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Cheboygan River Sea Lamprey Escapement
Escapement of spawning phase sea lampreys into the upper Cheboygan River
January 2011 - December 2011
The Cheboygan River is an important sea lamprey producing tributary to Lake Huron. It has a barrier-integrated trap near its mouth that captures more adult sea lampreys than any other Great Lakes trap. Despite having a significant dam and efficient trap, the upper river remains infested with sea lampreys and must be treated with lampricides every three years. Spawning migrations are presumed to circumvent the barrier by a vessel passageway (lock), though lampreys may also move through an adjacent power generation facility. It is not known what proportion of adult lampreys in the lower Cheboygan River access the upper River and how the escapement of sea lampreys upstream of the dam influences adult lamprey abundance estimates on the Cheboygan River. Lake-wide adult lamprey abundance estimates are highly sensitive to mark-recapture population estimates conducted on large rivers, such as the Cheboygan River, because a small proportion of large rivers are trapped within each Great Lake. We hypothesize that a measurable proportion (> 5%) of sea lampreys move upstream of the Cheboygan River dam given consistent yearly recruitment of larval sea lampreys in the upper Cheboygan River. Furthermore, we hypothesize that escapement of sea lampreys above the Cheboygan River dam results in an underestimate of adult lampreys in the Cheboygan River because marked lampreys are released at the trap site, which is upstream of the lock. Our goal is to independently estimate adult lamprey abundance in the lower Cheboygan River (below the dam) and in the upper Cheboygan River using acoustic telemetry and compare acoustic telemetry derived estimates to those derived using traditional mark-recapture techniques.