Measures of Condition and Determination of Total Lipids in Larval Pacific and Western Brook Lamprey

Pacific lampreys have been declining and information on basic ecology, biology, and life history is needed.  Relations of condition measures to lipid content are lacking.  Condition measures in lamprey may be correlated to lipid content.  We compared condition factor and body density to lipid content among species (Pacific lamprey and western brook lamprey) and size groups.  Lipid content was variable within and between species.  Mean condition factor of small lamprey was higher for larval Pacific than western brook lamprey.  Preliminary analyses indicated no correlation between lipid content and condition factor, or body density for either species.  Lipids were higher, particularly for large sizes, for larval western brook lamprey than Pacific lamprey.  Lipid content of western brook lamprey was higher than Pacific lamprey.  Lipid content was variable, but there was a trend for longer western brook lamprey to have higher lipids.  We did not detect a relationship between condition factor, body density, and lipid percentage.  Lampreys transform in spring-summer; individuals had likely completed metamorphosis at the time of our fall collection.  We likely collected non-metamorphic larvae that did not have increased lipid reserves we predicted.  Future investigation of condition measures should use collections at times when metamorphic larvae are available.