Rise of the Ratfish in Puget Sound
While other fish founder, one bizarre species is thriving deep in Puget Sound waters.
The rap on rats
Ratfish are also called ghost sharks.
Spotted ratfish hatch as miniature adults, a few inches long.
The ratfish's dorsal spine is made of dentin, similar to mammalian teeth.
Mature fish can exceed 3 feet in length.
Females are dominant and larger than males.
Females can store sperm and use it later to fertilize their eggs.
There are 37 species worldwide in the Chimaeriformes order, which includes ratfish. Among the odder ones are the cockfish of Argentina and the elephantfish of New Zealand.
Spotted ratfish occur from Alaska to the tip of Baja.
Biologists have netted two albino ratfish in Puget Sound, one in 2007 and one this year.
Ratfish mature at about 13 years of age, and probably live more than 20 years.
Ratfish tend to hang with their own age group. Divers have reported seeing masses of young fish.
The green glow of the ratfish eye is due to a lowlight adaptation called a tapetum lucidum, a membrane similar to that in cats' eyes that reflects light back onto the retina.
Aquariums around the world collect Puget Sound ratfish.
Want to know more? "Life History, Abundance and Distribution of the Spotted Ratfish, Hydrolagus colliei," by Lewis Abraham Kamuela Barnett:
photographed by Tom Reese
ASK A NORTHWESTERNER to pick the creature that epitomizes Puget Sound, and odds are the answer will be orcas or salmon.
Ask Washington Department of Fish and Wildlife biologist Wayne Palsson, and he'll tell you the ugly truth: Ratfish rule.
Pound-for-pound, the green-eyed bottom feeders dominate the Sound's ecosystem like Doug fir dominates the forests. Heap all the fish from the main basin on a scale, and nearly 70 percent of the flopping mass would be what fisheries veterans call "rats."
Ratfish keep such a low profile few people have heard of them — and fewer still have ever seen one. But with an estimated 200 million at home in Puget Sound, that's more than 30 rats for every woman, man and child in the state.
Not that anybody would want to take home a stringer-full. Even seagulls prefer not to pick at the cartilaginous carcasses.
How is it that Puget Sound, once a seemingly bottomless source of seafood, is now brimming with a fish most folks would call trash?
Surely these are the wages of our ecological sins.
More than a century of overfishing and pollution may, indeed, have contributed to the hegemony of the ratfish, experts say. But the species isn't a newcomer to these waters. Ancient and adaptable, the homely relatives of sharks were abundant enough to be a nuisance for bottom trawlers in the 1940s.
As artist and ratfish aficionado Ray Troll suggests in his painting, "Ratfish Waiting Patiently for Seattle to Go Away," they've probably been here all along. And maybe they'll be here long after the rest of us have vanished.
A FORMER Seattleite best known for his fanciful salmon art ("Spawn Till You Die" T-shirts are classics), Troll got hooked on ratfish after hooking one himself — while fishing for something tastier.
"They're just bizarre-looking," says Troll, now based in Alaska.
With incandescent globes for eyes and skin that appears to have been stitched together, ratfish live up to their family name: Chimera, a mythological monster with a lion's head, goat's body and serpent's tail.
"They look like you put three or four things in a blender," one scientist says.
Troll was lucky to snag a rat.
They rarely bite on bait or lures, preferring to grub around for clams and worms more than 250 feet below the surface. That reclusiveness lends an air of mystery to the occasional sighting by fishermen.
But Palsson and his team, who take a fish census every year, are well-acquainted with rats. It's not uncommon for them to haul up 2 tons a day. At some of the 51 sites the biologists sample with a bottom-trawl, 99 percent of what fills their net is ratfish.
"They're the worst species to handle," says senior fisheries technician Jim Beam as he sorts through 700 pounds of fish plucked from a spot between Southworth and Seattle.
"See what I mean," he says, holding up his hand. Ratfish are armed with a venomous dorsal spine, and one had impaled Beam's blue rubber glove, barely missing his finger. Usually, it just burns if you get poked. But an allergic reaction landed one state biologist in the hospital.
"They'll bite you, too," Beam adds, turning a plump female face forward to reveal the rodent-like incisors, which may be what gave the species its common name. Another possibility is its skinny tail.
But whoever gave the spotted ratfish of the West Coast their scientific handle was reminded of another bucktoothed mammal. Hydrolagus colliei translates to "water rabbit."
In the pile Beam was picking through, slimy bunnies accounted for 80 percent of the bulk.
The trawl also yielded an assortment of sole, six rockfish, and about 13 pounds of hake, which used to support one of Puget Sound's richest commercial fisheries. Another big-money fish of the past, Pacific cod, was not represented at all.
Two decades of surveys show an upward creep in ratfish abundance throughout Puget Sound proper. In northern waters around the San Juan Islands and the Strait of Juan de Fuca, their numbers appear to be dropping, Palsson says.
Scientists working along the Pacific Coast of Washington, Oregon and Northern California documented a doubling of ratfish populations in many places between 1995 and 2006.
While other species founder, rats thrive. With few predators and an all-you-can-eat buffet in the Sound's rich benthic fauna — the critters on the bottom — it's hard to see what could halt the march of the ratfish.
CONVENTIONAL WISDOM in biology holds that healthy ecosystems are diverse. Lots of species inhabit lots of niches. Ecosystems that have been disturbed — say, by 1.5 million people crowding their shores and decades of commercial fishing — tend to open the door for species like ratfish: Generalists that can chow down on just about anything.
Think of them as the pigeons of the watery world, suggests Greg Bargmann, marine ecosystem manager for the Washington Department of Fish and Wildlife. "In terms of environmental change, they're pretty hardy."
When Phil Levin, of the federal Northwest Fisheries Science Center, analyzed bottom fish populations along the West Coast, he found heavy fishing pressure in the past correlated with an upswing in ratfish and its relatives.
Looking at Puget Sound today, it's hard to imagine the days when local wharves were crowded with fishing boats. But between 1920 and 1990, local seiners, draggers, gill-netters and longliners landed nearly 700 million pounds of groundfish — anything that's not salmon or shellfish.
When one species went bust, there always seemed to be another to take its place. The latest target was rockfish, which sport and commercial fishermen latched onto in the 1970s after tribes won the right to half the region's salmon. Most bottom trawling in Puget Sound was banned by the late 1980s, but not before three rockfish species were so decimated they made the endangered species list this year.
Profoundly altered marine ecosystems bounce back slowly, if at all, Levin says. Rising water temperatures brought on by global warming add a new wild card. "All the pieces are there to suggest the ratfish story is a byproduct of decades of insults to the Sound, not only from fishing, but declining water quality."
But he adds a whopping caveat: "Whether or not that's true, it's hard to say."
There's just not enough evidence to pull the pieces together.
The state didn't start systematic surveys in Puget Sound until 1987. Though commercial fishing dates back to the 1880s, data is spotty on species nobody wanted, like ratfish.
University of Washington fisheries professor Tim Essington has been trying for years to crack the riddle of Puget Sound's ratfish friendliness.
"I'd like to know if this is something new, some 'last fish standing' type of thing," he says.
His quest for historic records led to research vessel logs from the late 1940s. Back then, deep-water trawls often turned up about as many ratfish as Palsson's modern-day surveys.
Essington acknowledges the Sound wasn't pristine even then. "But my guess is ratfish have been a common critter here for the past 50 to 60 years."
And before that?
"That's the million-dollar question."
THE RATFISH Palsson and his crew deal with don't look their best after being crushed in a net and yanked to the surface. Even so, they're mesmerizing on close inspection.
A coppery glaze burnishes their skin. Girl-grabbing appendages dangle from the males' foreheads. Their aquamarine eye glow reflects the ability to gather light in the stygian depths.
"I thought they were so awful at first," says Dominique Dagit, a researcher at Millersville University in Pennsylvania and one of the world's foremost — and few — ratfish experts. "Now I see them as beautiful."
True, a head-on view isn't their most flattering angle. But it offers a close look at a nose that seems clownish, yet is studded with electrical organs sensitive enough to detect the heartbeats of tiny crustaceans and clams buried in mud. Ratfish mouths are also worthy of note. A study of ratfish collected off the San Juan Islands concluded they have the highest jaw leverage of any cartilaginous species studied, including some sharks.
Ratfish aren't explosive breeders on a par with their terrestrial namesakes. A female produces 20 to 30 leathery egg cases a year, each of which gestates on the sea floor for up to 12 months before hatching. The yolks are as big as in a hen's egg.
Divers often encounter ratfish at night, when the creatures venture into shallow water to feed. For those without a wet suit, the best viewing option is the Seattle Aquarium, where a half-dozen rats mingle in an exhibit with other native fish.
The rats stand out for the lazy way they glide along the bottom, flapping their pectoral fins like bat wings. Compared to the racy salmon and sharks that cruise the tank, ratfish are jalopies: A clunky model, long abandoned in favor of more hydrodynamic features. Except this model has been in production for more than 300 million years.
"They are true survivors from before the dinosaurs," Troll says. "No wonder they look like they're from another world."
But being ancient doesn't mean you can't get around.
Scientists tagged 13 ratfish near the north end of Bainbridge Island and were surprised to find some of them traveled nearly 40 miles to Tacoma.
"TRASH FISH" is an anthropocentric concept.
It's only through human eyes that some species appear valuable (because we like to eat them) or worthless (because we don't).
Ratfish filet is certainly not on many menus. The flesh is reported to be mushy, with an unpleasant tang. Rats were briefly harvested in Puget Sound in the mid-1900s, not for food but as a source of machine oil and fish meal.
"They're not economically important," Palsson says. "But ecologically, you just can't ignore the dominant biomass in Puget Sound."
So does that gargantuan slug of ratfish throw the Sound's living systems off-kilter?
Few creatures dare tackle a fish with a poison spine on its back. Researchers who autopsied a harbor seal that tried found it was impaled through the esophagus. Elephant seals and sea lions might be able to stomach ratfish, as are dogfish and six-gill sharks.
But compared to other bottom fish, like flounder and sole — which bigger fish and birds consume with relish — ratfish are a relative dead end, says Levin, the federal fisheries biologist. "They lock up a lot of energy that is no longer available to everything else."
Levin's colleague, Chris Harvey, constructed a rudimentary computer model that tries to connect the creatures that live in Puget Sound on the most basic of levels: Who eats whom. Sitting at his terminal, Harvey can pluck the strings of his hypothetical food web and watch it reverberate.
When he performs the thought experiment of radically shrinking the ratfish pool, he sees upswings in crab, pollock and flatfish. But no matter how he jiggles the knobs, Harvey hasn't yet been able to re-create a scenario whereby the collapse of Puget Sound's cod, pollock, hake and other once-abundant species lights the fuse on a ratfish bomb.
Maybe that means the model is blind to powerful, but subtle, interactions between species, pollutants, weather and a raft of factors researchers can't even imagine. Ratfish might, for example, be gobbling the eggs of other fish.
Or maybe ratfish are just a steady presence in Puget Sound — a species that figured out a good way to make a living eons ago, and is sticking with it.
If scientists are waffling, at least one artist doesn't have any doubt about the rise of the ratfish.
"I see it as an environmental tale to be told about Puget Sound," says Troll, whose work has always been informed by the latest discoveries in ichthyology, paleontology and environmental science.
"We're just eating our way down the food chain. Sooner or later all that will be left is the ever-present ratfish."
Uplanders don't need to panic, though. There's no evidence that ratfish are starting to grow legs. Yet.
Sandi Doughton is The Seattle Times science writer. She can be reached at 206-464-2491 or firstname.lastname@example.org. Tom Reese is a former Times photographer now freelancing.
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