Overfishing more damaging than tsunami

Overfishing and destructive methods, such as cyanide and blast fishing, continue to threaten the health of coral reefs in Aceh, the epicentre of the fourth largest earthquake in history, according to a comprehensive report released today by Reef Check, the global coral reef conservation organization.

The October 2005 expedition that included scientists from four countries, discovered new earthquake damage, but this was confined to a few locations. No tsunami or earthquake damage was recorded at more than half of 200 coral reefs surveyed along the coast of Aceh, however wide-spread sedimentation remains a problem, smothering existing coral colonies and hampering the establishment of new ones.

“On most reefs we surveyed, fish were few and far between, and most were less than 25 cm (10 inches) long,” said Reef Check scientist Bob Foster, “The small size and low abundance of ten primary food fish families indicate serious overfishing that can destabilize the ecosystem. Poison and blast fishing are common in the region.”

Localized earthquake damage was sometimes severe. The December 26, 2004 magnitude 9.15 earthquake tilted several of the Banyak Islands, located 190 kilometers south of the epicenter, and raised many hectares of coral reef completely out of the water where the corals died. Survey scientists discovered large patches of the semi-precious, branching blue coral (Heliopora) that were knocked down and killed.

On most reefs, the earthquake-generated tsunami, which wiped out entire cities such as Banda Aceh, caused relatively minor immediate damage, overturning and killing less than 3% of the corals surveyed. A more serious impact of the tsunami is an increase in seawater turbidity and sedimentation that threatens the long-term health of the reefs. This was caused by the tsunami sweeping away coastal vegetation and exposing the bare ground to rainfall, erosion and increased runoff to the sea.

The Aceh Expedition was a joint project of Reef Check, the World Conservation Union and Khaled bin Sultan Living Oceans Foundation with primary funding from Living Oceans. The survey vessel started from the town of Sibolga, and recorded data at more than 200 reef sites over a 660-kilometer course to Pulau Rondo, the north-western tip of Indonesia.

“Very little was previously known about the health of the reefs in this area,” states Dr. Gregor Hodgson, Reef Check Founder and Executive Director, “This expedition points to the need for better management of coral reefs in this mega-biodiversity region. The wonderful thing about reefs is how quickly they can recover if we take care of them.”

Source: ReefCheck

Image: T Heeger/ReefCheck (Blast fishing in the Philippines)