I was scuba diving off my kayak on a deep water ledge at Pua’ena Point outside of Hale’iwa and got a big surprise. This 100-foot tall underwater cliff is open to the deep blue water and I often see game fish there like the Giant Trevally (ulua aukea) and the Bluefin Trevally (omilu), but on this dive I saw a large shape emerging out of the blue water and I thought it might be a humpback whale.
I was scuba diving off my kayak on a deep water ledge at Pua’ena Point outside of Hale’iwa and got a big surprise. This 100-foot tall underwater cliff is open to the deep blue water and I often see game fish there like the Giant Trevally (ulua aukea) and the Bluefin Trevally (omilu), but on this dive I saw a large shape emerging out of the blue water and I thought it might be a humpback whale.
As it got closer I could see it was moving too fast to be a whale and as it got closer I could see it was a huge school of over 100 large fish. At first I thought it might be ahi, but as it got closer I could see that it was some type of jack.
Most large jacks in Hawaii live close to the nearshore reef and don’t form schools except when they are small. At this size they are called papio and most of the larger jacks all look the same when they are a foot long, but sometimes in a big school of papio I will see some striped individuals. I often wonder what these fish look like when they get to be adults.
The huge school of jacks turned out to be the rarely seen pake ulua or Bigeye Trevally. This 3-foot long fish normally lives in the open ocean and they form huge schools of up to 1,000 individuals. They normally feed at night time on schools of bait fish or squid and that is why they have such large eyes.
It is super rare to see them close to shore, but I could see they were chasing a school of opelu. The large school of fish zoomed around me three times at high speed and I got some great video of the action. It turns out that the young pake ulua are striped and hang out with the large schools of papio when they are young, and then go off into the deep when they mature.
You can see this fast moving huge school of Bigeye Trevally in a video (https://youtu.be/xRIEKmr_rDw) on my YouTube channel at Underwater2web. Notice the black spot at the top of their gill cover as this is a good way to identify this species.
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Terry Lilley is a marine biologist living in Hanalei Kaua‘i and co-founder of Reef Guardians Hawai‘i, a nonprofit on a mission to provide education and resources to protect the coral reef. To donate to Reef Guardians Hawai‘i go to reefguardians.org
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