Mariners Asked to Avoid Kahalu‘u Bay for Coral Spawning

The COVID-19 pandemic has had devastating impacts on public and economic health nationwide, and Hawai‘i has been far from immune.

However, the crisis has proven beneficial to the natural world, providing opportunities for places damaged by too much human contact the chance to heal. One such example of this is Kahalu‘u Bay in Kailua-Kona. Both the bay and its inhabitants have been afforded the opportunity to rest, as Hawai‘i County’s Kahalu‘u Beach Park has been closed.

Now, the Kahalu‘u Bay Education Center (KBEC), a program of The Kohala Center, along with the DLNR Division of Aquatic Resources (DAR), is asking everyone to voluntarily refrain from swimming and snorkeling in the bay, particularly during the week of May 10 to May 16, to enhance the upcoming spawning of cauliflower coral.

Kahalu‘u Bay on Hawai‘i Island is one of the most popular and heavily visited snorkeling locations in all of Hawai‘i. Hundreds of thousands of people come to view colorful fish and coral colonies every year, and like in many other over-used locations, the aquatic life in the bay is struggling to survive.

According to DAR and Eyes of the Reef Network, cauliflower coral was once abundant on shallow coral reefs along West Hawaiʻi, including Kahaluʻu Bay. However, environmental stressors and very high ocean temperatures impacted West Hawaiʻi in 2015 and again at the end of 2019, causing catastrophic bleaching and mortality for more than 90% of the Kahaluʻu Bay population. 

KBEC director Cindi Punihaole Kennedy says next week is prime spawning time for the corals, as they only get one chance a year to spawn.

“We’re asking everyone to voluntarily avoid snorkeling or swimming in the bay from May 10 to May 16,” she said. “During broadcast spawning events, corals emit reproductive materials (“gametes”) into the water column, and these materials are carried by the tides to mix and generate planktonic coral larvae. Given the chance to settle undisturbed by human activity and/or pollutants, coral gametes will be able to find proper rubble colony areas to settle within the bay.” 

Coral at Kahaluu Bay. PC: Hawaii DLNR Division of Aquatic Resources

KBEC has been one of the state’s leaders in encouraging the use of reef-friendly sunscreens by conducting frequent sunscreen swaps and encouraging folks to cover up. In addition, ReefTeachers educate visitors to avoid stepping on rocks as they are home to many living animals and to please extend social distancing practices to help protect the bay’s natural resources.

“We totally support this voluntary measure as natural reproduction events are critically important,” said  DAR administrator Brian Neilson. “Researchers can accurately predict when cauliflower and other coral species will spawn.”

“Studies have shown that with the absence of daily visitors and a subsequent reduction in physical damage and impact of chemical sunscreens, growth and recovery along the shoreline has already been documented,” he continued. “Research has shown that it can take less than 24 hours for corals to successfully reproduce and settle properly.”