Numbering the Nautiluses: The Quest to Save A Living Fossil
The chambered nautilus is perfectly adapted for being caught. Its ample olfactory organ, situated right behind its large primitive eye, helps it pick up scents from a distance, and its behavior is highly motivated by food — any bits of meat will do. A cheap, simple trap baited with chicken will soon fill with nautiluses, the shells of which will sell internationally for anywhere from tens to hundreds of dollars.
But the nautilus is also perfectly positioned to be destroyed. Unlike its cephalopod cousin the squid, which lives for a year and births thousands of young at once, the nautilus takes at least 12 years to reach sexual maturity. It lays only one to 10 eggs at a time, each of which takes a year to hatch. Its limited range — about 1,000 feet below sea level; any higher and it’s too hot, any lower and the pressure causes it to explode — means few new nautiluses arrive to bolster a depleted population. In a burgeoning shell market, that great sense of smell is deadly.
“It's kind of a good adaptation for them in the deep sea, where they can't see,” Gregory Barord, a doctoral student in biology at City University of New York, told weather.com. “But it's a horrible adaptation when you're dealing with humans using it against them.”
Nautilus shells for sale in the Philippines. (Gregory Barord)
Barord is also a researcher with the Nautilus Files
, a group working to track the decline in nautilus populations in order to help establish regulations on trade. The United States alone imports about 20,000 whole shells every year, Rosemarie Gnam, chief of the Division of Scientific Authority at the U.S. Fish and Wildlife Service, told weather.com, with that number soaring to about 80,000 including items made out of shell bits. Trade is also active in Europe and China.
Contrary to popular belief, Gnam said, nautilus shells used for jewelry don’t just wash up on the beach. The only way to get an unbroken shell is to take it from a live animal — and, like an elephant’s tusk or shark fin, the shell is not an accessory but a necessary part of survival.
In the face of such fishing, anecdotal evidence has pointed to a nautilus decline for decades. A 2010 study
using reports from fishermen in the Philippines showed that nautiluses in fished areas had declined 80 percent since 1980, just three nautilus generations.
But when seeking protections for a species, anecdotal evidence is not enough. Governments need data, the only form of which been fishermen’s records dating back to the 1970s. The records are fairly complete — the nautilus is their livelihood — but they’re not scientific observations, and so, in 2010, Barord and team embarked on a study to number the nautiluses.
“All these fisheries throughout this time have been heavily fishing these populations, and they just haven’t been able to rebound because they just grow too slow,” Barord said. “[What] we're trying to do next is tying it all together, bringing in all the anecdotal data and bringing in all of our data and putting it out there saying, ‘We have a problem here.’”
The underwater camera setup used to film nautiluses. (Gregory Barord)
The team visited the Philippines, where nautilus fishing has been profitable for decades, plus Fiji, American Samoa and Australia, which have unfished populations. Using baited traps and remote underwater video cameras, the researchers counted nautiluses to make population estimates.
In its first paper, published
June 23 in the journal PLOS One, the team reported that unfished populations fared far better, with a population density nearly four times as high as the most established fisheries in the Philippines.
“In the ‘70s they were catching maybe . . . 60 nautiluses per trap,” Barord said. “What we were seeing in the Philippines [now] was you needed to use about 13 traps to catch one nautilus. So that's a huge difference.”
Protecting the nautilus is not simply a matter of halting existing fisheries. Generally, once fishing is regulated or banned, populations rebound, Gnam said. But because of the nautiluses’ unique circumstances — its small ecological niche, its slow growth and reproduction — some populations still haven’t recovered long after fruitless fisheries were abandoned.
“You can overexploit it very easily,” Gnam said. “You can basically catch all the nautilus in a certain geographic area, and there’s none left to repopulate . . . . Once the population crashes and is wiped out, it doesn’t recover very easily.”
One hope for the nautilus is to be listed on CITES
, the Convention for the International Trade in Endangered Species. Depending on the status given, listing wouldn’t eradicate fishing entirely, but would rather impose regulations that would allow the fishermen to keep their livelihood and the nautilus to continue to grow and reproduce. The nautilus is on the “short list” to be considered for the next convention in 2016, Gnam said.
“We're trying to find a happy medium where fishermen don't deplete their resources,” Barord said. “That's really what I hope for, is that middle ground where everyone, including nautiluses, is able to survive.”