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CITATION WITHOUT AUTHOR PERMISSION. The title, authors, and abstract for
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of the full completion report, please contact the author via e-mail at mccormick@umext.umass.edu. Questions? Contact the GLFC via email at slrp@glfc.org or via telephone at 734-662-3018.**
2 Univ.
of Massachusetts, Amherst, MA 01003 USA
3 Wilfrid
Laurier Univ., Waterloo, ON, N2L3C5 Canada
4 USGS,
Conte Anadromous Fish Res Ctr, Turners Falls, MA
01376 USA
April 2020
ABSTRACT:
The 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
its underlying osmoregulatory mechanisms. This study
investigated differences in survival, ion regulation in seawater and feeding of
juvenile (fully metamorphosed) sea lamprey from anadromous and landlocked
populations. Landlocked lamprey had lower survival in 35 ppt
seawater compared to anadromous lamprey. Landlocked and anadromous populations
showed strongly elevated gill NKA activity compared to ammocoetes,
which also increased over time after exposure to 30 ppt
seawater. Plasma ion concentrations after exposure to 30 ppt
seawater were elevated in two upper Great Lakes populations compared to the
anadromous population. These results suggest that there are small but
detectable population-based differences in salinity performance that are
consistent with recent, relaxed selection on traits for
seawater entry in landlocked populations. Additionally, feeding behavior
was assessed in landlocked and anadromous populations
in freshwater and seawater in several two-week experiments. Landlocked lamprey
showed greater attachments, increased number of feeders, and higher specific
growth rate in freshwater compared to anadromous sea lamprey. This indicates
that feeding in freshwater may be under positive selection for landlocked
populations.