Fish out of water don’t last long.

But prints of their dazzling scales, pressed into pools of ink, can preserve the aquatic creatures’ forms for centuries. Since the mid-19th century, Japanese fishers have been leveraging this unusual technique to create dazzling images known as gyotaku. As Sabrina Imbler wrote for Atlas Obscura last year, the term is quite literal: Split in two, it translates to “fish” (gyo) and “rubbing” (taku).

Like a pre-photography proxy for fish Instagram, the prints originally served as visual evidence for braggarts hoping to boast of an impressive catch. Now, some 150 years later, researchers have found a new and perhaps unexpected second use for the art: cataloging the historical biodiversity of the region’s fish.

Recently described in the journal ZooKeys, the art-meets-science approach could help conservationists track the ebb and flow of threatened and extinct populations in Japan’s past, filling in gaps where other data sets run dry, reports Hakim Bishara for Hyperallergic.

Though the identity of the first gyotaku print remains contested, experts agree that the earliest specimens date back to the 1800s, when Japanese fishers began smearing the flanks of ink-dipped fish on pieces of rice paper labeled with the date, location and species of the catch. Splattered in non-toxic ink, the fish could then be rinsed off and released, sold or eaten as usual.

Over time, fishers began embellishing the prints with brushwork, adding details omitted by the cruder dip-and-stick method, such as eyes or extra colors on scales.

Rendered directly from the animals themselves, gyotaku prints are, by and large, extremely anatomically accurate—and scientists soon recognized their educational value. By the middle of the 20th century, researchers had begun using the artwork in animal anatomy classes.

Conservation work, then, may seem like a logical next step. For the new study, researchers Yusuke Miyazaki and Atsunobu Murase collected 261 gyotaku from bait-and-tackle shops, including some that date back to 1839, toward the end of Japan’s Edo period. Scientific records from centuries past are spotty, but the prints seemed to corroborate the abundance of many of the region’s dwindling species. Among hundreds of prints, just seven found on the island of Hokkaido documented the critically endangered Japanese huchen (Hucho perryi). Three others from the Miyazaki Prefecture featured the threatened Japanese lates (Lates japonicus), according to Hyperallergic.

Continuing to gather gyotaku could reveal a wealth of scientific information, reports Erin Blakemore for the Washington Post. Some of the prints may even harbor bits of DNA, helping researchers validate and track the species listed.

Since the advent of cameras and smartphones, however, gyotaku itself has become something of a rarity. In a statement, Miyazaki advocates for the dying artform’s preservation, explaining that it could complement digital photography as a way “to record … memorable catches.”

For artist Naoki Hayashi, no replacement for the pure, unadulterated beauty of gyotaku exists—especially when it comes to commemorating an aspiring fisher’s first catch.

“That happens only once in a lifetime,” he told Atlas Obscura. “To capture it in this format and have it as a family treasure, that’s the true value of gyotaku.”