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National Wildlife Research Center (NWRC)

   
 

A Science-based Initiative to Manage Double-Crested Cormorant Damage to Southern Aquaculture

Issued September 2000

James F. Glahn, Mark E. Tobin, and Bradley F. Blackwell

Citation:

GLAHN, J. F., M. E. TOBIN, AND B. F. BLACKWELL, editors. 2000. A science-based initiative to manage double-crested cormorant damage to southern aquaculture. USDA Animal and Plant Health Inspection Service, Wildlife Services National Wildlife Research Center, Fort Collins, CO, APHIS 11-55-010.

Recommendations

Considering the status of cormorant depredation problems and the limitations of current methods to alleviate these conflicts, we make the following recommendations concerning research needs and management actions.

The following initiatives are listed in chronological order by completion date with the goal of implementing definitive solutions to cormorant depredation problems in the next 5 years. The time lines for achieving these initiatives are presented in the subsequent table. Cormorant Initiatives

Initiative 1 - Clarify the impact and economic threshold of cormorant predation on catfish production by December 2000.

  • Complete QA-634 to determine actual catfish production losses due to cormorant predation by December 2000.
  • In consultation with agricultural economists, define the economic threshold for cormorant predation on catfish ponds by December 2000.

Initiative 2 - Assess the need to expand the cormorant depredation order by June 2002.

  • Expand areas of coverage and continue to monitor wintering cormorant populations in Alabama, Arkansas, Louisiana, and Mississippi.
  • Develop feasible monitoring techniques and continue to monitor breeding populations in Alabama, Arkansas, Louisiana, and Mississippi.
  • Through questionnaire surveys, monitor the take of cormorants under the cormorant depredation order through May 2002.
  • Based on increasing breeding and wintering populations and stable take under the cormorant depredation order, petition the USDI-FWS to expand the cormorant depredation order to include shooting in winter roosts and southern breeding colonies.

Initiative 3 - Develop by October 2002 a goal-oriented population model to examine measures needed to reduce cormorant flyway populations.

  • Complete a study defining the demographics of wintering cormorant populations by July 2002.
  • Complete studies defining the demographics of Great Lakes breeding cormorant populations by October 2002
  • Develop a cormorant population model by October 2002

Initiative 4 - Determine flyway movements of cormorants along the Mississippi Flyway by April 2002.

  • Complete analysis of recent cormorant banding data by July 2000.
  • Complete a satellite telemetry study by April 2002 to define where and when flyway population management can be best implemented.


Initiative 5 - Evaluate by September 2003 all localized control options for managing cormorant depredations to southern aquaculture.

  • Using information on flyway movements and the cormorant population model determine by October 2002 the feasibility of managing cormorant populations under an expanded cormorant depredation order.
  • Complete by September 2003 research to assess the utility of non-lethal control strategies to reduce cormorant predation to southern aquaculture.

Initiative 6 - Develop and implement by April 2004 an integrated management plan for reducing cormorant damage to southern aquaculture.

  • In cooperation with the U.S. Fish and Wildlife Service, the Canadian Wildlife Service, State wildlife agencies, aquaculture interests, sport and commercial fisheries representatives, and other interested parties, set local and flyway population goals. In cooperation with the same entities and using information obtained from strategies 1-5, develop by January 2004 an integrated management plan for reducing double-crested cormorant conflicts.
  • Implement the integrated cormorant management plan by April 2004, including both localized and flyway management for reducing cormorant damage to southern aquaculture. Cormorant Initiatives

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Initiative 1 - Clarify the impact of FY 2000 FY 2001 FY 2002 FY 2003 FY 2004 Who cormorants on actual catfish production should losses by December 2000. FY2000 FY2001 FY2002 FY2003 FY2004 Who Should do it.

Task A - Clarify actual production losses. NWRC
Task B - Determine economic thresholds of predation. NWRC


Initiative 2 - Assess the need to expand the cormorant depredation order by June 2002.

Task A - Monitor wintering cormorant populations. WS

Task B - Monitor breeding cormorant populations. WS

Task C - Monitor take under depredation order. FWS

Task D - Petition to expand depredation order. WS


Initiative 3 - Develop a flyway population model by October 2002.

Task A - Complete study of wintering demographics. NWRC

Task B - Complete study of breeding demographics. NWRC/FWS

Task C - Develop Cormorant population model. NWRC/FWS


Initiative 4 - Study cormorant flyway movements

Task A - Complete analysis of cormorant banding data. NWRC

Task B - Complete satellite telemetry study. NWRC


Initiative 5 - Evaluate all localized control options for managing depredations.

Task A - Determine feasibility of managing cormorant populations under expanded depredation order. NWRC/WS

Task B - Complete research on non-lethal options. NWRC


Initiative 6 - Develop and implement an integrated cormorant management plan

Task A - Set population goals and develop an integrated cormorant management plan. WS/FWS

Task B - Implement the integrated cormorant management plan. WS & Others References Cited

 

 

 



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