| Abstract: | We determined age at metamorphosis to the juvenile or parasitic phase for sea lampreys Petromyzon marinus in a highly productive Great Lakes tributary to determine if the age at metamorphosis was earlier than expected. Ages determined from statoliths, a structure analogous to otoliths in teleost fishes, indicated that many sea lampreys collected from the Chippewa River, Michigan, in September 1995 were undergoing metamorphosis at age 2, at least 1 year earlier than previously observed. In all, 141 newly metamorphosed lampreys were examined, and 81% were estimated to be only 2 years old. The length-frequency distribution of newly metamorphosed sea lampreys in the Chippewa River also indicated the possibility of metamorphsis at age 2, but to a lesser extent than indicated by statolith aging. The Chippewa River is a highly productive stream that might require more frequent treatment than previously suspected. More careful examination of other highly productive streams is needed to determine if, and to what extent, sea lampreys metamorphose at age 2 in the Chippewa River and other Great Lakes tributaries. |
| Genre: | Article |
| ProdID: | 1000699 |
| Citation Author: | Morkert, Sidney B.; Swink, William D.; Seelye, James G. |
| Citation Contributing Office: | Great Lakes Science Center |
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| Citation End Page: | 971 |
| Citation Issue: | 4 |
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| Citation Language: | English |
| Citation Larger Work Title: | North American Journal of Fisheries Management |
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| Citation Number Of Pages: | 5 |
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| Citation Phsyical Description: | p. 966-971 |
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| Citation Public Comments: | Out-of-print |
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| Citation Search Results Text: | Evidence for early metamorphosis of sea lampreys in the Chippewa River, Michigan; 1998; Article; Journal; North American Journal of Fisheries Management; Morkert, Sidney B.; Swink, William D.; Seelye, James G. |
| Citation Start Page: | 966 |
| Citation Volume: | 18 |
| Citation Year: | 1998 |
| Type: | citation/reference |
| Text: | Evidence for early metamorphosis of sea lampreys in the Chippewa River, Michigan; 1998; Article; Journal; North American Journal of Fisheries Management; Morkert, Sidney B.; Swink, William D.; Seelye, James G. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Thu, 1 Jan 1998 00:00 -0600 |
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