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International Journal of Pure & Applied Bioscience (IJPAB)
Year : 2016, Volume : 4, Issue : 3
First page : (144) Last page : (153)
Article doi: http://dx.doi.org/10.18782/2320-7051.2285

Breeding Performance of Rainbow Trout, Oncorhynchus mykiss (Walbaum), the Raceways of Kathmandu, Nepal

Rakesh Prasad Bhagat1,2* and Sudip Barat2
1Department of Zoology, Tri-Chandra Multiple Campus, Tribhuvan University, Kathmandu- 44600, Nepal
2Aquaculture and Limnology Research Unit, Department of Zoology, University of North Bengal,
Siliguri-734013, District Darjeeling, West Bengal, India
*Corresponding Author E-mail: rakesh.bhagat2009@gmail.com
Received: 10.05.2016  |  Revised: 21.05.2016   |  Accepted: 25.05.2016  

As the requirement of small farmers’, artificial breeding performance of 1.0+ broods (first spawners) of rainbow trout, Oncorhynchus mykiss (Walbaum), was carried out in their own raceways. Fingerlings 5.433±0.06g and 6.70±0.02cm were stocked in the raceways in water discharge of 0.083-0.3L sec-1 for one year. When they became 375±18.097g and 31.5±0.19cm after one year, they were selected as future broods. Future broods passing through the stages of broods (426±16.165g and 33±0.40cm), segregated broods (454±18.641g and 34±0.39cm), and current broods (513±17.678g and 36±0.38), after five months, were converted into gravid broods attaining 519±19.191g and 36±0.38cm. Gravid broods, which were 1.0+ broods (first spawners) and which were put under artificial breeding, when collected before spawning were found to be 519.83±12.243g and 36.06±0.34cm. Induced breeding results under semi-intensive farming system of 12 female (520.±9.785g and 36.18±0.24cm) and 6 male (493.5±23.158g and 35.8±0.79cm) broods showed a total collection of 915g eggs (76.25±1.538g eggs female-1) and 18391 number eggs (1532.58±38.88 number eggs female-1) and 204ml milt (34±2.61ml milt male-1) respectively. Eggs were yellow-coloured, each egg 0.0499±0.001g and 0.303± 0.0095cm (diameter). Eggs laid were 146.65±1.404g eggs kg-1 body wt. (1759.82g eggs 12kg-1 body wt.) and 2947.42±51.54 number eggs kg-1 body wt. (35369 number eggs 12kg-1 body wt.) of female broods. 1g eggs comprised 20.12±0.38 number eggs (241376 number eggs 12kg-1 of eggs and 20115 eggs kg-1 of eggs). Milt was cream-coloured, each ml comprising 5millions spermatozoa. Milting was 68.53±2.36ml milt kg-1 body wt. (411.17ml milt 6kg-1 body wt.) of male broods. Fertilization was done by dry stripping method with 70.18±4.05g fertilized eggs female-1 (842.1g fertilized eggs 12females-1) and 1410.16±94.12 number fertilized eggs female-1 (16922 number fertilized eggs 12females-1) ensuring fertilization percentage to be 91.99±0.58%. Fertilized eggs were transferred into incubation cum hatching trays put into incubation cum hatching raceways. Cleaning and readjustment of incubation cum hatching trays were done thrice. Incubation period was 25 days in average temperature of 10.89±0.21oC day-1 and cumulative temperature (sum total of water temperature of 25 days) of 272oC with hatching of yolk-sac fries or alevins (survivability 41.82±3.16%), each 0.0365±0.0016g and 1.46±0.086cm with 0.0136±0.0012g yolk-sac. Alevins were shifted into endogenous feeding cum hatching cages put into endogenous feeding cum hatching raceways. Endogenous feeding period was 5 days in water temperature of 9.1oC liberating free swimming fries (survivability 76.92±4.91%), each 0.025±0.0007g and 1.65±0.083cm ready for exogenous feeding period. Results confirmed the utility of 1.0+ broods at small farmer’s level. 

Key words: 1.0+ (First Spawners) Rainbow Trout Broods, Eggs, Milt, Alevins, Free Swimming Fries

Full Text : PDF; Journal doi : http://dx.doi.org/10.18782

Cite this article: Bhagat, R.P. and Barat, S., Breeding Performance of Rainbow Trout, Oncorhynchus mykiss (Walbaum), the Raceways of Kathmandu, Nepal, Int. J. Pure App. Biosci.4(3): 144-153 (2016). doi: http://dx.doi.org/10.18782/2320-7051.2285