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Adopt-A-Fish update – May 4, 2006 for these native river fish By DAVE FULLER Montana Fish, Wildlife and Parks FORT PECK - The Wizard of Oz's Dorothy and many of our native Missouri River fish have something in common: a primal desire to return home. We've known for years that salmon return to the same river from which they were born, after spending several years in the ocean. Researchers have been finding that other species of fish also prefer to spawn where they were born, exhibiting what they call natal-site fidelity. Northern pike go to the same bay to spawn year after year. Bull trout will consistently choose one tributary over another to spawn in. And many marine fish will selct a particular reef for spawning, just to name a few. Well, it looks as though we can add paddlefish to that list. Many of the paddlefish in our area spend most of their time in the Missouri River below the confluence of the Yellowstone River and in Lake Sakakawea. When they are making their spawning migration in the spring, they are faced with the decision whether to come up the Missouri or Yellowstone River. The five years of this study have shown that they will choose the same river for their spawning migration. Let's use our Adopt-A-Fish as examples. Paddlefish #1 is a male whose last migration was up the Yellowstone River in 2004. He's on his way up the Yellowstone again this year (males generally spawn every 1-2 years). Paddlefish #2, a female, made a migration up the Missouri River in 2002, spent the last 3 ˝ years in Lake Sakakwea, now she's in the Poplar area and coming further up the Missouri River (females usually spawn every 2-4 years). Paddlefish #3 has made several migrations up only the Missouri River, as well. Interannual site fidelity, which seems to be very common in our blue suckers, is when a fish spends different portions of the year in different rivers or different areas of a river. This could be due to spawning areas, feeding areas, or over-wintering areas. Our telemetry results are showing that these fish swim an average of over 450 miles in a season. When they are done with their travels, they end up in the exact same spot that they were first relocated that spring, and the spring before that and……well, you get the picture. We generally think of fish making an upstream migration to their spawning areas and then returning somewhere downstream where they will remain until it is time to make another migration upstream to spawn again. This is true for most fish. However, the sauger, another one of Montana's native riverine fish, will actually make downstream migrations to spawning areas in the Yellowstone and swim back upstream to their home areas where they remain for the rest of the year. The fact that these fish return to their natal grounds has implications for fisheries management. The notion that there might be different stocks and a potential for biological differences between them makes each spawning site more valuable. Beyond that, if reproductive success depends on returning to a particular spawning site, the loss of that site would damage the reproductive output of an entire spawning population. Perhaps this is what contibuted to the decline of the pallid sturgeon on the lower Missouri River if there was a primary spawning area somewhere above Fort Peck Dam. Weekly updates on our radio-implanted fish can be found on the Missouri-Yellowstone Adopt-A-Fish home page with updates posted Thursday mornings in April and May. Just click on the Find your Fish button on the home page. School classrooms, youth fishing clubs and home schoolers can sign up for the program and adopt and name two fish. Just go to the Web site and click on the How To Adopt Button or send us an e-mail at Missouri-Yellowstone Adopt-A-Fish. Adopt-A-Fish correspondents Dave Fuller, at Fort Peck, and Matt Jaeger, at Glendive, are fisheries biologists with Montana Fish, Wildlife and Parks. They’ll post weekly updates every Thursday throughout April and May on this site and in the Outdoors section of The Billings Gazette. |
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