Effects of Sea Lamprey Sub-lethal Parasitism on Lake Trout
Historically, lake trout have been an important species
in the great lakes for commercial, subsistance and sport fisheries, not to
mention a top predator in Lake Superior. Although, many non-native species have
entered the Great Lakes over the years, the parasitic sea lamprey is showing to
be one of the most harmful, especially for lake trout populations. At their
parasitic stage, sea lamprey attach to their fish host, extracting blood and
tissue fluids with their specialized mouth parts (photo at right).
It is estimated that 45-75% of lake trout survive a sea
lamprey parasitism event. The sub-lethal
physiological effects of sea lamprey parasitism on their hosts are likely to
have significant population and management implications. Yet we currently know little about how fish
respond to sub-lethal parasitism events or how these events alter growth, body
condition or reproduction. Because of
this gap in knowledge, it is likely that we are underestimating the damage
caused by sea lamprey parasitism on lake trout populations.
In collaboration with UWSP NADF, Tyler Firkus, (doctoral
candidate) and Dr. Cheryl Murphy of Michigan State University, Dr. Rick Goetz
of NOAA, and Shawn Sitar of MI DNR, will assess the effects of sub-lethal sea
lamprey parasitism on two different lake trout morphotypes. Funding for this project is provided by the Great Lakes Fishery Commission.
Using siscowet and lean lake trout reared at the
UWSP-NADF in a common environment for 11 years, project partners will assess how
lake trout physiology is altered long-term after a parasitism event. Additionally, this information will be used
to refine current physiological and bioenergetics models to better predict how
sub-lethal Sea Lamprey parasitism affects growth, reproduction, and population
The data from this project will be most important for
understanding and preserving lake trout
populations in the Great Lakes.