SATURDAY, MAY 31, 1980
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FISH SURVIVAL DEVICE
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THE AGRICULTURE AND FISHERIES DEPARTMENT IS PLANNING TO INTRODUCE A NEW DEVICE AN AERATOR TO IMPROVE LOCAL FISH
FARMING TECHNOLOGY.
THIS DEVICE IS THE RESULT OF A JOINT STUDY BY STAFF OF THE DEPARTMENT'S FISHERIES RESEARCH DIVISION AND THE INDUSTRIAL ENGINEERING DEPARTMENT OF HONG KONG UNIVERSITY AND WILL HELP FISH FARMERS MINIMISE LOSS OF FISH DUE TO OXYGEN DEFICIENCY.
A SPOKESMAN FOR THE DEPARTMENT EXPLAINED THAT LACK OF OXYGEN IN WATER WAS ONE OF THE MAIN CAUSES IN FISH MORTALITY, SUCH SITUATION USUALLY OCCURS DURING OUTBREAKS OF RED ALGAE AND AT TIMES OF MINIMAL TIDAL MOVEMENTS, HIGH TEMPERATURES AND HEAVY RAINFALL.
UNDER THESE CIRCUMSTANCES, LOSS OF FISH KEPT UNDER CULTURE CAN BE REDUCED BY USING ALMOST ANY MEANS TO INCREASE AERATION.
THE COMMON WAY IS TO USE A PADDLE OR RUN A BOAT PROPELLER TO CREATE WATER MOVEMENT. HOWEVER, THESE METHODS CAN ONLY HELP IN AERATING THE SURFACE WATER.
THE NEW DEVICE, INCORPORATING THREE SETS OF SPECIALLY DESIGNED POWER-DRIVEN PROPELLERS, IS A MUCH MORE EFFECTIVE GADGET TO INCREASE OXYGEN CONTENT.
+ITS MAJOR ADVANTAGE IS THAT IT IS CAPABLE OF AERATING BOTH THE SURFACE AND LOWER PART OF THE WATER DOWN TO A DEPTH OF MORE THAN THREE METRES, THE SPOKESMAN EXPLAINED.
TEST RESULTS INDICATED THAT AFTER TURNING ON THE AERATOR, OXYGEN CONTENT IN WATER COULD INCREASE UP TO 12 PER CENT IN SATURATION. +THIS ADDITIONAL QUANTITY IS IMPORTANT DURING TIME OF DEFICIENCY AND THE EFFECT CAN HOLD FOR SOME TIME EVEN AFTER THE AERATOR IS TURNED OFF, HE ADDED.
THE AERATOR IS SUITABLE FOR USE BOTH IN FISH CAGES AND PONDS WHEN OXYGEN DEFICIENCY OCCURS.
+BUT DURING OUTBREAKS OF RED ALGAE, THE AERATOR CAN ONLY HELP TO SOLVE PART OF THE PROBLEM BECAUSE BESIDES CAUSING OXYGEN DEFICIENCY, RED ALGAE SOMETIMES PRODUCES TOXINS WHICH HAVE HARMFUL EFFECTS ON FISH, THE SPOKESMAN POINTED OUT.
FISH FARMERS WHO ARE INTERESTED IN THE AERATOR MAY CONTACT THE INDUSTRIAL ENGINEERING DEPARTMENT OF HONG KONG UNIVERSITY FOR FURTHER INFORMATION,
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