Condition factor and statolith aging in assessment of metamorphosis in sea lampreys, Petromyzon marinus, in the Great Lakes

grantor: University of TorontoA field study was conducted to test the utility of a condition factor for predicting metamorphosis in sea lampreys, using temperature as a blocking factor. The data indicate the utility of the selection criteria, however, the data also show that we need to alter the present length and mass criteria in order to reflect creek and/or watershed growth variation. The statolith aging technique was validated for immediately premetamorphic and metamorphosing sea lampreys using an oxytetracycline marker. The data show that the age of premetamorphic and metamorphosing sea lampreys is equal to the number of annuli counted on their statoliths. Immediately premetamorphic and metamorphosing sea lamprey larvae were aged using statoliths. It was found that metamorphosing animals are one year older than nonmetamorphosing animals of the same length, and that a specific premetamorphic (arrested growth) phase does exist in these populations of sea lampreys. Larvae in warm water do not metamorphose at a younger age than larvae in creeks with cooler temperatures.M.Sc