Zoological Sciences

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Browsing Zoological Sciences by Subject "abundance"

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    Diversity, Relative Abundance and Biology of Fishes in Angereb and Sanja Rivers, Tekeze Basin, Ethiopia
    (Addis Ababa University, 2006-06) Tesfaye, Genanaw; Getahun, Abebe (PhD)
    Diversity and relative abundance of fish species of Rivers Angereb and Sanja were studied from samples (923 specimens) collected during November 2004 to October 2005. The samples were collected in the dry season and wet season. Fish sampling was done using gill nets with various stretched mesh size, hooks and line, monofilament nets with different mesh size and cast nets. Ten fish species were identified from the two rivers and these are included in the families Cyprinidae, Cichlidae, Mormyridae, Clariidae and Bagridae. The fish species identified are East African and Nilo-Sudanic in forms. Cyprinid fish, L. forskalii, was the most dominant both in number and weight in both rivers during the two sampling seasons. Analysis of variance shows that there were significant variations both in number and weight of fish specimens between the two seasons. The three most dominant fish species in the rivers are L. forskalii, L. cf. intermedius and L. nedgia. The length-weight relationship for these species were found to be curvilinear and described by TW = 0.0715TL2.47, TW = 0.0269TL2.96 and TL = 0.0269TL2.74 respectively in Angereb River. It was TW = 0.01TL3.021, TW = 0.0057TL3.18 and TW = 0.006TL3.14 for L. forskalii, L. cf. intermedius and L. nedgia respectively in Sanja River. The mean FCF for L. forksalii, L.cf. intermedius and L. nedgia were 1.26, 1.14 and 1.18 in Angereb River and 1.09, 1.05 and 1.05 in Sanja River respectively. There was significant variation (ANOVA, P < 0.05) in mean FCF of L. forskalii and L. intermedius in the two rivers. In both rivers females were more numerous (Chi-square, P < 0.05) than males. The mean absolute fecundity of L. forskalii ranging in length from 21 to 25cm FL and mean body weight of 229 gm was 48120. The smallest count was 27094 eggs in fish with 14 gm total weight and 22.2 cm fork length. The highest was 120314 eggs in fish with 1023 gm total weight and 37 cm fork length. Fecundity of the species in the rivers was linear when related to total weight, fork length and gonad weight. Key words/phrases: Rivers, Angereb, Sanja, fish diversity, relative abundance, length-weight relationship, Fulton Condition Factor.
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    Population status, distribution and ecology of Gelada baboon (Theropithecus gelada) in Azwa and Arego, South wollo, Dessie, Ethiopia.
    (Addis Ababa University, 2009-07) Ayalew Yonatan; Belay Gurja (PhD); Bekele Afework (Professor)
    The population status and distribution of gelada baboon in Cliff Azwa and Arego was investigated and test statistics was applied to age-sex categorical variable. The study area was stratified into five study blocks namely Aba Tasho, Aba Gude, Doro Mezeleya, Azwa and Dikule genet. The study was carried out from August, 2008 to March, 2009. Data on movement, distribution and human gelada interaction were collected in the area based on the questionairre survey and field observation. Data were analyzed using descriptive statistics, and responses were compared using t-test and oneway ANOVA to compare age-sex categorical variables. The population size and abundance of geladas in the area was determined from total (direct) count. A total of 338 individual geladas were recorded with a density for the entire region of 0.071 geladas/km2 and actual density specific for the home ranges was 6.22/km2. Of this, males were 74, females 186 and juveniles 78. There was significant difference (P<0.05) between males and females, males and juveniles and females and juveniles. Large number of infants indicates that the population is increasing. Geladas spent more time feeding (57.26 %). Other activities such as vocalization, defecation and looking at the observer were the least (2.33%) in their time budget. They depend on grass during the wet season (82.77%) but during the dry season, they fed on roots (38.71%) and leaves (38.5%) in larger proportion and almost in equivalent amount. There are significant differences (P<0.05) on the type of food taken during the dry and wet seasons. Key words: abundance, body size, distribution, extinction, Gelada baboon, habitat, human activities, juvenile.