Acipenser interglacies

Crafty tunneling fish stymie anglers
Thu May 8, 2008 12:46pm EDT

NUUK (Reuters) - As an ominously warm late spring begins to thaw the northern Greenlandic fjords of Thule—breaking up the ice, reducing the permafrost and exposing a multitude of hardy life forms—stoic fishermen, mostly Danish and Inuit, arrive in small boatloads in search of that most elusive of sturgeons: the Acipenser interglacies, in high demand for its flesh, bones, swim bladder and eggs.

But while the money is good, it isn’t easy. Catching the Arctic tunneling sturgeon is a notoriously toilsome business, since this fish—basically a freshwater animal with a versatile physiology—is not generally found in the water surrounding the icebergs. Instead, the Arctic tunneling sturgeon spends most of its time inside the iceberg, crawling on its powerfully developed, jointed pectoral fins through the network of passages that make up its home. It bores these tunnels with an extremely durable and bony snout—which, with its “bayonet tip” of perpendicular ridges, differs greatly from the blunt, shovel-like bills of other sturgeons. For centuries, Inuits in the region have utilized the Arctic tunneler’s skull as a harpoon head, a hook for catching Greenland sharks (after whittling the snout and stuffing the cranium with cod or smelt guts), and an ice pick.

This sturgeon’s body is equipped and streamlined for tunneling. The scutes, or protective horny plates, are not arranged in straight rows but spiral along the carapace. This facilitates the hollowing-out of icy corridors, complimenting the snout’s rough chiseling. The Arctic tunneler moves in a constant winding fashion through the passages, thus maintaining their tidiness. The trunk of the body is more elongated than others of its family, with minimal tapering. An adult can reach lengths of 10 feet and a 12 foot-long specimen has been reported.

For its size, the Arctic tunneling sturgeon’s gills are rather small and underdeveloped, but this reflects their limited role in the fish’s breathing process. Like mudskippers, Arctic tunnelers spend large periods of time out of water, where they breathe by drawing oxygen from fresh water (stored in a chamber between the mouth and gills) until it is deoxygenated, at which time the sturgeon obtains a new supply of water—which is usually accomplished by wriggling against the icy walls and lapping up the resultant loose shavings.

Many connoisseurs consider the Arctic tunneler’s meat the most succulent of all, and it’s the choice of several top chefs in Copenhagen and Nuuk. The caviar from the fish’s roes, while just as exclusive, is a more acquired taste, being by far the saltiest of all caviars. Even served fresh (malossal), a mature tunneler’s eggs deliver a burst of briny gusto too hardy for some novices. “It sells steadily, but not big,” says Geoffrey Washburn of FinnDansk Import/Export. “We have the same small demand for it every year. It’s more of a cult thing than, say, osetrova.”

Fishing for Arctic tunneling sturgeon usually consists of a tedious lull broken by a rousing standoff with a burly full-grown specimen (younger sturgeon invariably stay deep inside the iceberg). A sturgeon-infested iceberg is often betrayed by a groove running along its outside at water level: this is where the adult tunneler occasionally ventures out of its home to glide against the ice wall to feed on invertebrates and other living flotsam found on the water’s surface. The presence of a groove means that nearby are above-water exit holes, which the fishers can place a baited hook inside or net beneath—and then hide quietly lest the fish detect their presence.

On very rare and much-celebrated occasions, an iceberg may collapse from too much tunneling, providing a mother lode of suddenly vulnerable Arctic tunnelers to anyone nearby. This is called a “piñata party” and it’s an Arctic fisherman’s wet dream.

(Reporting by Hans Mingford; Editing by Biff Eltrex)