Evaluating experimental control method for invasive Rusty Crayfish in Lake Michigan spawning reefs

Session: Great Lakes Reefs: Research, Monitoring, Creation, and Maintenance (1)

Dana Castle, Michigan Department of Natural Resources, [email protected]
Jake Kvistad, Central Michigan University, [email protected]
Lindsay Chadderton, The Nature Conservancy, [email protected]
Andrew Tucker, The Nature Conservancy, [email protected]
Matthew Herbert, The Nature Conservancy, [email protected]
David Clapp, Michigan DNR Fisheries Division, [email protected]
Tracy Galarowicz, Central Michigan Univ., [email protected]
Patrick O'Neill, Michigan Department of Natural Resources, [email protected]

Abstract

Rusty Crayfish is the most widespread invasive crayfish in the Great Lakes, where their documented effects include reducing macrophyte cover, displacing native crayfish, and consuming native fish eggs. Their role as egg predators has been implicated as an impediment to the recovery of native fish populations, such as Lake Trout and Coregonines, which utilize nearshore cobble reefs as spawning habitat. Despite this, an effective control strategy has not developed. We tested a Rusty Crayfish control strategy on known spawning habitat in Little Traverse Bay, MI.  We intensively trapped and removed Rusty Crayfish prior to fall spawning of native fish and installed a set of physical barriers around the reef to slow crayfish recolonization. A nearby reef was untreated and used as a reference site. Crayfish density was observed before, during, and after treatment at both sites from diver collections using replicate 1 m² quadrats. Treatment effects on non-target species were also measured.  Egg bags were installed in treatment and reference reef habitat and seeded with eggs to measure the extent to which crayfish removal on the treatment reef reduced predation pressure. If successful, our strategy may be applicable for crayfish control in other reef habitats impacted by invasive crayfish.