Creature of the Deep
My first encounter with this ancient chimera came on a research vessel trolling just outside New York Harbor, within sight of Coney Island’s Cyclone roller coaster. The big fish lay still on the deck, enduring its examination with an uncanny self-possession as we ran our hands across its mottled brown crocodilian form and measured its massive armored torso -- some four feet long and dense as a log sheathed in leather, studded head to tail with rows of hard, barbed scutes. Of course the antediluvian form was remarkable, but more so was the fish’s composure, a Zen-like patience we decided must derive from its antiquity.
Few animals are more ancient than the sturgeon. Two hundred million years ago, when the first dinosaurs were appearing and before the continents separated, sturgeon ancestors already inhabited the Triassic seas. The way they look now is pretty much the way they looked some 85 million years ago. Those that survived the spreading of continents, a global extinction, and the coming and going of ice ages inhabited the Northern Hemisphere’s largest river basins, lakes, and inland seas -- in Europe the Baltic, Black, and Caspian, the Danube and Volga; in Asia the Amur. In North America, a freshwater species colonized the Great Lakes, and other species flourished in the Missouri and Mississippi rivers and the Gulf of Mexico. Sturgeon roamed the estuaries and rivers of the Pacific Northwest; Atlantic sturgeon migrated along North America’s eastern coast from Labrador to Florida, spawning in nearly every major coastal estuary.
Yet for all their evolutionary prowess, sturgeon are now critically endangered. Once humans developed a taste for their roe -- processed as caviar -- and a craving for the profits it brought, species that had survived millions of years were devastated in little more than a century. The International Union for Conservation of Nature considers 18 sturgeon species worldwide to be endangered, 16 of them critically. The U.S. Fish and Wildlife Service lists four of the country’s nine species as endangered, two as threatened.
So it would not have seemed controversial when, in 2010, the National Marine Fisheries Service proposed adding all but one population of Acipenser oxyrinchus oxyrinchus, the Atlantic sturgeon, to the Endangered Species List. Concern for the precarious state of this once spectacularly abundant species was not new: in 1998 the Atlantic States Marine Fisheries Commission had called for a minimum 20-year ban on all sport or commercial fishing for the Atlantic sturgeon. Nine years later, an NMFS study found that, despite the ban, "only a few subpopulations seem to be increasing or stabilizing" and the majority "show no signs of recovery."
And yet if NMFS was looking for consensus among sturgeon scientists, it wasn’t finding any. The departments of natural resources and fisheries in nine states on the eastern seaboard opposed an endangered listing; only two supported it. The opponents called the move premature, unnecessary, an impediment to continuing research, a precursor to onerous new regulations at a time when their own as well as the federal agency’s resources were finite, and, most of all, not based on good -- or sufficient -- science. Many fisheries scientists pointed out that NMFS’s own 2007 status review, despite its grim findings, recommended only regional "threatened" listings -- meaning some populations of sturgeon were likely to become endangered within 20 years if nothing improved.
Proponents of an endangered listing, however, considered a 20-year bet on an 85-million-year-old species a reckless gamble. NMFS and the Natural Resources Defense Council, which filed a listing petition in 2009, claim that recent research shows Atlantic sturgeon face increasing environmental risks. Worsening water quality in the estuaries and rivers where the fish were once most abundant threatens young fish. In the Delaware Bay and the Delaware River, once the staging area for the greatest aggregations of Atlantic sturgeon, sightings of juveniles are rare and spawning adults rarer still. (Delaware and Pennsylvania already include the sturgeon on their state endangered lists and favor federal listing.)
Atlantic sturgeon are, of course, not the lone suffering species: 100 years of development, ship-channel dredging, and runoff have reduced to a shadow of their former selves populations of American shad, blueback herring, alewife, and American eel -- all of which migrate between freshwater and salt water.
Those arguing for an endangered listing believe it may be the only way to initiate the coast-wide effort they feel is needed to keep the Atlantic sturgeon from disappearing altogether. The population trend across the fish’s entire range, they contend, is clear, troubling, and in some cases alarming. Declare the Atlantic sturgeon endangered now, they say; fill in the scientific blanks later.
No one disputes that, for the Atlantic sturgeon, those blanks are big and plentiful. While charismatic is the first word many scientists use to describe the sturgeon, cryptic is usually the second. Its life history remains frustratingly inscrutable, a Rumsfeldian collection of knowns, known unknowns, and unknown unknowns.
Atlantic sturgeon can live past 60 (a lake sturgeon might live twice as long), grow to eight feet or more, and weigh 600 pounds. Yet despite their size and battle-ready appearance, they are a reclusive species. They are at home, out of sight, along deep river bottoms and coastal seabed channels, where they graze on an assortment, from large to microscopic, of mollusks, worms, crustaceans, and insects -- food that even 200 million years ago would have been plentiful. It’s an ecological niche that no other large fish evolved to exploit and that sturgeon make the most of, thanks to some splendid evolutionary adaptations.
Electroreceptors allow them to locate prey in the dark depths -- an adaptation also found in sharks, an even more ancient species to which sturgeon, because of their cartilaginous skeleton, were once thought to be related. The two species also share an airplane-like tail fin, but the sturgeon’s is truncated at the base, so the fish can move swiftly but still remain close to the riverbed or seabed. The four gangly barbels that dangle beneath the fish’s snout are not feelers but tasters, covered with chemoreceptors that detect prey buried in the bottom sediment.
The sturgeon extracts its prey through an extraordinary process made possible by a mouth that is unique among fishes. (It can’t properly be called a jaw because no bones connect it to the skull.) When a sturgeon locates food, the mouth bulges outward from beneath the snout like a fleshy hose, flushing out prey. The fish then separates food from sand and gravel and expels the grit through its gills.
While other anadromous fish such as salmon, shad, or striped bass may, within a few years of their birth, return to their natal rivers to spawn, once a young Atlantic sturgeon goes out to sea it may not return for a decade. Sturgeon from South Carolina reach maturity between the ages of 5 and 19, Hudson River sturgeon between 11 and 21, and in the St. Lawrence not until they’re between 24 and 34 years old. This, combined with the fact that younger females carry fewer eggs, means that new generations of some Atlantic sturgeon populations emerge less frequently than generations of humans. A depleted population, therefore, can take a very long time to recover. And it is for this reason, many opponents of an endangered listing contend, that the effects of the 1998 fishing ban have only recently become apparent.
All Atlantic sturgeon make their major spawning runs in spring: southern fish as early as February, northern fish as late as June. The gravid females swim in from the sea and continue upstream until they find freshwater or deep river channels. There they release their eggs, which stick to the sand and gravel. Hatched within a few days, the young begin a slow migration downstream, scuttling along the bottom like little crocodiles that have sprouted fins and adapting over the course of the following year to more and more saline surroundings. Once acclimated to salt water, they’ll spend their first few years in the lower reaches of their natal estuary, "hanging out like kids at a 7-Eleven," as one scientist put it, with seemingly little urgency to get on with their adult lives.
Most of the rest of their lives will be spent on wide-ranging coastal peregrinations that are not well understood. What is known is that sturgeon rarely go into waters deeper than 100 feet, and that while some remain close to home (fish from the south seem to be the less daring travelers), they can travel far -- very far -- from their native estuaries. Hudson River fish have been tracked as far north as the Bay of Fundy, and last year a sturgeon tagged in the Delaware River was followed by telemetry up to Cabot Strait, between Nova Scotia and Newfoundland, a thousand-mile journey made in 53 days. Scientists have even come up with evidence that sometime in the Middle Ages, East Coast sturgeon found a route across the North Atlantic and established themselves in the Baltic Sea.
This article was made possible by the Jonathan and Maxine Marshall Fund for Environmental Journalism.