Environmental Conditions Appear To Have Killed Hawaii Fish

Aug 1, 2019

HONOLULU — Changes to environmental conditions may have caused the deaths of multiple fish in a Honolulu stream, officials said.

Large numbers of tilapia were found dead in Waialae Stream in Waialae Beach Park Tuesday, The Honolulu Star-Advertiser reported Tuesday.

The Hawaii Department of Health and the state Department of Land & Natural Resources Division of Aquatic Resources are investigating the dead fish, officials said.

Tilapia is a freshwater species that inhabits Honolulu's streams and canals and is farmed in ponds.

The fish deaths could be the result of low oxygen in the water, which is often seen downstream of wetland habitats following large storms, the health department said.

Lowered oxygen levels can also happen after periods of hot, dry weather in low-lying canals where algae blooms can occur, officials said.

Honolulu has experienced only 0.12 inches (0.3 centimeters) of rainfall this month.

"The water did appear 'greener' than normal but no sheen or evidence of a wastewater spill was observed," said Myron Honda, coordinator of the health department's Clean Water Branch.

Waialae Stream formed a stagnant lagoon separated from the ocean by sand during Tuesday's low tide. The waterway is in an area between the Kahala neighborhood and the Waialae Country Club and Kahala Hotel & Resort.

Only tilapia appeared to have been affected. Crabs, mullet and papio were observed unharmed, Honda said.

"Based on the presence of other aquatic species, and no visible evidence of a petroleum or wastewater spill, there does not appear to be a clear cause of the fish kill," he said.