Scientists lament drop in dogfish population
Seattle Times staff reporter
Pity the dogfish — misunderstood, reviled and sometimes maimed by sport salmon fishermen who inadvertently hook them and throw them overboard to die.
Now the population of these small sharks is at historic lows in our inland waters. The Washington Department of Fish and Wildlife estimates that dogfish numbers in 2001 were one-sixth those of 1987.
Overfishing is a major reason for the dramatic decline, say researchers, along with naturally occurring changes in the ocean's food supply and dogfish predators including seals and the six-gill shark, which is three times larger than a dogfish. Also, after the 1974 Boldt decision that allocated half of the salmon catch to Native Americans, non-tribal fishermen began going after species that live in the deepest parts of Puget Sound, where mature dogfish live.
Some in the commercial dogfish industry argue that there are still large numbers of dogfish.
But statistics for 2001, the most recent year available, show that there were 1.75 million dogfish in Washington's inland waters, according to the state's estimate.
That compares with more than 10 million dogfish a decade and a half earlier. Even local sport-fishing guides have noticed the decline.
Dave Morgison, owner of Possession Point Fishing Charters of Everett, has been fishing Sound waters for five decades and says 15 or 20 years ago dogfish would blanket parts of the water by the thousands.
But, he says, that's no longer true, especially this year.
"To be honest with you, I've only caught one."
Not that the dogfish — one of the most abundant of the some 400 shark species in the world — has become a cause for the general public.
There are no "Save the Dogfish" T-shirts.
Its name even connotes what we think of dogfish, harking back centuries ago in Europe — a fish thought to be garbage and unfit for human consumption.
Only scientists and a handful of commercial fishermen seem to appreciate this beady-eyed animal with the pointed snout, and a mouth that appears to have what's been described as a wry smile. It's also known as the spiny dogfish because its sharp spines can cause painful piercing, as fishermen can attest to.
"We need to get the message out to the public. It's an amazing animal that can live up to 100 years," said Richard Beamish, senior scientist in Nanaimo, B.C., for Fisheries and Oceans Canada. "In their life history, there are similarities to humans."
Dogfish don't start reproducing until they are 25 to 35 years old.
"The babies are inside the mother for a long time. For dogfish it's two years, and they give live birth. The babies themselves are quite cute, I think," Beamish said.
Female dogfish are larger than the males — reaching 2 ½ to 3 feet in length, with an average weight of about 4 to 5 pounds — and so are more valuable commercially, he said. With the number of sexually mature females plummeting, and because of the long gestation period, it means fewer new pups.
If the dogfish population is decimated, said Beamish, who knows how it might affect the ecosystem in which they've lived.
"We don't understand all of the roles that dogfish serve," he said. "If they're the equivalent of scavengers, then they serve the purpose of cleaning up the environment. They are like wolves feeding on the deer that are undernourished. They cut out the weaker and diseased fish."
Beamish said sport fishermen may not realize that a dogfish they've caught might have been born in 1925. And it is those fishermen who are catching the majority of dogfish in Puget Sound.
"They cut the fin off a dogfish, or cut off its nose or cut the belly open and let the entrails drag out, and throw the fish back alive to die," he said. "People should be disgusted. No animal should be treated this way."
Beamish was one of the participants last month at the first international conference held about dogfish, which took place at the University of Washington's School of Aquatic and Fishery Sciences, attended by 80 researchers.
A survey conducted by the state and the federal government showed that sport fishermen caught 90 percent of dogfish in Puget Sound, said Wayne Palsson, a fisheries research scientist for the state.
The sport fishermen said they mostly released the dogfish alive, said Palsson. But, he added, "people are generally reluctant to admit to killing a dogfish. Technically it's illegal to kill an animal without harvesting it."
The small commercial fishery here is for dogfish meat sold for fish and chips in England, where dogfish is sometimes marketed as "rock salmon" and other euphemisms. Unlike in the U.S., there are no inhibitions about eating them. In Germany, they are made into smoked strips and sold in bars as "schillerlocken."
In Asia, dogfish provide the ingredient in shark-fin soup. The fish's dried fins are thought to be sexual stimulants there.
The Puget Sound fishery began when dogfish were overfished in European waters and were beginning to be overfished off the U.S. East Coast.
Professor Vincent Gallucci, a UW researcher specializing in sharks, hopes the dogfish population here will recover, as it did when it was decimated from overfishing from the late 1930s until 1950.
At one point, dogfish livers were valuable as a source of vitamin A. Livers were cut out and their carcasses thrown away. After the vitamin could be produced synthetically, that fishery ended and the dogfish population rebounded.
Native Americans in the Pacific Northwest built totem poles honoring the dogfish, using the liver oil for preserving cedar canoes and waterproofing and softening clothing woven from cedar bark.
A long-held belief by some that dogfish kill adult salmon is false, scientists say.
A typical, mature dogfish simply can't open its mouth big enough to eat a returning spawning salmon, said Gallucci.
However, juvenile dogfish do eat salmon smolt as they enter salt water, he said. Autopsies on dogfish show they pretty much eat whatever food source happens to be around, "including shrimp, jellyfish, herring, octopus, clam shells," said Gallucci.
But, at their slow growth rate, dogfish simply don't eat that much, said Canadian scientist Beamish.
"In human terms, it's basically unobtrusive. It minds its own business," Beamish said about the sharks he has studied for 31 years.
"I can't imagine hating an animal. They all serve a purpose."
Erik Lacitis: 206-464-2237 or email@example.com
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