Scientists have dropped listening devices into the water at some of Hawaii’s best sheltered bays for a study that aims to better understand spinner dolphins and how humans might be affecting them.

Taking advantage of the dearth of tourism during the pandemic, the devices were deployed in December and March by a coalition of conservation groups in collaboration with government agencies at Honolua-Mokuleia on Maui and Manele-Hulopoe on Lanai.

The devices will record the underwater sounds of the bays, including the activity of dolphins and humans, as tourists and tour boats return to them over the next year.

Known as Ecological Acoustic Recorders, or EARs, the devices were deployed even before the coalition had the money to pay for a formal analysis of the recording data.

“We knew we had to get them in the water sooner rather than later,” said Marc Lammers, research ecologist with the Hawaiian Islands Humpback Whale National Marine Sanctuary.

The project represents the combined efforts of the sanctuary, Nature Conservancy, state Division of Aquatic Resources, Oceanwide Science Institute, Hawai‘i Association for Marine Education and Research, and Pulama Lana‘i.

The coalition is now raising funds to help pay for the analysis of the data, which will be collected over a full year and expected to reflect the transition from fewer people to more people as tourism recovers.

In addition, the data will be combined with results of similar work being conducted on Oahu and Hawaii island by doctoral student Megan McEligott of the Hawaii Institute of Marine Biology.

Officials said the acoustic data will provide a better understanding of when dolphins come into the protected areas, how long they stay during daytime, whether their presence is greater or less over time and how human activities like snorkeling and boating might change their behavior.

The information will help marine resource managers develop targeted management strategies to minimize pressures on dolphins and other marine life, they said.

A couple thousand Hawaiian spinner dolphins — so named for their aerial acrobatics — are estimated to live in the waters around the main Hawaiian Islands. The nocturnal mammals use the sandy bottoms of Hawaii’s sheltered bays to rest during the day, according to scientists, before moving to deeper waters to hunt at night.

But a growing industry centered around swimming and watching dolphins has emerged in recent decades, causing concern about whether human interactions are disrupting resting dolphins, affecting mothers tending to their young and interrupting mating behavior. Some fear that the human interactions could lead to a reduction in the population’s size.

“Lanai residents say there used to be a lot more dolphins (in Holupoe and Ma­nele bays) years ago, before there was so much activity,” said Emily Fielding, Maui Marine Program director for the Nature Conservancy.

The spinners are protected by the U.S. Marine Mammal Protection Act with guidelines that call for keeping a distance of 50 yards. But the National Oceanic and Atmospheric Administration is now looking at turning the guidelines into formal regulations to better protect the popular dolphins.

A scientific study by researchers from the University of Hawaii and other institutions found last year that Hawaii’s wild-dolphin industry generates an estimated $102 million annually, although that was based on numbers collected in 2013 and the business has only gotten bigger since then.

Over the past decade the Nature Conservancy has worked with state and community partners to develop conservation action plans to guide management of the six marine conservation areas of Maui Nui. Those working on the plans have prioritized the provision of safe places for spinner dolphins to rest and play undisturbed, officials said.

Allen Tom, superintendent of the Hawaiian Islands Humpback Whale National Marine Sanctuary, said the latest project could have worldwide implications for marine protected area management.

“And it takes the effort of federal, state and local partners to move a project like this forward,” Tom said in a release.