 Radio Script 2001
Fingerprinting Pollock INTRO: Out on the vast North Pacific Ocean, fish from many countries mingle together in search of food. Figuring out which fish belong to what country would seem an impossible task. Yet, scientists are trying to do just that when it comes to pollock. And as Doug Schneider reports in this week's Arctic Science Journeys Radio, scientists say the fish's earbone may hold the answer. STORY: Many of us may not know what a pollock is, but most of us have almost certainly eaten one. Ever had fish sticks? Or perhaps you've put some imitation crabmeat in your salad? If you did, you ate pollock. Pollock is one of the ocean's most abundant fishes. Last year alone, U.S. fishermen caught more than one million tons of pollock. Most of that was caught in waters off Alaska. It's here that pollock from across the North Pacific Ocean come to feed. And it's here that scientists face a daunting management problem. Ken Severin is a researcher at the University of Alaska Fairbanks. SEVERIN: "The goal of this project is to try to identify individual fish stocks, individual pollock stocks. There are about five recognized pollock stocks in the North Pacific. One of the problems is that even though we know that pollock spawn in certain areas, they then kind of swim together in a big mass. We don't know if they came from one place or another." Clues to figuring out where a particular pollock comes from may lie within the fish's hard, disk-shaped bone called the otolith, or earbone. The tiny bony disk doesn't really allow fish to hear the way humans do, but it does help them feel sound as well as maintain balance and orientation. What's of interest to scientists isn't how fish hear, but rather it's what the otolith is made of, and what it can tell them about where the fish comes from. Because while a typical otolith is made mostly of calcium, it also absorbs other elements—things like magnesium and strontium—found naturally in the ocean. Ken Severin says pollock in one part of the ocean may absorb different elements, or absorb elements in different concentrations, than pollock in another part of the ocean. Such differences could serve as a kind of fingerprint to reveal where that fish came from. SEVERIN: "There have been a lot of studies that have shown that if you grab fish from one area and grab fish from another area, the elemental composition of the otoliths is different. But the overall picture is that they are incorporating these elements in abundance roughly similar to the surrounding seawater. So if fish are living in areas that have different oceanographic composition, different chemical composition, from place to place, we should be able to pick this up in their otoliths. Since these otoliths contain an entire life history of the fish, ideally we should be able to trace the elemental abundance from the inside of the otolith to the outside, and say the fish was here at one point in its life and there at another point in its life."
Severin is among a group of scientists trying to understand just what those otolith differences are among the pollock stocks that intermingle in the North Pacific. Their work is aimed at better managing pollock, and is being conducted with funding from the North Pacific Marine Research Program at the University of Alaska Fairbanks. SEVERIN: "It's important because there are about five different countries fishing pollock. And of course when you get different countries fishing, a lot of them are going to say well, all of the fish born off Alaska belong to the U.S. and all of the fish born off of Canada belong to the Canadians. This is the exact same thing that's happened to the salmon fisheries. How do you divide up the fish in an equitable fashion between the different countries?" Severin says it may also be possible to use otoliths as a way to distinguish between Alaska's many regional pollock stocks, such as pollock from Prince William Sound and those from the Shelikof Strait near Kodiak Island. Ultimately, Severin hopes the techniques he and his colleagues are perfecting can be used to distinguish among all of the pollock stocks that live together in the vast North Pacific Ocean. OUTRO: This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. I'm Doug Schneider. Audio version and related Web sites (sidebar at top right) Thanks to the following individual for help preparing this script: Kenneth Severin, Director 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.
Alaska Sea Grant In the News The URL for
this page is http://seagrant.uaf.edu/news/ |
Listen to story on RealAudio Related Web sites North Pacific Marine Research Program (NPMR): Pollock Fingerprinting Project Kenneth Severin faculty profile |
