Middle East – Research
BY ALYA AL-GHABSHI
Disease data in young industry Stirling PhD student gathers information to help improve the aquatic environment of Oman
F
ISH farming commenced in Oman in 1986, but it was only in 2011 that it became a more commercially driven sector, due to investment and the development of a reg-
ulatory body to govern aquaculture practi ces. Currently, two species are farmed in the coun-
try, Indian white shrimp (Penaeus indicus) and Nile ti lapia (Oreochromis niloti cus). The majority of aquaculture producti on was
exported as whole fi sh or shrimp products to the United Arab Emirates, with a small quanti ty sold on the domesti c market. The total produc- ti on of farmed ti lapia and shrimp combined was 353 tons, with the approximate value of $2 million, in 2013 (according to the Oman fi sheries ministry). An emerging industry can learn valuable lessons from other aquati c farming sectors, and it’s important to have baseline data on the existence and prevalence of aquati c diseases and pathogens. Therefore, a questi onnaire based study was
conducted to understand the strengths and weakness of the current ti lapia producti on. This study was performed from September to November 2012 using a questi onnaire designed to include both open and closed questi ons, supplemented by individual interviews with the farm owners and staff . This was conducted in nine farms from four
areas, all acti ve in aquaculture (Al Bati nah, Ad Dhahirah, Ad Dakhiliyah and Ash Sharqiyah North). The study showed that most farms in the area follow very similar husbandry practi ces. The informati on generated from this survey
identi fi ed some water quality issues faced by the farmers and lack of general knowledge on opti mal fi sh health management. The second study investi gated the aquati c
bacterial species compositi on and distributi on in diff erent aquati c environments in Oman during a seven-month period from December, 2011, to May, 2012. In total, 417 fi sh represent- ing fi ve target species were chosen on the basis of the commercial importance and their poten- ti al for aquaculture in Oman, including red spot emperor (Lethrinus lentjan), king soldier bream (Argyrops spinifer), white spott ed rabbit fi sh (Si-
www.fishfarmer-magazine.com
ganus canaliculatus), abalone (Halioti s mariae) and ti lapia (Oreochromis niloti cus). The fi sh were collected from fi ve main sampling areas in Oman (Muscat, Mudhaibi, Manah, Sohar and Salalah). Bacterial isolates were recovered using traditi onal methods and identi fi ed to species level using phenotypic and molecular methods. The results gave a total of 420 diff erent
bacteria isolates, with 83 per cent of the total isolates identi fi ed as Gram negati ve, rod-shaped bacteria. The most frequently isolated groups from marine and cultured fi sh were Aeromonas spp., Vibrio spp., Sphingobacterium spp., Micrococcus spp. and Staphylococcus spp. with
lack of general knowledge on opti mal fi sh health management
“The survey identi fi ed ”
Aeromonas spp. being the predominant group, representi ng 25 per cent of the isolates recov- ered in this study. A third study focused on characterising the
Aeromonas spp using a range of molecular and traditi onal bacterial methods and determined seven species as the dominant organisims:
A.ve- ronii, A. jandaei, A. caviae, A. trota, A. encheleia and A. salmonicida. Of these, the sequence homologies were 99 per cent and the dominant species was A. veronii. In conclusion, the aquaculture sector in Oman is emerging and the study will help support the development of appropriate fi eld and labora- tory based tools to identi fy bacterial infecti ous diseases impacti ng producti on levels. As found in other aquati c farming systems, the Aeromonas isolates recovered from fi sh with clinical signs of disease showed hetero- geneity in their identi fi cati on profi les and their pathogenicity as determined by experimental challenges. It is anti cipated that the data from this study will assist in the development of good health management practi ces for fi sh farmers. FF
Above: Collecti ng data from Omani fi sh farmers 39
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