State growing urchins to fight invasive seaweed in Kaneohe Bay - Hawaii News Now - KGMB and KHNL

State growing urchins to fight invasive seaweed in Kaneohe Bay

Sea urchins raised in captivity Sea urchins raised in captivity
Jono Blodgett Jono Blodgett
David Cohen David Cohen
Invasive seaweed in Kaneohe Bay Invasive seaweed in Kaneohe Bay
HONOLULU (HawaiiNewsNow) -

The state is raising mass quantities of a native sea urchin to battle an invasive seaweed that has smothered coral reefs in Kaneohe Bay.

The state Division of Aquatic Resources has been spawning and growing thousands of Hawaiian collector urchins at the Anuenue Fisheries Research Center on Sand Island. The urchins are the newest weapon against fast-growing "smothering seaweed," which overtook Kaneohe Bay.

"They were being tested for years before then, but we needed to mass-produce them to really make a difference on the reef," said Jono Blodgett, an aquatic invasive species program leader with the state. 

"When they're about four to five months old, they're at about 15 millimeters," said Dave Cohen, the urchin hatchery manager. "They're about the size of a nickel. At that point we introduce them into Kaneohe Bay to eat the invasive seaweed."

The wana are the second part of the effort to rid the bay of the invasive algae and seaweed. The other tool involves the use of so-called "super suckers." Divers hand-pick and feed the bad algae into a giant hose attached to a barge. Once topside, the algae is sifted, bagged, and given to local farmers for compost.

"These urchins were native throughout the Pacific and also in Kaneohe Bay," said Blodgett. "Over the past decades their population has dropped dramatically, so we have just increased their population back up to previous levels."

State officials said more than 100,000 urchins from the hatchery have been released into Kaneohe Bay since 2011. The division wanted to perfect the process of hatching the urchins, which are difficult to raise in captivity. Divers will place another large group of five-month-old urchins in Kaneohe Bay on Thursday.


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