Too Many Divers and Snorkelers Reduce Molokini Fish Populations

If you have been to Maui, no doubt you have either dived or snorkeled at the offshore crescent-shaped Molokini Island, a Marine Protected Area. And that's the problem. Everyone else has too.

A new study that examined years of data on the presence of fish in Molokini Crater before, during, and after the pandemic has found that the daily barrage of tour boats and snorkelers drastically reduced the fish population.

Before the pandemic, the number of tourists flocking to Maui was reaching all-time highs. More than 40,000 tourists came in August 2019 to snorkel or dive in Molokini. By the following spring, Hawaii was locked down to stop the spread of COVID-19, and for the first time in recent history, there were no visitors to Molokini.

During the height of the pandemic, researchers sent divers to Molokini to document the volume and types of fish in the area, building on similar surveys that had been conducted regularly years before. The scientists also captured fish and put tracking devices on them to shed light on how they moved in and around Molokini during the day and night.

The findings were clear. Since 2004, the volume of fish at Molokini had dropped, even though fishing hasn't been allowed for decades. But the fish population suddenly rebounded when the lockdown hit and tourist boats disappeared.

The biomass of fish - the measurement used to estimate how many pounds of fish are living per square meter or acre - surged. And more predators, like bluefin trevally, arrived.

When the tourists returned, things changed again. When Molokini was packed with boats and people - usually in the mornings when the wind is calmer - the predators left for deeper waters, something they didn't do when the area was free of people. The volume of fish dropped again to pre-pandemic levels.

The research calls for examining ways to reduce the traffic in Molokini by attracting fewer tourists willing to spend more money rather than making things cheap to attract as many paying customers as possible.

"Molokini is being over-used," said Russel Sparks of the Hawaii Department of Land and Natural Resources. "Management is needed to improve not only ecosystem health but the visitor experience."

Hawaii has shown that tighter management can work. Hanauma Bay on O'ahu is one of the most-visited MPAs in the world and has undergone a series of management changes to reduce visitor numbers, including weekly rest days when the park is closed, a ban on fish feeding, a reservation system, mandatory visitor education, and an increase in fees, which reduced visitors from 8,000 per day in the 1980s to 1,000 per day in 2022.

See the complete Molokini study here: https://tinyurl.com/2a6xuksu

From an article in Civil Beat, by Marina Starleaf Riker.