Onihitode (COTS, Crown-of Thorns Starfish) have long been natural predators against coral reefs, inflicting tremendous damages since 1970s. Not much was known about the mechanism of their outbreaks, and enormous time and cost have been spent for Onihitode-control. However, the recent finding of specific protein that induces aggregation of Onihitode sheds light on countermeasures that have remained rather reactive till today, and voices of expectations are raised among those who have been tackling on Onihitode issue.
According to Yaeyama Environmental Network, in the peak year of 2011, as many as 286,000 Onihitode were removed by local fishermen’s cooperatives and diving shop staff members. Once there is an outbreak, Onihitode should be captured one by one sitting on the extensive sea bed. There are even some Onihitode hiding behind corals and sometimes, extra care is required to catch them.
Responding to the future possibility of developing so-called Onihitode Trap Motel with specific protein inducing Onihitode aggregation, the chairman of the Yaeyama Diving Association, Mr. Masakazu Taniya (44) commented, “It would be an ice-breaking approach if we could gather a number of Onihitodes at one spot to remove them with our limited number of divers and time.”
From FY 2012 to FY 2017, the Okinawa Prefectural Government (OPG) has spent approximately 297 million yen to elucidate the mechanism and countermeasures of Ohinitode outbreaks. As a result, OPG can now predict Onihitode outbreaks two years prior to the actual outbreaks, but in order to make such prediction, they need to find baby Onihitode when they are as small as one centimeter long. One OPG official commented with high expectation, “If we could attract baby Onihitode through this technology, it can also be applied for prediction of outbreaks.”
Meanwhile, there are some critical voices against the mere control of Onihitode without enough consideration. Mr. Nobuo Saeki (69), the first chairperson of Yaeyama Environment Network, pointed out, “There would not be an essential solution unless we mitigate the issue of eutrophication due to runoff from the terrestrial areas,” even though he acknowledged the achievement of research outcome.
Mr. Hideo Matayoshi, the chairperson of Zamami Diving Association, which has been monitoring the surrounding seas of Kerama Islands, commented, “We may be able to have some expectation at times of outbreaks, however, Onihitode are also part of living-beings in the ocean. We sh