Are Japanese researchers of fauna and flora becoming more like their U.S. counterparts? They may well be. Some now talk about the environment, ecology and biodiversity only to disguise their anthropocentric expediency.

This thought occurred to me recently when I was checking a couple of things to revise a translation for publication. One of them had to do with the carp.

At one point in his childhood memoir Gin no saji (“The Silver Spoon”), Kansuke Naka (1885-1965) describes yoka-yoka-ameya (“yummy-yummy candy vendors”) who went about in couples. With the man-and-woman duo who used to visit his neighborhood around 1890, Naka recollected, the man wore a yukata with the design of a carp leaping up a waterfall splashed across it.

Ah, a carp leaping up a waterfall! The image is a familiar one in Japan. Koinobori, the carp-shaped streamers hoisted in the early May sky, are the most colorful, lively representation of it.

Like many such traditional customs, the idea behind it comes from China — in this instance, from the history of the later Han Dynasty of the fifth century. One episode in it says that every year thousands of fish and turtles gather at the downstream end of the torrents called the Dragon Gate in the Yellow River, but only a few succeed in leaping up them. The Japanese thought those successful ones were carp.

But something is wrong with this, I long thought. The carp is a sluggish, bottom-feeding fish, isn’t it? How can it swim up a violent flow like the salmon?

My vague wonderment continued until another “invasive” species grabbed the headlines several years ago. The Asian carp in the Mississippi River was multiplying so fast that they threatened to take over the Great Lakes, endangering America’s, nay, the world’s greatest freshwater ecosystem!

What made me pause was not the species “invasion,” however. In the United States nowadays, every organism that grows and moves is suspected to be “invasive.”

Rather, the news came with an arresting bit of information: This sizable fish jumps up into the air en masse, sometimes injuring people on a boat.

So, when the time came to revise The Silver Spoon once more, I thought to upgrade the footnote on “a carp leaping up a waterfall” and checked the Japanese Wikipedia entry on the carp. And what I read made me wonder.

As environmental concerns have extended to waterways, the entry says, communities have started stocking “natural” rivers with carp, utterly unaware that could drive to extinction “the endemic species that have developed over tens of thousands of years.”

Could that be true? Most Japanese rivers are heavily tampered with and seem unlikely to maintain “endemic” species. Am I wrong again?

Not entirely, it seems. The entry mentions briefly that “the destruction of ecosystem” resulting from “river improvements” and that’s one reason the International Union for Conservation of Nature (IUCN) added the carp to the “vulnerable” list in 2008.

If the concern for endemic species is so great, what about the artificially improved variety known as nishikigoi (“brocade carp”), which appears to have made the word koi part of the English language?

The entry sets aside a section for it, listing all the color variations, but the only negative thing it mentions is the “koi herpes virus” that could kill thousands of carp. The koi is important not just for the Japanese market but for foreign markets as well. Hugh Hefner and Larry Ellison, among others, are known to keep them in their gardens.

The entry says the carp is “omnivorous” and eats “aquatic plants, shellfish, earthworms, insects, crustaceans, frogs, and the roe of other fish, and small fish, most anything that can enter its mouth,” so it is “an evil eater.”

By that standard, homo sapiens is the evilist of them all.

The carp’s “greediness,” along with its tolerance of low temperature and lack of potential natural enemies when fully grown — again the attributes of the homo sapiens — led the IUCN to put the fish on its list of “100 of the World’s Worst Invasive Alien Species,” the entry adds. It does this by way of bringing up the black bass as Japan’s top “invasive” species.

And that brings us back to this quintessentially anthropocentric term.

I didn’t think it existed a couple of decades ago. Back then, the term was “alien.” So I checked. Sure enough, a NOAA site says 1999 Executive Order 13112 defined “invasive” as a category within the “alien” category.

But, be it alien, invasive, exotic or nuisance — words on the NOAA list — such categorizations strike me as all wrong. Species started propagating the moment they came into being.

In the Anthropocene, humans have aided and abetted the process. A great many among the IUCN “worst 100” were and continue to be deliberately introduced or else migrated to nonendemic places because of human movements.

The kudzu, for instance, was brought to the U.S. for the Philadelphia Continental Exposition in 1876 and farmers were paid to plant the vine in the 1930s and 1940s. Its rapid growth in amplitude was regarded as a godsend to stop soil erosion.

The Asian carp was introduced to the U.S. in the 1970s “in hope that they would control weed and parasite growth in aquatic farms,” as the National Park Service puts it.

Conversely the black bass was introduced to Japan from the U.S. in 1925 and it continued to be stocked until the end of the 1980s. Only in 1992 steps to control it began.

Americans, in fact, may be shocked to learn eradication programs are now in place in Japan for one of their favorite species in sport fishing. For that matter, the brown trout and rainbow trout are also on the IUCN list.

Oh yes, the Japanese Wikipedia entry does say that the carp is a bottom dweller who prefers to live in slow-moving waters. But it also says that the smaller ones can jump up as high as 2 meters.

It goes on to add that the fish doesn’t “climb a waterfall.” But that may be taking a metaphorical imagining too literally. An unrelated video shows a bunch of carp trying to swim up a spillway.

Hiroaki Sato is a translator and essayist in New York.

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