Parrotfishes at Risk

One of the most beloved fishes on Hawaii’s reefs is also one of the most threatened.

Parrotfishes, locally known as uhu, play a key role in coral reef ecosystems, grinding up dead coral with their teeth to create sand and eating invasive algae that can smother the reefs.

Seven species are found in Hawaii, of which three are found nowhere else on Earth. But unsustainable fishing pressure and other threats are putting Hawaii’s parrotfishes at risk.

According to a NOAA and Oceanic Institute assessment, three-fourths of reef fishes in the main Hawaiian Islands — including parrotfishes — are either depleted or in critical condition, as compared to the largely unfished populations of the Northwestern Hawaiian Islands.

The practice of fishing using SCUBA, especially at night when parrotfishes are resting, may be contributing to the depletion of these fish species.

“Parrotfishes should be found in shallow water, but they’ve been pushed out of their natural reef habitat into the deeper sea,” said study lead Dr. Alan Friedlander. “This is resulting in a major disturbance to the near-shore ecosystem.”

Possible solutions include control on the use of SCUBA equipment for fishing and temporarily setting aside areas for the purpose of replenishing plant-eating fishes. Campaigns such as Fair Catch are raising awareness about responsible fishing for Hawaii’s reefs.

“There are areas in the main Hawaiian Islands where the reefs are still healthy,” said Dr. Eric Conklin, the Conservancy’s marine science advisor. “So everything hasn’t collapsed yet. But we need to protect the healthy reefs, because it’s so much easier and safer to conserve now than it is to try to rebuild later.”

Did You Know?

Harem of red females, Hanauma Bay, O‘ahu.

Parrotfishes have the ability to change genders from female to male once they reach reproductive maturity.

Typically, parrotfish begin life as females. Groups of females, or harems, are led by a single male with bright blue-green or yellow coloring (most female parrotfishes are red). There are usually far fewer males than females.

If a fisherman catches one of these blue-green males, the biggest female has to change into a male. That means the biggest female is no longer producing the harem’s healthiest and strongest eggs for replenishing the population. If fishermen have to catch a parrotfish for consumption, it’s best to take the medium-sized red females.

Nature picture credits (top to bottom, left to right): Parrotfishes play a key role in coral reef ecosystems © Jim Maragos/USFWS; Male parrotfish © Keoki Stender; Harem of red females, Hanauma Bay, Oahu © Keoki Stender.