Not far off the Kona coast, near the airport, one or more of these nets can often be seen. They’re the submersible net pens of a fish farm run by Blue Ocean Mariculture. The farm raises Almaco jack which it markets under the name Hawaiian Kanpachi.
In the wild, the fish is prone to ciguatera, a toxin that can cause diarrhea, vomiting, numbness, and other unpleasant symptoms. This is the reason almaco jacks aren’t fished commercially. But the farmed fish are free of this problem. I have mixed feelings about farmed fish, but this farm seems to be well regarded and is approved by Monterey Bay Aquarium’s Seafood Watch.
Part of my ambivalence may be down to the fact that, last year, one of the few resident monk seals living around the island became trapped in a pen and drowned. I’ve since heard that when work is being done on a pen, it should be raised so part is above the surface. That way, if something swims into a pen and can’t get out again, it can at least surface inside the pens to breathe. Whether that happened in this case, I can’t say. The official word is that mariculture projects in Hawaii are under review by the Army Corps of Engineers and NOAA.