Age and Growth of Oreochromis Niloticus (Pisces:Cichlidae) in Lake Hayq, Ethiopia
| dc.contributor.advisor | Tefera, Getachew (PhD) | |
| dc.contributor.advisor | Admassu, Demeke (PhD) | |
| dc.contributor.author | Alemu, Kebede | |
| dc.date.accessioned | 2018-07-03T07:58:26Z | |
| dc.date.accessioned | 2023-11-08T16:32:45Z | |
| dc.date.available | 2018-07-03T07:58:26Z | |
| dc.date.available | 2023-11-08T16:32:45Z | |
| dc.date.issued | 1995-06 | |
| dc.description.abstract | otoliths from 447 mature and 308 immature Oreochromis niloticus (10 to 304 mm total length) from Lake Hayq were measured and examined for translucent and opaque macrozones. Microzone analysis was also conducted on the 308 immature O. niloticus otoliths. Macrozonal daily age estimate was determined by extrapolating the number of days between the date of capture and calender birth dates. utilization of the number of macrozones, condition on the edge of otoliths and date of capture enabled the separation of fish into recruitment groups. Microzones on the otoliths were enumerated and used as a measure of age in days and to hind cast hatch dates. The relationship between otolith size and fish total length 11as also examined. It appears that the breeding of o.niloticus in Lake Hayq is continuous with high peaks during !·larch-May and July-October. Two translucent macrozones '''ere formed per year during January-February and June-July. Fish spa~ned between January and May and July and November of the same year form the first translucent zone associated with biannuli at different times. The close agreement between macrozonal and microzonal daily age estimates (r=O. 84) sUbstantiates the usefulness macrozone analysis to assess the age of O.niloticus. There was a strong linear relationship between otolith size and fish size and also between microzone count and fish length. HOI-leVer, a linear relationship underestimates fish size at later ages. Values of size-at-age estimates obtained from macro zone and microzone analysis and fish total length-otolith radius relationship were close to each other. This demonstrates the usefulness of results from the latter method in supporting conclusions drawn from macrozone and microzone analysis. | en_US |
| dc.identifier.uri | http://etd.aau.edu.et/handle/123456789/5753 | |
| dc.language.iso | en | en_US |
| dc.publisher | Addis Ababa University | en_US |
| dc.subject | Biology | en_US |
| dc.title | Age and Growth of Oreochromis Niloticus (Pisces:Cichlidae) in Lake Hayq, Ethiopia | en_US |
| dc.type | Thesis | en_US |