Double-crested cormorant (DCCO) populations have increased significantly in the Great Lakes Region in recent years.  Currently, there are about 113,000 breeding pairs in the U.S. and Canadian Great Lakes, which is a 27% increase over the 1997 census. 

Growing concern about DCCO impacts on natural resources caused the Fish and Wildlife Service (FWS) to establish a Public Resource Depredation Order (PRDO) in 2003.  The PRDO authorizes USDA’s Wildlife Services Program, State wildlife agencies, and Tribes (acting on tribal lands) to take DCCOs when they cause significant impacts on fish, vegetation, and other birds. 

DCCOs are of biological and social concern at several “hot spots” within FWS Region 3. To address these conflicts, about 5,800 birds were killed, and eggs were oiled in about 3,000 nests, in Michigan (primarily in the Les Cheneaux Islands area of Lake Huron to address yellow perch impacts) and Minnesota (at Leech Lake to alleviate impacts on walleye and common terns) in 2005.  In 2006, efforts were continued at those sites and expanded in Michigan (fish impacts in Lakes Huron and Michigan), Ohio (impacts on heron and egret habitat on several Lake Erie islands), and Wisconsin (fish impacts in Green Bay).  Final tallies of birds taken and eggs oiled in 2006 are not yet available. 

Studies are underway at these sites to better determine DCCO impacts and to evaluate the effects of DCCO management on affected resources.  Debate continues over the degree to which DCCOs affect fish populations and fishing interests.  It is often difficult to definitively demonstrate that DCCOs affect fish populations, and study results are very site-specific.  Documenting impacts on vegetation that is either botanically important or that provides habitat for other birds is easier.

The FWS has oversight responsibility to ensure that the PRDO does not cause significant negative impacts to regional DCCO populations, other birds that nest with DCCOs, or Federally-listed species.  The FWS co-organized (with USDA) a meeting in Lansing, MI, in 2006, that brought together all of the agencies involved with DCCO management in the Great Lakes Region, plus DCCO researchers, to review past DCCO control activities, plan 2006 activities, and discuss monitoring to assess the impacts of the PRDO on DCCO populations in FWS Regions 3 and 5.  The agencies are cooperating in the development of state-level environmental assessments on DCCO management (see http://www.fws.gov/midwest/MidwestBird/cormorants.htm) that  ensure the PRDO is used appropriately, effectively, and in a coordinated manner.