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Collaborating scientists have an ear on Lanai, Maui dolphins

Devices deployed recently to monitor marine life as human numbers rise

Spinner dolphins enjoy Hulopo‘e Bay off Lanai. Scientists have deployed underwater recording devices off Maui and Lanai to monitor dolphin noises and use the data to better learn how to protect the animals. ALANA YURKANIN / The Nature Conservancy photo

With an influx of humans returning to Hawaii’s waters, Maui and Lanai’s beloved spinner dolphins have something to say — and scientists are now listening more closely.

Underwater recording devices called ecological acoustic recorders, or EARs, that detect distinctive dolphin noises were recently deployed in Honolua Bay, Manele Bay and Hulopo’e Bay, according to Emily Fielding, The Nature Conservancy’s Maui Marine Program director.

As a higher volume of visitors returns to the Honolua-Mokule’ia and Manele-Hulopo’e Marine Life Conservation districts, scientists will be regularly retrieving the recordings and listening for key data over the next year that will be used to better protect marine life there.

Fielding said that because there were so few tourists when the recorders were initially dropped, experts will have a “unique opportunity” to observe changes as the state reopens to more people.

“Spinner dolphins produce distinctive sounds such as whistles, burst pulses and echolocation clicks that the EAR is programmed to capture,” she said.

A diver with The Nature Conservancy deploys an ecological acoustic recorder in Honolua Bay off Maui to monitor the behavior of spinner dolphins and other marine animals. JASON STURGIS photo

The noises tell experts when dolphins enter the areas, how long they stay during daytime resting periods, if their presence changes over time and how human activities like snorkeling and boating may alter marine behavior.

Fielding said each EAR is about the size of a box of facial tissue and fits inside a waterproof tube made of rugged plastic. The tube is then attached to a concrete weight and lowered to the ocean floor where it rests on sand.

One device was deployed at each of the bays: Maui’s Honolua in December, and Lanai’s Manele and Hulopo’e bays in March, according to Fielding. The devices are pulled every four months by Oceanwide Science Institute scientists to collect the drive housing the recordings and change the battery.

Known as one of the most acrobatic among all dolphin species, spinner dolphins have a habit of leaping from the water and spinning up to seven times before falling back into the ocean, according to the National Oceanic and Atmospheric Administration. Some of Hawaii’s spinner dolphins are found in deeper waters, but many of the state’s population have a coastal distribution. They seek sanctuary in nearshore waters, where they return to certain areas to rest, socialize and nurture young.

Spinner dolphins are protected under the Marine Mammal Protection Act, which prohibits harassing, hunting, capturing or killing any marine mammal, or attempting to do so. The state and federal government tell people to stay at least 50 yards away from dolphins, among other rules.

Human interactions can disrupt resting dolphins, impact mothers tending to their young or interrupt mating behavior, all of which could lead to a reduction in the size of the population, The Nature Conservancy said.

“We are seeking to better understand how spinner dolphins respond to human use in these (conservation districts) so that we can ensure the dolphins are getting the time and space they need to survive and thrive in Maui’s waters,” Russell Sparks, state Department of Land and Natural Resources Division of Aquatic Resources’ Maui-based biologist, said in a news release.

The project is a collaboration among The Nature Conservancy, Hawaiian Islands Humpback Whale National Marine Sanctuary, DLNR’s Division of Aquatic Resources, Oceanwide Science Institute, Hawaii Association for Marine Education and Research and Pulama Lana’i.

* Kehaulani Cerizo can be reached at kcerizo@mauinews.com.

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