Channel NewsAsia 21 Nov 17;
SINGAPORE: The grouper you’re thinking of cooking for dinner was very likely kept healthy with vaccines, if it came from a Singapore fish farm, said experts at Nanyang Polytechnic’s (NYP) inaugural seminar on Singapore’s aquaculture industry on Tuesday (Nov 21).
Titled Food Fish Made in Singapore - A More Sustainable & Healthier Choice, the event discussed how vaccination can be key to help the local aquaculture industry increase production for the dining table.
Currently, Singapore’s fish farms meet just 10 per cent of the country’s fish consumption, said Dr Koh Poh Koon, Senior Minister of State for National Development and Trade & Industry.
Singapore imports up to 95 per cent of the food the population consumes.
Coupled with declining global fish production caused by climate change, it is important to “build up some degree of local production to buffer against intermittent, and sometimes, very sudden supply shocks,” said Dr Koh at NYP's School of Chemical & Life Sciences Applied Science Conference.
“We will therefore need to ensure that our local food fish stock takes on a lot more protection for disease prevention, even as we scale up our local aquaculture production,” he said.
But ramping up production also means keeping fish in a higher density in a given area. This spells greater susceptibility to bacterial and parasitic infection.
The scenario has spurred researchers to create vaccines that are specific to the unique combination of bacteria in Singapore’s waters. One such solution is a locally developed autogenous vaccine that help fight microbial infections in fish, said Dr Koh.
The vaccine has led to Singapore’s first autogenous fish vaccine production company UVaxx Pte Ltd, which plans to work with several local fish farms to develop customised fish vaccines specific to the disease situation of individual farms.
HOW IS FISH VACCINATED?
Like human vaccinations, fish vaccinations are carried out via injection, said Dr Diana Chee, deputy director of aquaculture from the Agri-Food & Veterinary Authority of Singapore’s (AVA) Technology & Industry Development Group.
Before the injection is administered in the fish’s abdomen, they are not fed for 24 hours to let them empty their stomachs, said Dr Chee.
A sedative is added to the water to calm them before they are lifted out for a quick jab that delivers a minute amount of vaccine into their abdomens. The vaccinated fish is then placed in a recovery tank where they are monitored for the next 24 hours, she said.
Dr Jeffrey Seng, senior specialist (aquatic health and diagnostics) and senior lecturer at NYP’s School of Chemical & Life Sciences, said that fish weighing 10g are ideal for vaccination as they fit well in the palm.
The ease of handling also makes it less stressful for the fish, he said.
By the time the fish reaches 1kg and is ready for sale, typically in eight or 10 months’ time, the vaccine would have been expelled from the fish’s system, said Dr Seng.
To ensure food safety, AVA also conducts frequent checks for the presence of chemicals used in the vaccines.
According to him, Singapore's top three most common fish produced are the grouper, local sea bass and threadfin (or ikan kurau in Malay).
THE EFFECT ON ANTIMICROBIAL RESISTANCE
Vaccination isn’t just about minimising the fishes’ odds of falling sick but also about reducing their reliance on antibiotics.
This tampered use of antibiotics arises from the global concern of antimicrobial resistance, where the over-use of antibiotics has led to superbugs that no longer respond to current drugs, said Dr Lee.
“Residual antibiotics in the food chain entering into the human food chain will become a threat to antimicrobial resistance. That has a lot of downstream implications for us,” he said.
Fish vaccination is a practice not unique to Singapore. Norway, which is known for its export of farmed salmon, mandates that its salmon are vaccinated as part of its quality assurance and accreditation, said Dr Chee.
“Vaccines enable the animal’s natural defences, the immune system, to fight and defend itself against disease,” said Dr Chee.
Similar to human vaccines, the fish versions consist of a weakened or killed pathogen that causes disease in fish. It is usually combined with an adjuvant, a substance that increases the body's immune response to the vaccine.
Quality controls and safety checks are carried out before the vaccine is released for sale, said Dr Chee.
Find out the difference between fresh and frozen fish as well as the pros and cons of choosing wild fish vs farmed fish here.
Source: CNA/bk
