Evidence for Early Metamorphosis of Sea Lampreys in the Chippewa River, Michigan

Autor:	Sidney B. Morkert, William D. Swink, James G. Seelye
Rok vydání:	1998
Předmět:	geography geography.geographical_feature_category Ecology media_common.quotation_subject Management Monitoring Policy and Law Aquatic Science Biology Fishery Petromyzon Tributary Juvenile Metamorphosis human activities Ecology Evolution Behavior and Systematics Sea lampreys media_common
Zdroj:	North American Journal of Fisheries Management. 18:966-971
ISSN:	1548-8675 0275-5947
Popis:	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 ...
Databáze:	OpenAIRE
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