Seawater tolerance and feeding behavior in landlocked and anadromous populations of Sea Lamprey
Sea lamprey (Petromyzon marinus) are a native parasitic anadromous species to the Atlantic Ocean, ranging from Florida to the Gulf of St. Lawrence (light green). Lamprey were observed in Lake Ontario in the mid-1830s, where Niagara Falls acted as a natural barrier to the upper Great Lakes. In the late 1800s, renovations of the Welland Canal (yellow oval) took place, allowing for cargo ships to bypass Niagara Falls into Lake Erie. Sea lamprey quickly invaded the upper Great Lakes between 1921 and 1938 (red).
Lamprey in the Great Lakes significantly impacted harvests of local fisheries, dropping from approximately 15 million pounds in the 1940s to approximately 300,000 pounds in the 1960s. Origins of Sea Lamprey in Lake Ontario and Lake Champlain are less clear because these populations may have originated from multiple postglacial recolonization routes, invasion-by-canals, marine remnants or any combinations of these sources. Genetic based studies using two types of neutral genetic markers provide evidence that lamprey are native to these lakes. However, historical and ecological information questions the native status of lamprey in these two lakes. Native or invasive status has important implications for the management of local populations.
Life histories of anadromous and landlocked Sea Lamprey are similar, though landlocked populations lack exposure to seawater and thus experience relaxed selection on traits associated with survival in seawater, including salinity tolerance and associated physiological traits. In normally anadromous species such as salmon and alewife, landlocked populations have significantly lower seawater tolerance after hundreds to thousands years of isolation.
This study will provide a robust comparison of population differences in osmoregulation and feeding capacity between native anadromous and invasive landlocked populations. We predict that transformers from landlocked populations will have poorer osmoregulatory ability in seawater compared to anadromous populations. We also predict that transformers from landlocked populations will have lower feeding rates in seawater and higher feeding rates in freshwater compared to anadromous populations. Failure to find effects of population-level differences in these physiological and behavioral parameters will indicate that Sea Lamprey populations in the Great Lakes have only recently been separated from anadromous populations.
Dr. Stephen McCormick, USGS Conte Anadromous Fish Research Center, Turners Falls, MA
Dr. Johnathan Wilson, Wilfrid Laurier Univ., Waterloo, ON, N2L3C5 Canada.
Jessica Norstog, University of Massachusetts Amherst, Amherst, MA
Dr. Nicholas Johnson, USGS Hammond Bay Biological Station, Millersburg, MI
Research funded by Great Lakes Fishery Commission