HAENA — Some Kauai residents say injured, invasive tilapia could be bringing sharks closer to shore during a season traditionally known for frequent shark sightings.

Wednesday morning, Haena and Ke‘e beaches were closed to swimming after a surfer saw at least two sharks attack and kill a dolphin while he was surfing in the waters off Ke‘e. The size and type of shark is unknown, according to Kauai County.

The state Department of Land and Natural Resources has been notified of the dolphin carcass.

In July, several sharks were seen in waters off Polihale State Park during an agency search for a missing Kalaheo swimmer, Fathi Twalib. The two-day search for Twalib was suspended July 25.

Before that, a shark encounter was recorded by DLNR in February at Poipu Beach. Several encounters have been reported on other islands throughout past months as well.

And last Thursday, a small shark was filmed cruising in the surf along the shore at Anahola. Later that evening, a small shark cruised by the Hanalei Pier, pretty much right where swimmers had been in the water just minutes before.

In Hawaiian tradition, knowledge was passed down orally through oli, or chants. Oli about sharks point to certain times of year when activity is heightened, and connects that to the blossoming of the wiliwili tree.

Translated, part of it says: “When the flowers of the wiliwili tree (blossom), that is the time when Mano Nui, the shark-god, bites.”

Kumu Sabra Kauka explains that the verse refers to the time when the tiger sharks come closer to shore. According to the University of Hawaii, the trees bloom from spring through the summer.

But there could be more at play.

In July, Kauka and a group of people were at Nualolo Kai, the ancient Hawaiian village on Kauai’s North Shore, doing a cleanup project, when they noticed large schools of fish clustered near freshwater seeps in the area.

It was thousands of black-chin tilapia, mostly juveniles, thought to have been washed down the ditches on the Westside of the island during heavy rains around that time.

The tilapia sighting was reported to the state DLNR Division of Aquatic Resources. They received additional reports and did some surveys. Now they’re waiting on a special activity permit to gather community members to try and remove the tilapia with a surround net.

Kauka says when they saw the tilapia, they weren’t in the greatest shape, and that, she thinks, could be bringing sharks closer to shore.

“They were unhealthy-looking, clustered around where the fresh water comes out into the ocean in places, some with sores and cuts on them,” Kauka said. “That could be bringing in the sharks, like the ones out at Polihale when that swimmer went missing.”

Research from the Hawaii Institute of Marine Biology Shark Lab confirms tiger sharks are the most prevalent through the Main Hawaiian Islands. They are scavengers, and eat turtles, crustaceans and other sharks, as well as reef fish and octopus.

A long-term project is ongoing at HIMB to “understand tiger shark long-term movement patterns to determine whether these are related to the rare incidences of shark attacks on humans.”

Ke‘e and Haena beaches are closed, and lifeguards are assessing them today.

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Jessica Else, environment reporter, can be reached at 245-0452 or jelse@thegardenisland.com.