LIHU‘E — Fish kills are typically easy to explain, said Don Heacock, aquatic biologist for the state Department of Land and Natural Resources’ Division of Aquatic Resources, in a phone interview Friday. However, the large number of dead fish that
LIHU‘E — Fish kills are typically easy to explain, said Don Heacock, aquatic biologist for the state Department of Land and Natural Resources’ Division of Aquatic Resources, in a phone interview Friday.
However, the large number of dead fish that washed ashore on Ni‘ihau, Lehua and Kaua‘i earlier this year has had community members and researchers scratching their heads for some time.
It is possible that a logical explanation can now be linked to the mysterious deaths based on a biotoxin — cyanobacteria, or blue-green algae — which was found in the stomachs of frozen specimens collected February on Ni‘ihau.
“The State of California Department of Fish and Game laboratory found a freshwater blue-green algae toxin (microcystins) in the gut of a few specimens from the fish kill,” said Deborah Ward, spokesperson for DLNR, per the Division of Aquatic Resources in an e-mail Friday.
“The only way that might be explained is if some of the ephemeral lakes (a body of water that only exists for a short period of time) on Ni‘ihau might have had cyanobacteria that could have been discharged during the last week of December when Ni‘ihau experienced a major winter storm and heavy run-off,” Heacock said during a phone interview Friday. “It is the only link we seem to have of some kind of toxin that could have caused the fish kill.”
There are a number of ephemeral bodies of water throughout Hawai‘i, including Salt Pond on Kaua‘i. They can be springs, streams, rivers or any other water body that has an existence based upon seasonal changes and are created following precipitation.
These ephemeral ponds and lakes develop in winter storms, and by late summer, they generally dry up, Heacock said.
“It’s possible during that big storm that some of those lakes could have already had some kind of blue-green algae growing in them and those may have discharged into coastal waters during that period,” he said.
As triggerfishes (humuhumu) showed up in abundant amounts on the shores of Ni‘ihau and Lehua in January, and since they are known to consume algae and “things drifting by,” it might suggest that they were susceptible to the biotoxin which they ingested, Heacock said.
“I’m not saying that’s what caused the fish kill, but it’s the only clue we have right now,” he added.
Residents of Ni‘ihau were concerned about their food supply since they first received warning not to consume fish that appearing to be acting, for lack of a better word, “fishy”.
Perhaps now they may be able to breathe a deeper sigh of relief, though finding a 100 percent verifiable answer might still be difficult to ever come by.
“To state how this toxin showed up in fish specimens would be conjecture at this point,” Ward said, per the Division of Aquatic Resources.
To report a fish kill 24 hours a day, seven days a week, call the DLNR immediately at 643-3567 or the Department of Health at 808-247-2191.
• Coco Zickos, business and environmental writer, can be reached at 245-3681 (ext. 251) or czickos@kauaipubco.com.
