GEORGE TOWN: At least 50, 000 fishes have died in Teluk Bahang, the second such case within three months.
Test results from previous water samples after the first case of poisoning from Teluk Bahang confirmed that there was contamination of heavy metals.
However, state environment committee chairman Phee Boon Poh said the level of heavy metal was at a “permissible level”.
“No, not nickel. But heavy metal but within the permissible level. The death is due to a lack of oxygen, ” he said.
Yesterday, fish breeder Ooi Hye Hin estimated that he suffered losses of about RM800, 000 after more than 50, 000 of his fishes died.
Ooi said he was alarmed to find that the fishes started “jumping” in the waters at about 1am yesterday.
“I knew something was wrong then. True enough, I found all of them dead this morning.”
Ooi, 57, said he had been hit twice by such a case this year.
“It happened in May. Now, this is worse because all 50, 000 plus of my fishes are dead and none could be salvaged. They are worth about RM800, 000, ” he said when met at his fish farm.
“I cannot resume this business anymore, ” said Ooi, adding that he had been in the fish breeding business for close to 20 years.
Fish farms are scattered throughout Teluk Bahang town. During a visit to this fishing village yesterday, there was a pungent smell in the air.
The Star reported about the death of thousands of grouper in Teluk Bahang on May 28 with fishermen complaining that their livelihood had been affected.
In June, it was reported that there was still uncertainty about the cause of the deaths at the Teluk Bahang farms.
Centre for Marine and Coastal Studies (Cemacs) director Prof Datuk Dr Aileen Tan said yesterday there were heavy metals detected but the level was not high enough to kill the fishes in the May incident.
“We have detected the shift of phytoplankton diversity and also a high concentration.
“Sign of eutrophication (excessive nutrients) in the shallow bay which may cause the depletion of dissolved oxygen - excessive nutrients in the water (phosphate and ammonia).
“In our monitoring since then, the nutrient levels are still high.
“The state government is very concerned and have committed to look more in-depth with collaboration from the Fisheries Department, Environment Department and other agencies, ” she said.
“This time it might be slightly different because the strong current and waves from Typhoon Lekima might have stirred some toxins from the seabed.
“We are not sure because the high mortality is so drastic.
“The earlier incident happened gradually with groupers, followed by other fishes like snappers a couple of weeks later, ” she said.
Prof Tan also did not rule out the water quality in Teluk Bahang, which has degraded over the years, as the reason the fishes were dying.
“The dissolved oxygen at the affected area is extremely low which is below 4mg/L even though the sampling was done almost mid-day.
“The whole area is a very shallow bay and the mass mortality happened during neap tide where the water movement is minimal.
“The strong wind and current that happened during the Lekima Typhoon a day before might have stirred up toxic materials from the seabed.
“Combined factors of toxin and low dissolved oxygen may have caused a stressed environment to the fishes around the area, ” she said.Prof Tan said water and fish samples collected will be analysed for nutrients, phytoplankton and heavy metals.
“We cannot comment much on this latest case until the results of those analysis are out.
“We will do a more thorough survey on Tuesday.
“We need to look at more parameters but dissolved oxygen is definitely not favourable to the culture of fish, ” she added.
Prof Tan said in the earlier incidents, they found there was extremely high phytoplankton bloom which has depleted the oxygen level during the night and caused a “Dead Zone” (hypoxia) environment.
“Long term monitoring is needed. So the authorities can advise the breeders when the first sign of degradation in water quality has been detected, ” she added.
Cemacs science officer Sim Yee Kwang, who was part of the team of officers from Cemacs at Ooi’s site, said the water temperate, salt and pH levels were normal, but oxygen levels in water was low compared to normal.
“We will be bringing the fish and water samples back to USM for analysis, ” he added.