A Napoleon wrasse (Cheilinus undulates) cruises past a photographer, curious but seemingly unperturbed by the human interloper’s presence—and oblivious to the price some have put on the fish’s head. Such is the tranquility in this part of the Red Sea, near Egypt’s Sharm el-Sheikh. The residents of these waters are protected from fishing, allowing even large, long-lived predators like Napoleon wrasses and groupers to maintain relatively healthy populations. Here, and in a few other protected reef habitats across the species’ range, the fish are known to gather in groups of dozens to more than a hundred spawning individuals, all responding in sync to mysterious tidal cues.

Unfortunately, healthy Napoleon wrasse populations are not the norm throughout the rest of the world. Across much of the species’ range—spanning from the Red Sea south and east across much of the Indo-Pacific—their numbers are plummeting. The International Union for Conservation of Nature (IUCN), which now lists the species as endangered, has documented “rapid serial depletions” of Napoleon wrasse populations in many areas over the past 10 to 15 years as fishermen decimate their numbers and then move on to do the same elsewhere. The primary reason for the wrasse’s steep decline is simple, says Luiz Rocha, Curator of Ichthyology at the California Academy of Sciences: “They’re big, tasty, and easy to catch.”

The wrasse’s tendency to spawn in large groups hasn’t helped its chances. Fishermen know about these aggregations, says Rocha, “so they know where to go to score big.” What’s more, these heavy-bodied fish, which can grow to 2 meters (6 feet) in length, weigh as much as 180 kilograms (400 pounds), and live 30 years or more, are slow to reproduce. Napoleon wrasses typically reach sexual maturity at age six, which means a new generation is produced on average only every 10 years or so.

In recent years, the wrasse’s decline has been driven by yet another of the species’ traits: its lips. Inexplicably, the fish’s bulbous lips have become a prized delicacy in certain parts of Asia. In Hong Kong, for instance, the lips of a large wrasse can fetch as much as $20,000 per pair. With such a huge price tag on its head, the species has effectively been extirpated from waters near Hong Kong, says Rocha. With fishermen now expanding their hunt for a big payoff to waters off Indonesia and the Philippines, the Napoleon wrasse’s only real hope is an increase in the number and size of marine protected areas, like this one in the Red Sea.