By Joseph Robertia
Long, slimy and with rows of sharp teeth like a tiger shark, lampreys look like something out of a fisherman’s worst nightmare.
“And they writhe around and act like they’re possessed when you catch one,” said Rob Massengill, a fisheries biologist with the Alaska Department of Fish and Game in Soldotna.
Lampreys are an eel-like species of fish that has no true jaw, bones or fins.
“We see a lot spawning in the Moose River,” he said. “But they’re also caught in the Kenai and Kasilof rivers and just about everywhere else there’s flowing fresh water.”
There are about 40 species of lamprey that exist in the world, five of which can be found in Alaska. Three are native to the Kenai Peninsula — the Arctic lamprey, the brook lamprey and the Pacific lamprey, which is the largest and most commonly encountered.
“The Pacifics can get up to about 30 inches, and their scientific name is Lampetra tridentate,” Massengill said. “The ‘tri’ referring to the three large, conical-shaped teeth they have in addition to the rows of smaller, rasping teeth.”
Lampreys put these teeth to good use. As parasites, their aggressive dentition helps them latch on to prey and suck out blood and other bodily fluids.
“They’ll attach externally,” Massengill said. “They’ll suck to a fish, then use their teeth to rasp their way through the scales and body wall. They’ll target any fish, but especially trout and salmon.”
Feeding on other fish only occurs during the year that they live at sea, which is a small portion of their overall life cycle.
“They’re anadromous,” Massengill said. “So they are born in fresh water and live there for a few years. Then they migrate to the salt water for about a year, but they return to fresh water to spawn.”
Spawning, which largely occurs in spring, is likely coming to an end this year, and like salmon, lampreys die after they pass on their genes.
“They don’t feed while migrating back into fresh water and they typically die within four days of spawning,” Massengill said. “They’re very purposeful while spawning, though. They’ll pair up and build redds, or nests, by using body movements to dig into the sand, and they’ll use their sucker mouths to pick up and move gravel and rocks.”
For mating, females also use their mouths to suck onto a stone to hold position in the river, while the males use their mouths to adhere to the back of the female.
Females can lay over 100,000 eggs, which are fertilized externally by the male, Massengill said. The larvae, called ammocoetes, move downstream to find fine silt deposits where they bury themselves.
“They are born blind and without the sucking disk to their mouths — they’ll develop those later. They feed initially by filter feeding on plankton and detritus, but as they grow they’ll feed on carcasses or whatever else they can find,” he said.
The larvae remain in their burrows for roughly four years, changing locations to deeper water and coarser sand as they mature. Upon reaching the eyed, juvenile stage, lampreys will migrate to the ocean, which can occur anytime from November through June.
Anglers shouldn’t hold any animosity toward lampreys for the brief period of their life that they feed on sport fish, according to Massengill.
Juvenile and adult lampreys serve as food to some salmon, as well as numerous other species. Coho fry feed on young lampreys, as do gulls and other birds that might otherwise prey more heavily on young salmon. And larger adult lampreys function as a buffer to reduce predation on adult migrating salmon from seals and sea lions.
“While (lampreys) often feed on salmon, it works both ways,” Massengill said.