By Terry Xu
In recent days, fish farmers off the coast of Pasir Ris have seen almost all their fish stocks die off. Death of the fish stock in alarming numbers started from 16 February and have persisted since.
The fish farmers have been working furiously for the past few weeks to salvage their fish farms, but the scene at the farms remains one of devastation, with a sea of dead fishes floating in the fishnets.
Many of the fish farmers have given up. Mr Philip Lim, a fish farmer and Chairman of Singapore Marine Aquaculture Cooperative lost $50,000 worth of his fish stock at his farm.
Cause of death for the fishes – suffocation or toxins?
In a statement, AVA said that post-mortem of fish samples collected from the affected farms indicated the fish had died as a result of gill damage caused by a kind of plankton. These are micro-organisms are found in seawater and they bloomed or multiply quickly in a very short time, draining the seawater of oxygen. AVA also declared that there were no marine biotoxins detected in the waters to have caused the death.
It would appear that while AVA concedes that there is algae bloom, it has decided that it was not Harmful Algae Bloom (HAB), which would might lead to the production of marine biotoxins that could kill fish.
Mr Lim disagreed with the verdict. From his many years of experience as a fish farmer, he said that he would be able to tell if a fish died from suffocation or poisoning. “If a fish is suffocating, it will swim to the surface, and can be kept alive with an air pump. However, if it is suffering from poisoning, it will die in a very short time. This is what has happened.”
Pointing to the dead fishes in one of his nets, he was convinced that there was something toxic in the water. He also pointed out that the fishes that were transferred into water tanks with the air pump eventually died.
Mr Lim also asked if AVA has the in-house marine biology expertise to make such a conclusion, and noted that he has not personally seen the report from the laboratory tests that AVA has done.
In the previous occurrence in February 2014, a seminar was held subsequently in May at AVA’s auditorium at Lim Chu Kang about HAB soon after the death of the fishes in February. The seminar was presented by Dr Sandric Leong from Tropical Marine Science Institute, National University of Singapore (NUS).
Replying to TOC’s enquiry about whether HAB was the cause of mass death in the fish stocks of the coastal fish farms last year. Dr Sendric said that it was not conclusive to say that HAB was the cause.
Mr Lim felt that Dr Sandric was not forthright in his reply to TOC. In the latest occurrence, AVA also said that no marine biotoxins were detected in the waters and that bewildered Lim .
“It was clearly HAB”, said Mr Lim. “If the deaths were not related to HAB, why would AVA make such arrangements and not on other potential causes?”, He also stated that that was also the first time the fish farmers were asked to attend such a seminar.
He stated that AVA specifically arranged the NUS professor to make a speech on HAB to the fishermen affected by the fish deaths.
No action by AVA despite early warning
In its statement on 27 February, AVA said it would monitor the situation, and work closely with the fish farmers to mitigate the problem. AVA also said that it had warned the farmers early last week after detecting elevated plankton levels in the area.
However, Mr Lim said that it was he and the others at the coastal fish farms who had first alerted AVA about potential HAB along the Johor Straits on 27 January 2015.
A fish farmer for more than 10 years, Mr Lim had created an early-warning system to monitor water conditions and track signs of HAB. He complained that AVA did not respond to his alarm although they replied that they would look into the matter.
“This time the problem is graver than the episode last year, as even the wild fishes are affected. Wild fishes are more resilient as they are in the open sea and are able to swim away from the affected area instinctively.”
Photographs by nature enthusiast Sean Yap last week showed Pasir Ris beaches with a huge quantity and variety of dead marine life washed up on the shores.
Cause of HAB a result of mulitple factors
Mr Lim, who is currently involved in an Urban Redevelopment Authority’s (URA) project to enhance the natural habitat to support recovering of species of plant and animals in Palau Ubin, said that HAB is caused by three main factors – rising sea temperature, dumping of palm tree seeds from neighbouring countries, and the damage of the ecology due to reclamation and coastal activities.
He believed that, beyond environment controls, there must be political will to protect the livelihood of the fish farmers and ensure food safety and security.
No assistance for independently run fish farms
AVA said that it deployed waste disposal vessels to assist farmers in the disposal of dead fish at the East Johor Straits caused by the elevated plankton levels.
However, Mr Lim said that AVA only sent the vessels to industrial fish farms and not small independent fish farms run by local Singaporeans like him.
“So far, AVA only sent technicians down to collect dead fishes and water samples,” he said. “They did not even have the courtesy to provide the results of their laboratory tests to us.”
He has another grouse with AVA: The differential treatments received by the industrial fish farms. “AVA sent boats to help pull the industrial fish farms to safer areas behind Tekong Island, where the HAB has yet to spread. But we independent fish farmers are caught in a bind. Without AVA’s authorization we are unable to take similar appropriate actions. We would be fined if we were caught by AVA.”
TOC has written to AVA for their response on Monday and will include its comments when they reply.
Toxin in fishes?
AVA said, “Laboratory tests conducted so far did not detect marine biotoxins in the fish,”.
“Says who?” asked Mr Lim. According to Mr Lim, AVA does not have an in-house marine biologist and ask if there is any 3rd party laboratory which AVA is basing their report on.
According to Amercia’s Centres for Disease Control and Prevention (CDC)
“Harmful marine algae, such as those associated with red tides , occur in the ocean and can produce toxins that may harm or kill fish and marine animals.
…In addition to killing fish, brevetoxins can become concentrated in the tissues of shellfish that feed on K. brevis. People who eat these shellfish may suffer from neurotoxic shellfish poisoning, a food poisoning that can cause severe gastrointestinal and neurologic symptoms, such as tingling fingers or toes.”
Mr Lim feels that AVA should have the sale of seafood at the Pasir Ris fish farms suspended till the reports from the laboratory certify that it is safe to do so.
In fact, that was what AVA did in the mass fish deaths incident in February last year by sending letters to fish farmers when the fishes started dying and instructing them to stop the sale of fishes until it is safe to do so.
Some of the fish farmers had already sold their fishes since 16 February when the fishes started dying and still are. Mr Lim said he did not sell any fishes from his farm even if it meant making a loss.
In an interview with Channel 8, Mr Chan Wei Loong, Head of Department in Marine Science and Aquaculture of Republic Polytechnic said that fishes will remain unsafe for consumption if death is caused by poisoning, even if the fish is thoroughly cooked.
In addition, if the fishes are collected to be sold when they are dead, micro-organism may find its way into the fish bodies and produce toxins which cannot be removed through cooking.
Laboratory test supports fish farmers’ suspicion
In the laboratory test commissioned by TODAY, it is said that the species of algae behind the mass fish deaths off Pasir Ris likely belongs to the Gymnodinium group.
It is suspected to be Gymnodinium mikimotoi, according to the experts at DHI Water & Environment, but the exact species can only be confirmed through further genetic tests. Gymnodinium mikimotoi, also known as Karenia mikimotoi, is not toxic to humans, but has been associated with massive kills of wild and farmed fishes in Japan and Korea.
The test showed concentrations of the algae at 88,529 cells per millilitre – a “very, very high” concentration, according to Dr Hans Eikaas, head of environmental technology and chemistry at DHI, a not-for-profit group offering consultancy and water-modelling services.
However, Dr Eikaas said that the algae is not known to cause any effect to humans who have eaten affected fish if the suspected species is indeed the Gymnodinium mikimotoi.