AI audio analysis reveals scale of blast fishing crisis in Indonesia

Researchers from the Zoological Society of London have estimated that fishers off the coast of Sulawesi, Indonesia, detonate more than 8,500 underwater explosives annually in the Spermonde Archipelago. The study, which utilised AI-assisted audio analysis of underwater microphones, identifies blast fishing as a leading cause of reef loss in the region. The practice converts vibrant coral habitats into rubble, threatening the biodiversity of the Coral Triangle, often referred to as the “Amazon of the Seas”.

The research team deployed $150 audio recorders to the seafloor in 2023, capturing over 3,500 explosions in just 3,600 hours of recording. By analysing 16 months of audio data using open-source AI software, the scientists were able to identify detonations from over 10 miles away. Each suggested sound wave was manually verified to distinguish between bomb blasts and misfiring boat engines, providing a more accurate count of the destructive activity.

A single bomb can destroy approximately 200 square feet of reef, killing marine life within a 90-foot radius. The total annual destruction is equivalent to three football fields, occurring within an area of just 350 square miles. The data revealed that the practice occurs year-round, peaks during the mornings, and significantly reduces on Fridays, the local day of prayer. This pattern highlights the ongoing pressure on an ecosystem that has already lost an estimated 75 percent of its coral since 1990 due to human activities, bleaching, and warming waters.

Experts note that while blast fishing is often attributed to poverty, the method is likely driven by middle-income fishers and ineffective enforcement. The cost barrier to purchasing boats, bombs, and detonators suggests a more complex economic incentive than previously assumed. Melissa Hampton-Smith, a postdoctoral researcher at James Cook University, emphasised that equitable and consistent enforcement is key to managing the illegal fishing that varies from place to place.

The study suggests that real-time audio sensor networks with GPS syncs could help authorities detect and stop the destruction. Jamaluddin Jompa, a research professor at Hasanuddin University, stated that restoration efforts struggle to keep up with the rapid rates of destruction caused by bombing. Unlike bleaching events or warming waters, bomb fishing represents a rare form of coral crisis where a local fix exists. If the practice stops, researchers believe the reefs could be restored and thrive for quite some time to come.