The question of whether or not Sea Lamprey are native to Lake Ontario and Lake Champlain has important implications to our understanding of their biology and management, and to accurately model how they have been associated with key events that altered species composition over the past 150 years. Our group and others have established that in normally anadromous (AN) species such as salmon and alewife, landlocked (LL) populations have significantly lower seawater (SW) tolerance. These differences are detectable after several thousand years of isolation, but are less likely to be detected after only a hundred years of isolation. In a pilot study funded by the GLFC, we found that gill Na+/K+-ATPase (NKA) activity (necessary for high SW tolerance) of recently metamorphosed Sea Lamprey (transformers) is elevated compared to ammocoetes in both LL and AN populations, but to lesser degree in one LL population from Lake Michigan. We have also seen that feeding of AN transformers is stimulated to a greater degree in SW than FW. Feeding in FW would be under strong positive selection in LL populations, and thus we would expect to see differences in LL and AN populations that are genetically isolated. Our working hypothesis is that Sea Lampreys were native to Lake Ontario and as such, we predict that Sea Lamprey from the Great Lakes will have lower SW tolerance and would be more likely to feed in FW than AN populations. Our objectives are to test the hypotheses that there will be differences in LL and AN populations of Sea Lamprey in 1) the capacity for ion regulation in FW (greater in LL) and SW (greater in AN) and their underlying physiological mechanisms, and 2) feeding (parasitic) behavior in FW and SW, which will be greater in LL and AN, respectively.
SEAWATER TOLERANCE AND FEEDING IN FRESHWATER & ANADROMOUS POPULATIONS OF SEA LAMPREY