Animal science

Sociology

Demography

Zooplankton

Oreochromis

Population

Fish <Actinopterygii>

Fishery

Biology

3 Abstract: Fishes are good sources of proteins. In some of the reservoirs of Tigray, fishes have been introduced for fish production. The objective of this study was to understand the productivity and condition factor of the fish in Tigray dams. Most relevant information associated with fish population dynamics were collected and fish morphological measurements such as total length, weight, maturity were registered. Fish samples were collected four times for the collected four months, December 2012, March, April and May 2013. Fishes were sampled by deploying 40 meter monofilament commercial net with 12cm mesh size for 1 hour. Fifteen species of phytoplankton, eight taxa of rotifer and seven taxa of other zooplankton were recorded. A total of 286 Oreochromis niloticus were collected from five dams and no significant difference was observed in fish catch among the studied dams during the sampled seasons ( 2 = 7.77, p> 0.05). Schlesinger and Regier (15) fish yield estimation model depicts 5.5 in Mai Sesela, 4.5 in Mai Nigus, 4.9 in Mai Seye, 4.5 in Lailay Wukro and 4.4 quintals in Korir. L50 maturity of O. niloticus in the dams is 24.5cm. The fishes mature while they are very small ( 2 = 81.32, d.f.= 2, p= 0.000). Almost half (49.65%) of the O. niloticus caught were weighing less than 300gm ( 2 = 23.22, d.f= 6, p< 0.001). The condition factor of O. niloticus in the reservoirs remains high, more than 60% of the fishes caught were having k-factor greater than 1.75 ( 2 = 17.88, d.f.= 6, p< 0.007). In general, if the dams are better managed, the Tigray dams have high potential for fish culture, thus they can be used as promising sites of pisciculture by the unemployed youth who want to be engaged in fish production in the region.

Yield and condition factor of Oreochromis niloticus L. in tropical small dams, Tigray, northern Ethiopia.