Tilapia invasion along Napali Coast shoreline

State officials announced Thursday they are working to stop an invasion of black-chin tilapia in the near-shore waters of the Napali Coast State Wilderness Park on Kauai.

Thousands of the introduced tilapia have invaded the coastline, and the state Department of Land and Natural Resources plans to take aggressive steps to keep them from moving any further.

“I consider this an emergency situation,” said Ka‘ili Shayler, a Fish & Habitat Monitoring Coordinator with Department of Aquatic Resources, in a news release. “We don’t want this species proliferating down the coast. We need to remove them before winter swells make it difficult or impossible to do anything.”

According to DLNR, fishermen first reported seeing juvenile tilapia over the past two weeks. On Wednesday, a team conducted in-water surveys at the Nualolo Kai section of the park and upon snorkeling to several spots close to the shoreline, soon discovered thousands of fish in schools.

If they proliferate down the coast, they can become a problem by ultimately out-competing native species for resources like food in the aquatic ecosystem.

Kaʻili Shayler, a Fish & Habitat Monitoring Coordinator with Department of Aquatic Resources, theorizes that the fish washed into the ocean from one of the ditch systems on the west side of Kauai. Since they are considered mostly a freshwater species, he thinks they are seeking areas where freshwater flows into the ocean, including the Napali Coast’s many streams and waterfalls.

Several dozens of the tilapia have been caught and analyzed by aquatic biologists to see what they are eating, along with samples of the ocean water where they are schooling to determine its salinity.

The state is also working on issuing a special activity permit allowing community members to remove the tilapia with a surround net.

Several dozens of the tilapia have been caught and analyzed by aquatic biologists to see what they are eating, along with samples of the ocean water to determine salinity of where they are schooling.

“The Napali Coast State Wilderness Park is among the most pristine, intact, natural areas in all of Hawaii,” said DLNR chair Suzanne Case in a statement. “It’s absolutely critical that we aggressively address any new invasive species threats and with this invasion of black-chin tilapia, that is precisely what we’re planning.”