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Howe, Eric Austen

Natural Resources

2006

PhD

Sea lamprey (Petromyzon marinus) are a nuisance species in the Great Lakes and Lake Champlain that has had devastating impacts on native fish and the development of sport fisheries. The effect of this parasitism has inhibited the restoration of the sport fisheries, with significant ecological and economic impacts in these regions. Control programs to restrict sea lamprey population growth rely heavily on application of lampricides to tributaries, but are moving toward an integrated pest management (IPM) approach to managing sea lamprey. One tool for optimizing an IPM approach is population modeling. A matrix model was constacted using vital rates to predict population growth rates, and reveal gaps in current knowledge of certain life history traits. Early model simulations indicated that tributary contributions to the parasiticphase population and movement among the lake basins were important. Between 2001 and 2002, 4,125 recently metamorphosed sea lamprey were individually marked and returned to their natal tributary. Forty-one of these lamprey were recaptured (6 parasites, 35 spawning adults); results indicated that sea lamprey can move among basins, but the extent of this movement could not be determined. To assess tributary contributions to the parasitic-population, statoliths from larval sea lamprey collected in 19 tributaries and 1 delta (n=3 to 23 samples per tributary) were analyzed for trace elemental concentrations to determine their usefulness for discriminating sea lamprey from different tributaries. Correct classification among tributaries from larval samples was high (77%), although predicting the origin of 34 adult sea lamprey of known origin was very low (2.9%). This result suggests that material deposited on the statolith during the parasitic phase may overlap larval material, and further exploration into correctly accessing the larval material from parasite or adult sea lamprey statoliths is necessary before this method is useful. Life history model simulations indicate that selection of tributaries by spawners is important to the population growth rate, and for management programs to be successful, growth during the larval period must be restricted in all major tributaries, regardless of alternate control techniques.