Scientists: Half of Hawaii’s coral reefs bleached in 2014-15

Nearly half of Hawaii’s coral reefs were bleached during heat waves in 2014 and 2015 and fisheries close to shore are declining, a group of scientists told state lawmakers.

The scientists from the Nature Conservancy briefed the lawmakers on Thursday about what they called unprecedented for Hawaii’s sea life.

National Oceanic and Atmospheric Administration officials said 56 per cent of the Big Island’s coral were bleached, along with 44 per cent along West Maui and 32 per cent around Oahu.

The scientists said more severe and frequent bleaching is predicted.

“In the 2030s, 30 to 50 per cent of the years will have major bleaching events in Hawaii,” said Kuulei Rogers of the Hawaii Institute of Marine Biology.

When ocean temperatures rise, coral expel the algae they rely on for food. This causes their skeletons to lose their colour and appear “bleached.”

Coral can recover if the water cools. But they die if high temperatures persist. Eventually reefs degrade, leaving fish without habitats and coastlines less protected from storm surges.

As for Hawaii’s fish, University of Hawaii researchers compiled data for 15 years and found a 90 per cent decline in overall catch from the last 100 years, which includes fish such as ulua, moi and oio.

“What we found was pretty overwhelming,” University of Hawaii scientist Alan Friedlander said. “About 40 per cent of the species will be classified as overfished. The correlations are more people, less fish.”

Friedlander suggested expanding marine reserves and said gear restrictions and size limits help, but bag limits and quotas don’t work.