Between 30 and 50 green sea turtles were found dead or dying with stab wounds to their necks on a beach in remote Kumejima island last Thursday.
Today, local officials expressed anguish at the episode and said they have found the perpetrator but did not name the individual.
The unnamed suspect told the local fisherman cooperative that the turtles got caught in his fishing nets and he became frustrated trying to untangle them.
He said he released lots of the sea creatures, but after struggling for so long he began stabbing them to try and weaken them.
Yoshimitsu Tsukakoshi, a senior staff member at local sea turtle conservation body Kumejima Umigame-kan, told Japan’s national daily paper The Mainichi that it was “an extremely grisly scene.”
Police are reportedly investigating the deaths, but a source declined to comment on whether the fisherman could face punishment.
Tsukakoshi was outraged at the fisherman’s outburst, saying turtles are such gentle creatures and he could not believe what happened.
Yuji Tabata, the head of the cooperative, explained the situation and claimed the fisherman had never seen so many turtles on his nets but now regrets his actions.
Green sea turtles are listed as an endangered species by Japan’s Ministry of Environment and are on the International Union for Conservation of Nature’s ‘red list’ of threatened species.
Dr Isao Kawazu, a sea turtle expert at the Okinawa Churashima Research Center, told the New York Times that he often hears similar stories from fishermen, saying: “Many say that there are too many sea turtles and that they are struggling because of it.”
He continued: “On a global scale, there are not enough sea turtles, but depending on the region, the sea turtles trouble many.”