Dead fish in Dubai Creek keeps alive controversy

DUBAI — The washing up of dead fish in certain parts of Dubai Creek is a natural event that occurs each year and has absolutely nothing to do with pollution, Redha Hassan Salman, Head of the Environment Protection and Safety Section told Khaleej Times yesterday.

By Prerna Suri And Zaigham Ali Mirza

Published: Thu 14 Oct 2004, 12:41 PM

Last updated: Thu 2 Apr 2015, 2:41 PM

“We have been constantly checking for the quality of water in the creek for several years now, and we are quite sure there is no question of pollution. This is a natural phenomenon that happens each year mainly due to fluctuation in water temperature,” Salman said, adding that the fluctuating water temperature decreases the immune system of the fish, and initially kills a part of the shoal.

He explained, “Initially some of the fish die and the decomposition process of their dead bodies affects the level of oxygen in the sea water negatively. With a depletion of oxygen from the water, more fish are killed and the process continues.”

According to Salman, the phenomenon occurs in many neighbouring countries annually and those too have nothing to do with marine pollution.

“We have conducted tests on the fish to see if they contained a clue to this phenomenon and we know for a fact now that it is a high level of a naturally occurring bacteria, in the water as in the fish, that kill the species,” he explained.

He said that tests were also conducted by the Central Veterinary Research Laboratory in Dubai and have determined the role of bacteria in this phenomenon.

The dead fish belongs to a particular species locally known as the Yawafa, which though not popular is still eaten.

Dr Waleed Hamza, Associate Professor for Aquatic Ecology, UAE University, however, believes that the death of the 'Yawafa' fish cannot be due to the bacteria growing in the creek waters since the large quantity of fish washed up ashore is too large in number for the bacteria to kill.

“To say that this may be a 'natural phenomenon' is ludicrous. There may be several other reasons which may account for the death of these fishes,” he said. “One reason could be the acute effect on the fish by chemical pollutants and discharge in the water. Another could be the large population of these particular species of fish in the creek waters, which may have lead to their overcrowding. What happens in such an instance is that the older fish die leaving behind the younger ones to survive,” he added.

The difference in temperature, he explained, couldn’t be a factor as “this kind of a phenomenon occurs only from January to March when a real change in the temperature is noticed. It is too early for that kind of a phenomenon to occur here,” he added.

Dr Hamza also said that the reasons for fish death could be due to a 'red tide' effect, which is caused by the discharge of contaminants from municipality sewerage treatment plants.

“The fish could have died from the toxins discharged by an algae bloom. When there is a large amount of discharge from municipality sewerage treatments, a number of chemicals are released in the waters, which enhance certain species of algae leading them to develop rapidly. This, coupled with the optimum temperature of the water at 20 to 25 degrees, lead to the contaminants being discharged by the algae, thereby killing the fish.”

In order to get to the root of the problem, Dr Hamza suggested that water samples from the creek should be taken for further examination. “We have to take samples of the creek water and examine their phytoplankton composition to ascertain as to how the fish died,” he said.