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Larval Metamorphosis of Individual Pacific Lampreys Reared in Captivity
Author(s) -
McGree Michelle,
Whitesel Timothy A.,
Stone Jen
Publication year - 2008
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/t07-206.1
Subject(s) - metamorphosis , lampetra , biology , captivity , larva , zoology , lamprey , snout , ecology , fishery
Abstract This study is one of the first to follow individual Pacific lampreys Lampetra tridentata through the process of metamorphosis. Readily observable external changes were described for 13 individual Pacific lampreys undergoing metamorphosis. Changes occurred to the mouth, eyes, and branchial region from July to at least November. During metamorphosis, Pacific lampreys also exhibited asymmetric growth, including an increase in snout depth, that had not previously been reported in the literature. The order of the morphological changes and the patterns of asymmetric growth in the Pacific lamprey closely matched those reported for another Lampetra species, the American brook lamprey L. appendix , but exhibited unexpected variations from those reported in other species of lampreys. Excepting one catastrophic event, under captive rearing conditions 96.4% of the ammocoetes survived and the maximum growth rates of 0.040‐0.071 mm/d were within the range of those estimated for ammocoetes rearing naturally in stream environments. Supplemental feeding improved larval growth but did not influence the incidence of metamorphosis in captively reared animals. To develop effective conservation strategies for Pacific lampreys in the Columbia River basin, it would be prudent to consider that metamorphosis, a time when the animals are relatively vulnerable, may last from July to December.