Dubai: The use of inappropriate fishing methods and illegal net sizes were the main causes behind the death of mackerel tuna in Dubai waters this week. Known as saddah, the fish were found dead in large numbers in waters west of Dubai.
Major General Mohammad Al Merri, chairman of the Fishermen's Cooperative Association of Dubai, explained how the fish died and said that a similar incident had occurred off the coast of Umm Al Quwain too.
Al Merri explained that the incorrect use of a professional fishing technique, combined with the use of illegal net sizes, around four times larger than that allowed by the law — were the main reasons behind the death of the fish in Dubai.
The technique, Al Merri said, needs professional fishermen and is used worldwide without any problems. But because it is relatively new in the UAE — introduced only two years ago — only a few boats are authorised to use it, six boats in Dubai and two in Sharjah, he explained.
Al Merri noted that in advanced countries, the technique takes around a month to execute. He explained that boats follow the fish for around a month, surround them with nets and then pull them to shallower waters, and then catch them at the correct time and in controlled amounts. But in the UAE, he said, the nets are pulled within the same day.
Al Merri said that there are a lot of artificial reefs (human-made underwater structures built to promote marine life) in the area, and so when the fishermen were trying to drag the nets to shallower waters, the large nets, weighed down with the large fish — mackerel tuna grow as long as 70 centimetres — caught on the reefs, tore and then tangled.
The fish that slipped through the torn nets fell to the seabed and probably stayed there for two days, Al Merri explained. The fish were already dead by then, as tuna die within two to three minutes once they cannot move, he added.
The tuna carcasses resurfaced last Thursday morning. Al Merri explained that this delay was because fish does not get spoilt fast in winter owing to the cold waters. The dead fish only resurface once it starts decomposing and filling with air bubbles from bacterial activity.
Fishermen who witnessed the floating dead fish on Thursday immediately contacted the Fishermen's Association, which alerted the Ministry of Environment. The Coast Guards arrived and took samples of the dead fish to ensure that they did not die of an environmental cause, Al Merri said.
Al Merri said that the fishermen responsible should have immediately alerted authorities and condemned them for failing to do so. He said that what they did "was irresponsible".
Al Merri said the Umm Al Quwain incident was caused solely due to the use of excessively large nets, which is against the law. Due to the large size of the net and the large number of fish caught, the nets sank to the bottom, tangled and got caught on the artificial reef.
