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11-08-2010, 03:12 PM #1
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Pink Salmon Populations in the U.S. Waters of Lake Superior, 1981-1984,
By Mark S. Bagdovitz, William W. Taylor, Wilbert C. Wagner, Joseph P. Nicolette, George R. Spangler
Journal of Great Lakes Research, Volume 12, Issue 1, 1986, Pages 72-81, ISSN 0380-1330, DOI: 10.1016/S0380-1330(86)71701-2.
Pink salmon were introduced to Lake Superior in very small numbers at Thunder Bay, Ontario, Canada in 1956. Since that time, they have established themselves as permanent members of the Lake Superior ecosystem. Peak spawner densities were observed in the U.S. tributaries of Lake Superior in 1979 when many streams experienced runs of 10,000 fish or more. To better understand the population dynamics of pink salmon, population characteristics, fecundity and egg deposition of spawners, egg and larval survival, and fry outmigration were studied in several Michigan and Minnesota tributaries in 1980. Population estimates indicate a significant decline of pink salmon in the U. S. waters of Lake Superior since 1979. This decline appears to be related to instream fry survival, which is in turn related to the hydrological conditions of the streams in fall and winter. Lake Superior pink salmon are phenotypically similar to their Pacific Coast counterparts, the major difference being age structure and smaller size of adults. Approximately 90% of the adults mature as 2-year-olds while the remaining 10% mature as 3-year-olds. Pink salmon maturing as 3-year-olds have different growth patterns than those maturing at 2 years of age. Two-year-old pink salmon average 390 mm in length, which is about 30% smaller than 2-year-olds from the Pacific Ocean. Three-year-old females have a lower fecundity and a poorer egg quality than 2-year-old females.
Keywords: Fish populations; fish establishment; stream flow; dissolved oxygen