The Pacific lamprey is an ancient fish of great importance to the ecosystems and indigenous cultures of the U.S. Pacific Northwest. Pacific lamprey have declined in abundance and range from historic levels, thus leading to increased conservation efforts for the species . E fforts to conserve this native fish include development of culture techniques, which the present research aims to address. The larval stage of this species occurs in freshwater and can take up to seven years to reach metamorphosis in the wild. During the larval stage lamprey are filter feeders and a slurry of active dry yeast paired with a fine larval fish diet (4:1) is commonly employed as a standard lamprey diet in the hatchery. This project tested two levels of feeding frequency through two experimental trials with 65 days post hatch (DPH) larvae (Trial 1) and 803 DPH larvae (Trial 2). The trials compared the control feeding frequency of two feeding events per week to a high frequency of five feeding events per week. Trials were 8 weeks long. Survival, growth, condition factor , whole body lipid and fatty acid profile (Trial 2 only) were measured at the end of the trials.
For the younger fish in Trial 1 the high frequency feeding regime lead to heavier larvae relative to the control frequency larvae, but there was no difference in length, condition factor or survival. Higher feeding frequency increased both length and weight of the older larvae of Trial 2, but did not affect survival or condition factor. More feedings also elevated whole body lipid content and altered the fatty acid profile of the older larvae. Results from both trials will be presented and discussed. The findings from this research will enhance our ability to effectively culture lamprey.