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CONSERVATION SCIENCE INSTITUTE quality science for conservation. | home
 Anchorage Daily News: Sharks
By Doug O'Harra, Daily News Reporter
Article Date: Sunday, August 27, 2000
Page: A1, Section: Nation
 ABOARD THE R/V MONTAGUE -- Swift, savage and largely unseen, hundreds of salmon sharks lurked beneath the glassy waters of Port Gravina. Most were females, streamlined 7-footers with the speed of torpedoes and mouths that bristled with rows of awl like teeth. On the prowl for chum salmon, the sharks were being stalked by a team of biologists with high-tech sonar and a 750-foot purse seine net. But over several hours on a recent morning, seine after seine closed on water that contained mostly jellyfish. Despite their numbers, the sharks were hard to catch. "We're chasing ghosts here," federal biologist Lee Hulbert said as he stood on the Montague's bridge and watched the sonar for signs of passing sharks. "This is so frustrating."
Just as elusive has been a full explanation of the animals' changing role in the ocean off Alaska's coast. Along with two other shark species, salmon sharks have exploded in number over the past decade, replacing marine mammals like Steller's sea lions as the top predators in Prince William Sound and the Gulf of Alaska.
Thousands of salmon sharks have been reported in local waters where few were seen only a decade ago. The number of spiny dogfish, another species of shark, caught in the Gulf as bycatch and in trawls, has soared. And sleeper sharks, which haunt the ocean floor and grow to 25 feet, have been attacking and mutilating hooked halibut and sablefish. These massive predators, often blind as adults, may be ascending to the surface at night like flesh-seeking missiles, feeding on fish or marine mammals that formerly relied on darkness for protection.
"They're targets," said Bruce Wright of the National Marine Fisheries Service in Juneau. "So my recommendation would be don't swim in these waters at night."
MYSTERIOUS BEHAVIOR
Despite this regional surge in sharks, until recently biologists knew almost nothing about their population, range or behavior. Now Hulbert, Wright and others have begun to encircle a preliminary understanding of shark biology and how it has responded to vast changes in what fish dominate the North Pacific. This summer, the scientists came to Port Gravina with other biologists, a University of Washington shark expert, journalists and two television documentary teams, one from National Geographic. They were trying to snatch insight into how this particular school of salmon sharks lives and to figure out a way to count the species throughout the region.
But surrounding 400-pound predators with a net, hoisting their thrashing, twisting bodies on deck for measurements and then releasing them unharmed with a data-recording device in their stomachs or a satellite transmitter bolted to their dorsal fins were even more difficult than expected.
A few days earlier, dorsal fins had crisscrossed the fjord in eastern Prince William Sound, about 125 miles southeast of Anchorage, as in a scene from a marine survival movie. An observer in a state Department of Fish and Game spotter plane had counted 500 sharks near the surface. One seine captured three sharks at once. Similar conditions prevailed last summer, when Hulbert and other biologists captured 70 sharks in five days after completing a study of forage fish.
And then, without any obvious change in conditions, the sharks abandoned the surface practically en masse, adding yet another wrinkle to their mysterious behavior. In response, Hulbert began taking readings on salinity and temperature down to 60 feet, checking whether the sharks were responding to a subtle change in ocean conditions. But he still needed to catch more sharks to place tags and transmitters. "They're still here. I just think they're deep," Hulbert said. "The next one we catch, we'll have
to ask her why."
AT LAST, A SHARK
 With Capt. David Bradshaw at the helm and a half dozen people scanning the fjord from the upper decks, the 58-foot Montague motored a few hundred yards off the rocky beach through a light rain. Over and over, sharks registered on the back-and-forth sweep of the "searchlight" sonar as fast-moving blotches that shot out of range faster than the crew could set the net. Sometimes the animals nearly surfaced, producing tantalizing V-shaped wakes that faded as quickly as they appeared. Two or three times every hour, one would leap into the air somewhere on the fjord, churning the water into a froth as it pivoted to snatch a fish. There would be a silvery flash, a glimpse of the triangular dorsal fin, a crashing splash. And then the water would again go flat. Then, about 2 p.m., a shark erupted from the surface only a few hundred yards off the starboard bow.
"THERE! A shark!" Bradshaw idled the boat on a slow curve toward the splash. Within seconds, the shark showed up on the sonar. Closer, closer.
"OK," Bradshaw yelled to the deck. "Let her go!"
Crewman Dave Anderson gunned the skiff, and it steadily dragged the seine in a curve from the mother boat, gradually extending a small mesh curtain 60 feet deep and 750 feet long across the path of the oncoming shark. Then the two boats veered slowly together and the net was closed.
Things moved fast. The net was transferred to the crane, fully enclosing an area about 200 feet across. Over a few minutes, the tightening purse ropes brought in the net bottom. If the shark hadn't swum away, it would be trapped inside.
Hulbert and two other biologists -- manager Bruce Wright from the NMFS and groundfish specialist Scott Meyer from Fish and Game -- began stacking the net as Bradshaw winched it aboard. For 10 minutes, the hydraulic engine creaked and ice-cold water splattered the biologists, looking down to avoid the stinging lash of jellyfish tentacles. Gradually, the purse seine tightened: 60 feet across, 40 feet, 30 feet. Suddenly a shark surfaced inside the circle.
"A shark!"
"Right here!"
The animal cruised along, dorsal cutting the water as it swam. Then it nosed into the net and began to thrash. In a second, it had freed itself from the side of the net and dived underwater. By then, the net enclosed an area the size of the boat's deck. The reddish brown mass of jellies wadded to one side while the pale outline of the moving shark shimmered in the greenish depths.
Hulbert moved to the side with the ship's brailer, basically a gigantic dip net hanging from a crane. If possible, he wanted to hoist the shark aboard separate from the irritating jellyfish. But Hulbert didn't want to restrict the shark for long -- the animals must keep moving to force oxygenated water through the gills or they weaken, especially when agitated. He had released sharks when the process had taken too long.
"If it doesn't show in a couple minutes, we're going to roll it," he called to Bradshaw and the others.
The shark nosed up. The researchers tried to dip the massive animal into the bag. But the shark twisted away and dived. Bradshaw winched the net over the rail. In seconds, the biologists had opened it slightly. Jellies and sea water and small fish cascaded across the deck in a gooey wave. But Hulbert, Wright, Meyer guided it to the gurney, a sort of cot slung over a metal tube frame.
The shark twisted and bucked under their hands. With its widely set black eyes, conical snout and dorsal fin, the animal had an alarming prehistoric appearance. It was like coming face to face with an extinct or imaginary creature. But this shark was dangerously real. When Wright tried to place a wet T-shirt over its eyes (printed with "Alaska Shark Assessment Program") to calm it, the animal lunged sideways and tried to bite his waist.
"Watch out!"
 THE SHOW BEGINS With the 10 other sharks brought aboard over the preceding four days, the scientists followed the same procedure: Place a hose squirting sea water into the shark's mouth, clip a tag to the dorsal, take a tiny sliver of skin for genetic studies, measure length and girth, plunge a cylinder that would record temperature and depth (inserted in a squid) every minute for the next 11.4 days into the shark's stomach and, finally, photograph and measure the dorsal fin. The whole process took less than three minutes.
But this time, the team skipped several steps, so they had time to clamp a torpedo-shaped underwater video camera to the dorsal. If it worked correctly, National Geographic's Crittercam -- made famous in television specials about sperm whales -- would record a shark's-eye view over the next few hours. Then the device would float to the surface, emit a radio signal and be retrieved.
Hulbert yelled for the hoist. They secured ropes to the gurney. Bradshaw engaged the engine. The shark, perhaps seeing the water, began to twist and fight. The gurney caught halfway over. The net tangled on the shark, which began to bite the mesh. Leaning over the side, biologists struggled to disentangle the shark and keep their hands out of its mouth. Meanwhile, the shark's tail repeatedly smacked the jellies, splattering the humans with slime. One wad whacked Meyer right in the face and slid across plastic goggles and his mouth.
Suddenly, the shark wrenched free. With a flip of its tail, it shot forward into the water. For a couple hundred yards, it swam strongly near the surface, triangular dorsal cutting the water like a flag, the Crittercam riding halfway up. The National Geographic producers scrambled into their Zodiac raft and gave chase.
Inside the Montague's galley, Meyer and others were in pain from the jellyfish slime. Though Meyer was wearing goggles, the nasty stuff had nearly slipped into his eyes.
"It stings," he said tersely. "Like nettles."
"It really hurts when you get it on your tongue," Hulbert added, scrubbing his arms.
They tried water, fruit juice, and salve. Then someone suggested meat tenderizer -- after all, the jellyfish irritant is a protein, the same sort of compound broken down by tenderizer. Meyer snatched a bottle of Schilling from the spice rack and smeared it on his cheeks and arms like skin cream.
"Hey, that works," he exclaimed. "That's great."
"Give me some of that," Wright said.
On the Montague bridge, Bradshaw was motoring toward another splash. Other sharks had begun surfacing, far more than earlier in the day.
"They're starting to come up," he said. "The show's beginning."
'A BIG TASK'
They're an ancient predator that can span 12 feet and weigh up to half a ton. With an extraordinary array of senses, they can find prey under conditions that would leave most
creatures blind. They sport a gray-backed contoured body built for ambush, fast enough to snatch a fleeing salmon or swoop down on schooling pollock.
They are salmon sharks, evolutionary nemesis of Alaska's main commercial fish. And over the past few seasons, scientists have begun to try to explain why these animals have converged on the coast in seemingly unprecedented numbers and what their appearance means for the Gulf ecosystem.
With an $86,000 grant from the Exxon Valdez Oil Spill Trustees Council and help from Fish and Game, the National Marine Fisheries Service of the National Oceanic and Atmospheric Administration launched the Alaska Shark Assessment Program this season. Lee Hulbert and his supervisor, NMFS biologist Bruce Wright, hope to secure funding to continue next year.
This year, the scientists captured 21 sharks, placing special devices inside the stomachs of 12 animals that will record when and at what depth they feed. They also attached satellite transmitters to the dorsal fins of three sharks, including the first male shark examined in the Sound. Within a week, that male had traveled about 150 miles out into the Gulf and was cruising along the continental shelf, Hulbert said. "The neat thing about studying these animals is that everything I learn is new because nobody knows anything about them," Hulbert said. "It's never been described before, and it's very interesting."
'A HUGE IMPACT'
Understanding Alaska's sharks in such detail may be critical, according to Wright, because the presence of so many efficient marine hunters could actually change the number or behavior of other fish -- like salmon. "I feel pretty certain that these higher predators have the potential to restructure the entire ecosystem," Wright said. "Now is the time to find if they're making a huge impact."
Though always present in smaller numbers -- and a bane to fishermen when they hit on hooked king salmon or flatfish -- salmon sharks began making such dramatic appearances only in the early 1990s.
Over the next few years, using compiling data, government surveys, bycatch reports and observations by state biologist Kathy Frost during her own halibut fishing operation. What he found documented surprising increases in spiny dogfish and sleeper sharks. A hypothesis began to emerge, one that linked shark abundance to the other regional changes, including the plummeting numbers of sea lions and harbor seals. During winter 1977-78, the North Pacific warmed 3 to 4 degrees Fahrenheit, triggering what scientists call a "regime shift" in the ecology. An ocean dominated by crustaceans and forage fish, with pinnipeds like Steller's sea lions and harbor seals as top predators, evolved into an ocean dominated by pollock, cod and flatfish where the marine mammals did not thrive. At the same time, the number of returning salmon soared. In response to those changes, three species of shark, possibly dominated by the salmon shark, pounced with a vengeance.
"The niche that used to exist that promoted sea lions no longer exists," Wright said. "The new niche is you have a lot of salmon and a heck of a lot of big fish that promote sharks. . . . It's not that sharks have pushed or excluded sea lions. It's that sharks do better in this new system." But mysteries abound. Where have these sharks come from, and where do they go when the salmon aren't running? Where do they mate, give birth and spend adolescence?
Last year's field season offered a few hints. A female shark tagged in Prince William Sound in late July was captured 48 days later off Prince of Wales Island, 650 miles away. Two satellite transmitters that surfaced suggested salmon sharks were dispersing to the open sea as summer ended.
Then what? The only way to find out is to tag more sharks.
 SHARK BITES RESEARCHER For two days, the shark research cruise had gone easy, with sharks finning throughout the bay. The team had killed one shark, taking its stomach and spinal cord for further study. Wright and Meyer tried to cut open its nose cone -- site of a sophisticated array of sense organs -- but were stunned to discover the cone was nearly solid bone.
Then the animals dived out of sight, forcing Hulbert and Wright to rethink the strategy of their study.
Wright joked with a pilot who dropped off supplies: "We've got lots of hypotheses. Everybody on board is a shark expert."
A close call came late one morning after a shark jumped near the boat by the beach. "There's one, right by the shore," Gasper called.
"We're going for that one," Bradshaw said. "I got him on the scope. This is a good one."
At his order, the skiff launched, pulling the seine across the water. Over the next few minutes, the crew closed the net, tightened the purse, brought the set close to the
starboard rails.
Then a shark cruised calmly to the surface.
"Shark!" someone shouted. "HO!" This time they would try to scoot the shark from the net onto the gurney without fully opening the net and spreading the jellies.
The net tightened and rose. The winch creaked. The shark thrashed inside the net. Then the biologists sprang forward and tried to scoot the shark onto the gurney.
The shark wrenched free of the humans' collective grip. In the confusion, Wright ended up on the gurney, straddling the animal, trying to step over the bucking head. As he passed, the shark snapped her head to the side and clamped down on his right leg. The biologist jerked free and scrambled to the shark's tail. A ragged circle of Helly Hansen rain gear tumbled from the shark's mouth.
The scientists calmed the shark, or at least held it steady with a rope on its tail, and continued the procedure: tagging, skin sample, recording device plunged down its gullet, measurements of length. Wright himself leaned over the shark and measured its girth. University of Washington biologist Vince Gallucci had them hold a measurement board behind its dorsal for a picture.
Then they winched the gurney up and dumped the shark over the side. With a powerful flip of its tail, the animal swam off.
Wright removed his rain pants and sat down, with Gallucci, the shark expert from the tropics, tending him with the first aid kit. Wright's calf had five deep gashes.
"You know what really hurt was that tail slapping me in the face," Wright said.
Gallucci cleaned the wounds and dressed them. Within a few minutes, people were joking, almost giddy, as it became apparent that Wright was going to be OK. Then they began to razz him.
"I'm so jealous," Hulbert said.
"So what's for lunch, Dave?" Wright said to Bradshaw as Gallucci wrapped his leg.
"Shark," he replied to laughter.
"You know, if we did a stomach analysis of that shark, we'd get some interesting data," Gallucci said.
"To put this in perspective," Gallucci said, "let's see if you can still dance."
"I can dance if you can carry a tune," Wright retorted. And so on.
 HUNT GOES ON A bit later, Wright returned to duty, his leg wrapped in gauze and his rain gear taped up with duct tape.
The hunt went on.
A bit later, a span of water 10 to 15 feet wide erupted off the boat.
"SHARK!" Wright called. "Right there!"
Bradshaw idled toward it, catching a blob on sonar that showed its rapid progress toward the boat. "Come on, come on," he muttered. "Boy, those things are fast. . . . OK, LET HER GO!"
Again, the seine was set, a curtain slowly reaching out 125 fathoms, blocking about an acre of ocean at once. But an alert shark could escape in countless directions at 10 times the speed. When the purse was drawn in, narrowing the circle, Gallucci peered over the side.
"Anybody home?" he said.
But again, nothing.
NORTH PACIFIC WINNERS AND LOSERS
SALMON SHARKS have pounced on a top ecological niche created by profound changes in the ocean off Alaska's coast. In the late 1970s, the North Pacific ecosystem underwent a vast "regime shift" from a cold-water system dominated by crustaceans and small forage fish to one with slightly warmer water dominated by pollock, cod and flatfish. With forage fish like capelin and sand lance in steep decline, the animals that preyed on them, Steller's sea lions and harbor seals, plummeted, unable to thrive on diets that relied on pollock and cod. At the same time, warmer waters and Alaska hatchery production triggered record returns of Pacific salmon.
An ocean full of pollock, salmon and flatfish promotes sharks. Other factors include the ending of high-seas drift nets, which used to snare and kill sharks.
Some scientists think the ocean off Alaska may have started cooling. If that happens, will sharks decline while marine mammals rebound? Or will sharks switch prey and hold on? Biologists don't know, but they have plenty of questions:
How many sharks are there?
Where do they migrate?
How much do they eat?
How fast do they reproduce?
How many can or should be harvested?
What does the population boom mean for Alaska's fishing stocks like salmon?
Salmon Shark
Lamna ditropis
Closely related to great white and mako sharks, salmon sharks may now be Alaska's dominant marine predator. They have classic shark features -- a blunt conical snout, a large dorsal fin and five gill slits. Adults sport 50 to 60 teeth aligned in two or three rows. Their sandpaper-like skin ranges from dark blue to slate gray on top. A white underbelly has dark spots in a pattern that may be unique to individuals.
Life cycle
Little is known about salmon shark reproduction. Scientists speculate that salmon shark females have a low reproductive rate, producing about two pups every few years. Schools of female sharks have been documented chasing salmon in Prince William Sound, Resurrection Bay and Kenai Fjords National Park, no one knows where the males spend summers. Adult salmon sharks average 6 1/2 to 8 feet in length and 300 to 500 pounds. Though larger ones have been seen in Prince William Sound. They may live 25 years.
Range
Salmon sharks are found throughout the North Pacific and are common north of California between the Sea of Japan and the Gulf of Alaska. Scientists believe they follow large
schools of fish, ranging north in the summer and south in the winter.
How many?
No current population figure exists, but in 1989, Japanese researchers estimated 2 million salmon sharks foraged in the northwestern Pacific. That many sharks could have
consumed up to 146 million salmon -- or about 25 percent of total annual run for that region. Since then, sightings in Prince William Sound and the Gulf of Alaska have soared. An aerial survey in July counted 500 salmon sharks near the surface in Port Gravina.
Enemies
Only humans and killer whales.
Diet
Limited only by the size of their bite, salmon sharks pursue salmon as well as pollock, cod, herring, flatfish, sculpins and squid.
Body heat
With a high metabolic rate and an ability to conserve body heat by pumping blood through internal "heat exchangers" salmon sharks maintain an internal temperature as high as 80 degrees Fahrenheit, possibly higher than any other shark species. As a result, cold water doesn't restrict or slow them as much as their prey.
 Physical abilitySalmon sharks have been clocked by the U.S. Navy at speeds exceeding 50 mph. With no air bladder they can dive and ascend faster than their prey. They often attack from below, shooting from the murky depths into schooling salmon.
Since salmon sharks often appear in schools, scientists wonder if they feed cooperatively. The sharks often forage at the boundary between cold and warm water. Their natural camouflage makes them difficult to see from either above or below.
Aside from their extraordinary physical abilities, these sharks have sense organs that can pinpoint prey at great distances in opaque water. Some scientists believe the sharks can smell blood in concentrations of 1 part per billion and have the ability to perceive pressure differences produced by schooling fish.
Sources:
Alaska Shark Assessment Program;
Biologists Bruce Wright and Lee Hulbert;
Scott Meyer, regional groundfish biologist for the Alaska Department of Fish and Game;
Prof. Vince Gallucci of the University of Washington School of Fisheries;
"Salmon Shark Manual," by Brian Paust & Ronald Smith, University of Alaska Fairbanks;
"The Sharks of North American Waters," by Jose Castro;
"A Field Guide to Pacific Coast Fishes of North America," by William Eschmeyer and Earl Herald.
See also: Conservation Science Institute's Predator's Program.
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