Research from the Zoological Society of London (ZSL) has revealed that underwater bombs are being set off at a rate of almost one per hour in a wildlife hotspot in the Indo-Pacific Ocean – despite the destructive fishing method being banned since 2004.
Bomb fishing (also referred to as blast fishing) is a fishing practice that uses explosives to quickly kill fish. It’s been made illegal in countries around the world due to the detrimental effect it has on other wildlife and ecosystems such as coral reefs.
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The fishing practice typically leaves behind a ‘rubble field’ – an area where the calcified skeletons of coral have shattered during high-energy events. Rubble fields can also be seen in the wake of coral bleaching or bottom trawling.
They often cannot regenerate quickly enough to support life without significant human intervention.
Recording the reefs
To study the frequency of bomb fishing, as well as its impact, a team of Indonesian and British scientists placed microphones on coral reefs in the Spermonde Archipelago; a group of 120 islands located off the large Indonesian island of Sulawesi.
Over a period of 16 months, the sounds of the reefs, as well as bombs being dropped as far as 17 kilometres away, were recorded.
The differences in recordings before and after the bomb fishing was significant.
“On any reef, we hear an ever-present backing track of distant snapping shrimps, which sound like a campfire in the rain,” explains Ben Williams, who led the study at ZSL’s Institute of Zoology and UCL.
“On a healthy reef, this soundscape is also filled with the purrs, pops and grunts from a thriving fish community. But on a reef destroyed by bomb fishing, this soundscape is much more desolate – those vibrant fish sounds are gone.”
Almost 3,570 cases of bomb fishing, taken from 3,650 hours of underwater audio, were documented in the findings (published in the journal Remote Sensing in Ecology and Conservation). The researchers say that this is the equivalent of a bomb being set off every 62 minutes, resulting in 160,000 metres squared of degraded coral reefs.
The team hope that the study can be used to identify hotspots where bomb fishing is taking place, allowing conservationists to work with local communities to develop alternative solutions and enforce regulations.
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“We hadn’t expected the scale to be quite so big, yet the rate at which bombs are being used to fish in this area alone is enough to destroy sections of coral reef as large as the Vatican City in just three years,” says Williams.
“Bomb fishing threatens dozens of reefs off the coast of Indonesia and is thought to be the leading cause of reef loss on the Spermonde Archipelago,” adds Professor Jamaluddin Jompa, a researcher at Hasanuddin University, Indonesia, and co-author of the paper.
“Over the last 20 years of working in the archipelago, we’ve seen the difference that restoration can make – but restoration efforts struggle to keep up with such rapid rates of destruction caused by bombing. Immediate work to tackle bomb fishing is needed to protect these reefs, and our work shows how technology can ensure action is as rapid and effective as possible.”
Read the full paper here: Widespread Bomb Fishing in Indo-Pacific Archipelago Revealed Through Machine Learning Accelerated Passive Acoustic Monitoring
Top image: a coral reef restored after bomb fishing. Credit: The Ocean Agency
