Earlier this week, still suffering from an election hangover, I found myself taking a long, solo snorkel at Mahukona. I was thinking about the devastation that the coral bleaching event of 2015 had wrought upon the entire West Hawaii coast. About the greatly reduced coral density and the consequently* reduced fish abundance and diversity. I was lamenting to myself how fish species that had appeared with some regularity at Mahukona prior to 2015 were now absent or nearly so. (Heller’s barracuda and scrawled filefish come to mind, but there are several others.) I was thinking that Mahukona seemed to be offering little new and different for fish watchers these days.
A small portion of the opelu school.
The week proved me wrong about that. About an hour into my snorkel, in about thirty feet of water, I ran into an enormous school of opelu, or mackerel scad. While we often see these fish at Mahukona and elsewhere, I had never seen a school this large—easily several hundred fish. Their frenzied swimming, sometimes as a highly coordinated group and sometimes in what appeared to be random chaos, was mesmerizing and irresistibly spirit-lifting.
Later, up close to the dock in just a few feet of water, I spotted what appeared be a piece of leaf among the rocks on the bottom. Something about it seemed odd, so I stuck my head down for a closer look. It was a leaf scorpionfish, a new species for me. (A couple of months ago Marla and I had tried to see one of these with Jeff and Sandra Hill. They’d found a leaf scorpion at Kahaluu Beach that had stuck around in the same location for several weeks, but by the time we got down there for a look it had disappeared. If you’re reading this you should check out Jeff’s highly amusing—not to mention informative—blog: konafishwatching.blogspot.com.)
A couple of days later Marla and I went back to where I’d seen the leaf scorpionfish to see if it was still there. We couldn’t find it, but Marla spotted a small fish wedged motionless between two large rocks. We couldn’t figure out what it was, but I took the best photo of it that I could and went home to consult the books. It turned out to be a speckled scorpionfish, also a new species to us. So it ended up a good week, with two new fish species observed. Maybe Mahukona isn’t so boring after all.
With its camouflage coloration, leaf scorpionfish, like many scorpionfish, can be hard to identify as fish. The eye is perhaps the best giveaway. John Hoover writes that looking into these strangely vacant eyes is “like peering into another universe.” I agree.
Another view of the leaf scorpion. These ambush predators are supposedly fairly common in Hawaii, but they usually stay well hidden during the day.
A speckled scorpionfish wedged head first between the rocks. These fish are allegedly very common. They’re usually hidden among the branches of antler coral by day, moving to more exposed spots at night. Antler corals are almost absent in waters less than thirty feet deep at Mahukona, but we find them in shallower water at other sites. I intend to start checking these corals for speckled scorpions when I encounter them in the future.
*I’m speculating to some degree here. I’m pretty sure that the coral beaching is at least partially responsible for the fish decline, but there may be other unrelated causes. Unexplained fluctuations in fish populations are not uncommon. A striking example is the 2014 surgeonfish explosion along the West Hawaii coast, described in an August 2014 post.