As summer temperatures approach 90 degrees, restaurants boast their outdoor patios and decks, and Americans pull out their biggest knives to hack through watermelons and cantaloupe, the Japanese fill up on charcoal-grilled unagi, glazed with a sweet, rich sauce and served on a bed of steamed white rice. Gone are the days of simmered kabocha squash and stew-like oden.

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In Japan, summer is eel season.

And being the pragmatists that the Japanese are, this summertime unagi-eating ritual isn’t without purpose. Though Western thinkers may not be accustomed to Eastern theories about balancing internal and external body temperatures, Japanese tradition dictates that when the summer heat gets debilitating (the average July temperature in Tokyo is 84 degrees Fahrenheit), eating unagi gives your body strength to help fight off heat fatigue. So as Americans are busy licking drippy ice cream off our fingers, the Japanese are gorging on sticky, fatty chunks of unagi.

On Doyo no ushi no hi, also known as Midsummer Day of the Ox and “Eel Day,” which falls on July 29 this year, the unagi-eating tradition gets serious. Though the exact date changes every year according the lunar calendar, Doyo no ushi no hi falls in the peak of summer heat when it’s believed that you need omega 3-rich, appetite-stimulating unagi the most. Since the Edo Period (1603-1867), Japanese have been practicing this ritual with the belief that unagi’s nutrients can help them fight off natsube, or summer fatigue.

It’s a tradition as heartfelt to the Japanese as turkey on Thanksgiving, or a hot dog on Fourth of July.

But with unagi populations having been in decline and prices soaring due to overfishing and habitat degredation since the late 1980s, and organizations like the Monterey Bay Seafood Watch having warned against the consumption of unagi, this eel-eating ritual has been suffering. When the International Union for Conservation of Nature put the species on the Endangered Animal list last June, panic took hold over Japan.

Unagi was listed as a code red, and Japanese consumers are feeling the heat.

Every year, the Japanese consume 100,000 tons—about 70 percent—of the worldwide eel catch, but they’ve always had a particular soft spot for unagi, the freshwater species that’s known as the Japanese Eel. But with the unagi population decreasing and prices rising, the future of unagi-yas, restaurants in Japan that specialize in unagi, and this age-old consumption tradition is uncertain.

Akiko Ishibashi has been serving unagi since 1972 when she married Kikutaro Ishibashi, whose family has been running one of Narita, Japan’s popular unagi-yas, Kikuya Chrysanthemum House, for 11 generations. She stands clad in her kimono outside her restaurant and greets customers before they enter, where she says 99 out of 100 customers will order unadon, or barbecued eel on steamed rice. Eel sauce runs thick through Akiko’s blood, but she knows her country’s unagi obsession has to change.

“In old days, unagi was a special food—only on special occasions did we eat eel,” Akiko says. “When supermarkets began to sell unagi, it became so popular—for everybody. But many supermarkets catch too much eel and dump, and now the unagi is endangered. When people eat normally like they did in old days, it’s no problem, but it’s a big problem now.”

With market prices soaring, she worries about the unagi business. A small bamboo box of the fatty, grilled meat on rice sold for 600 yen when she first started; today, it’s 3250 yen.

“Already, many eel restaurants have quit the business because it isn’t good,” Akiko says. “We’ll be alright, I hope.”

Catering to its panic-stricken audience, the Japan Times published an article last month about how to appreciate anago, Japanese saltwater eel. However, it came with a small disclaimer: “The flesh is softer and sweet, with none of the oiliness that gives unagi its rich flavor and reputation for boosting energy levels,” which takes away half the Japanese reason behind eating the delicacy.

But the predicament is bigger than anago vs unagi—it’s about the worldwide eel population, and more than that, it’s about the state of our favorite sea delicacies. In 2008, the IUCN placed the European eel on the endangered species list, and struggling oyster and shrimp populations have been on conservationists' and chefs' minds as of late.

“While the status of this species is of great concern, the assessment of the Japanese Eel and other eels is a hugely positive step,” Matthew Gollock, Chair of the IUCN Anguillid Specialist Sub-Group, says in an IUCN press release. “This information will allow us to prioritize conservation efforts for eel species and the freshwater ecosystem more broadly.”

There are fewer things as sad as the loss of a tradition or piece of culture, but the loss of an entire species is up there.

Maybe it is time we all suck it up and try some of those Asian carp of lionfish that have been invading our lakes and rivers. Anything charcoal-grilled, glazed, and served on rice is destined to be pretty good.