Shading Of Breeding Hapas Enhances Reproductive Performance Of Nile Tilapia (Oreochromis 205 Niloticus) And Seed Output

By : Ram C. Bhujel , Anusha Perera

Page No: 205-216

Abstract
During summer, temperature of water in fishponds often rises excessively high which has been aggravated further by global warming. When the water temperature reaches above 35o C it hampers growth and reproduction. Facing this critical problem, an experiment was conducted for 120 days during May – September 2015 to investigate the effects of shading on seed output of Nile tilapia (Oreochromis niloticus). The trial was conducted using 12 hapas (12m x 5m) with net cover installed in a green water pond randomly assigned four replications for each of the three treatments, namely; (i) black net; (ii) blue net; and (iii) without cover as “Control”. Each hapa was initially stocked with 150 females (Mean weight ± SE, 118.8 ± 5.7 g) and 75 male Nile tilapia (Mean weight ± SE, 120.3 ± 4.6 g). During the trial period, pond water temperature ranged from 26.7oC – 37.8oC. Average weekly egg production was 15,622±842 hapa-1 from the hapas shaded with black net, which was 9 % and 18 % higher than that from the control and the hapa shaded with blue net respectively. Percentage of clutch hapa-1 week-1 from the black shaded hapas increased by 9% and 10%, as compared to the one shaded with blue net and control hapa respectively. Present study, therefore, showed that shading with black net helps increase seed output whereas blue net does not.

Authors :
Ram C. Bhujel and Anusha Perera
Aqua-Centre, School of Environment, Resources and Development (SERD) Asian Institute of Technology (AIT), THAILAND.