22 Sampling Sites Eight sampling sites were selected fromboth rivers based on flow nature and accessibility (Figure 1)The basic habitat characteristics and geographical locationsof the sampling sites are summarized in Table 1 The SorRiver sampling sites are located relatively at higher altitude(gt1500m above sea level) than the Geba River sites which arelocated below 1300m above sea level The channel diameterof the sampling sites ranged from 29 to 40m with a meanvalue of 3321mAll the sampling sites except theHora site onSor River (S1) had clear water with sandy gravel and rockybottom Hora site was turbid with largely muddy bottomMost parts of the Sor River were highly irrigated and had lessvegetation cover

23 Fish Sampling and Identification Fish samples werecollected during one wet season and one dry season between

October 2012 andMarch 2013 Fish specimens were collectedusing gillnets of various mesh sizes (12 16 20 and 24 cmstretched mesh) and hooks Gillnets were set late in theafternoon and collected early in themorning the next dayThesame extent of fishing effort was used across the seasons andsites Field-level identification of the fish specimenswasmadeto species level using relevant taxonomic literature [3 9ndash12]Total length (TL) and total weight (TW) measurements weretaken to the nearest 01 cm and 01 g respectively Ultimatelyvoucher specimens from each species were preserved in 10formalin solution and transported to the Department ofBiology Jimma University where they are deposited

24 Data Analysis Shannon diversity index (1198671015840) [13] wasused for assessing the diversity of fish species for eachsampling site and the rivers as follows

1198671015840 = minus119878

sum119894=1

ni119873 ln(ni119873) (1)

where sum is the sum from species 1 to 119878 ni is the number ofindividuals of species ldquo119894rdquo119873 is the total number of individualsof all species 119878 is species richness

Estimation of the relative abundance of fishes in thestudy rivers was made by comparing the relative catch innumber and weight in the total sampling An index ofrelative importance (IRI) which is a measure of the relativeabundance or commonness of the species based on number




Sor


E 35∘3210158404210158401015840



E 35∘3510158404710158401015840


E 35∘3710158403810158401015840


E 35∘3810158405510158401015840

Geba


E 35∘4910158402310158401015840



E 35∘4610158402910158401015840



E 35∘4210158405210158401015840



E 35∘3810158405310158401015840





TW = 119886TL119887 (3)







(5)






(a) (b)

(c) (d)

(e) (f)

(g) (h)

(i)






























4 Conclusion




Acknowledgments


References








































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




Sor


E 35∘3210158404210158401015840



E 35∘3510158404710158401015840


E 35∘3710158403810158401015840


E 35∘3810158405510158401015840

Geba


E 35∘4910158402310158401015840



E 35∘4610158402910158401015840



E 35∘4210158405210158401015840



E 35∘3810158405310158401015840





TW = 119886TL119887 (3)







(5)






(a) (b)

(c) (d)

(e) (f)

(g) (h)

(i)






























4 Conclusion




Acknowledgments


References








































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


(a) (b)

(c) (d)

(e) (f)

(g) (h)

(i)






























4 Conclusion




Acknowledgments


References








































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology
























4 Conclusion




Acknowledgments


References








































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology






















Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

Research Article Population Aspects of Fishes in Geba and ...

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