LIHUE — The last aerial drop of rodenticide-laced bait pellets onto Lehua Island was completed Tuesday, and with it the state is hailing a successfully completed operation.
What’s left now is to monitor the effects for the next year to see if the project worked and all of the rats on the island are dead.
“Active monitoring continues for a week until the bait is no longer available,” said Heath Packard, spokesman for Island Conservation, one of the entities involved in the project.
Before the project started, two dozen rats were equipped with radio transmitters; all have died from lethal doses of the rodenticide, according to Packard.
Island Conservation and state Department of Land and Natural Resources teams, as well as independent U.S. Department of Agriculture monitors will be “looking for any unusual outcomes”, he said.
The DLNR, Island Conservation and U.S Fish and Wildlife project to create a seabird nesting sanctuary on Lehua Island began five years ago with planning and studies, according to Suzanne Case, chairperson of DLNR.
After years of planning and three community meetings on Kauai, the project commenced amid outcry from some Kauai residents and conservationists.
Three applications of the restricted use pesticide diphacinone were delivered to the island from a helicopter, encased in rat bait pellets that were made of cereal — the first on Aug. 23, then again on Aug. 30 and on Tuesday.
“Today’s third application completes the operational plan,” Case said in a Tuesday press conference.
Before the first application of rodenticide to the island, community members voiced concerns about the project at meetings and through several letters to both DLNR and the Department of Agriculture.
Rep. Dee Morikawa also wrote several letters requesting a delay in the project until community concerns could be answered.
“We would have preferred 100 percent community consensus,” Case said. “With the long-term benefits of what we are trying to do, we believe we did the right thing.”
Days after the second drop 45 dead mullet fish and two dead juvenile Brown booby birds were discovered in tide pools in Lehua’s crater.
Teams from DLNR gathered samples from the carcasses and are awaiting results on the animals’ cause of death from the USDA.
“It could be weeks or months (before we get the results),” Case said. “There is no evidence of bioaccumulation in the environment.”
After that second application, on Sept. 7, Morikawa sent her latest letter to the departments, asking them to delay the third and last drop until those the results from the dead animals were available.
“A delay for the third application of rodenticide could almost certainly require additional applications and significant associated costs,” Case wrote in response on Sept. 11.
That’s because diphacinone has been proven to be most effective when bait is available for a 25-30 day window.
“Additionally, the operational window is getting short due to forthcoming rainy season,” Case wrote in her response.
She acknowledged risk to non-target species in both her response to Morikawa and in Tuesday’s press conference, citing the more than 10 federal and state permits for the project.
“The long term benefits, we’re confident, outweigh the short-term potential risks,” Case said.
“We went out of our way to make sure we do everything possible to avoid, minimize or mitigate those risks,” Packard said.
An example of that was an increased buffer zone on the third application around the tidepools where the dead animals were found, Case said.
Morikawa said she’s waiting for reports from her constituents, plans to remain vigilant as time progresses, and supports citizen scientists who are going out to study the effects to the island’s ecosystem.
“If this does not succeed and they (DLNR and partners) feel another application is needed next year, I will fight it,” she said.