Samples to be sent to US and Australia – MRC

In order to assess the reasons for the mass fish kill phenomenon that occurred in Maldives between July and December last year, samples are being prepared to be sent to laboratories in Australia and America reveal Marine Research Center (MRC).

Executive Director of Marine Research Center Mohamed Shiham Adam has said work is underway to send the samples to Virginia Institute of Marine Sciences of the US.

“Currently we have about 60 samples, we are unable to send these samples by air hence we are talking to the concerned authorities” said Shiham.

Marine Research Center in a press release issued last December revealed that mass fish kill was not due to any toxic algae.

Widespread fish mortalities of massive scale were reported in different regions of the Maldives between July and December 2007. According to MRC reports on the incident published on their website the species composition of dead fish and the characteristics of the surrounding water suggest that most of the reported events were closely related to each other.

MRC reports say that the related fish kills consisted predominantly of the red-toothed triggerfish, (Vaalan Rondu), which comprised approximately 95% of the fish that were found dead. The Reports noted unconfirmed incidents of similar fish kills in the Arabian Sea in November 2007, trigger fishes being the major group affected as well as in Reunion Island in 2000 and 2001, where groups of triggerfish were found dead. Test results from the latter event reported the presence of a species of bacteria known to be associated with fish kills, in the spleens of the dead fish. Similarly mass mortality was also reported in the neighboring Sri Lanka in the mid 1980s.

According to MRC website initial reports of mass fish kill were received from Raiymandhoo, Meemu Atoll, on the 8th of July, 2007. These fish kills were also associated with a red substance floating in the lagoon. Different varieties of surgeon fishes, locally known as kaalhu and parrot fishes, locally known as landaa were among the species that were mostly affected during this event says MRC website.

On receiving reports of these fish kills, teams from MRC as well as the Environment Research Centre (ERC) visited the site for sampling. As per press release issued by MRC observation of water samples under light microscopy did not reveal the presence of any microorganisms that could explain the fish kills athough water samples collected by ERC were when examined by light microscopy, revealed the presence of microorganisms suggestive of lack of oxygen which may or may not be the primary causative agent of these fish kills.

On July 2007, similar fish death reports were received from Mundoo, Laamu Atoll. Unlike the Raiymandhoo incident, there were no floating substances or murkiness in the water in Mundoo. Since this report in July, MRC has received fish death reports from North and South Ari Atoll, Baa, Faafu, Vaavu, Dhaalu and Kaafu Atoll in that order. Unlike the Raiymandhoo incident, none of these incidents reported any discoloration of the surrounding waters.

According to MRC,the Center was following the trend of these fish deaths by means of phone surveys to the island offices. As MRC does not have capacity to conduct serious field investigation toward finding the cause of these events, no field studies were carried out until November 2007, when teams from MRC visited Baa, Vaavu and Dhaalu atolls for sampling purposes. It was suspected that these deaths could have occurred as a result of low levels of dissolved oxygen (DO) in the water column. DO measurements at various depths showed they were not less than 6 mg/dl. Dawn dives showed lower DO levels (which is expected even under normal conditions), but not low enough to explain the fish mortalities of the scale that was being observed.

An unexplained fish-kill incident occurred in Raa Atoll Ungoofaaru during Dec 2007. Large number of herbivores fish, was seen washed onto the shallow lagoon and the beach on the eastern side. The incident lasted 2 days and nothing unusual appears to have happened during the period around the area. No other reef was affected said MRC.