Sea Lamprey (Petromyzon marinus) in the Cheboygan River, Michigan, Watershed: Parasitic Feeding Ecology and Origin of Adults

Abstract

Historic and recent evidence suggests that a landlocked population of Sea Lamprey (Petromyzon marinus) complete their life cycle in the upper Cheboygan watershed. In this watershed, the fish communities of Burt and Mullett lakes support the parasitic-stage for this population, while the surrounding tributaries provide spawning and larval rearing habitat. The Cheboygan River lock and dam system serves as a partial barrier between this ‘upper-river’ population and Sea Lamprey that feed in Lake Huron. Despite this barrier, Lake Huron Sea Lamprey still may escape into the ‘upper-river’ and utilize the same spawning grounds as those from Burt and Mullett lakes. The objectives of this study were to determine (1) what fishes Sea Lamprey feed on in Burt and Mullett lakes and (2) whether spawning-phase Sea Lamprey from Lake Huron can be distinguished from those from Burt and Mullett lakes through morphological characteristics and stable isotopes. Results indicate that ‘upper-river’ Sea Lamprey feed on ‘less desirable’ fishes when compared to their Lake Huron counterparts. Parasitic-phase Sea lamprey from the ‘upper river’ did not differ significantly in size relative to Sea Lamprey from Lake Huron as a group. However, when stratified by month of capture, ‘upper-river’ Sea Lamprey were significantly larger than parasites from Lake Huron. Spawning-phase Sea Lamprey differed significantly in size with Lake Huron Sea Lamprey being larger than those of unknown origins. Stable isotope data showed that ‘upper-river’ Sea Lamprey heads had significantly lower deuterium (δ2H) and δ18O values than those from Lake Huron. Therefore, measurement of total length and weight of spawning-phase Sea Lamprey and deuterium from Sea Lamprey heads should be a useful method for managers to distinguish between spawning-phase Sea Lamprey as either originating from Lake Huron or from the ‘upper-river’, allowing for more accurate population estimates of landlocked Sea Lamprey from Burt and Mullett lakes, aiding in their control.