NUTRITIONAL CONDITION OF THE PACIFIC LAMPREY (LAMPETRA-TRIDENTATA) DEPRIVED OF FOOD FOR PERIODS OF UP TO 2 YEARS

The anadromous parasitic Pacific lamprey (Lampetra tridentata) does no t feed during metamorphosis or its spawning migration. To assess the u tilization of body reserves, we compared the compositions of an adult lamprey held for 2 yr without food, recently metamorphosed lampreys, a nd lampreys starved for 6 mo. Moisture was higher and soluble ash and lipid levels in tissue of the 2-yr-starved than in metamorphosed lampr eys (2.67 and 3.39 kJ.g-1, respectively). Fatty acid profiles of 2-yr- starved and metamorphosed lampreys were qualitatively similar except f or the presence of 15:0 in the latter. Substantially lower levels of 1 4:0 and 16:1n7 and higher levels of polyunsaturated fatty acids occurr ed in starved lampreys. Changes in composition of lampreys starved for 6 mo were similar to changes between the 2-vr-starved and metamorphos ed lampreys. Maintenance energy in a normalized 1-g lamprey starved fo r 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 surviv e extended periods on endogenous reserves, which may have allowed L. t ridentata to survive past environment catastrophes, allows it to migra te considerable distances to spawning areas in the headwaters of river s.