Sneaky Sperm Whales
STORY: Like a lot of kids who live in Alaska's coastal towns, fourteen-year-old Adam Wilkie is a crewman on his father's commercial fishing boat, the Spectre. Each summer he works alongside older crewmen, laying out long lines of baited hooks on the seafloor in hopes of catching sablefish and halibut. Most days pass without incident, but recently Adam Wilkie's small fishing boat received a visit by some very large, very hungry guests.
WILKIE: "They looked a lot like a nuclear submarine to me."
The visitors were sperm whales, one of the largest creatures in the world. Although the sight of these railroad-car-sized behemoths was breathtaking, Adam Wilkie says the whales have one bad habit.
WILKIE: "Well, basically they were eating our fish off the hooks. We were watching them a lot. They'd come up and blow and then go down and get the fish."
Adam Wilkie isn't the only fishermen with sperm whales in his wake. Across the Gulf of Alaska, sperm whales are fast learning the fine art of plucking fish from the hooks of commercial fishermen. Elizabeth Mitchell is a federal fisheries observer and a researcher based in Oregon.
MITCHELL: "When I first started seeing them back in 1992 they weren't really hanging around the vessels too much. They were off in the distance. When I went out in 1995 they were hanging off the stern, which led me to believe they were eating the discards only."
But gradually, the whales have grown bolder. Much bolder.
MITCHELL: "They just come immediately, frequently even before the first hook is brought aboard. Some fishermen say that when they are alone, they don't present a problem, but when there are three or four or five, then that's when it becomes a problem."
Fishermen and observers report seeing fish tails bitten off, entire bodies chomped off just below the head and the hook, large gashes along the sides of the fish, smashed heads and torn stomachs.
MITCHELL: "What I think is happening is that they come in on their side and just chomp on the line. That's the only way I can visualize it."
Some sperm whales seem to have learned to make a pretty good living by following fishing boats in Alaska. One whale in particular has been prowling the waters of Southeast Alaska since 1984. Fishermen recognize it from the narrow grooves worn into the whale's head, created by battles with other whales.
HILL: "That's probably "Old Cablehead."
That's Scott Hill, a scientist with the National Marine Mammal Lab in Seattle. According to a study by Scott Hill and Elizabeth Mitchell, Alaska sperm whales ate the fish off of more than a quarter of the longline sets they monitored in a 1997 study.
HILL: "Well, then I went and looked at catch rates and it was pretty clear that the whales had an effect on catch rates. The catch rates were lower when whales were present. Whether it was because they were ripping fish off the lines or whether they were competing with fishermen for the fish in the area or whether it was because of a small sample size, I don't know."
Scientists estimate that some 140,000 sperm whales live in the North Pacific Ocean, although no one really knows how many of these whales live in waters right off Alaska. They are listed as a federally protected endangered species, and because of that, scientists and fishermen want to find a way to safely discourage the whales from stealing fish. Fourteen-year-old Adam Wilkie thinks he has a solution.
WILKIE: "But what we found out about them is they cannot find them unless the gear is moving. That's what we figured out because when we'd stop and start hauling again, then we'd get a few fish by them."
Elizabeth Mitchell also wants to find a solution to the problem. She hopes to obtain research funding to explore ways to break the whale's association of fishermen with food. That may mean working with fishermen to find new ways of fishing that prevent the whales from getting a free meal.
OUTRO: For Arctic Science Journeys, this is Doug Schneider, reporting from Fairbanks, Alaska.
Arctic Science Journeys is a radio service highlighting science, culture, and the environment of the circumpolar north. Produced by the Alaska Sea Grant College Program and the University of Alaska Fairbanks.
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