Nutritional Condition of the Pacific Lamprey (Lampetra tridentata) Deprived of Food for Periods of Up to Two Years

Abstract

The anadromous parasitic Pacific lamprey (Lampetra tridentata) does not feed during metamorphosis or its spawning migration. To assess the utilization of body reserves, we compared the compositions of an adult lamprey held for 2 yr without food, recently metamorphosed lampreys, and lampreys starved for 6 mo. Moisture was higher and soluble ash and lipid levels were lower in tissue of the 2-yr-starved than in metamorphosed lampreys (2.67 and 3.39 kj∙g−1, respectively). Fatty acid profiles of 2-yr-starved and metamorphosed lampreys were qualitatively similar except for the presence of 15:0 in the latter. Substantially lower levels of 14:0 and 16:1 n7 and higher levels of polyunsaturated fatty acids occurred in starved lampreys. Changes in composition of lampreys starved for 6 mo were similar to changes between the 2-yr-starved and metamorphosed lampreys. Maintenance energy in a normalized 1-g lamprey starved for 6 mo was derived from catabolism of 71% lipid and 29% protein; total loss was 2.56 kJ or 49% of the original energy. The ability to survive extended periods on endogenous reserves, which may have allowed L. tridentata to survive past environmental catastrophes, allows it to migrate considerable distances to spawning areas in the headwaters of rivers.