Many impressive ghost-net removal operations are being carried out by scuba divers around the world – but clearing 44 tonnes on breath-hold over 15 days is something else again.
That’s what a group of 16 freedivers from the US state of Hawaii recently achieved on remote north Pacific coral reefs. The non-profit group Papahanaumokuakea Marine Debris Project (PMDP) targeted the Papahanaumokuakea Marine National Monument (PMNM), a string of remote uninhabited islands that make up the last 1,300 miles of the Hawaiian island chain.
They spent a total of 27 days at sea surveying and clearing discarded fishing nets and plastic waste from a 445-hectare area of reef. Removal operations were carried out over 15 days on which the team managed to rid the coral of nearly 3 tonnes of damaging debris a day.
The PMNM hosts more than 7,000 species of wildlife, 23 of them endangered, says the group, with a quarter of the marine species found only in the Hawaiian archipelago. Its coral reefs spread over 1.4 million hectares and represent more than 70% of all the USA’s tropical, shallow reefs.
Operating from their 56m ship Imua, the freedivers used 6m RIBs from which to dive and collect the waste. Most of it – 39 tonnes – came from a single central reef called Kamokuokamohoalii (Island of the Shark God), which lies 800 miles from the nearest city, Honolulu, where the group is based. The remainder came from around two other islands, Kamole and Kapou.
The marine debris had been carried to the area by ocean currents before snagging on a mainly shallow (less than 3m) 13km section of the reef comprising 37 coral species. Animals threatened by entanglement in the ghost-net include endangered Hawaiian monk seals, green turtles, rays and sharks as well as reef fish.
Using breath-hold to keep the team “quick and nimble”, the divers were reported to have carefully cut away each piece of net under water to avoid further damage to the coral. One single trawl-net had been plastered across nearly 60m of reef, smothering much of the coral.
“The fact that we are seeing this kind of accumulation in such a single small area is really indicative of the scale of the global marine debris issue,” commented PMDP president Kevin O’Brien. “Kamokuokamohoalii is one of the most pristine and isolated places on the planet, and if it’s ending up here in these quantities, it means we’ve got a problem.”
In September PMDP hopes to remove a similar amount of debris on a repeat clean-up mission at the same location. “I’ve fallen in love with Papahanaumokuakea,” said team lead Namele Naipo-Arsiga. “There is no other place like it. And it’s quite simple, when you love a place and it has woven itself into your heart, your body lunges to the work calling to be done.”
After recyclable plastics have been set aside for PMDP’s student-led recycling project, remaining debris will be burnt to power hundreds of homes on the Hawaiian island of Oahu.