Hawaiian fishponds are threatened by climate change. They can also mitigate it. How are their...
A couple weeks ago, I was sitting on a fishpond wall—the permeable barrier that distinguishes aquacultural waters from the wild sea—and the tide was low. The trade winds smelled like seaweed. Some clouds floated overhead, faint brushstrokes against a scumbled sky. A small dinghy pulled against its mooring a few yards away. Murky water—hardly five feet deep—splashed against the wall.
On Oahu, winter brings massive swells to the North Shore. I’ve heard that 100-foot waves have crashed there, but none have in a while. This year, though, the surf was forceful enough to collapse a beachfront house, and people are worried the coastal highway will erode away. There’s talk of oceans rising and acidic seawater. An ocean like that didn’t seem plausible, where I sat on the windward side of the island. Atop the fishpond wall, on that breezy summer day, the ocean was like a coddled pet, content to sit at my feet and observe the world with me.
Two fat pufferfish flirted by the mākāhā, the sluice gate that allows baby fish to swim from the ocean into the pond. First, I saw their translucent pectoral fins, sculling vigorously. A couple minutes later, one of their heads breached the surface. Pufferfish have big, misshapen pupils, and I looked in this one’s eye. We did not regard each other for long. The fish sank below the surface and focused on its mate. I looked down at my toes.
Beneath my feet was the fishpond wall, called a kuapā. It was more than a yard wide. Its outer lengths were made of lava rocks, each one about 10 inches in diameter, all hand stacked. The interior of the wall, the stuff I was absentmindedly digging my toes in, was composed of small coral bits. This wall was recently repaired, but very old ones are topped with smooth, river-run pebbles called ili ili, better for walking barefoot.
A group of schoolkids approached, carrying scrawny bamboo stalks. They teased each other and giggled. Someone helped them transfigure the sticks into rods, and the kids started casting. They were fishing for toʻau, a predatory, invasive snapper. I peered into the water, which, near the wall, was inch deep. Dark crabs scurried to their crabholes. The pufferfish had departed, but I saw the Argentine flash of aholehole (a native fish, also called silver flagtail). Suddenly, one of the kids caught a toʻau. It was only four inches long, with a yellow belly, and what appeared to be an aggressive frown. It was swiftly dumped in a cooler.
I started walking along the fishpond wall, back to the shoreline. If you walk along the edge of a fishpond wall and look down, you can sometimes see little white flecks on the pond bottom. These are coral fragments, pushed off the wall by high waves. There are troughs in the kuapā, empty spaces where the fallen coral used to be. On the shoreline, a coconut tree leaned, its roots exposed where the high tide crashed.
Since 2016, fishponds have been reporting oversized waves that can knock down stones or release fish. They’re called king tides. Most likely a consequence of climate change. Unlike the sort of annual destructive storms that I’m used to in New Orleans, these king tides are quotidian.
I didn’t see any king tides this summer, for the three weeks I was on the island—just their vestiges. These were ghostly waves, then, and knowing they were there, where I was standing, leant a chronological dimension to the space. What did the coconut tree, crooked in the sand, look like before the waves bent its back? How level was this kuapā, before the waves tumbled its top? How turbid did the water get, how turbid was it before? Did a visitor notice these things—and therefore were they able to notice a change—or did flapping fins and swirling water pass by them like a blink?
Now that I’m looking back in time, I’m inclined to look forward too. Monstrous climate chaos will be easy to qualify, like big waves and Category 5 hurricanes—but what of the elusive, gradual changes? How different, for example, will the interior ecosystem of the fishpond be from its fountainhead? Will the fish keep flirting by the mākāhā?
Will the crabs crawl around the fallen coral from the wall? To know, we must watch the water, count the fish, smell the seaweed, hear the waves… In short, we must do more than see that there are fish in water.
I was almost back on shore, when I heard a splash. A spotted eagle ray—a near-threatened fish—flicked its fin and sidled beside the kuapā. It swam towards the shore. Perhaps that was an ichthyic goodbye. A goodbye for now.
