U.S. Fish and Wildlife Service

Final Environmental Impact Statement 

Double-crested Cormorant Management in the United 

States 

U.S. Department of Interior Fish and Wildlife Service

“Working with others to conserve, protect, and enhance fish, wildlife, and 

plants and their habitats for the continuing benefit of the American people”

in cooperation with

U.S. Department of Agriculture APHIS Wildlife Services

“Providing leadership in wildlife damage management in the protection of 

America’s agricultural, industrial and natural resources, and safeguarding public 

health and safety”

2003
i 

FINAL ENVIRONMENTAL IMPACT STATEMENT:

Double-crested Cormorant Management

RESPONSIBLE AGENCY: Department of the Interior 

 U.S. Fish and Wildlife Service 

COOPERATING AGENCY: Department of Agriculture 

Animal and Plant Health Inspection Service 

 Wildlife Services 

RESPONSIBLE OFFICIAL: Steve Williams, Director 

 U.S. Fish and Wildlife Service 

 Main Interior Building 

 1849 C Street 

 Washington, D.C. 20240 

FOR FURTHER INFORMATION 

CONTACT: Shauna Hanisch, EIS Project Manager 

 Division of Migratory Bird Management 

 U.S. Fish and Wildlife Service 

 4401 N. Fairfax Drive MS-MBSP-4107 

 Arlington, Virginia 22203 

 (703) 358-1714 

 Brian Millsap, Chief 

Division of Migratory Bird Management 

U.S. Fish and Wildlife Service 

 4401 N. Fairfax Drive MS-MBSP-4107 

 Arlington, Virginia 22203 

 (703) 358-1714 
ii 

SUMMARY

Populations of Double-crested Cormorants have been increasing rapidly in many parts of 

the U.S. since the mid-1970s. This abundance has led to increased conflicts, both real 

and perceived, with various biological and socioeconomic resources, including 

recreational fisheries, other birds, vegetation, and hatchery and commercial aquaculture 

production. This document describes and evaluates six alternatives (including the 

proposed action) for the purposes of reducing conflicts associated with cormorants, 

enhancing the flexibility of natural resource agencies to deal with cormorant conflicts, 

and ensuring the long-term conservation of cormorant populations. There are four 

chapters that make up the critical components of an Environmental Impact Statement. 

Chapter 1, Purpose and Need, describes the purpose of and need for the action. Chapter 

2, Alternatives, describes the six management alternatives that we considered: (1) 

Continue current cormorant management practices (No Action); (2) implement only nonlethal management techniques; (3) expand current cormorant damage management 

practices; (4) establish a new depredation order to address public resource conflicts 

(PROPOSED ACTION); (5) reduce regional cormorant populations; and (6) establish 

frameworks for a cormorant hunting season. Chapter 3, Affected Environment, introduces 

the reader to the environmental categories upon which the analysis of alternatives in 

chapter 4 is based: cormorant populations, fish, other birds, vegetation, Federally-listed 

Threatened and Endangered species, water quality and human health, economic impacts, 

fish hatcheries and environmental justice, property losses, and existence and aesthetic 

values. Chapter 4, Environmental Consequences, analyzes the predicted impacts of each 

alternative on the environmental categories outlined in chapter 3 and in comparison to the 

No Action alternative. The environmental analysis presented in Chapter 4 indicates that 

the PROPOSED ACTION: will cause the estimated take of <160,000 DCCOs, which is 

not predicted to have a significant negative impact on regional or continental DCCO 

populations; will cause localized disturbances to other birds but these can be minimized 

by taking preventive measures, leading to the action having beneficial effects overall; 

will help reduce localized fishery and vegetation impacts; will not adversely affect any 

Federally-listed species; is likely to help reduce localized water quality impacts; will help 

reduce depredation of aquaculture and hatchery stock; is not likely to significantly benefit 

recreational fishing economies or commercial fishing; may indirectly reduce property 

damages; and will have variable effects on existence and aesthetic values, depending on 

perspective. 
iii 

TABLE OF CONTENTS

CHAPTER 1: PURPOSE OF AND NEED FOR ACTION.............................................................1 

1.1 Introduction...................................................................................................................1 

1.2 Purpose of Action..........................................................................................................2 

1.3 Need for Action.............................................................................................................2 

1.3.1 Biological...................................................................................................2 

1.3.2 Socioeconomic...........................................................................................3 

1.4 Background Information...............................................................................................3 

1.4.1 Lead and Cooperating Agencies................................................................3 

1.4.2 Policy, Authority, and Legal Compliance.................................................3 

1.4.3 Other Considerations.................................................................................6 

1.4.4 Cormorant Management Practices............................................................8 

1.4.5 The Role of Other Agencies in Cormorant Management.......................11 

CHAPTER 2: ALTERNATIVES...................................................................................................13 

 2.1 Introduction..................................................................................................................13 

 2.2 Rationale for Alternative Design.................................................................................13 

 2.3 Proposed Action...........................................................................................................13 

 2.4 Description of Alternatives..........................................................................................13 

 2.4.1 Alternative A: No Action.............................................................................13 

 2.4.2 Alternative B: Non-lethal Management.......................................................15 

 2.4.3 Alternative C: Increased Local Damage Control.........................................16 

2.4.4 Alternative D: Public Resource Depredation Order (PROPOSED ACTION) 

..............................................................................................................................17 

 2.4.5 Alternative E: Regional Population Reduction...........................................18 

 2.4.6 Alternative F: Regulated Hunting...............................................................19 

 2.5 Alternatives Considered but Eliminated from Detailed Study....................................19 

 2.5.1 No Management..........................................................................................19 

 2.5.2 Rescindment of MBTA Protection..............................................................19 

 2.6 Comparison of Alternatives.........................................................................................19 

CHAPTER 3: AFFECTED ENVIRONMENT...............................................................................22 

 3.1 Introduction..................................................................................................................22 

 3.2 Biological Environment...............................................................................................22 

 3.2.1 Double-crested Cormorants.........................................................................22 

 3.2.2 Fish...............................................................................................................31 

 3.2.3 Other Birds...................................................................................................35 

 3.2.4 Vegetation....................................................................................................38 

 3.2.5 Federally-listed Species...............................................................................38 

 3.3 Socioeconomic Environment.......................................................................................39 

 3.3.1 Water Quality and Human Health...............................................................39 

 3.3.2 Economic Environment...............................................................................40 

 3.3.3 Fish Hatcheries and Environmental Justice................................................45 

 3.3.4 Property Losses...........................................................................................46 

 3.3.5 Existence and Aesthetic Values..................................................................46 

 3.3.6 Issues Raised but Eliminated from Detailed Study....................................47 

CHAPTER 4: ENVIRONMENTAL CONSEQUENCES.............................................................51 

 4.1 Introduction.................................................................................................................51 
iv 

 4.2 Environmental Analysis of Alternatives....................................................................52 

 4.2.1 Impacts to Double-crested Cormorants.......................................................52 

 4.2.2 Impacts to Fish............................................................................................59 

 4.2.3 Impacts to Other Birds................................................................................66 

 4.2.4 Impacts to Vegetation.................................................................................75 

 4.2.5 Impacts to Federally-listed Species...........................................................78 

 4.2.6 Impacts to Water Quality and Human Health............................................80 

4.2.7 Economic Environment..............................................................................82 

 4.2.8 Impacts to Hatcheries and Environmental Justice......................................92 

 4.2.9 Impacts to Property Losses..........................................................................95 

 4.2.10 Impacts to Existence and Aesthetic Values..............................................96 

 

 4.3 Further Discussion of Alternatives..............................................................................98 

 4.3.1 Alternative A: No Action............................................................................98 

 4.3.2 Alternative B: Non-lethal Management....................................................100 

 4.3.3 Alternative C: Increased Local Damage Control......................................101 

4.3.4 Alternative D: Public Resource Depredation Order (PROPOSED ACTION) 

............................................................................................................................103

 4.3.5 Alternative E: Regional Population Reduction.........................................105 

 4.3.6 Alternative F: Regulated Hunting.............................................................106 

 4.3.7 Mitigating Measures.................................................................................107 

CHAPTER 5: LIST OF PREPARERS.........................................................................................114 

CHAPTER 6: CONSULTATION AND COORDINATION AGENCIES..................................116 

 6.1 Introduction...............................................................................................................116 

 6.2 Issues of Concern and Management Options Identified During Scoping................116 

 6.3 Public Comments Expressed During the DEIS Comment Period............................117 

6.4 List of Agencies, Organizations, and Individuals.....................................................119 

CHAPTER 7: PUBLIC COMMENT ON DEIS AND RESPONSE...........................................121 

CHAPTER 8: REFERENCES CITED........................................................................................139 

APPENDICES 

Appendix 1: List of Scientific Names 

Appendix 2: Distribution of DCCO Breeding Colonies in North America 

Appendix 3: DCCO Foraging Behavior at Aquaculture Facilities 

Appendix 4: DCCO Management Techniques 

Appendix 5: Methodology for Estimating Take under the Aquaculture Depredation Order 

Appendix 6: Discussion of Fishery Impacts 

Appendix 7: Guidelines for Distinguishing DCCOs from Anhingas and Neotropic Cormorants 

Appendix 8: Overview of Aquaculture Production in 13 States 

Appendix 9: Costs of Control Methods and Techniques 

Appendix 10: Comparison Tables Using Christmas Bird Count Data 

Appendix 11: Public Scoping Report
1 – Chapter 1 

CHAPTER 1: PURPOSE OF AND NEED FOR ACTION 

1.1 Introduction 

The persistence of conflicts associated with Double-crested Cormorants (hereafter, 

DCCOs or cormorants; see Appendix 1 for a list of scientific names), widespread public 

and agency dissatisfaction with the status quo, and the desire to develop a more 

consistent and effective management strategy for DCCOs led the U.S. Fish & Wildlife 

Service (Service or we) to reexamine, and if deemed necessary, to amend our policies and 

practices for the management of cormorants in the contiguous United States. 

We chose to prepare an Environmental Impact Statement (EIS), as suggested by National 

Environmental Policy Act (NEPA) guidelines, including: (1) Council on Environmental 

Quality (CEQ) regulations in 40 CFR 1508.18, which define a “major Federal action” as 

“adoption of formal plans, such as official documents prepared or approved by Federal 

agencies which guide or prescribe alternative uses of Federal resources, upon which 

future agency actions will be based;” and (2) Service policy in section 550FW 3.3B(2) 

which states that criteria triggering the preparation of an EIS include precedent-setting 

actions with wide-reaching or long-term implications, changes in Service policy having a 

major positive or negative environmental effect, and/or conflicts with local, regional, 

State or Federal proposed or adopted plans or policies. 

As stated in 40 CFR 1502.1, the purpose of an EIS is to provide a detailed explanation of 

the significant environmental consequences, both good and bad, of a proposed action. 

This explanation includes significant effects on the natural, economic, social, and cultural 

resources of the affected environment. An EIS is to be prepared to inform decisionmakers and the public of the proposed action and its reasonable alternatives. It should 

focus on significant environmental issues. This Final EIS (FEIS) identifies and provides 

an evaluation of six alternative approaches for managing DCCOs, including the proposed 

action (Alternative D). Each alternative is analyzed based on anticipated impacts to 

various biological and socioeconomic impact areas. This FEIS is a comprehensive, 

programmatic plan intended to guide and direct DCCO management activities in the 48 

States (excluding Hawaii and Alaska). Where NEPA analysis is suggested or required 

for site-specific control projects carried out under the guidance of this document, 

analyses would “tier to” or reference the FEIS. Site-specific NEPA analysis would focus 

on issues, alternatives, and environmental effects unique to the project. 

Because of the important role of the Wildlife Services program of the USDA Animal and 

Plant Health Inspection Service (APHIS/WS) in DCCO management and research, and 

the need for interagency coordination in developing future cormorant management 

strategies, this FEIS is being prepared cooperatively by the Service and APHIS/WS. 

This section of the FEIS discusses the purpose of and need for the action, gives 

background information on the lead and cooperating agencies and the legal and policy 

context of the action, describes current DCCO management activities, and summarizes 

public involvement in this issue. 
2 – Chapter 1 

1.2 Purpose of Action 

In recent years, increasing populations of DCCOs have led to growing concern from the 

public and natural resource management professionals about impacts of DCCOs on 

various human and natural resources. Based on internal and interagency scoping and the 

direction set forth in 40 CFR 1508.18 and 550 FFW3.3B (described in further detail 

below), we published a Notice of Intent in the Federal Register on November 8, 1999 (64 

FR 60826) announcing that we would prepare, in cooperation with APHIS/WS, an EIS 

and national management plan “to [address] impacts caused by population and range 

expansion of the double-crested cormorant in the contiguous United States.” 

The purpose of the proposed action is threefold: to reduce resource conflicts associated 

with DCCOs in the contiguous United States, to enhance the flexibility of natural 

resource agencies in dealing with DCCO-related resource conflicts, and to ensure the 

long-term conservation of DCCO populations. 

1.3 Need for Action 

While cormorant-human conflicts are not new, from either a historical or a global 

perspective (Siegel-Causey 1999; Hatch 1995, van Eerden et al. 1995, Wires et al. 2001), 

the DCCO’s rapid population increase over the past 25 years has brought these conflicts 

in the U.S. to the point of justifying greater management attention. There is a need for 

the Service to allow others to conduct DCCO control to limit negative impacts to the 

maximum extent practicable. 

The issue of “need” can also be considered from the perspective of other agencies and 

parties with a stake in DCCO management. APHIS/WS issued a position statement 

emphasizing the need for scientifically-based DCCO population reduction in order to 

reduce impacts to aquaculture producers and other resources. Of the 27 States that 

commented during the public scoping period, 16 of these expressed desire for increased 

management flexibility and/or greater population management of DCCOs. Many nonagency stakeholders also stated that there is a need for increased DCCO control to reduce 

resource impacts. 

1.3.1 Biological 

The recent increase in the North American DCCO population, and subsequent range 

expansion, has been well-documented (Scharf and Shugart 1981, Milton and AustinSmith 1983, Buckley and Buckley 1984, Hatch 1984, Ludwig 1984, Blokpoel and 

Harfenist 1986, Price and Weseloh 1986, Roney 1986, Craven and Lev 1987, Hobson et 

al. 1989, Hatch 1995, Weseloh et al. 1995, Glahn et al. 1999, Tyson et al. 1999, Hatch 

and Weseloh 1999, Wires et al. 2001). There is a need to reduce the biological impacts 

resulting from this population increase which include: adverse effects on other bird 

species through habitat destruction, exclusion, and/or nest competition; declines in fish 

populations associated with DCCO predation; destruction of vegetation, particularly 

where DCCOs nest; and predation on Federally-listed fish species. There is a need to 

provide for localized variation in DCCO control because the occurrence and severity of 

these impacts varies from region to region. 
3 – Chapter 1 

1.3.2 Socioeconomic 

Socioeconomic impacts include economic losses to aquaculture producers, commercial 

fisheries, and fishing-related businesses; losses to private resources (including fish in 

private lakes and damaged trees); and compromised water quality. As with biological 

impacts, the occurrence and severity of these impacts varies from region to region. There 

is a need to reduce these impacts. 

1.4 Background Information 

1.4.1 Lead and Cooperating Agencies 

USDI Fish and Wildlife Service. The primary responsibility of the Service is fish, 

wildlife, and plant conservation. Our mission is “working with others to conserve, 

protect, and enhance fish, wildlife, and plants and their habitats for the continuing benefit 

of the American people.” While some of the Service's responsibilities are shared with 

other Federal, State, Tribal, and local entities, we have special authorities in managing 

the National Wildlife Refuge System; conserving migratory birds, endangered species, 

certain marine mammals, and nationally significant fisheries; and enforcing Federal 

wildlife laws. The Division of Migratory Bird Management mission is “providing global 

leadership in the conservation and management of migratory birds for present and future 

generations.” One of the Service’s long-term goals, as stated in the 2000-2005 Service 

Strategic Plan, is “migratory bird conservation.” The purpose of this goal is “to improve 

the status of migratory bird populations that have evidenced decline or other significant 

problems, including overabundance.”

USDA Animal and Plant Health Inspection Service-Wildlife Services. The Wildlife 

Services program of the U.S. Department of Agriculture Animal and Plant Health 

Inspection Service (APHIS/WS) is responsible for managing conflicts with and damages 

caused by wildlife, including migratory birds. APHIS/WS' mission is to “provide 

leadership in wildlife damage management in the protection of America's agricultural, 

industrial and natural resources, and to safeguard public health and safety.” This is 

accomplished through: training of wildlife damage management professionals; 

development and improvement of strategies to reduce economic losses and threats to 

humans from wildlife; collection, evaluation, and dissemination of management 

information; cooperative wildlife damage management programs; informing and 

educating the public on how to reduce wildlife damage and; providing data and a source 

for limited use management materials and equipment, including pesticides (USDAAPHIS 1989).

1.4.2 Policy, Authority, and Legal Compliance 

Migratory Bird Treaty Act of 1918, as amended (16 U.S.C. 703-711: 40 Stat. 755).

The Service has the primary statutory authority to manage migratory bird populations in 

the United States, authority which comes from the Migratory Bird Treaty Act (MBTA). 

The original treaty was signed by the U.S. and Great Britain (on behalf of Canada) in 

1918 and imposed certain obligations on the U.S. for the conservation of migratory birds, 

including the responsibilities to: conserve and manage migratory birds internationally; 

sustain healthy migratory bird populations for consumptive and non-consumptive uses; 

and restore depleted populations of migratory birds. Conventions with Mexico, Japan, 
4 – Chapter 1 

and Russia occurred in later years. The cormorant taxonomic family, Phalacrocoracidae, 

and 31 other families were added to the List of Migratory Birds (that is, those bird 

species protected by the MBTA) in 1972 as a result of an amendment to the 1936 

“Convention between the United States of America and the United Mexican States for the 

Protection of Migratory Birds and Game Mammals” (23 U.S.T. 260, T.I.A.S. 7302). 

Thus, since 1972, DCCOs have been a trust resource managed by the Service for the 

American people under the authority of the MBTA.

 

Animal Damage Control Act of 1931 and Rural Development, Agriculture, and Related 

Agencies Appropriations Act of 1988 (7 U.S.C. 426-426c; 46 Stat. 1468).

The U.S. Department of Agriculture is directed by law to protect American agriculture 

and other resources from damage associated with wildlife. The primary statutory 

authority for the APHIS/WS program is the Animal Damage Control Act of March 2, 

1931 (7 U.S.C. 426-426c; 46 Stat. 1468), as amended in the Fiscal Year 2001 Agriculture 

Appropriations Bill, which provides that: 

The Secretary of Agriculture may conduct a program of wildlife services with respect to injurious animal 

species and take any action the Secretary considers necessary in conducting the program. The Secretary 

shall administer the program in a manner consistent with all of the wildlife services authorities in effect on 

the day before the date of the enactment of the Agriculture, Rural Development, Food and Drug 

Administration, and Related Agencies Appropriations Act, 2001. 

Since 1931, with the changes in societal values, APHIS/WS policies and programs place 

greater emphasis on the part of the Act discussing “bringing [damage] under control,” 

rather than “eradication” and “suppression” of wildlife populations. In 1988, Congress 

strengthened the legislative mandate of APHIS/WS with the Rural Development, 

Agriculture, and Related Agencies Appropriations Act. This Act states, in part: 

That hereafter, the Secretary of Agriculture is authorized, except for urban rodent control, to conduct 

activities and to enter into agreements with States, local jurisdictions, individuals, and public and private 

agencies, organizations, and institutions in the control of nuisance mammals and birds and those mammal 

and bird species that are reservoirs for zoonotic diseases, and to deposit any money collected under any 

such agreement into the appropriation accounts that incur the costs to be available immediately and to 

remain available until expended for Animal Damage Control activities. 

Endangered Species Act (ESA), as amended (7 U.S.C. 136; 16 U.S.C. 460 et seq.).

It is Federal policy, under the ESA, that all Federal agencies seek to conserve threatened 

and endangered species and utilize their authorities in furtherance of the purposes of the 

Act (Sec.2(c)). In accordance with section 7 of the Act, the Service has prepared a 

Biological Evaluation and conducted informal consultation with the Service Endangered 

Species Program to evaluate Federally-listed species that may be affected by the 

proposed action. 

National Environmental Policy Act of 1969 (NEPA), as amended (42 U.S.C. 4321-4347). 

NEPA is our national charter for protection of the environment; it requires Federal 

agencies to evaluate the potential environmental impacts when planning a major Federal 

action and ensures that environmental information is available to public officials and 

citizens before decisions are made and before actions are taken. 
5 – Chapter 1 

In general, the NEPA process entails: determining what need must be addressed; 

identifying alternative ways of meeting the need; analyzing the environmental impacts of 

each alternative; and deciding which alternative to pursue and how. While NEPA does 

not place environmental protection over all other public values, it does require a thorough 

consideration of the environmental impacts associated with management actions. NEPA 

neither requires a particular outcome nor that the “environmentally-best” alternative is 

selected. It mandates a process for thoroughly considering what an action may do to the 

human environment and how any adverse impacts can be mitigated 

(http://npi.org/nepa/process.html). 

More specifically, there are seven major steps in the planning process for the 

development of an EIS and the implementation of the proposed action. These include: 

1) Publication of Notice of Intent – The Notice of Intent to prepare an Environmental 

Impact Statement and national cormorant management plan was published in the Federal 

Register (64 FR 60826) on November 8, 1999. This initiated the scoping process. 

2) Identification of Issues and Concerns – The Notice of Intent solicited public 

participation in the scoping process, which is the chief way that issues, concerns, and 

potential management options are communicated from the public to the lead agency. In 

addition to writing or e-mailing comments, citizens could attend any of twelve public 

meetings held across the country. The scoping period ended on June 30, 2000. All 

comments were read, compiled, and summarized in a public scoping report. 

3) Development of Alternatives – Following scoping, six alternatives were developed to 

offer a range of options for managing DCCOs. These were based on NEPA regulations, 

public comments, interagency meetings, internal discussion, and review of available 

scientific information. 

4) Analysis of Environmental Effects – After significant issues and alternatives were 

established, the environmental analysis was prepared in order to help the public and 

decision-makers understand the environmental consequences of the various alternatives. 

5) Publication of Notice of Availability of Draft Environmental Impact Statement – The 

notice of availability for the DEIS was published in the Federal Register on December 3, 

2001 (66 FR 60218) and announced the completion of the DEIS and its availability for 

public review. It was followed by 10 public meetings and a 100-day comment period. 

6) Publication of Notice of Availability of Final Environmental Impact Statement – This 

Federal Register publication follows the public comment period for the DEIS and 

announces the completion of the Final EIS, followed by a 30-day waiting period. 

7) Publication of Record of Decision – This is the final step of the EIS decision-making 

process, which states the selected alternative and why it was chosen. The actions 

associated with the EIS cannot be taken until the Record of Decision is issued. 
6 – Chapter 1 

Environmental Justice and Executive Order 12898. Executive Order 12898, entitled 

“Federal Actions to Address Environmental Justice in Minority Populations and LowIncome Populations,” promotes the fair treatment of people of all races, income levels 

and cultures with respect to the development, implementation and enforcement of 

environmental laws, regulations and policies. Environmental justice is the pursuit of 

equal justice and protection under the law for all environmental statutes and regulations 

without discrimination based on race, ethnicity, or socioeconomic status. 

Executive Order 13186. Executive Order 13186, entitled “Responsibilities of Federal 

Agencies to Protect Migratory Birds,” directs any Federal agency whose actions have a 

measurable negative impact on migratory bird populations to develop a Memorandum of 

Understanding (MOU) with the Service to promote conservation of migratory birds. The 

MOUs would identify positive actions that Federal agencies can apply to ensure their 

activities consider the conservation of migratory birds. The Executive Order (EO) also 

requires the Secretary of Interior to establish a Council for the Conservation of Migratory 

Birds to oversee implementation of the EO. The council will be composed of 

representatives from the Departments of Interior, Commerce, Agriculture, State, 

Transportation, Energy, and Defense; the Environmental Protection Agency; and other 

agencies as appropriate. 

1.4.3 Other Considerations 

Conceptual Foundations. “Conceptual foundations” are the set of principles and 

assumptions that direct management activities (Anderson 1991). They influence how we 

interpret information, identify problems, and select approaches to their resolution (ISG 

1999). Similarly, they are an expression of agency goals and philosophy, which guide 

management decisions. The following five statements form the conceptual foundations 

on which DCCO management is based: 

(1) DCCOs are an international migratory bird resource and as such they have inherent 

value regardless of their direct use to humans; 

(2) While DCCOs have undergone recent range expansions, they are native to North 

America; 

(3) DCCOs are predators that, while a natural part of the ecosystem, can compete with 

humans for fisheries, with consequences of varying ecological and socioeconomic 

significance; 

(4) DCCO populations have increased significantly in the past 25 years in North America 

and this increase has led to both real and perceived resource conflicts; 

(5) There are sound biological and socioeconomic rationales for developing a 

comprehensive DCCO management strategy in the U.S. 

Human Dimensions. Wildlife management is fundamentally a human, or social, 

construct. One popular introductory wildlife ecology text noted that, “the practice of 

wildlife management is rooted in the intermingling of human ethics, culture, [and] 

perceptions” (Robinson and Bolen 1989). As human populations have grown and placed 

greater demands on nature, and as human values toward wildlife resources have become 

increasingly diverse, the need to better understand the “human dimensions” side of 
7 – Chapter 1 

wildlife management has increased. Human dimensions entail “identifying what people 

think and do regarding wildlife, understanding why, and incorporating that insight into 

policy and management decision-making processes and programs” (Decker and 

Lipscomb 1991). Thus, human dimensions address the social nature of today’s natural 

resource problems (Manfredo et al. 1998), with particular relevance to “people-wildlife 

problems” in which the behavior of wildlife creates a negative impact for some 

stakeholders, or is perceived by some stakeholders as having adverse impacts (Decker 

and Chase 1997). In a paper discussing the “social causes of the cormorant revival in the 

Netherlands” (where Great Cormorants have become an overabundant species) the 

authors (van Bommel et al. 2003) stated:

Ecological processes determine the potential cormorant population but social processes play a large role in 

determining the actual cormorant population. Ecological systems function within the subjective boundaries 

set by [people]... A problem situation can occur in which different parties disagree on the definition of 

these boundaries (Pretty 1995, Pimbert and Pretty 1995). This is often the case in nature conservation 

because ecosystems carry a high level of intrinsic uncertainty... When dealing with these uncertainties, 

people will have different views and opinions on reality. 

At a 1998 workshop on cormorant management in New York, participants agreed that 

human dimensions are important in the DCCO issue because: (1) economics and 

recreation are important factors; (2) it is an emotional issue that can cause polarization; 

and (3) it accentuates the conflict between politics and science-based management. For 

these reasons and others, the DCCO conflict can be viewed as a classic “people-wildlife 

problem,” entailing both biological and social elements. The social element is made 

prominent by the fact that, just as with other examples of abundant species management, 

from white-tailed deer to Canada Geese, public perception of the proper way to deal with 

the problem varies considerably. Conover (2002) wrote that the government’s role in 

wildlife management is “to regulate the harvest of wildlife by people, to restrict human 

behavior that would be detrimental to the wildlife resource, to conduct largescale 

management activities, and to manage wildlife for the benefit of society.” Naturally, the 

difficulty in doing so is because society is made up of diverse individuals who vary in 

their perceptions of wildlife and how they want that resource managed. When conflicts 

occur between wildlife and other resources that humans value, wildlife damage 

management decisions must be made; these are difficult decisions to make because 

stakeholder opinions are often highly polarized. 

In regard to societal expectations in natural resource controversies, the Great Lakes 

Fishery Resources Restoration Study (USFWS 1995), in a discussion on decision-making 

and public expectations, stated: 

When different segments of society place competing demands on nature, conflicts are inevitable and often 

contentious... Agencies and publics are often prevented from realizing resource potential when special 

interest groups fail to recognize public trust responsibilities...and the legitimacy and roles of other users. 

The director of the Montana Department of Fish, Wildlife, and Parks, in the July/August 

2002 edition of Montana Outdoors, succinctly described the unique position of public 

agencies when he wrote: 
8 – Chapter 1 

Some have accused us of [being extreme], of being far too biased on one issue or another. Usually the 

charge comes from those who disagree with our position... The fact is, we’re rarely on the extreme ends of 

any issue. Nor should we be. We’re a public agency representing the diverse interests of all [Americans]. 

Not just the ones who yell the loudest. Not just the ones with the most money and political clout. And not 

just the ones who buy licenses. What that means is that we often take a moderate position on issues. If it 

appears that we ever go “too far” on any issue or policy, believe me when I say that I could always find a 

group of citizens angry that we didn’t go nearly far enough... No matter how hard we try, we won’t be able 

to make everyone happy. There will always be committed, well-meaning people on either side of an issue 

who think we either sold out and didn’t do enough—or that we went way too far. 

In sum, management of abundant wildlife populations is a particularly challenging aspect 

of wildlife conservation, one that demands that decision-makers consider a number of 

important biological and socioeconomic factors. As a public agency, the Service 

recognizes the importance of social, political, and economic factors in policy-making, but 

emphasizes that the foundation of the Service’s mission is fish and wildlife biology. 

Thus we are committed to pursuing biologically justified management strategies that are 

based on the best available science and, additionally, on the knowledge and experience of 

wildlife resource professionals. It is here where Romesburg’s (1981) advice that “science 

and planning are different kinds of decision-making” is most relevant. Planning is the 

domain of wildlife management and it: 

exposes alternative images of a future possible world to the decision-maker’s values, or preferences, and 

selects the best image...the images in planning are composed of scientific knowledge, common sense, ruleof-thumb knowledge, and theories that are as yet untested... Although science and planning share common 

tools, science and planning have different norms for certifying ideas, and hence criticism of these tools 

must take into account the domain of their use. 

The Service and APHIS/WS recognize both the controversial nature of DCCO 

management and the range of values reflected in public and professional views about best 

management actions. This FEIS reflects full consideration of the diverse views brought 

forth during public scoping and the DEIS comment period and provides an analytical 

foundation on which to base final management decisions. 

1.4.4 Cormorant Management Practices 

Depredation Permits. While the MBTA provides migratory birds with protection from 

unauthorized take, it maintains a high degree of flexibility for dealing with human-bird 

conflicts (Trapp et al. 1995). According to the MBTA, the “take” of DCCOs is strictly 

prohibited except as allowed under the terms of a migratory bird permit or pursuant to 

regulations. 

Depredation permits to take DCCOs have been issued by the Service since 1986 and may 

allow the take of eggs, adults and young, or active nests. Guidelines governing permit 

issuance for migratory birds are authorized by the MBTA and subsequent regulations (50 

CFR Parts 13 and 21). Specifically, Part 21.41 of Subpart D of these regulations outlines 

procedures for issuing permits for the control of depredating birds. These regulations 

state that all private individuals, organizations, and Federal and State agencies seeking to 

control migratory birds must file an application for a depredation permit that contains the 

following information: (1) a description of the area where depredations are occurring; (2) 

the nature of the crops or other interests being injured; (3) the extent of such injury; and 
9 – Chapter 1 

(4) the particular species of migratory birds committing the injury. Thus, Part 21.41 

authorizes the take of migratory birds that are injuring “crops or other interests.” In 

issuing depredation permits, the Service has historically interpreted “other interests” to 

mean threatened and endangered species, property damage on private or public land, and 

human health and safety, although permits have been issued to protect natural resources.

In 1990, Director’s Order No. 27 was instated which clarifies that the Service can issue 

depredation permits for migratory, fish-eating birds preying on fish aquaculture and 

hatchery facilities. 

APHIS/WS typically responds to requests for assistance with bird depredation and 

damage by collecting information on the type of resource being damaged, where the 

damage is occurring, the number and species of birds responsible for the damage, the 

economic losses resulting from the damage, and the control methods which have been 

used in attempting to resolve the damage. Based upon these evaluations, APHIS/WS 

personnel recommend an Integrated Damage Management approach for resolving bird 

depredation and damage conflicts, which could include providing recommendations to 

the Service for issuance of a depredation permit. While APHIS/WS provides 

recommendations to the Service for the issuance of migratory bird depredation permits to 

private entities in the cases of severe bird depredation and damage (Mastrangelo et al. 

1997), the responsibility of issuing these permits rests solely with the Service (Trapp et 

al. 1995). In most States, a permit is also needed from the State fish and wildlife agency. 

APHIS/WS maintains a Management Information System (MIS) database documenting 

the assistance that the agency provides in resolving wildlife damage conflicts. A review 

of MIS data collected from FY 1995-2001 revealed that the agency responded to 1,916 

technical assistance requests (“the provision of advice, recommendations, information, or 

materials for use in managing wildlife damage problems” [USDA-APHIS 1997b]) to 

reduce DCCO conflicts in 42 States, with Alabama, Arkansas, Florida, Louisiana, 

Mississippi, and Texas representing 65 percent of the requests over the 7-year period. 

MIS resource categories included aquaculture (commercially propagated finfish and 

shellfish) with 72 percent of technical assistance requests; natural resources (habitat, 

wildlife, wild fisheries) with 19 percent of requests; property (structures, boats, 

automobiles, aircraft, pets, timber/trees) with 6 percent of requests; and human health and 

safety (disease transmission to humans, wildlife aircraft strikes, direct personal injury) 

with 3 percent of requests. Of those 1,916 requests, APHIS/WS recommended the 

issuance of 533 depredation permits to the Service, of which over 95 percent were for the 

protection of aquaculture and natural resources. 

Depredation Order. In 1998, the Service issued a depredation order (USFWS 1998b; 50 

CFR 21.47 ) authorizing commercial freshwater aquaculture producers in 13 States 

(Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Minnesota, Mississippi, 

North Carolina, Oklahoma, South Carolina, Tennessee, and Texas) to take DCCOs, 

without a Federal permit, when found committing or about to commit depredations to 

aquaculture stocks. The depredation order states that DCCOs may be taken by shooting 

only during daylight hours, and only when necessary to protect freshwater commercial 
10 – Chapter 1 

aquaculture and State-operated hatchery stocks and that such actions must be carried out 

in conjunction with a non-lethal harassment program certified by APHIS/WS officials. 

 

Research and Population Surveys. Prior to 1950, the U.S. Biological Survey (predecessor 

of the Fish and Wildlife Service) conducted extensive food habits studies on DCCOs and 

other fish-eating birds across the continent, with particular emphasis on potential 

economic impacts. More recently, the Service has conducted or funded several sitespecific studies of cormorant food habits in areas such as the Penobscot River and upper 

Penobscot Bay, Maine; Les Cheneaux Islands, Michigan; and the Mississippi River 

Delta, Mississippi. In 1999, the Service provided funding for a DCCO population status 

assessment to be prepared by researchers from the University of Minnesota and utilized 

in the development of this EIS (Wires et al. 2001). This report, “The Status of the 

Double-Crested Cormorant (Phalacrocorax auritus) in North America,” is available 

online at http://migratorybirds.fws.gov/issues/cormorant/status.pdf. 

DCCO population monitoring is carried out cooperatively by the Service, APHIS/WS, 

the Canadian Wildlife Service, the States, and various universities. The U.S. Geological 

Survey (Patuxent Wildlife Research Center) and non-governmental organizations 

participate in recording and analyzing the population data. The various types of surveys 

include the Great Lakes Colonial Waterbird Survey, Atlantic Coast Colonial Waterbird 

Survey, winter roost surveys, Christmas Bird Counts, and Breeding Bird Surveys. 

Additionally, the APHIS/WS National Wildlife Research Center is involved in a variety 

of DCCO research projects, including controlled experiments to assess DCCO impacts to 

gross catfish production; a two-year satellite telemetry study in Alabama, Arkansas, 

Louisiana, and Mississippi aimed at monitoring migratory movements of DCCOs 

captured at aquaculture areas; a two-year satellite telemetry study in eastern Lake Ontario 

(in cooperation with the New York State Department of Environmental Conservation) 

aimed at assessing the efficacy of control activities at the Little Galloo Island breeding 

colony in eastern Lake Ontario; development of a deterministic population model for 

DCCOs; and preparation of a report titled “A Science-Based Initiative to Manage 

Double-Crested Cormorant Damage to Southern Aquaculture.” 

Information and Education Outreach. The Service participates in outreach activities to 

respond to public concerns and to educate the public about DCCOs. In 1998, the 

Service’s Division of Migratory Bird Management developed a fact sheet on DCCOs, 

and placed it on its website at http:// migratorybirds.fws.gov/issues/cormorant/ 

cormorant.html. Subsequently, the cormorant subcommittee of the Service’s Great Lakes 

Ecosystem Team, with involvement by State fish and wildlife agency personnel, has 

produced a cormorant fact sheet series. Additionally, the Service provided funding and 

production assistance to New York Sea Grant to produce the video “Managing 

Cormorants in the Great Lakes.” 

 

Service personnel have attended numerous public workshops pertaining to DCCOs and 

their management, often participating with State fish and wildlife agency personnel. In 

1997, the Service, together with APHIS/WS, organized a symposium on the biology and 
11 – Chapter 1 

management of DCCOs in the Midwest and published the proceedings (Tobin 2000). In 

November 2000, the Service cooperated with University of Minnesota researchers in 

putting together a one-day workshop on the DCCO-fisheries conflict, which brought 

together biologists and managers from around the nation and the world. Service 

personnel have also accepted many invitations to speak to citizens around the U.S. who 

are interested in cormorants and the Service’s role in managing migratory birds. 

1.4.5 The Role of Other Agencies in Cormorant Management 

Because DCCOs fall under the authority of the MBTA, the Service has the primary 

responsibility for establishing guidelines for the take of cormorants. Consequently, 

management options available to States and other agencies are limited by our policies and 

practices. However, some States have been and continue to be actively engaged in 

research activities and the implementation of management activities authorized by the 

Service. 

Control Activities. A survey completed by Wires et al. (2001) found that 10 States (out of 

37 States and provinces that responded to the survey) reported the use of DCCO control 

methods. Six of the States employing control measures were in the southern U.S.; these 

States were conducting control programs because of depredations at aquaculture facilities 

and fish hatcheries. All of these States incorporated lethal and non-lethal control 

measures. In the Northeast, New York and Vermont are employing control measures due 

to habitat destruction and impacts to other colonial waterbirds in Lake Ontario and Lake 

Champlain. Massachusetts has undertaken limited control measures at specific sites. 

Additionally, the State of Oregon conducts annual DCCO harassment programs near the 

Oregon coast. 

Table 1. States Practicing DCCO Control (from Wires et al. 2001) 

State Lethal measures Non-lethal measures

AL Shooting Harassment 

AR Shooting Harassment, noise-making, decoys 

LA Shooting Multiple harassment techniques 

MA None Harassment 

MS Shooting Harassment; Night roost dispersal program 

NY Egg destruction, egg oiling Nest destruction 

OK Shooting Hazing 

TX Shooting Harassment 

VA Yes1 Yes1

VT Egg oiling Harassment; nest destruction 

1 Both lethal and non-lethal measures are undertaken, but details on specific measures employed were not 

provided. 

DCCOs also occur in Canada and Mexico. In Canada, DCCOs are not protected 

federally and thus are managed at the provincial level. The Province of Québec has 

conducted limited DCCO population control and Ontario is in the process of evaluating 

the need for such action. As in the U.S., Canadian DCCO populations are generally 

increasing. We are currently unaware of any involvement by Mexico in management of 

DCCOs. The precise status of DCCO populations in Mexico is unknown but probably 
12 – Chapter 1 

stable (Wires et al. 2001). It was last estimated by Carter et al. (1995b) at about 6,969 

breeding pairs. 
13 – Chapter 2 

CHAPTER 2: ALTERNATIVES 

2.1 Introduction 

This chapter, considered the “heart of the environmental impact statement” (40 CFR 

1502.14), describes the six alternatives being evaluated for the purpose of managing 

DCCOs in the contiguous United States. It also states the “proposed action” (Alternative 

D), which is our preferred alternative for meeting the purpose and need stated in Chapter 

1. 

2.2 Rationale for Alternative Design 

All alternatives considered were evaluated in relation to their ability to reduce resource 

conflicts associated with DCCOs, increase management flexibility, and conserve healthy 

populations of DCCOs over the long term. NEPA regulations require the analysis of a 

No Action (or “status quo”) alternative. The other alternatives were developed after 

evaluating comments received during the public scoping period, holding interagency 

meetings and internal discussions, and reviewing the best available information. After 

the DEIS public comment period, we discussed and developed changes to the proposed 

action to improve its potential for efficacy in dealing with cormorant conflicts and in 

ensuring the conservation of populations of DCCOs and other Federally-protected 

species. Each alternative described below is analyzed in more detail in Chapter 4, 

ENVIRONMENTAL CONSEQUENCES. 

2.3 Proposed Action 

The agency’s proposed action is the alternative that the agency believes would satisfy the 

purpose and need (as stated in Chapter 1) and fulfill its mission and statutory 

responsibilities, while giving consideration to economic, environmental, technical, and 

other factors. The proposed action, Alternative D, would: (1) create a public resource 

depredation order to authorize State fish and wildlife agencies, Tribes, and APHIS/WS in 

24 States to control DCCOs on public and private lands and freshwaters to protect public 

resources; (2) expand the aquaculture depredation order to allow winter roost control by 

APHIS/WS in 13 States; and (3) allow take of DCCOs at public fish hatcheries under the 

depredation orders. Based on our analysis, the proposed action would be more effective 

than the current program; is environmentally sound, cost effective, and flexible enough to 

meet different management needs around the country; and does not threaten the longterm sustainability of DCCO populations or populations of any other natural resource. 

2.4 Description of Alternatives 

2.4.1 Alternative A: No Action (Continue existing DCCO damage management 

policies)

Under this alternative, existing wildlife management policies and practices would 

continue with no additional regulatory methods or strategies being authorized. This 

alternative includes non-lethal management techniques (as described under Alternative 

B) and activities carried out under depredation permits and the aquaculture depredation 

order. Control techniques include the take of adults and young (by shooting), eggs (by 

means of oiling or destruction), and active nests (by removal or destruction). Because of 

Director’s Order No. 27, “Issuance of Permits to Kill Depredating Migratory Birds at 
14 – Chapter 2 

Fish Cultural Facilities,” depredation permits are not issued for the take of DCCOs at 

National Fish Hatcheries. However, the aquaculture depredation order allows DCCOs to 

be killed at State-operated fish hatcheries in 13 States (and at commercial freshwater 

aquaculture facilities). All other conflicts are dealt with on a case-by-case basis, 

requiring a Federal permit for every locality and occurrence where DCCO control actions 

take place. All depredation permits would continue to be issued by the appropriate 

Service Regional Office. Population surveys on breeding grounds would continue to be 

conducted at regular intervals. 

The issuance of depredation permits to take cormorants and other depredating migratory 

birds is guided by the regulations found in 50 CFR §21.41. There it states that an 

application for a depredation permit must be submitted to the appropriate Service 

Regional Director and that each application must contain a description of the area where 

depredations are occurring; the nature of the crops or other interests being injured; the 

extent of such injury; and the particular species of migratory birds committing the injury. 

The following table describes how the Service Regional Migratory Bird Permit Offices 

have interpreted 50 CFR §21.41 and §21.47 for various resource categories. 
15 – Chapter 2 

Table 2. Service Practice for Issuance of Depredation Permits for DCCOs under 

Alternative A (No Action) 

Aquaculture

Private and State facilities in 13 States do not require a permit because they fall under the aquaculture 

depredation order (AL, AR, FL, GA, KY, LA, MN, MS, NC, OK, SC, TN, and TX). 

In States not covered by the depredation order APHIS/WS makes recommendations and USFWS issues 

permits to take birds, eggs, and/or active nests. 

Director’s Order No. 27 prohibits lethal control of fish-eating birds at “public” hatcheries except when an 

“emergency” exists. 

Natural Resource Issues on Public Lands/Waters

Permits issued by USFWS when action is considered necessary to ensure survival and/or recovery of 

Federal- or State-listed threatened and endangered species. 

Permits may be issued by USFWS if there exists convincing evidence that a regionally significant bird 

population or rare and declining plant communities are being adversely affected by DCCOs. 

Permits may be issued by USFWS to alleviate depredation at the site of fish stocking but requests for 

permits are generally not issued for birds taking free-swimming fish in public waters. 

Other Natural Resource and Economic Issues

Permits may be issued by USFWS if there is significant economic damage to privately-stocked fish on a 

privately-owned water body that maximizes fishing opportunities for patrons, whether done for a fee or 

for recreation. 

Permits typically issued by USFWS for significant property damage (for example, physical structures or 

vegetation) on public or private lands and waters. 

Human Health and Safety

Permits issued by USFWS when evidence exists of significant human health and safety risks (for 

example, airports or water quality). 

2.4.2 Alternative B: Non-lethal Management (Do not allow lethal management 

actions)

Under this alternative, permits allowing the lethal take of DCCOs or their eggs would not 

be issued. The aquaculture depredation order would be revoked and depredation permits 

would not be issued. To reduce impacts associated with DCCOs, this option would allow 

only non-lethal management techniques such as harassment, habitat modification, 

exclusion devices at production facilities, and changes in fish stocking practices. 

Essentially, only those management techniques not currently requiring a Federal 

depredation permit would be continued under this alternative. Population surveys would 

be conducted at regular intervals. 

 
16 – Chapter 2 

2.4.3 Alternative C: Increased Local Damage Control (Expand current wildlife 

damage management policy) 

The intent of this alternative would be to expand the current DCCO depredation policy to 

address a broader range of resource conflicts than under the No Action (see Table 3 

below). The permit renewal period for DCCO depredation permits would change from 

annual to biennial in order to help alleviate the increased permit review requirements 

(this means that permittees would reapply for a permit every two years instead of each 

year). The aquaculture depredation order would continue to allow DCCOs to be killed at 

commercial freshwater aquaculture facilities and State-owned fish hatcheries in 13 States 

and would be expanded to include winter roost control at aquacultural facilities in those 

States. Director’s Order No. 27 prohibiting lethal control of DCCOs at public fish 

hatcheries would be revoked. Non-lethal techniques would remain part of the 

management program. Population surveys would be conducted at regular intervals. 
17 – Chapter 2 

Table 3. Service Policy for Issuance of Depredation Permits for DCCOs under 

Alternative C 

Aquaculture

Private and State facilities in 13 States do not require a permit because they fall under the aquaculture depredation 

order (AL, AR, FL, GA, KY, LA, MN, MS, NC, OK, SC, TN, and TX). (Same as No Action) 

In States not covered by the depredation order APHIS/WS makes recommendations for permit issuance and 

USFWS may issue permit to take birds, eggs, and/or active nests. (Same as No Action) 

Aquaculture depredation order expanded to include lethal control at winter roost sites in those 13 States. (Different 

than No Action) 

Director’s Order No. 27 prohibiting lethal take at public hatcheries revoked. (Different than No Action) 

Natural Resource Issues on Public Lands/Waters

Permits issued by USFWS when action is considered necessary to ensure survival and/or recovery of Federal- or 

State-listed threatened and endangered species. (Same as No Action) 

Permits issued by USFWS for conflicts with fish, wildlife, plants, and other wild species when there is 

documentation of significant impacts or when best professional judgment has determined that there is a high 

likelihood that DCCOs are a significant detriment to the resource in question. In the latter case, a permit will be 

issued when the control efforts will not threaten the viability of DCCO or other wildlife populations and the agency 

requesting the permit prepares a site-specific management plan containing: (1) a definition of the conflict(s) with 

DCCOs, including a statement of the management objectives for the area in question; (2) a description of the 

evidence supporting the hypothesis that DCCOs are contributing to these resource conflicts; (3) a discussion of 

other limiting factors affecting the resource (e.g., biological, environmental, socioeconomic); and (4) a discussion 

of how control efforts are expected to alleviate resource conflicts. (Different than No Action) 

Other Natural Resource and Economic Issues 

Permits issued by USFWS if there is significant economic damage to privately-stocked fish on a privately-owned 

water body that maximizes fishing opportunities for patrons, whether done for a fee or for recreation. (Same as No 

Action) 

Permits issued by USFWS for significant property damage (for example, physical structures or vegetation) on 

public or private lands and waters. (Same as No Action) 

Human Health and Safety

Permits issued by USFWS when evidence exists of significant human health and safety risks (for example, airports 

water quality). (Same as No Action) 

2.4.4 PROPOSED ACTION – Alternative D: Public Resource Depredation Order 

(Establish a new depredation order to address public resource conflicts)

Alternative D creates a public resource depredation order to authorize State fish and 

wildlife agencies, Federally-recognized Tribes, and APHIS/WS to take DCCOs found 

committing or about to commit, and to prevent, depredations on the public resources of 

fish (including hatchery stock at Federal, State, and Tribal facilities), wildlife, plants, and 

their habitats. This authority applies to all lands and freshwaters (with appropriate 

landowner permission) in 24 States (Alabama, Arkansas, Florida, Georgia, Illinois, 

Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, 
18 – Chapter 2 

Missouri, New York, North Carolina, Ohio, Oklahoma, South Carolina, Tennessee, 

Texas, Vermont, West Virginia, and Wisconsin). This alternative also revises the 

aquaculture depredation order by specifying that it is applicable to commercial freshwater 

facilities and State and Federal fish hatcheries, and by authorizing APHIS/WS employees 

to take DCCOs at roost sites in the vicinity of aquaculture facilities during the months of 

October, November, December, January, February, March, and April. Director’s Order 

No. 27 prohibiting lethal control of DCCOs at public hatcheries will not be revoked at 

this time, as was stated in the DEIS. Depredation permits would continue to be used to 

address conflicts outside the authority of the depredation orders. Agencies acting under 

the public resource depredation order will be required to comply with monitoring and 

reporting requirements and persons operating under the aquaculture depredation order 

must annually provide a current mortality log. Population surveys will be conducted at 

regular intervals. 

Table 4. Service Depredation Policy under Alternative D (PROPOSED ACTION) 

Aquaculture 

Private, State, and Federal facilities in 13 States do not require a permit because they fall under the 

aquaculture depredation order. (Different than No Action) 

In States not covered by the depredation order APHIS/WS makes recommendations for permit issuance and 

USFWS may issue permit to take birds, eggs, and/or active nests. (Same as No Action) 

Aquaculture depredation order expanded to include lethal control at winter roost sites in 13 States. 

(Different than No Action)

Natural Resource and Economic Issues on Public Lands/Waters 

In 24 States, State fish and wildlife agencies, Tribes, and APHIS/WS may take DCCOs to protect public 

resources (fish, wildlife, plants, and their habitats) on private and public lands and freshwaters. In nondepredation order States, depredation permits for public resource damages will be issued in accordance 

with 50 CFR 21.41 and applicable Service policies. (Different than No Action) 

Permits issued by USFWS for significant property damage (for example, to physical structures or 

vegetation) on public or private lands and waters. (Same as No Action)

Human Health and Safety 

Permits issued by USFWS when evidence exists of significant human health and safety risks (for example, 

at airports or when water quality is compromised). (Same as No Action)

2.4.5 Alternative E: Regional Population Reduction (Develop population objectives 

and implement actions aimed at reducing overall DCCO populations) 

This alternative would entail the development of regional DCCO population objectives 

designed to reduce damages associated with DCCOs. Population objectives would be 

developed on an interdisciplinary, interagency basis and would be based on the best 

available data, while giving consideration to other values. Control would be carried out 

at nesting, roosting, wintering and all other sites in order to achieve those objectives as 

rapidly as possible without adversely affecting other protected migratory birds or 

threatened and endangered species. The aquaculture depredation order would allow 

DCCOs to be killed at commercial freshwater aquaculture facilities and Federal, State, 

and Tribal fish hatcheries in 13 States and would be expanded to include winter roost 

control in those States. For all conflicts not addressed under the aquaculture depredation 

Comment: 
19 – Chapter 2 

order or the special statewide cormorant permit, depredation permits would be issued 

according to the policy outlined in Alternative C above. Non-lethal techniques would 

remain part of the management program, but only voluntarily. Population surveys would 

be conducted at regular intervals. 

2.4.6 Alternative F: Regulated Hunting (Establish frameworks for a hunting season 

on DCCOs)

Under this alternative, frameworks to develop seasons and bag limits for hunting DCCOs 

would be established jointly by Federal and State wildlife agencies. These seasons would 

coincide with those for waterfowl hunting. Additionally, the depredation policy outlined 

in Alternative C, above, would address DCCO conflicts (issuance of depredation permits 

and the aquaculture depredation order). Population monitoring would be conducted at 

regular intervals. 

2.5 Alternatives Considered but Eliminated from Detailed Study 

2.5.1 No Management Alternative 

This alternative would not allow for any Federal management or control of DCCOs (no 

depredation permit issuance, no depredation order, no harassment or habitat modification, 

etc.). To implement this alternative would be to ignore conflicts associated with 

cormorants that must be addressed if we are to fulfill our duties to manage America’s 

migratory birds responsibly. Since there is real biological and socioeconomic evidence 

(as described in Chapter 3, AFFECTED ENVIRONMENT) justifying the need for 

DCCO management, we find this alternative to be unreasonable (NEPA states that only 

“reasonable” alternatives must be considered). 

2.5.2 Rescindment of Migratory Bird Treaty Act Protection Alternative 

This alternative would entail amending the MBTA and associated international 

conventions to remove the DCCO from the List of Migratory Birds (those species 

protected under the MBTA). DCCOs would still be protected under the laws of most 

States. This action would require amending the Mexican treaty and could have the 

undesirable result of losing protection for all species in the cormorant family 

(Phalacrocoracidae). We feel that this would be a drastic action that would establish 

precedent for removing other species and would undermine the authority of the MBTA. 

 

2.6 Comparison of Alternatives 

Each alternative described above would utilize a variety of non-lethal management 

techniques. All of the alternatives we analyzed, except Alternative B, would allow for 

limited lethal take (shooting, egg oiling or destruction, and/or nest destruction), either 

through depredation orders or the issuance of depredation permits. Additionally, 

Alternative F would develop hunting frameworks for DCCOs. Differences among 

alternatives in the degree of lethal take are primarily related to the circumstances under 

which permits are issued (to control local damages or to reach population objectives) and 

which depredation order is in effect (aquaculture, expanded aquaculture, and/or public 

resource). 
20 – Chapter 2 

Table 5. Actions by Alternative 

Alternative Actions

Alternative A – No Action non-lethal management1; aquaculture depredation order2; 

depredation permits3 

Alternative B – Non-lethal 

management

non-lethal management1

Alternative C – Increased Local 

Damage Control

non-lethal management1

; expanded aquaculture depredation order2; 

depredation permits3 

Alternative D – PROPOSED 

ACTION 

non-lethal management1

; expanded aquaculture depredation order2; 

depredation permits3

; public resource depredation order4 

Alternative E – Regional 

Population Reduction

non-lethal management1

; expanded aquaculture depredation order2; 

depredation permits3

Alternative F – Regulated Hunting non-lethal management1

; aquaculture depredation order2; 

depredation permits3

, hunting seasons in participating States 

1 = includes all management techniques that are not considered “take” and thus do not 

require a depredation permit (harassment, exclusion devices, habitat modification, etc.) 

2 = under the aquaculture depredation order, DCCOs may be taken by shooting with 

firearms during daylight hours; those using shotguns are required to use nontoxic shot 

3 = under depredation permits, shooting, egg oiling or destruction, and nest destruction 

are the most common techniques utilized 

4

 = under the public resource depredation order, DCCOs may be taken by shooting, egg 

oiling or destruction, nest destruction, cervical dislocation, and CO2 asphyxiation (all of 

which are classified as humane euthanasia techniques for birds by the American 

Veterinary Medical Association) 
21 – Chapter 2 

Table 6. Actions by Alternatives 

A: No 

Action 

B: Nonlethal 

Management

C: 

Increased 

Local 

Damage 

Control 

PROPOSED 

ACTION 

D: Public 

Resource 

Depredation 

Order 

E: 

Regional 

Population 

Reduction 

F: 

Regulated 

Hunting 

New regulatory 

strategies no no no yes yes yes 

Continued issuance of 

depredation permits yes no yes yes yes yes 

Continuation of 

aquaculture depredation 

order yes no yes yes yes yes 

Expansion of 

aquaculture depredation 

order no no yes yes yes yes 

Creation of public 

resource depredation 

order no no no yes no no 

Allows take of nests yes yes yes yes yes yes 

Allows take of eggs yes no yes yes yes yes 

Allows take of adults 

and young yes no yes yes yes yes 

Allows harassment of 

adults and young yes yes yes yes yes yes 

Development of 

regional population 

objectives no no no maybe yes no 

Management activities 

occur on public lands yes yes yes yes yes yes 

Management activities 

occur on private lands yes yes yes yes yes yes 

Requires additional 

monitoring and 

evaluation no no no yes yes yes 
22 – Chapter 3

CHAPTER 3: AFFECTED ENVIRONMENT

3.1 Introduction

The “affected environment” section of an EIS should “succinctly describe the 

environment of the area(s) to be affected by the alternatives under consideration” (40 

CFR 1502.15). Thus, this chapter contains a discussion of the biological and 

socioeconomic environments relevant to the issues raised during scoping. 

3.2 Biological Environment 

3.2.1 Double-crested Cormorants 

The Service’s goals in migratory bird management are to conserve DCCO populations at 

sufficient levels to prevent them from becoming threatened or endangered and to ensure 

that American citizens have continued opportunities to enjoy DCCOs. 

Species Range. DCCOs are native to North America and range widely there. There are 

essentially five different breeding populations, variously described by different authors 

as: Alaska, Pacific Coast, Interior, Atlantic, and Southern. Recent population expansion, 

however, has blurred the boundaries for the Interior, Atlantic, and Southern populations 

(Hatch and Weseloh 1999, Wires et al. 2001). There is high variation in the migratory 

tendencies of these different breeding populations. Birds that breed in Florida and 

elsewhere in the Southeastern U.S. are essentially sedentary, those along the Pacific coast 

are only slightly migratory, while Atlantic and Interior birds show the greatest seasonal 

movements (Johnsgard 1993). The two primary migration routes appear to be down the 

Atlantic coast and through the Mississippi-Missouri River valleys to the Gulf coast 

(Palmer 1962) with increasing numbers of birds remaining in the Mississippi Delta 

(Jackson and Jackson 1995). Refer to Appendix 2 for a map of the distribution of DCCO 

breeding colonies in North America. 

Habitat Requirements. In the breeding season, two factors are critical to DCCOs: suitable 

nesting sites and nearby feeding grounds (van Eerden and Gregersen 1995, Hatch and 

Weseloh 1999, Wires et al. 2001). Ponds, lakes, slow-moving rivers, lagoons, estuaries 

and open coastlines are utilized. Small rocky or sandy islands are utilized when 

available. Nests are built in trees, on structures, or on the ground. Nesting trees and 

structures are usually standing in or near water, on islands, in swamps, or at tree-lined 

lakes. 

Nonbreeding habitats are diverse and include lakes, ponds, rivers, lagoons, estuaries, 

coastal bays, marine islands, and open coastlines (Johnsgard 1993). Wintering DCCOs 

require similar characteristics in feeding, loafing, and roosting sites as when breeding. 

Where DCCOs winter on the coast, sandbars, shoals, coastal cliffs, offshore rocks, 

channel markers, and pilings are used for roosting. Birds wintering along the lower 

Mississippi River roost on perching sites such as trees, utility poles, or fishing piers and 

in isolated cypress swamps (Reinhold and Sloan 1999, Wires et al. 2001). In all seasons 

DCCOs require suitable places for nighttime roosts and daytime resting or loafing. 

Roosts and resting places are often on exposed sites such as rocks or sandbars, pilings, 

wrecks, high-tension wires, or trees near favored fishing locations (Wires et al. 2001). 
23 – Chapter 3

From the time DCCOs return to their breeding colonies in the spring until the adults are 

brooding young, the colony site is their main “center of activity,” (i.e., they roost at the 

colony overnight and their daily foraging activities emanate from there). While most 

adults are attending young, however, auxiliary overnight roosts begin to develop. These 

may be on nearby unoccupied islands or they may be several miles away. The origin of 

the birds forming these roosts is not known for certain but they are most likely adults who 

have failed in their breeding attempts and/or non-breeding birds. The net result is that a 

new or additional “center of activity” is created in an area where the birds themselves do 

not otherwise breed. These late season roosts often remain active until the birds have left 

on migration in September or October. For example, DCCOs do not breed in the Bay of 

Quinte, a 60 mile-long, Z-shaped bay in northeastern Lake Ontario. However, in June, 

well before the migratory season, DCCOs begin to roost, at night, on islands in the bay 

and their numbers increase there through September. Birds come from these islands on 

daily foraging trips and have, in essence, established new centers of activity that are not 

related to the breeding colony, nor are they (yet) comprised of migrant birds (D.V. 

Weseloh, CWS, pers. comm.). 

Double-crested Cormorant Demographics. The DCCO is the most abundant of five 

species of cormorants occurring in the contiguous United States (the other species are 

Great Cormorant, Neotropic Cormorant, Pelagic Cormorant, and Brandt’s Cormorant). A 

conservative estimate of the total population of DCCOs in the U.S. and Canada is greater 

than 1 million birds, including breeding and non-breeding individuals, but is probably 

closer to 2 million (Tyson et al. 1999). We estimate that the current continental 

population of DCCOs is approximately 2 million birds. This number was derived by 

consulting the literature and discussing our estimate with waterbird biologists Linda 

Wires (University of Minnesota), Dr. Francie Cuthbert (University of Minnesota), Dr. 

Chip Weseloh (Canadian Wildlife Service), and John Trapp (USFWS). We used the 

Tyson et al. estimate of 372,400 breeding pairs as our base number. We multiplied that 

by 2 to get the number of breeding individuals (744,280). Then we multiplied that by 

2.26, an estimate for the ratio of non-breeding to breeding birds (Weseloh unpubl. data) 

that is well within the published estimates ranging from 1-4 nonbreeders per breeder). 

This amounts to 1,682,073 and adding that to 744,280 comes to 2,426,353 birds total. In 

2000, Chip Weseloh (unpubl. data) estimated the North American population for 

breeding and non-breeding immature DCCOs (but not adult non-breeders) at 1.850 

million. Based on this information and discussions with the individuals mentioned 

above, we adjusted our estimate of 2.4 million to 2.0 million. 

While the total number of DCCOs in North America increased rapidly from the 1970s 

into the 1990s (Hatch 1995), estimates of Tyson et al. (1999) indicated that the overall 

rate of growth in the U.S. and Canada slowed during the early 1990s. This is consistent 

with declines in the growth rate of expanding Great Cormorant populations in 

northwestern Europe (van Eerden and Gregersen 1995) and with the general rule that the 

growth rate of wildlife populations decreases as it gets closer to carrying capacity. 
24 – Chapter 3

For the U.S. as a whole, according to Breeding Bird Survey (BBS) data (which are 

indices of relative abundance), the breeding population of DCCOs increased at a 

statistically significant rate of approximately 7.5 percent per year from 1975-2002 (Sauer 

et al. 2003). Within this period, growth rates of regional populations varied substantially 

and thus it is important to look at DCCO population growth rates from a regional 

perspective as well. The table below summarizes the regional populations as described in 

Tyson et al. 1999. The narratives that follow integrate the populations delineations used 

by Tyson et al. 1999 and Wires et al. 2001. See Appendix 2 for the distribution of DCCO 

breeding colonies in North America. 

Table 7. DCCO Breeding Population Estimates (from Tyson et al. 1999) 

 Estimated # of nesting 

pairs 

Percent of continental 

population 

Estimated population 

growth rate * 

Atlantic 85,510 23% -6.5% (15.8%) 

Interior 256,212 68% 6.0% (20.8%) 

Southeast 13,604 4% 2.6% (76.9%) 

West Coast-Alaska 17,084 5% -7.9% (-0.6%) 

TOTAL > or = 372,410 2.6% (16.2%) 

* number in parentheses indicates “category A” estimates (i.e., results of surveys in which nests were 

systematically counted) 

Atlantic 

Twenty-three percent of North America’s DCCOs are found in the Atlantic population 

(Tyson et al. 1999). In this region, DCCOs are strongly migratory and, on the coast, 

occur with smaller numbers of Great Cormorants. From the early 1970s to the early 

1990s, the Atlantic population increased from about 25,000 pairs to 96,000 pairs (Hatch 

1995). While the number of DCCOs in this region declined by 6.5 percent overall in the 

early to mid-1990s, some populations were still increasing during this period (Tyson et 

al. 1999). Very large numbers breed in Quebec and the surrounding area (including the 

St. Lawrence River and its estuary) and in Nova Scotia and Prince Edward Island. Very 

large breeding concentrations also occur in New England along the coasts of Maine and 

Massachusetts. With the exception of Maine (where numbers began declining between 

the mid-1980s and early 1990s), rapid increases have occurred since the 1970s (Wires et 

al. 2001). From 1977 to the 1990s, the number of DCCOs in the northeastern U.S. 

increased from 17,100 nesting pairs to 34,200 pairs (Krohn et al. 1995). In parts of 

southern New England (Connecticut, Rhode Island, coastal New York) the DCCO has 

recently been documented as a breeding species and numbers are growing fairly rapidly. 

First breeding records were obtained in New Jersey and Pennsylvania between the late 

1970s and 1990s (Wires et al. 2001). The total estimated number of nesting pairs in this 

population is $85,510 (Tyson et al. 1999). 

Small numbers of DCCOs winter in some New England States but most Atlantic birds 

winter along the coast from Virginia (where numbers of wintering birds are increasing) 

southward, along the Gulf of Mexico, and in the lower Mississippi valley (Dolbeer 1991, 

Hatch 1995, Wires et al. 2001). 
25 – Chapter 3

Interior 

Nearly 70 percent of North American DCCOs are found in the Interior region (Tyson et 

al. 1999). DCCOs in this region are highly migratory and are concentrated in the 

northern prairies, particularly on the large, shallow lakes of Manitoba (Canada), which 

has the largest number of breeding DCCOs in North America (Hatch 1995, Wires et al. 

2001). A large number of Interior DCCOs nest on or around the Great Lakes as well, and 

recent evidence indicates that they are beginning to establish themselves at small inland 

lakes in the vicinity (Alvo et al. 2002). Since the early 1970s, numbers of Interior 

DCCOs have increased rapidly. 

From 1990 to 1997, the overall growth rate in the Interior region was estimated at 6 

percent (Tyson et al. 1999) with the most dramatic increases occurring on Ontario, 

Michigan, and Wisconsin waters (Wires et al. 2001). From 1970 to 1991, the Great 

Lakes breeding population alone increased from 89 nests to over 38,000 nests, an average 

annual increase of 29 percent (Weseloh et al. 1995). From 1991 to 1997, the number of 

nests in the Great Lakes further increased to approximately 93,000, an average annual 

increase of 22 percent. Nest counts in 2000 estimated 115,000 nests in the Great Lakes 

(Weseloh et al. 2002). Average annual growth rates in the Great Lakes were lower for 

the period 1990-2000 than the period 1980-1990 (Weseloh et al. 2002). The total 

estimated number of nesting pairs in the Interior population (including Canada) is 

$256,212 (Tyson et al. 1999). 

Southern 

Most DCCOs in this region are wintering migrants from the Interior and Atlantic regions 

(Dolbeer 1991, Jackson and Jackson 1995). However, nesting DCCOs in this region are 

on the rise with some nesting occurrences representing first record and others 

recolonizations (Wires et al. 2001). Historically, sedentary breeding populations of 

DCCOs occurred in Florida and other southern states north to North Carolina (Hatch 

1995), while in recent years DCCOs have started breeding again in Arkansas, Georgia, 

Mississippi, and Tennessee (Wires et al. 2001). Today, four percent of the North 

American breeding population of DCCOs occurs in the Southeast region (Tyson et al. 

1999). Currently, breeding colonies exist in Arkansas, Delaware, Florida, Georgia, 

Louisiana, Maryland, Mississippi, North Carolina, South Carolina, Tennesee, Texas, and 

Virginia (Wires et al. 2001). The total estimated number of nesting pairs in this 

population is >13,604 (Tyson et al. 1999). 

Over the last few decades, numbers of wintering DCCOs have dramatically increased in 

several southern States. Since the late 1970s, wintering DCCOs have increased by nearly 

225 percent since the early 1990s in the Mississippi Delta. From an average of 30,000 

DCCOs counted during the winters of 1989-93 (Glahn et al. 1996) to over 73,000 

counted in the winter of 2001-2002 (G. Ellis, APHIS/WS, unpubl. data). Data from 

Christmas Bird Counts conducted between 1959-1988 show increases ranging from 3.5-

18.7 percent in several States within this region, with the largest increases occurring in 

Louisiana, Mississippi, and Texas (Wires et al. 2001). In New Mexico, Texas, and 

Louisiana DCCOs overlap in range with Neotropic Cormorants. 
26 – Chapter 3

Pacific Coast-Alaska 

Approximately 5-7 percent of North America=s DCCOs are found in this population, 

which has approximately 27,500 nesting pairs according to Carter et al. (1995b) or 

>17,084 pairs according to Tyson et al. (1999). Alaska DCCOs represent approximately 

12 percent of the entire Pacific coast marine population (Carter et al. 1995b) and occur 

with Red-faced Cormorants. Throughout their coastal range DCCOs exist with larger 

numbers of Pelagic and Brandt=s Cormorants and at the southern extent of their range in 

Mexico they occur with Neotropic Cormorants (Hatch 1995). Alaska breeding 

populations (P. a. cincinatus) are thought to have declined since historical times, but 

recent population trends are not known (Wires et al. 2001). Non-Alaska Pacific coast 

breeding DCCOs (P. a. albociliatus) occur from British Columbia through Sinaloa, 

Mexico. Historical declines throughout the range are well documented and recent 

population status and trends for coastal populations, from British Columbia through 

California, are reasonably complete. However, because recent data are not available for 

significant portions of this subspecies range (e.g., Mexico and some interior areas) it is 

not possible to summarize recent trends for the population as a whole. Carter et al. 

(1995) documented recent increases in California and Oregon, and declines in British 

Columbia, Washington, and Baja California. Tyson et al. (1999) did not consider 

Mexican populations and calculated a decline for the entire West Coast-Alaska region. In 

the past 20 years, the largest increases in the region have taken place in the Columbia 

River Estuary, where East Sand Island supports the largest active colony along the coast 

with 6,390 pairs in 2000 (Carter et al. 1995b, Collis et al. 2000, Wires et al. 2001). 

Increases at East Sand Island coincided with declines in British Columbia, Washington, 

and locations in interior Oregon and the rapid increase undoubtedly reflected some 

immigration from these other areas (Carter et al. 1995). 

Another area of recent explosive population increase is Salton Sea, California. Complete 

surveys of interior California populations were conducted between 1997-1999 (Shuford 

2002). Shuford estimated 6,825 pairs breeding at 29 active colonies and 80 percent of all 

interior pairs occurred at Salton Sea. DCCOs at Salton Sea, increased from zero (1990-

1994) to 5,600 pairs in 1999, and then back to zero from 2001 through 2003 (Shuford 

2002, C. Pelizza pers. comm.). 

Factors associated with population increases. Factors contributing to the resurgence of 

DCCO populations include reduced levels of environmental contaminants, particularly 

DDT; increased food availability in breeding and wintering areas; and reduced human 

persecution (Ludwig 1984, Vermeer and Rankin 1984, Price and Weseloh 1986, Fox and 

Weseloh 1987, Hobson et al. 1989, Weseloh et al. 1995, Wires et al. 2001). A brief case 

study of DCCOs in the Great Lakes provides an example of factors associated with 

changes in DCCO population numbers: 

In the early 1940s, DCCO populations in the American and Canadian Great Lakes were increasing rapidly 

(Postupalsky 1978, Weseloh et al. 1995). After 1945, however, organochlorine pesticides came to be 

widely used in the Great Lakes basin. The residues of such chemicals, particularly DDT, are ecologically 

persistent and rapidly bioaccumulate in the aquatic food web, and this led to severe eggshell thinning in 

DCCOs and other waterbirds. Cormorant eggs with thinned shells broke easily during incubation and led 

to a period, in the 1950s and 1960s, of almost zero productivity due to low hatching success (Postupalsky 

1978, Weseloh et al. 1983, Weseloh et al. 1995). Similar eggshell thinning and reproductive failure were 
27 – Chapter 3

also found in DCCOs in southern California in the late 1960s (Gress et al. 1973). Following restrictions on 

the use of DDT in 1972, levels of organocholorine contaminants found in DCCO eggs declined in much of 

the Great Lakes (Ryckman et al. 1998) and DCCO productivity increased accordingly during the late 1970s 

(Scharf and Shugart 1981, Ludwig 1984, Noble and Elliot 1986, Price and Weseloh 1986, Bishop et al. 

1992a and b). Organochlorine contaminant-related eggshell thinning no longer appears to be a major 

limiting factor for DCCO reproduction on the Great Lakes (Ryckman et al. 1998), even though there are 

still lingering effects of these chemicals in parts of this ecosystem three decades after they were banned 

(Custer et al. 1999). 

Changes in the food supply available to Great Lakes cormorants, on both the breeding 

and wintering grounds, have also played a role in their population increase. Great Lakes 

fish populations underwent major changes in the 20th century. Populations of forage fish 

species increased significantly during the late 1950s through the 1980s, likely as a result 

of dramatic declines in large, native predatory fish, such as lake trout and burbot, that 

occurred during the 1940s and 1950s. These declines in larger predatory fish were 

brought about by a combination of such factors as overfishing, sea lamprey predation, 

and loss of spawning habitat (Weseloh et al. 1995) and led to population explosions of 

smaller forage fish species. In particular, rainbow smelt and alewife, neither of which are 

native to the upper Great Lakes, became very abundant in Lakes Michigan, Huron, 

Ontario, and Erie through the 1970s and 1980s (Environment Canada 1995). Various 

studies suggest that annual productivity and post-fledging survival of DCCO young are 

high in years of alewife abundance (Palmer 1962; van der Veen 1973, Weseloh and 

Ewins 1994). In fact, changes in prey abundance have been associated with increases in 

populations of several fish-eating bird species worldwide (Environment Canada 1995). 

The growth of the aquaculture industry has provided DCCOs with an abundant food 

supply on their southern wintering grounds. The aquaculture industry (consisting largely 

of channel catfish production) has experienced significant growth in the southern U.S. 

over the last 20 years. While Great Lakes DCCOs historically migrated down to the 

coastal areas of the Gulf of Mexico to winter, since the early 1970s wintering populations 

of DCCOs in the lower Mississippi valley have been increasing (Reinhold and Sloan 

1999, Glahn et al. 1996). The DCCO is the primary avian predator utilizing channel 

catfish stocks (Wywialowski 1998, Reinhold and Sloan 1999). Glahn et al. (1999b) 

analyzed monthly changes in body mass of wintering DCCOs in the delta region of 

Mississippi and in areas without extensive aquaculture production and found that DCCO 

utilization of catfish has likely increased winter survival and contributed to the 

cormorant’s recent population resurgence. 

Human persecution has also been a factor. DCCOs were not Federally protected until 

1972. Weseloh et al. (1995) suggested that the cormorant’s initial rate of colonization 

into the Great Lakes was suppressed by human persecution until the 1950s. Indeed, 

destruction of DCCO nests, eggs, young, and adults, by fishermen and government 

agencies, was a common occurrence in the Great Lakes basin from the 1940s into the 

1960s (Baillie 1947, Omand 1947, Postupalsky 1978, Ludwig 1984, Craven and Lev 

1987, Ludwig et al. 1989, Weseloh and Ewins 1994, Weseloh et al. 1995, Matteson et al. 

1999) and in the Pacific Northwest (Gabrielson and Jewett 1940, Ferris 1940, Mathewson 

1986, Bayer and Ferris 1987, Carter et al. 1995a). Similar control efforts, involving 

large-scale spraying of eggs, occurred in Maine in the 1940s and 1950s (Gross 1951, 
28 – Chapter 3

Krohn et al. 1995, Hatch 1995) and in Manitoba on Lake Winnipegosis during the same 

period (McLeod and Bondar 1953, Hatch 1995). In 1972, DCCOs were added to the list 

of birds protected by the MBTA, which made it illegal to kill them in the U.S. without a 

Federal permit. 

Double-crested Cormorant Population Parameters. Compared to other common colonial 

waterbirds, the population dynamics of DCCOs have not been well-studied (Wires et al. 

2001, Hatch and Weseloh 1999). The similar life histories of DCCOs and Great 

Cormorants (i.e., their being ecological counterparts), however, allow North American 

managers to gain insight from management efforts in Europe (Glahn et al. 2000b). Due 

to their large clutch size and persistent renesting efforts, DCCO breeding success is fairly 

high compared to other North American cormorants and colonial waterbirds in general 

(Johnsgard 1993). 

Age at First Breeding 

Van der Veen (1973) found that most birds bred for the first time at age 3 (i.e., entering 

their fourth year). Johnsgard (1993, citing van Tets in Palmer 1962) also stated that “the 

usual age of initial breeding in this species is probably three years, although successful 

breeding has occurred among two-year-olds.” In the early 1990s, Weseloh and Ewins 

(1994) observed first-breeding by many 2-year olds on Little Galloo Island in Lake 

Ontario. Blackwell et al. (2002) estimated that at least 17 percent of 2-year old, and 98.4 

percent of age-3+, Lake Ontario DCCOs breed. 

Clutch Size

Average clutch sizes observed over the years include: 3.8 eggs in Utah (Mitchell 1977); 

3.5 eggs in Maine (Mendall 1936); 3.11 eggs in Ontario (Peck and James 1983); 3.2 eggs 

in Alberta (Vermeer 1969); 3.6 and 3.2 on the Madeleine Islands in Quebec (Pilon et al. 

1983); 2.7-4.1 eggs, with a mode of 4, in British Columbia (van der Veen 1973); an 

average of 3.12 eggs over four years on Little Galloo Island, Lake Ontario (Weseloh and 

Ewins 1994); and 4.1-4.2 eggs at Columbia River Estuary colonies in Oregon (Roby et al. 

1998, Collis et al. 2000). 

Hatching Success 

Van der Veen (1973) found that hatching success varied from 50-75 percent in DCCOs in 

British Columbia. Drent et al. (1964) reported an average hatching success of 60.4 

percent on Mandarte Island in British Columbia, while Mitchell (1977) observed a 

hatching success of 54.2 percent in Utah. During two years of study on the Madeleine 

Islands, Quebec, hatching success rates of 74.5 and 71.8 percent were observed by Pilon 

et al. (1983). Roby et al. (1998) estimated hatching success in the Columbia River 

Estuary to be 56 percent. Wires et al. (2001) reported that DCCO hatching success is 

usually 50-75 percent. 

Fledging Success 

Van der Veen (1973) estimated fledging success at 74-95 percent (1.2-2.4 young per 

nest). Drent et al. (1964) observed a 95 percent fledging success rate on Mandarte Island, 

British Columbia, or an average of 2.4 young fledged per nest. In Utah, Mitchell (1977) 
29 – Chapter 3

reported a 72 percent fledging success rate. Pilon et al. (1983) reported fledging success 

rates of 2.1 and 2.4 young per year in Québec. Slightly lower average rates of 1.8 young 

fledged per nest (Hobson et al. 1989) and 1.9 young fledged per nest (Vermeer 1969) 

were observed in Manitoba and Alberta, respectively. Average productivity for the Great 

Lakes, between 1979 and 1991, ranged from 1.5 to 2.4 young per nest (Weseloh et al. 

1995). Roby et al. (1998) and Collis et al. (2000) estimated that cormorants in the 

Columbia River Estuary fledged an average of 1.6 and 1.2 chicks on East Sand Island and 

2.1 and 1.6 chicks on channel markers in the estuary during 1997 and 1998, respectively. 

Fowle et al. (1999) estimated productivity to be 2.5 young fledged per nest on Young 

Island in Lake Champlain, Vermont. Wires et al. (2001) reported that fledging success 

for DCCOs is typically 1.2-2.4 young per nest. 

Survivorship 

Average lifetime production has been estimated at 3.28 young per female (van der Veen 

1973). Mean adult life expectancy was approximated at 6.1 years, with an estimated 

first-year survival rate of 48 percent, second-year survival rate of 74 percent, and 3+ 

years survival rate of 85 percent (van der Veen 1973). Madenjian and Gabrey (1995) 

estimated DCCO survival rates at: 58 percent from age 0 to age1; 75 percent from age 1 

to 2 and age 2 to 3; and 80 percent for ages 3 to 4 and beyond. This is similar to survival 

rates estimated in European Great Cormorants: 35-54 percent in the first year, 75 percent 

in the second year, and 85 percent for year three and beyond (Veldkamp 1997, 

Bregnballe et al. 1997). Blackwell et al. (2002) estimated that annual survival of Lake 

Ontario DCCOs from fledging to just before age 1 was 30-35 percent and annual adult 

survival was 85 percent. Mean annual productivity for Lake Ontario DCCOs was 

estimated at 1.7-2.5 young per nest (Blackwell et al. 2002). 

A major mortality factor throughout the species’ range is predation. Johnsgard (1993) 

cited several studies indicating the following species as predators of DCCO chicks and/or 

eggs: California Gulls, Ring-billed Gulls, Herring Gulls, Great black-backed Gulls, 

American Crows, Fish Crows, Northwestern Crows, Common Ravens, and Bald Eagles. 

The British Columbia Wildlife Branch has associated DCCO colony failures with 

disturbance by Bald Eagles and predation by Northwestern Crows and Glaucous-winged 

Gulls (1999 unpubl. data). 

Other causes of mortality include disease (e.g., Newcastle disease which killed over 

20,000 DCCOs in colonies in the Great Lakes, Minnesota, and North and South Dakota 

in 1992 [Glaser et al. 1999]), illegal human persecution, and entanglement in fishing gear 

(Hatch and Weseloh 1999). Cormorant populations are influenced by both densitydependent and density-independent factors (Cairns 1992a), with age of first breeding, 

occurrence of non-breeding, and clutch abandonment the demographic parameters most 

likely to respond to density (Hatch and Weseloh 1999). In a population model developed 

for great cormorants in Europe, Bregnballe et al. (1997) assumed three types of density 

dependent mechanisms: increased exclusion of potential breeders, reduced fledgling 

production, and increased food competition on wintering grounds. 
30 – Chapter 3

Cormorants, like other fish-eating birds, accumulate contaminants from the fish they eat. 

DCCO populations declined dramatically in association with high levels of contaminants 

during the 1960s and early 1970s. In fact, eggs of Herring Gulls, DCCOs, and Common 

Terns were found to contain some of the highest levels of organochlorine compounds in 

the world (Struger et al. 1985). Effects of chlorinated hydrocarbons on DCCOs have 

been most studied in the Great Lakes, where breeding populations had accumulated high 

contaminant burdens and showed severe impacts (Ryckman et al. 1998, Hatch and 

Weseloh 1999). Avian eggs and carcasses in Wisconsin were examined and contained 

detectable levels of several organochlorine contaminants (Dale and Stromborg 1993). 

The effects of these contaminants on DCCOs includes eggshell thinning (Anderson and 

Hickey 1972, Postupalsky 1978), elevated embryonic mortality (Gilbertson et al. 1991), 

reproductive failure and population declines (Weseloh et al. 1983, 1995), increased adult 

mortality (Greichus and Hannon 1973), increased embryonic abnormalities and crossed 

bills (Fox et al. 1991, Yamashita et al. 1993, Ludwig et al. 1996), egg mortality (Tillitt et 

al. 1992), and brain asymmetry (Henschel et al. 1997). 

Over the years, the Service and the Canadian Wildlife Service have used fish-eating birds 

such as cormorants to study the impacts of long-term exposure to persistent lipophilic 

environmental contaminants within the Great Lakes ecosystem (Fox et al. 1991). 

Contaminant levels started decreasing in the 1970s and have continued to do so up to the 

present, with most associated biological parameters improving accordingly (Hatch and 

Weseloh 1999) . For example, by 1995, most contaminant residues in DCCO eggs had 

declined by 83-94 percent (Ryckman et al. 1998). However, contaminant levels in Great 

Lakes DCCOs continue to be significantly higher than in most other parts of North 

America (Somers et al. 1993, Sanderson et al. 1994), partly because of the long 

hydrologic retention times and depth of the Great Lakes, which renders them particularly 

sensitive to chemical inputs (De Vault et al. 1996). 

Little work has been done on the effects or occurrence of metals in cormorants. Mercury 

is most often reported, but no effects have been identified in the wild (Hatch and Weseloh 

1999). Methyl mercury is highly toxic; animal studies have indicated that chronic 

exposure to high mercury levels is associated with kidney damage, reproductive 

problems, nervous system effects, and other health problems (Johnson et al. 1998). In 

New Brunswick, total mercury concentrations in tissues of DCCOs were highest of nine 

seabird species examined (Braune 1987). A study in the Carson River, Nevada, found 

that DCCOs had the highest mercury concentrations of three species examined (Henny et 

al. unpubl. data). Additionally, recent research on loons in New York State and New 

England has shown that loons are exposed to high levels of methylmercury in these areas 

(“Loons sound alarm on mercury contamination,” Natl. Geog. Today, May 16, 2003). 

Because of their similar niche, it can be safely assumed that DCCOs also harbor high 

mercury levels in certain areas. However, contaminants are not currently a significant 

limiting factor of DCCO populations at the regional or continental scale. 

Double-crested Cormorant Foraging Ecology. DCCOs are rarely seen out of sight of 

land and are opportunistic, generalist feeders, preying mainly upon abundant fish species 

that are easy to catch (usually slow-moving or schooling fish, ranging in size from 3-40 
31 – Chapter 3

cm [1.2-16 in]), although most commonly less than 15 cm (6 in). Glahn et al. (1998) 

reported that availability (i.e., abundance), rather than size, is probably the most 

important factor in prey selection, but given equal availability DCCOs prefer prey fish 

that are greater than 7.5 cm (3 in) in length. They also suggested that prey fish 

accessibility is important in DCCO prey selection. Neuman et al. (1997) attributed 

variation in DCCO diet in Lakes Huron, Erie, and Ontario to movements of fish into 

shallow spawning areas and to spatial heterogeneity of fish habitat. 

Studies indicate that DCCOs have strong habitat preferences with respect to depth, 

distance from the breeding colony, and distance from nearest shore (Stapanian and Bur 

2002). The prey of Atlantic birds suggests that they feed at the bottom of the water 

column, while that of Pacific and inland birds suggests that they feed in mid-water. 

DCCOs usually forage in shallow, open water (less than 8m) within 5 km of shore (Hatch 

and Weseloh 1999), although they will go farther. In freshwater lakes, DCCOs forage at 

fairly shallow depths and likely take prey from all levels fairly uniformly (Johnsgard 

1993). A study examining DCCOs in the western basin of Lake Erie found that the most 

significant foraging pressure occurred in areas within a 20 km radius of nesting colonies, 

within 3 km of shore, and in waters less than or equal to 10 m in depth (Stapanian et al. 

2002). Neuman et al. (1997) determined that cormorant foraging distances at Little 

Galloo Island (Lake Ontario) ranged from 3.7 to 20 km (with an average distance of 13 

km). Custer and Bunk (1992) reported that birds from two colonies in the Wisconsin 

waters of Lake Michigan foraged an average of 2-2.4 km from the colonies, with over 90 

percent of flights being within 9 km of the colonies. In Texas, Campo et al. (1993) found 

that the average estimated distance from the foraging area to the nearest shore ranged 

from 20 to 975 meters. 

DCCOs respond rapidly to high concentrations of fish and will congregate where fish are 

easily caught, such as “put and take” lakes, stocking release sites, and aquaculture ponds 

(Hatch and Weseloh 1999, Wires et al. 2001). The DCCO appears to be almost 

completely diurnal in its feeding habits. When pursuing prey, it dives from the surface 

and chases fish underwater. While bottom-feeding is usually solitary, DCCOs may form 

loose foraging flocks when feeding on schooling prey. In this way, birds create a line 

that moves forward as individuals at the rear fly short distances to “leapfrog” diving birds 

in the front. DCCOs engaged in this behavior have been documented in Georgian Bay, 

Ontario; Massachusetts; and Green Bay, Wisconsin, as have Great Cormorants in The 

Netherlands (Glanville 1992, Custer and Bunck 1992, van Eerden and Voslamber 1995, 

Hatch and Weseloh 1999). Observations of such behavior were also mentioned frequently 

during the public scoping period. For specifics of foraging behavior at aquaculture 

facilities see Appendix 3. 

3.2.2 Fish 

Among natural resource agencies, a survey conducted by Wires et al. (2001) indicated 

that DCCO predation was perceived to be of major importance to sport and/or 

commercial fish in at least three States (Arkansas, Tennessee, and Texas), and of 

moderate importance in at least eight States (Alabama, Connecticut, Louisiana, Maine, 

Massachusetts, New York, Rhode Island, and Virginia). The APHIS/WS MIS database 
32 – Chapter 3

reveals that, from FY 1995-2001, of the 29 States reporting losses to natural resources, 27 

reported losses to wild fish species. During public scoping, letters received from the 

following States indicated concern about impacts to sport fisheries: Arkansas, Georgia, 

Illinois, Kansas, Kentucky, Louisiana, Maine, Michigan, Nebraska, New York, North 

Dakota, Ohio, Oklahoma, Oregon, Texas, Vermont, Wisconsin, and Wyoming. 

The diet of DCCOs consists largely of fish (generally slow-moving or schooling species), 

with some occurrence of aquatic animals such as insects, crustaceans, reptiles, and 

amphibians (Johnsgard 1993, Hatch and Weseloh 1999). Trapp et al. (1999) conducted a 

review of diet studies carried out between 1923 and 1994 and found that of 75 fish 

species detected as DCCO prey items, only 29 species comprised more than 10 percent of 

the diet at a specific site and, of those 29, five species consistently comprised greater than 

10 percent of the diet: alewife, brook stickleback, ninespine stickleback, yellow perch, 

and slimy sculpin. These results confirm the popular notion that the DCCO is an 

opportunistic feeder, utilizing a wide diversity of prey. A review of the diet literature by 

Wires et al. (2001) indicated that, in general, sport and commercial fish species do not 

contribute substantially to DCCO diet, although they and Trapp et al. (1999) both cited 

exceptions to this rule. 

In general, DCCO diet varies highly among locations and tends to reflect the fish species 

composition for each location, making it necessary to examine diet on a site-specific 

basis (Belyea et al. 1999, Wires et al. 2001). But some regional generalizations can be 

made about fish consumed by DCCOs. On the Pacific coast, no single species emerged 

as the most important prey item in past studies, although some species were very 

important in certain regions. In the Columbia River Estuary, diet composition differed at 

the two main colonies. At Rice Island, salmonids were the most important prey item with 

stickleback and peamouth also being important; at East Sand Island, shad, herring, and 

sardine were the most important prey items, with salmonids and starry flounder also 

important (Collis et al. 2000). In other areas, fish such as shiner perch, sculpin, gunnel, 

snake prickleback, sucker, and sand lance proved important components of DCCO diet 

(Wires et al. 2001). Aside from Pacific salmonids, several of which are Federally-listed 

as threatened or endangered, the populations of none of these fish species are a regional 

or national concern. 

In the Great Lakes, fish species such as alewife and gizzard shad, appear to be the most 

important prey items. Stickleback, sculpin, cyprinids, and yellow perch and, at some 

localities, burbot, freshwater drum, and lake/northern chub are also important prey fish 

species (Wires et al. 2001). Stapanian et al. (2002) wrote that, “Diet and foraging studies 

in the Great Lakes suggest that cormorants are opportunistic foragers that eat mostly 

small prey fish, such as young-of-the-year and yearling gizzard shad..., emerald 

shiner..., freshwater drum..., alewives..., and sticklebacks...,” most of which have little 

sport or commercial value, while noting that “cormorants consume large quantities of 

smallmouth bass and yellow perch in the waters near Little Galloo Island in Lake 

Ontario.” Studies suggest that considerable temporal variation exists in the diet of Great 

Lakes DCCOs (Johnson et al. 2002, Neuman et al. 1997); this can likely be attributed to 

fish movement, much of which is related to spawning (Johnson et al. 2002). 
33 – Chapter 3

In the southeastern U.S., most of the diet consists of shad, catfish, and sunfish species 

(Wires et al. 2001). In the Atlantic region, diet varies to a great extent, with no single 

species emerging as most important. In coastal habitats, cod, sculpin, cunner, and gunnel 

are important as well as sand lance and capelin. Where DCCOs are found inland or at 

estuaries, alewife, rainbow smelt, stickleback, smallmouth bass, yellow perch, 

pumpkinseed, cyprinids, and salmonids (mainly Atlantic salmon) are important prey 

items (Wires et al. 2001). Of these species, Atlantic salmon are Federally-listed as 

threatened, smallmouth bass and yellow perch are important sport fish, and cod, alewife, 

and rainbow smelt are commercially fished. Concern about impacts of DCCO predation 

on these fish has been expressed. 
34 – Chapter 3

Table 8. Geographic Range of Common DCCO Prey Species 

Largemouth Bass: originally ranged in the Atlantic slope watersheds south of Maryland, the St. Lawrence River 

basin, Great Lakes, and Mississippi River basin to northeastern Mexico. They have been stocked throughout the 

United States. 

Smallmouth Bass: originally ranged from Minnesota to Quebec, including the Great Lakes, southward to northern 

Alabama, and west to eastern Kansas and Oklahoma. Because of its sporting qualities, it has been introduced to 

many other states, Canadian provinces, and 41 other countries. 

Channel Catfish: naturally occurred in the central and eastern United States and southern Canada. They ranged 

throughout the Mississippi River drainage to northeast Mexico; to the east from the St. Lawrence River, along the 

western slope of the Appalachian Mountains to central Florida. They were conspicuously absent along the 

watersheds of the Atlantic seaboard. The species has been widely introduced for sport fishing throughout the 

United States. 

Walleye: native range is throughout most of eastern North America, including Great Lakes, but has been 

introduced to Western North American streams where habitat is suitable. 

Northern Pike: range is extensive, greater than any other freshwater game fish. Pike can be found throughout the 

northern half of North America, including the Great Lakes. 

Yellow Perch: on the Atlantic coast, range from South Carolina north to Nova Scotia. They can also be found west 

through the southern Hudson Bay region to Saskatchewan, including the Great Lakes, and south to the northern 

half of the Mississippi drainage. 

Bluegill: original range includes most of central and eastern United States, north into southern Canada. 

Alewife: native to the Atlantic Coast and entered the upper Great Lakes through the Welland Canal. Alewife 

populations have become established in Great Lakes and many landlocked lakes in New York, Maine, 

Connecticut, and other New England states. 

Gizzard Shad: Mississippi and Atlantic drainages, including the Great Lakes. 

Rainbow Smelt: essentially a marine species with chief distribution along Canadian coastal waters. Intruded into 

fresh waters of northeastern U.S. and the Great Lakes. 

Health of the Great Lakes: An Overview. In order to examine the cormorant population 

explosion in the U.S. and Canadian Great Lakes and its impact to fisheries from an 

“ecological” perspective, it helps to examine the ecosystem health of the Great Lakes. 

An excellent overview of the aquatic community health of the Great Lakes is that of a 

working paper presented at the State of the Lake Ecosystem Conference (Koonce 1995). 

This discussion is derived largely from that source. By most standards, the Great Lakes 

ecosystems are “extremely unhealthy.” The most notable justifications for this 

description are the Lakes’ dramatic loss of biological diversity and the establishment of 

non-indigenous populations (Koonce 1995). 

The Great Lakes Fact Sheet produced by Environment Canada’s Ontario Region 

(available online at http://www.on.ec.gc.ca/wildlife/factsheets/fs_cormorants-e.html)

provides a concise summary of the “rise and fall of Great Lakes fish populations”: 

Great Lakes fish populations have undergone some profound changes in the last 60 years. One of these was 

the dramatic decline of large predatory fish, primarily Lake Trout and, to a lesser extent, Burbot. In Lake 

Ontario the most dramatic declines of these species occurred in the late 1930s and 1940s, while in Lake 

Huron they occurred during the 1940s and 1950s. The decline of the predatory fish was caused by many 

factors, including years of heavy fishing, the invasion of the sea lamprey, the loss of spawning areas. 

Increased amounts of toxic contaminants entering the lakes may have also been a factor. 

With the decline of larger predatory fish, the smaller fish species underwent an unprecedented population 

explosion. The main species involved in this increase were Rainbow Smelt and Alewife, neither of which 

was native to the upper Great Lakes. Rainbow Smelt were introduced to the Great Lakes in Michigan in 

1912. They spread slowly through the lakes, becoming common in Lakes Michigan and Huron by the 
35 – Chapter 3

1930s and in Lakes Ontario and Erie by the late 1940s. Alewife were abundant in Lake Ontario by the 

1890s but did not become common in Lakes Michigan and Huron until the demise of the Lake Trout in the 

mid-late 1940s. 

Thus, for a period of 30 years (1950s - 1970s) these smaller prey species increased in a manner more or less 

unchecked by any predatory fish or birds higher up the food web. The smaller prey fish came under heavy 

predation pressure in the 1980s, with the massive stocking of salmon and trout in most of the Great Lakes. 

As a result, the population of smaller fish decreased. However, in spite of this predation, Alewife remained 

abundant throughout much of the Great Lakes and were fed upon heavily by cormorants during this period. 

Indeed, fish play a major role in structuring aquatic ecosystems. At least 18 fish species 

of historical importance have declined significantly or disappeared from one or more of 

the Great Lakes (Koonce 1995). Accompanying these changes in native biodiversity 

have been a series of invasions and introductions of non-native fish species. Species that 

have established substantial populations include: sea lamprey, alewife, rainbow smelt, 

gizzard shad, white perch, carp, brown trout, Chinook salmon, coho salmon, pink salmon, 

rainbow trout, ruffe, rudd, fourspine stickleback, and two species of goby. In total, 139 

non-native aquatic organisms (including plants, invertebrates, and fish) have become 

established in Great Lakes ecosystems (Koonce 1995). 

These changes in the biodiversity of the Great Lakes have been, and continue to be, 

caused by a number of chemical, physical, and biological stresses, the most important of 

which include: (1) large-scale degradation of tributary and nearshore habitat for fish and 

wildlife; (2) imbalances in aquatic communities due to population explosions of invading 

species such as sea lamprey, alewife, white perch, and zebra and quagga mussels; (3) 

reproductive failure of lake trout; (4) alterations of fish communities and loss of 

biodiversity associated with overfishing and fish stocking practices; and (5) impacts of 

persistent toxic chemicals on fish and wildlife (Koonce 1995). 

Koonce (1995) also noted that “evaluation of the health of the aquatic community of the 

Great Lakes is complicated,” mainly due to three important factors. First, identification 

of factors responsible for particular population effects (e.g., increased mortality rates or 

decreased reproductive rates) is difficult because different factors can produce similar 

effects on populations. Second, since populations and communities are adaptive, with 

healthy communities able to self-regulate in the presence of internal/external stresses, a 

variety of “healthy” states may be functionally equivalent (in at least an ecological 

sense). Third, the Great Lakes are disturbed ecosystems for which there are no 

undisturbed communities to serve as benchmarks for recovery; thus, “the determination 

of the wellness of an ecosystem requires a value judgment.” 

3.2.3 Other Birds 

In a survey conducted by Wires et al. (2001), impacts to other bird species were reported 

by the States of Arkansas, Illinois, Iowa, Maine, Massachusetts, Michigan, Mississippi, 

New York, Ohio, Vermont, and Wisconsin. Impacts to other colonial waterbirds, 

particularly herons and egrets, were reported most often and these impacts were 

associated mainly with habitat degradation and competition for nest sites. During our 

EIS public comment periods, several resource agencies expressed concern about actual or 

potential impacts to other birds. 
36 – Chapter 3

Over the course of their life cycle, individual DCCOs may interact with other species of 

birds in a variety of ways. These interactions may involve competition for nest sites, 

competition for food, and disease transmission. 
37 – Chapter 3

Table 9. Avian Associates of DCCOs (Source: Kaufman 1996 and Ehrlich et al. 1988) 

American White Pelican: Habitat includes lakes, marshes, salt bays. Total population probably declined through 

first half of 20th century, but has increased substantially since 1970s. 

Anhinga: Habitat includes cypress swamps, rivers, and wooded ponds in the southern U.S. 

Black-crowned Night-Heron: Habitat includes marshes and shores; roosts in trees. Populations probably declined 

in 20th century due mostly to habitat loss; in recent years, overall population is generally stable or increasing, but 

declining in the U.S. Great Lakes. See Table 10 below. 

Brandt’s Cormorant: Habitat includes rocky areas along Pacific coast. Local populations fluctuate, but overall 

numbers probably stable. 

Caspian Tern: Habitat includes large lakes, coastal waters, beaches, bays. Overall population probably stable, 

perhaps increasing. 

Common Tern: Habitat includes lakes, ocean, bays, beaches. Northeastern populations probably lower than they 

were historically. Some inland populations declining, including Great Lakes. 

Great Black-backed Gull: Habitat mostly includes coastal waters and estuaries along the Atlantic coast. Populations 

increasing and breeding range steadily expanding. 

Great Blue Heron: Habitat includes marshes, swamps, shores, tideflats; very adaptable. Common and widespread, 

numbers stable or increasing. 

Great Cormorant: Habitat includes ocean cliffs with some found on large inland rivers in winter. North American 

population (also found throughout Europe) has increased dramatically in recent decades, and breeding range has 

expanded southward along Atlantic coast. 

Great Egret: Habitat includes marshes, ponds, shores, mudflats. Nearly decimated by plume hunters in 19th century, 

recovered in 20th century. In recent decades, breeding range has gradually expanded northward, with some 

evidence that southern populations have declined. 

Herring Gull: Habitat includes ocean coasts, bays, beaches, lakes, piers, farmlands, dumps. Populations increased 

greatly in 20th century and breeding range expanded. 

Neotropic Cormorant: Habitat includes tidal waters and lakes in the southern U.S. After declines in Texas numbers 

in the 1950s and 1960s, is increasing again and may be spreading north inland. 

Pelagic Cormorant: Habitat includes cliffs and other rocky areas along Pacific coast. Population probably stable, 

with close to 75% occurring in Alaska. 

Ring-billed Gull: Habitat includes lakes, bays, coasts, piers, dumps, plowed fields. Populations high and probably 

still increasing. 

Snowy Egret: Habitat includes marshes, swamps, ponds, shores. Nearly decimated by plume hunters in 19th

century, recovered in 20th century. Has expanded breeding range northward in recent decades; populations 

increasing. 

Western Gull: Habitat includes coastal waters, estuaries, beaches, offshore islands, city waterfronts. Common, with 

overall numbers stable. 
38 – Chapter 3

Table 10. Comparisons of population estimates of Black-crowned Night-Herons in the 

Great Lakes in 1976–80, 1989–91, and 1997–2000 (from Blokpoel and Tessier 1998; 

Cuthbert et al. 2002; C. Weseloh unpubl. data; L. Harper unpubl. data) 

Body of 

Water 

1976–1980 1989–1991 1997–2000 

 No. of 

breeding 

pairs 

No. of 

colonies 

No. of 

breeding 

pairs 

No. of 

colonies 

No. of 

breeding 

pairs 

No. of 

colonies 

Lake 

Michigan 

558 11 859 10 927 11 

Lake Huron 491 12 562 13 810 19 

Lake St. 

Clair 

0 0 98 2 0 0 

Lake Erie 4,220 2 1,719 5 529 3 

Niagara 

River 

65 1 213 2 185 3 

Lake Ontario 362 6 1,221 12 1,514 10 

TOTAL 5,696 32 4,672 44 3,965 46 

3.2.4 Vegetation 

Concern about negative impacts of nesting and roosting DCCOs to vegetation has been 

expressed by the public as well as natural resource professionals. In a survey conducted 

by Wires et al. (2001) respondents from Alabama, Arkansas, Connecticut, Florida, Iowa, 

Maine, Maryland, Michigan, New Hampshire, New York, North Carolina, Ohio, 

Oklahoma, Rhode Island, Vermont, and Wisconsin reported impacts to trees, while the 

States of Iowa, Maine, Maryland, Michigan, New Hampshire, Ohio, Oklahoma, Vermont, 

Virginia, and Wisconsin reported impacts to herbaceous layers. 

DCCOs seem to prefer nesting in trees to nesting on the ground, and trees are probably 

used by older, more experienced, earlier-breeding individuals (Weseloh and Ewins 1994). 

Along the Pacific coast, however, DCCOs nest primarily on the ground, either in low 

vegetation or on the barren ground of offshore islands and coastal cliffs. Typically, 

islands with avian breeding colonies have less vegetative cover than adjacent islands with 

none and, in general, plant species diversity tends to be low in colonial waterbird nesting 

colonies (Chapdelaine and Bédard 1995). The chief concerns associated with DCCOinduced vegetation damage are displacement of other colonial waterbird species (caused 

by habitat changes) and harm to plant species/communities of special management 

significance. Into the latter category falls the Carolinian forest vegetation type, the 

northernmost geographic extension of the eastern deciduous forest ecosystem. In 

Canada, even though the Carolinian vegetation zone makes up only 1 percent of Canada's 

total land area, it boasts a greater number of species of flora and fauna, many of which 

are considered rare, than any other ecosystem in Canada 

(http://www.carolinian.org/Cc1.htm). 

3.2.5 Federally-listed Species 

A concern among members of the public and wildlife professionals, including Service 

and Wildlife Services personnel, is the impact of damage management methods and 

activities on non-target species, particularly Threatened and Endangered species. 
39 – Chapter 3

Another concern is potential impacts to Threatened and Endangered species caused by 

DCCOs themselves. For example, during the public scoping period, the Maine 

Department of Inland Fisheries and Wildlife listed DCCO predation on stocked and 

native Atlantic salmon as an issue of concern. Additionally, during the DEIS comment 

period, the State of Washington stated their concern about impacts of DCCO predation on 

wild salmonids. 

Section 7 of the Endangered Species Act (ESA), as amended (16 U.S.C. 1531-1543; 87 

Stat. 884), provides that, “The Secretary shall review other programs administered by 

him and utilize such programs in furtherance of the purposes of this Act'' (and) shall 

“ensure that any action authorized, funded or carried out ... is not likely to jeopardize the 

continued existence of any endangered species or threatened species or result in the 

destruction or adverse modification of (critical) habitat ...'' Consequently, we completed 

an intra-Service biological evaluation and informal Section 7 consultation under the ESA 

for the proposed action. 

3.3 Socioeconomic Environment 

Concerns about increasing DCCO populations extend beyond the biological to include 

social and economic impacts as well. 

3.3.1 Water Quality and Human Health 

The major human health concern expressed during public scoping was contamination of 

water supplies by DCCO excrement. Eight States expressed concern over possible 

DCCO-related impacts to water quality in a survey conducted by Wires et al. (2001). 

Those States were Alabama, Arkansas, Connecticut, Maine, Massachusetts, Michigan, 

Rhode Island, and South Carolina. Additionally, residents of Henderson, New York, near 

Little Galloo Island in eastern Lake Ontario (home to a very large DCCO colony), 

expressed concern about DCCOs presenting a threat to their groundwater. 

Waterbird excrement can contain coliform bacteria, streptococcus bacteria, Salmonella, 

toxic chemicals, and nutrients, and it is known to compromise water quality, depending 

on the number of birds, the amount of excrement, and the size of the water body. 

Although the 1992 Section 305(b) State Water Quality Reports indicate that, overall, the 

Nation's groundwater quality is good to excellent, many local areas have experienced 

significant groundwater contamination. The sources and types of groundwater 

contamination vary depending upon the region of the country, but those most frequently 

reported by States include: leaking underground storage tanks, septic tanks, municipal 

landfills, agricultural activities, and abandoned hazardous waste sites (EPA 1992). 

Concerns about water quality and DCCOs exist on two levels: contaminants and 

pathogens. 

Contaminants. Elevated contaminant levels associated with breeding and/or roosting 

concentrations of DCCOs and their potential effects on groundwater supplies are the 

major concerns regarding DCCO impacts to human health. Metals and toxic organic 

chemicals typically originate in industrial discharges, runoff from city streets, mining 

activities, leachate from landfills, and a variety of other sources. These toxic chemicals, 
40 – Chapter 3

which are generally persistent in the environment, can cause death or reproductive failure 

in fish, shellfish, and wildlife. In addition, they can accumulate in animal tissue, be 

absorbed in sediments, or find their way into drinking water supplies, posing long-term 

health risks to humans (EPA 1992). 

The most toxic and persistent environmental contaminants include chlorinated 

hydrocarbons (also known as organochlorine chemicals; e.g., PCBs, dioxin-like 

compounds, and certain pesticides such as DDT). These compounds are lipophilic 

(meaning they become chemically bound to fat molecules) and accumulate in individual 

organisms via a process known as bioaccumulation. Then, as a result of 

biomagnification, these chemicals, bound in organisms, occur at greater concentrations 

with each step of the food chain. Thus, species at the top of the food chain, such as 

DCCOs, harbor the greatest, and most toxic, levels of these contaminants. 

Pathogens. Escherichia coli (E. coli) are fecal coliform bacteria associated with fecal 

material of warm blooded animals. There are over 200 specific serological types of E. 

coli and the majority are harmless (Sterritt and Lester 1988). Aquatic birds can be a 

source of fecal contamination of water resources. For example, Simmons et al. (1995) 

used genetic fingerprinting to link fecal contamination of small ponds on Fisherman 

Island, Virginia to waterfowl. Klett et al. (1998) were able to implicate waterfowl and 

gulls as the source of fecal coliform bacteria at the Kensico Watershed, a water supply for 

New York City. Also, fecal coliform bacteria counts correlated with the number of 

Canada Geese and gulls roosting at the reservoir (Klett et al. 1998). Additionally, 

excessive numbers of resident Canada Geese can affect water quality around beaches and 

in wetlands (Draft EIS: Resident Canada Geese Management, USFWS 2002). 

3.3.2 Economic Environment 

Commercial Aquaculture Production. The APHIS/WS Management Information System 

(MIS) database reveals that, from FY 1995-2001, aquacultural resource losses to DCCO 

predation were reported in 33 states, with catfish, baitfish, and trout being the most 

commonly identified fish species. In 1996, roughly half (53 percent) of U.S. catfish 

farmers considered DCCOs to be a problem, with farmers from Mississippi (77 percent), 

Arkansas (74 percent), and Alabama (50 percent) most likely to have DCCO conflicts 

(Wywialowski 1999). In the Mississippi Delta, 87 percent of catfish farmers surveyed 

felt that they had a bird problem and losses to birds (harassment costs plus value of fish 

lost) were estimated at $5.4 million, or 3 percent of total sales (Stickley and Andrews 

1989). A survey conducted by Wires et al. (2001) found that DCCO predation at 

aquaculture facilities was perceived as a “major” problem in at least 6 States (Alabama, 

Arkansas, Louisiana, Mississippi, Tennessee, and Texas). It was perceived as a 

“moderate” problem in the States of Connecticut, Florida, Illinois, Maine, Massachusetts, 

Oklahoma, and Rhode Island. 

Aquaculture, the cultivation of finfish and invertebrates in captivity, has grown 

exponentially in the past several decades (Price and Nickum 1995, Glahn et al. 2002). 

The principal species propagated in the United States are catfish, trout, salmon, tilapia, 

hybrid striped bass, mollusks, shrimp, crayfish, baitfish and ornamental tropical fish 
41 – Chapter 3

(Price and Nickum 1995; USDA 2000a). A 1998 census revealed that the U.S. domestic 

aquaculture industry represents slightly over 4,000 farms, with total sales reaching $978 

million (USDA 2000a). Freshwater and saltwater farms accounted for over 320,700 and 

92,600 acres (129,884 and 37,503 ha) of production, respectively, in 1998 (USDA 

2000a). The 13 State southern region represented over two-thirds of the reported farms 

and total sales, followed by the western region, eastern region, north-central region, and 

the tropical and subtropical region, respectively (USDA 2000a). USDA (2000a) reported 

the top five States in U.S. aquaculture sales in 1998 were Mississippi, with sales of $290 

million of catfish; Arkansas, with $84 million of catfish and baitfish; Florida, with $77 

million of ornamental fish, mollusks and other products; Maine, with $67 million of 

Atlantic salmon; and Alabama, with $59 million of catfish. 

Catfish Industry 

Channel catfish production is the largest segment of the aquaculture industry, and the one 

which appears to be most susceptible to predation by DCCOs. See Appendix 3 for details 

of DCCO foraging behavior at aquaculture facilities. Catfish production accounts for 

approximately 50 percent of the aquaculture industry in the U.S. (Mott and Brunson 

1997. Catfish growers in 13 States reported sales of $488 million during 1999, with the 

top four production states of Mississippi, Alabama, Arkansas, and Louisiana accounting 

for 96 percent of the U.S. total sales. Mississippi farms represented over half of the 

catfish sales in 1999, with slightly over $294 million dollars in sales. There were more 

than 76,612 hectares of catfish ponds in the United States as of January 1, 2000. The four 

principal catfish-producing States accounted for 95 percent of this total, with Mississippi 

alone accounting for about 58 percent (USDA-NASS 2000a). About 90 percent of 

Mississippi’s ponds are found in northwest Mississippi; this region, known as the 

Mississippi Delta, includes 16, 000 km2

 of the Mississippi River alluvial plain (Glahn et 

al. 2002). This intensively farmed region includes catfish farms interspersed with cotton, 

soybean, rice, and corn fields and contains over 10 percent of its original wetland habitat, 

consisting of cypress swamps and bayous (Glahn et al. 2002). 

Other Industries 

Louisiana and Arkansas together represent 90 percent of the baitfish production in the 

U.S. (Price and Nickum 1995). A National Agricultural Statistics Service 1998 Census 

of Aquaculture (USDA 2000a) reported that Arkansas baitfish growers accounted for $23 

million in sales in 1998, which represented over 60% of U.S. baitfish sales. 

Trout producers in 20 states reported sales of $76.9 million in 1999, with Idaho, North 

Carolina, California, and Pennsylvania representing the top 4 states in production. Idaho 

accounted for almost half of the trout sold in the U.S. in 1999 (USDA-NASS 2000a). In 

1993, the Atlantic salmon industry was valued at $55-60 million (Price and Nickum 

1995). A National Agricultural Statistics Service 1998 Census of Aquaculture (USDANASS 2000b) reported that 47 salmon producers in the U.S. reported sales of over $103 

million, with Maine accounting for over $64 million in sales. 

 
42 – Chapter 3

USDA (2000) reported in 1998 there were 345 ornamental fish growers in the U.S. with 

$69 million in sales. Florida was reported dominating the industry, accounting for 171 of 

the ornamental fish growers and 81 percent of total U.S. sales (USDA 2000a). 

 

USDA-NASS (2000b) reported over $10 million in reported crayfish sales in 1998. The 

crayfish aquaculture industry is centered primarily in Louisiana, accounting for 

approximately 92 percent of U.S. production. Freshwater crayfishes have been most 

commonly used as food and fish bait but are also commercially used in the pet trade as 

pets and food for predaceous pet fishes, and in the academic community for teaching and 

research purposes (Huner 1997). Between 1960 and 1996, commercial crayfish acreage 

in Louisiana increased from 800 ha to 45,000 ha (Glahn et al. In Press). 

Recreational Fishing Economies. The many public benefits provided by recreational 

fishing are supported by an extensive body of Federal legislation and international treaty 

conventions. These include the Anadromous Fish Conservation Act of 1985, the Fish 

and Wildlife Coordination Act, the Fish and Wildlife Act of 1956, the Great Lakes 

Fishery Act of 1956, the Great Lakes Fish and Wildlife Restoration Act of 1990, and the 

Boundary Waters Treaty of 1909 between the United States and Great Britain (USFWS 

1995). Moreover, Executive Order 12962, signed by President Clinton in 1995, 

recognizes the social, cultural, and economic importance of recreational fisheries and 

directs Federal agencies, to the extent practicable and where permitted by law, “to 

improve the quantity, function, sustainable productivity, and distribution of U.S. aquatic 

resources for increased recreational fishing opportunities...” (USFWS 1997). 

The Service’s responsibilities related to recreational fisheries management include 

administering the Fisheries Across America grant program, in which the Service pursues 

cost-sharing opportunities with non-Federal entities to enhance recreational fishing 

opportunities by restoring aquatic ecosystems and native fish populations. Under the 

Land and Water Conservation Fund, the Service also acquires lands and waters that 

address the needs of recreationally important species. On National Wildlife Refuges, the 

Service manages recreational fisheries such as rainbow trout, arctic char, grayling, and 

sheefish in Alaska, and largemouth bass and sunfish in the lower 48 States. Outside of 

Federal lands, the Service assists States and Tribes with management of migratory 

interjurisdictional recreational fish species of national concern, such as Atlantic and 

Pacific salmon and lake trout. Finally, the Service, through its National Fish Hatchery 

System, propagates fish that are important to the survival, maintenance, and restoration of 

recreationally valuable stocks of freshwater, anadromous, and coastal fisheries (USFWS 

1997). 

Recreational fishing benefits local and regional economies in many areas of the U.S. As 

participation in a recreational fishery increases, so does the total amount of money 

entering local and regional economies as angler expenditures. In this way, growth of 

recreational fishing can stimulate economic activity (Royce 1987 in Ross 1997). During 

public scoping, concern was expressed that increased DCCO predation has negatively 

impacted recreational fisheries which has, in turn, impacted the economies of 

communities that rely heavily on income associated with recreational fishing. 
43 – Chapter 3

In 2001, 34.1 million adult anglers in the United States spent $35.6 billion and fished the 

equivalent of 557 million days. These anglers spent an average of $1,046 on fishingrelated expenses (USDI/USDC 2002). When adjusted to account for economic-multiplier 

effects, anglers’ annual spending was shown to have a nationwide economic impact of 

about $108.4 billion, support 1.2 million jobs, and add $5.5 billion to Federal and State 

tax revenues (ASA 1996). Additionally, through the Federal Aid in Sport Fish 

Restoration Program, a portion of the money that is spent by anglers on equipment and 

supplies is used to support sport fish restoration, management, or enhancement programs, 

including research activities, boating access development and maintenance, aquatic 

resource outreach and education projects, land acquisition, hatchery construction, and 

habitat enhancement. The States with the highest levels of annual fishing expenditures in 

2001 were: Florida ($4.1 billion), California ($2.0 billion), Texas ($2.0 billion), 

Minnesota ($1.3 billion), North Carolina ($1.1 billion), New York ($1.1 billion), and 

Wisconsin ($1.0 billion). 

In addition to measuring expenditure levels, “net economic value” is an indicator of the 

economic benefit to individual participants; it is measured as participants’ willingness to 

pay beyond what they spend to participate. Adding the net economic values of all 

individuals who participate in an activity derives the value to society (Boyle et al. 1998). 

For example, the mean net economic value per year for trout fishing in California, Idaho, 

Nevada, Oregon, and Washington is estimated at $126 per angler. The net economic 

value per day for the same angler would be $12. For bass and trout fishing in New York, 

the mean net economic value per year is estimated at $150, or $10 per day. However, we 

did not use net economic value determinations because we felt it would not add much 

substance to the analysis. 

The Great Lakes 

The total annual fishing expenditures for all eight Great Lakes States (IL, IN, MI, MN, 

NY, OH, PA, and WI) combined amounted to $6.7 billion in 2001 (USDI/USDC 2002). 

Outdoor recreation in the Great Lakes makes a substantial contribution to the region's 

economy and quality of life (Allardice and Thorp1995). The 2001 National Survey of 

Fishing, Hunting and Wildlife-Associated Recreation indicated that 1.8 million U.S. 

anglers fished the Great Lakes that year. Great Lakes anglers participated in 23 million 

days of fishing, or an average of 13 days per angler. Two types of fish, perch and “black 

bass” (largemouth and smallmouth bass, etc.), dominated fishing activity, together 

comprising 58 percent of the time spent fishing. Walleye and salmon fishing made up 22 

and 17 percent, respectively, of fishing activity in the Great Lakes (USDI/USDC 2001). 

Great Lakes sport fishing results in a substantial economic impact, particularly for coastal 

communities that are near popular fishing spots. Various studies (Brown et al. 1991, 

Connelly and Brown 1988) have provided evidence for the positive relationship between 

Great Lakes fisheries and tourism-related economic benefits to local communities. In 

2001, total U.S. Great Lakes fishing expenditures were projected at $1.3 billion. Triprelated expenditures, including food, lodging, transportation and guide/package fees 

amounted to $776 million and equipment-related costs totaled about $ 498 million. 
44 – Chapter 3

Expenditures per angler were figured at about $690 for the year. About half of Great 

Lakes sport fishing is done from boats, some of which make up a growing charter fishing 

industry. Since the mid-1970s, roughly paralleling the growth in sport fishing, the 

number of charter boats increased from 500 to more than 3,000 (USDI/USDC 2002; 

USDI/USDC 1997; Dawson et al. 1988). The current number of charter boats in the 

Great Lakes is unknown, but has reportedly dwindled in recent years. 

The dynamics between the availability of sport fish and the willingness of sport anglers to 

spend money in pursuit of their prey is poorly known, at least in well-documented, 

quantitative terms. A 1976 survey of licensed New York State anglers suggested that 

days of angler participation in bass fishing were found to be significantly influenced by 

angler preferences, travel costs to angling sites, proximity of neighboring sites, and the 

quantity of shoreline distance available for angling (Menz 1981). In a survey conducted 

in 1996, 65 percent of 35 million adult anglers nationwide reported that "they did not fish 

as often in 1996 as they would have liked" for two key reasons: (1) family or work 

commitments (43 percent) and not enough time (21 percent). "Not enough fish" was 

listed as a main reason by only 1 percent of respondents (USDI/USDC 1997). 

New York 

In New York, 1.3 million anglers fished for 19.3 million days and spent $ 1.1 billion in 

2001 (USDI/USDC 2002). The Lake Ontario fishery alone has been estimated to 

generate over $100 million in annual angler expenditures (Connelly et al. 1990) and, in 

1996, an estimated 188,000 anglers spent a daily average of about $34 en route and at 

location fishing in Lake Ontario and its bays (Connelly et al. 1997). 

The eastern basin of Lake Ontario is an important tourist destination, but one that faces 

major economic challenges. Jefferson and St. Lawrence counties, for example, have 

some of the highest unemployment rates in the State of New York (Schusler and Decker 

2000). The area is rich in natural and scenic resources and the success of many local 

businesses is closely related to the fish and wildlife resources of the region. Thus, many 

communities look to recreation (such as fishing) and tourism for “economic salvation” 

(Schusler and Decker 2000). In 1996, anglers spent $40.9 million in Jefferson County 

(Brown et al. 2002). Throughout the 1990s a number of businesses that depend heavily 

on eastern basin sport fisheries experienced declines in business (Brown et al. 2002). 

Recreational fishing is also economically important to the Oneida Lake area. In 1996, 

fishing trips to Oneida Lake generated an estimated $10.6 million (Cornell Cooperative 

Extension of Onondaga County 2000). In that same year, an estimated 50,850 anglers 

spent a daily average of $18 en route and at location fishing in Oneida Lake (Connelly 

1997). A report of the socioeconomic impacts associated with declining fisheries on New 

York’s Oneida Lake came to the following conclusions based on surveys of local marinas 

and sporting good shops: hundreds of anglers had moved their boats from the lake’s 

marinas, fewer out-of-state anglers were coming to the area, daily boat rentals had 

declined, bait and tackle business had declined, and fewer anglers were participating in 

local fishing derbies (Schriever and Henke 2000). 
45 – Chapter 3

Commercial Fishing. The two chief areas where DCCO impacts to open water 

commercial fish stocks are a potential concern are the Great Lakes and New England 

(both riverine and coastal). During scoping, we received a small number of complaints 

about such impacts and we thus limited our discussion of this issue in the DEIS. Upon 

further consideration, we decided to include commercial fishing discussions in the FEIS 

environmental analysis. Overall, the economic importance of commercial fishing in both 

of these areas has experienced a steady decline for reasons unrelated to fish-eating birds. 

The Great Lakes Fishery Resources Restoration Study (USFWS 1995) noted that: 

“Historically, large numbers of lake trout, lake whitefish, lake herring, walleye, blue pike, 

lake sturgeon, yellow perch and other fish populated the Great Lakes and supported a 

major commercial fishing industry. In Lake Ontario, Atlantic salmon were gone by 1900 

and sturgeon were severely depleted. Populations of commercially valuable fish further 

declined precipitously during the 1950s and 1960s due to a combination of factors, 

including overfishing, sea lamprey predation, competition with nonindigenous nuisance 

species, and pollution.” Today, commercial fishing activity in the U.S. Great Lakes is 

highest in Lake Erie and northern Lake Michigan (Hebert et al. 1999). Commercially 

exploited fish species include lake trout, lake whitefish, smelt, bloater chubs, perch, and 

alewife (EPA 1995, Crane 1996). Commercial fishing continues to face pressure on 

several fronts, including toxic contaminants, pressure by sport fishing groups to limit 

commercial catch, and restricted harvest methods (EPA 1995). In New England, 

commercial extinction of Atlantic groundfish stocks has occurred in recent years. 

Between 1990 and 1996, the reported commercial harvest of yellow perch in New York 

waters averaged 16,524 kg per year (Cluett 1997 in Burnett et al. 2002). In 1999, total 

U.S. Great Lakes commercial landings for walleye and yellow perch were valued at 

$14,830 and $2.6 million, respectively (http://www.st.nmfs.gov/pls/webpls/

MF_GL_LANDINGS.RESULTS). In comparison, the Northeast's commercial oceanic 

and estuarine fisheries produced domestic landings worth $1.098 billion dockside in 

1999, an increase of $98 million over 1998. Finfish landings brought in $360 million in 

1999, representing 33% of the revenue generated in the region. Shellfish landings brought 

in $739 million, accounting for the remaining 67 percent of revenue. (NOAA 2001; 

http://www.nefsc.noaa.gov/sos/econ/#regsum). 

3.3.3 Fish Hatcheries and Environmental Justice 

The Service has a responsibility to conserve, restore, enhance, and manage the Nation's 

fishery resources and aquatic ecosystems for the benefit of future generations. Federal 

stewardship of the Nation's fishery resources has been a core responsibility of the Service 

for over 120 years. The National Fish Hatchery System (NFHS) was established in 1871 

by Congress through the creation of a U.S. Commissioner of Fish and Fisheries. The 

original purpose of the NFHS was to provide additional domestic food fish to replace 

declining native fish populations. Cultured fish were used to replace fish that were lost 

from natural (drought, flood, habitat destruction) or human (over-harvest, pollution, 

habitat loss due to development and dam construction) influences, to establish fish 

populations to meet specific management needs, and to provide for the creation of new 

and expanded recreational fisheries opportunities. The NFHS also has a unique 

responsibility in helping to recover species listed under the ESA, restoring native aquatic 
46 – Chapter 3

populations, mitigating for fisheries lost as a result of Federal water projects, and 

providing fish to benefit Tribes and National Wildlife Refuges. 

The Service’s responsibility to provide fish stock to Tribes raises an Environmental 

Justice concern. Executive Order 12898 ("Federal Actions to Address Environmental 

Justice in Minority Populations and Low-Income Populations") requires Federal agencies 

to make environmental justice part of their mission, and to identify and address 

disproportionately high and adverse human health and environmental effects of Federal 

programs, policies and activities on minority and low-income persons or populations. 

Additionally, States and Tribes manage numerous public fish hatcheries across the 

country. For example, in Oregon, approximately 80 percent of all trout harvested come 

from Oregon fish hatcheries. In Wisconsin, fourteen State hatcheries raise fish such as 

walleye, steelhead, lake trout, and suckers. Texas fish hatcheries, such as the Texas 

Freshwater Fisheries Center, not only raise fish to stock lakes and rivers, but also offer 

opportunities for entertainment and education. Additionally, nine of eleven Great Lakes 

Indian Fish and Wildlife Commission member Tribes operate tribal fish hatcheries, 

annually stocking millions of fry and fingerlings into reservation and off-reservation 

waters. The costs associated with raising hatchery stock can be significant. For example, 

in 2001, the Oneida Lake Hatchery in New York spent approximately $265,000 

producing fry, pond fingerlings, and advanced fingerlings for stocking Oneida Lake 

(Richard Colesante, NYSDEC, Warmwater Hatchery Program Supervisor, pers. comm.). 

3.3.4 Property Losses 

Private property losses associated with DCCOs include impacts to privately-owned lakes 

and ponds that are stocked with fish, damage to boats and marinas or other properties 

found near DCCO breeding or roosting sites, and damage to vegetation on privatelyowned land. 

Conover (2002) noted the conflict arising when publicly-owned wildlife inflicts damage 

on private property. He noted that for “individual property owners who are suffering 

from wildlife damage, it is in their self-interest to stop the damage by any means 

possible, including lethal methods.” On the other hand, the perspective of others is such 

that they see “their wildlife, which they own as members of society, being destroyed for 

someone else’s private gain.” These people are not really impacted by the wildlife 

damage and so “their sentiments may lie with the wildlife and not with the property 

owners.” 

3.3.5 Existence and Aesthetic Values 

One sensible philosophy toward wildlife management is that it aims “to increase the net 

value of the wildlife resource for society while avoiding those actions which might cause 

the irrevocable loss of any part of this resource” (Conover 2002). Wildlife resources 

provide numerous benefits to society. Positive values of wildlife can be grouped into 

several categories, including physical utility, monetary, recreational, scientific, 

ecological, existence, and historic values (Giles 1978), while negative values include 

damages associated with loss of agricultural productivity, destruction of property, human 
47 – Chapter 3

injuries or fatalities, and loss of biodiversity. In general, human-wildlife conflicts occur 

more frequently and with more intensity as wildlife populations increase (Conover 2002). 

Existence value is the value a person associates with the knowledge that a resource exists, 

even if that person has no plans to directly use that resource. Individuals may hold this 

value for a number of reasons: 1) they wish to preserve the resource for future 

generations; 2) they wish to hold open the option to use the resource in some way in the 

future although they have no immediate plans to do so; or 3) they may simply feel that 

preservation of a resource is the right thing to do, and therefore attach a value to it 

(USFWS 2000a). Existence value is independent of the size of the wildlife population 

(Conover 2002). 

In addition to existence value, wildlife has aesthetic value. In fact, aesthetic benefits are 

one of the qualities commonly attributed to wildlife (Decker and Goff 1987). Aesthetic 

value refers to our sense of beauty and is, by nature, subjective and difficult to quantify. 

Koonce (1995) noted that, “a pathology from one perspective...may be a beneficial 

condition to another.” He gives an example of how, in Lake Ontario, the need to 

supplement salmonids via stocking, in order to work around the failure of lake trout 

reproduction, is a pathological symptom (at least from a naturalistic perspective). Yet 

many recreational anglers prefer catching non-native Chinook salmon and view emphasis 

on lake trout rehabilitation as disagreeable if it means a declining Chinook fishery. Thus, 

to some individuals or groups of society, aesthetic value is maximized when ecosystems 

are recovered to historic pristine levels while, to others, the existence of a good sport 

fishery is the epitome of “beautiful.” 

Aesthetic and existence value benefits are much more difficult to quantify than are 

economic impacts. No studies have been carried out to estimate the dollar value that 

Americans assign to DCCOs and, if there were, this value would certainly vary 

considerably from person to person. While we were not able to quantify the existence or 

aesthetic value of DCCOs to various stakeholders, we still feel that these are valuable 

concepts because they remind us that, although the direct economic benefits of DCCOs 

may be limited when compared to economic impacts, they are not devoid of value. 

3.3.6 Issues Raised, but Eliminated from Detailed Study 

Air and Soil. There are no significant impacts to air quality associated with DCCOs and 

none of the potential management actions would affect air quality.

Service biologists conducted sampling of soil/guano beneath DCCO nest trees on islands 

in Green Bay in 1987 and 1988 and found elevated PCB and DDE levels (Dale and 

Stromborg 1993). In 1999, soil/guano samples carried out by a private consulting firm 

found high levels of PCBs, DDE, and mercury on Little Galloo Island (LGI) in the 

eastern Lake Ontario waters of New York, home of one of North America’s largest 

DCCO colonies and greater than 55,000 Ring-Billed Gulls (Anon. 1999; J. Farquhar, 

NYSDEC, pers. comm). The report showed that, from a limited pool of soil samples, 

PCBs, DDE, and mercury were detected in levels below that for an “inactive Hazardous 

Waste Site” designation, but in three samples levels did exceed the thresholds 
48 – Chapter 3

recommended for an “unlimited human use” designation (such as a playground for 

children). However, human use of LGI, and most other DCCO colony sites, is very 

limited. Greater numbers of samples are necessary to draw more scientifically accurate 

conclusions about soil contaminant levels at LGI and other areas where DCCO excrement 

accumulates. Currently, there is not enough information to evaluate DCCO management 

alternatives in regard to this impact area. 

Aircraft Damage and Safety. Wildlife-aircraft interactions may result in loss of human 

life and/or injury to passengers or people on the ground. The risk that birds pose to 

aircraft is well documented with the worst case reported in Boston in 1960 when 62 

people were killed in the crash of an airliner which collided with a flock of starlings 

(Terres 1980). Wildlife strikes may cause expensive structural and mechanical damage 

to aircraft even if they do not result in a crash (Blokpoel 1976; Cleary et al.1997). In the 

United States in 1994, the estimated cost of bird strikes to military aircraft was $112 

million (Conover et al. 1995). The cost of wildlife aircraft strikes to civil aviation for 

1990-1998 in the United States was estimated to be in excess of 461,165 hours/year in 

aircraft down time, $253.02 million/year in direct monetary losses, and $132.96 

million/year in associated costs (Cleary et al. 1999). Associated costs include passenger 

delays, labor, parts, and costs associated with emergency services and ferrying damaged 

aircraft to repair facilities. 

All birds are potentially hazardous to aircraft and human safety; however, DCCOs 

typically do not forage or loaf in abundance near airports, making them less likely to be 

involved in collisions (USDA-APHIS 1999). According to the Federal Aviation 

Administration’s Bird Strike Database, there were a total of 26,644 reported bird strikes 

to civil aircraft in the U.S. from 1990-2000, with 16 of the strikes involving cormorants. 

Of these 16 strikes, 3 were classified as minor and resulted in wing damage to the 

aircraft, 2 were classified as substantial requiring major repair and grounding of the 

aircraft, and 11 were reported as strikes with no damage/reported damage to aircraft. The 

risk to aircraft safety associated with DCCOs is low and not considered to be a significant 

impact area. Current depredation permit practices allow for DCCO control when 

necessary to ensure aircraft safety. 

Affected Human Communities. Social impacts refer to changes in the affected area’s 

customary condition of the human environment. Specifically, this refers to changes in 

the way people live, work, play, and relate to one another. A large part of the concern 

caused by DCCOs stems from alterations in the “way of life” that is familiar to those who 

live or recreate in areas where DCCO numbers are increasing. For example, residents of 

and visitors to the Great Lakes region view outdoor recreation not only as a quality of life 

issue, but as a “way of life” (USFWS 1995). Declines in the quality of sport fishing in 

these and other areas are a major concern as is evidenced by the level of participation 

from anglers in the public scoping process. 

Based on responses received during the public scoping period, DCCOs do not appear to 

be a significant issue for Native American Tribes. We received three letters from Tribes 

or members of Tribes: (1) a member of the Kiowa Tribe of the State of Oklahoma felt 
49 – Chapter 3

that since waterbirds are sacred, they should be given to Tribal people for use in their 

native ceremonies; (2) the White Mountain Apache Tribe of Arizona recommended that 

we use a hunting season to manage DCCOs; and (3) a Conservation Officer from the 

Wampanoag Tribe of Gay Head (of southeastern Massachusetts) said that they have 

experienced some trouble with DCCOs roosting on the Tribal Shellfish Aquaculture 

Program’s spawning/rearing cages and recommended limited hunting. 

In the Great Lakes, fish are valuable economically and as an important food supply for a 

number of Native American Tribes who engage in commercial and subsistence fishing, 

particularly in Lake Superior and northern Lakes Michigan and Huron. For example, the 

Chippewa/Ottawa Indians annually harvest an average of 1.1 million kg from their Lake 

Michigan commercial lake trout fishery (USFWS 1995). However, we did not receive 

comments during scoping from regional Tribes expressing concern about DCCO impacts. 

No scientific evidence has implicated DCCOs as having a major negative impact on lake 

trout reintroduction in the Great Lakes, although they have been known to consume 

stocked smolts (USFWS 1995). 

Potentially affected human communities occur anywhere DCCOs and people coexist. Of 

particular concern are areas where DCCOs are abundant and viewed as a nuisance. We 

received a number of scoping comments expressing concerns about negative cultural 

impacts such as young people losing a safe and healthy form of recreation, retired 

citizens no longer being able to enjoy their favorite pastime, and parents losing the 

opportunity to pass on recreational knowledge to their children. Unfortunately, research 

on the sociocultural impacts associated with changes in a community’s recreational 

patterns is limited and it would be very difficult to analyze the effects of DCCO 

management alternatives on this impact area in a meaningful way. 

Historic and Cultural Resources. “Historic and cultural” aspects of the environment 

generally include historic properties, other culturally valued pieces of real property, 

cultural use of the biophysical environment, and such "intangible" sociocultural attributes 

as social cohesion, social institutions, lifeways, religious practices, and other cultural 

institutions (http://npi.org/nepa/whatare.html). These could include:

• Historic sites, buildings, districts, structures, and objects with historic, 

architectural, archeological, engineering, and cultural values. 

• Historical objects such as the equipment that might be found in a surplus 

industrial facility, objects found at or excavated from an archeological site, and 

objects associated with the history and culture of an Indian Tribe or Native 

Hawaiian group. 

• Documents with historic, folkloric, or archeological significance. 

• Places of traditional religious or cultural importance to an Indian Tribe or Native 

Hawaiian organization. 
50 – Chapter 3

• Locations regarded by a community or neighborhood, or others, as contributing to 

its "sense of place." 

• The traditional religious and cultural practices of a community, neighborhood, 

Indian Tribe, or Native Hawaiian group (http://gsa.gov/pbs/pt/callin/envbook/page41.htm). 

For the most part, the effects of DCCO populations or management actions related to 

them would have very minor, if any, impacts on these types of resources. Control 

activities are not anticipated to have any significant negative impacts on historic sites or 

other resources. In the cultural category, three issues of concern have been raised: 1) 

cormorants are considered “sacred” to some Native American Tribes, 2) the religious 

practice of abstaining from work on Sundays (i.e., observing the “Sabbath”) is inhibited 

by the need to patrol aquaculture ponds seven days a week to protect them from DCCO 

depredation, and 3) popular fishing areas could be considered an important part of a 

specific area’s “sense of place” and DCCOs are viewed by some members of the public 

as inhibiting that value. Presumably, some Tribes would disagree with killing DCCOs, 

while the latter two cultural concerns would be alleviated by control actions that 

contributed to less DCCO presence. Due to lack of empirical information, a full analysis 

of these concerns is not possible. 
51 – Chapter 4 

CHAPTER 4: ENVIRONMENTAL CONSEQUENCES

4.1 Introduction 

The “environmental consequences” section of an EIS “forms the scientific and analytic 

basis for the comparison [of alternatives]” (40 CFR 1502.16). This chapter analyzes the 

environmental consequences of each of the five alternatives in relation to issues identified 

in Chapter 3, AFFECTED ENVIRONMENT, and in comparison to the No Action 

alternative to determine if impacts would be greater, lesser, or the same. Thus, the No 

Action alternative is the baseline for the analysis. Details of the alternatives are laid out in 

Chapter 2, ALTERNATIVES. As stated in the CEQ regulations, “the agency’s preferred 

alternative is the alternative which the agency believes would fulfill its statutory mission 

and responsibilities, giving consideration to economic, environmental, technical and other 

factors.” 

NEPA requires disclosures of direct, indirect, and cumulative effects as well as mitigation 

measures. If a management activity greatly changes the amount or quality of an 

environmental factor (i.e., those issues identified in Chapter 3), the effect qualifies as 

significant. Significant effects may be positive or negative. Significant effects of some 

management activities may be unavoidable, have different short and long-term 

consequences or involve irreversible changes. Some negative effects may be mitigated to 

a level of insignificance. 

Management Activities

• Shooting 

• Oiling or destruction of eggs 

• Nest destruction 

• Cervical dislocation 

• CO2 asphyxiation 

• Harassment (may include pyrotechnics, scarecrow devices, propane exploders, 

live ammunition, vehicle horns, etc.) 

Environmental Factors

• DCCO populations 

• Fish 

• Other birds 

• Vegetation 

• Threatened and Endangered species 

• Water quality and human health 

• Economic conditions (aquaculture, recreational fishing, and commercial fishing) 

• Hatcheries and Environmental Justice 

• Property losses 

• Existence and aesthetic values 
52 – Chapter 4 

4.2 Environmental Analysis of Alternatives

4.2.1 Impacts to Double-crested Cormorants 

Alternative A: No Action 

The average actual take, as reported, under the depredation order and depredation permits 

in recent years (1998-2001) is 46,664 DCCOs per year. Since the total estimate of the 

continental DCCO population is 2 million, this represents an average annual take of 

approximately 2.1 percent of the continental population. However, the vast majority of 

this mortality affects Atlantic and Interior DCCOs while on their wintering grounds 

(since most of it is take associated with the aquaculture depredation order) so it is not 

spread evenly across the continent but concentrated in the southern U.S. The Breeding 

Bird Survey trend (mean percent change per year) for DCCOs in the U.S. and Canada, 

from 1990-2002, was 7.29 percent (P = .00127)(Sauer et al. 2002). Tyson et al. (1999), 

using a different survey technique, estimated that the overall mean percent annual change 

for the continental population of DCCOs from 1990-1994 was 2.6 percent although 

regional trends varied considerably from this average. 

Appendix 4 presents an overview of DCCO management techniques. The chief 

management actions taken under this alternative are shooting (especially at aquaculture 

facilities), egg oiling, and harassment. Shooting at aquaculture facilities is, by itself, not 

considered an effective technique for controlling DCCO populations (Thompson et al. 

1995; Simmonds et al. 1997). Indeed, despite the take of greater than 200,000 DCCOs in 

the U.S. since 1987, neither numbers of wintering birds nor of breeding birds appear to 

have been adversely impacted. This is supported by the continued steady growth seen in 

DCCO populations and by the observations of two papers on this topic: (1) Belant et al. 

(2000) documented lethal control at aquaculture facilities in the southeastern U.S. 

(including Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, 

South Carolina, and Tennessee) to evaluate the effects of these control activities on 

winter DCCO populations. Based on depredation permit data for 1987-1995, they 

estimated that 35,332 DCCOs were taken under 847 permits. The authors concluded that 

lethal control at aquaculture facilities did not adversely impact regional winter or 

continental breeding populations; and (2) Glahn et al. (2000a) concluded that the reported 

take of 9,557 DCCOs under the aquaculture depredation order by Mississippi aquaculture 

producers had no “apparent impact” on the number of DCCOs wintering in the Delta 

region. 

Table 11. Annual Estimated Take Under No Action Alternative 

Year Reported take 

under permits

Estimated take 

under Depr. 

Order (MN)

Estimated take 

under Depr. Order 

(southern)1

Total take 

(does not 

include eggs)

Percentage of 

estimated 

continental 

population

1998 12,484 2,100 29,634 44,218 2.2% 

1999 12,385 1,600 38,098 52,083 2.6% 

2000 10,493 2,200 33,990 46,683 2.3% 

2001 21,6692

 2,000 20,0003 43,6692 2.3% 1

See Appendix 5 for the methodology we used to estimate this take. 2

This number includes all reported take under depredation permits and some reported take under the depredation order. 3

These numbers are estimates based on the assumption that levels of take did not change significantly in 2001. 
53 – Chapter 4 

Table 12. Number of DCCO Depredation Permits Issued by Region 

USFWS Region Number of Permits – 2001

1 (CA, ID, NV, OR, WA) 12 

2 (AZ, NM, OK, TX) 4 

3 (IA, IL, IN, MI, MN, MO, OH, WI) 21 

4 (AL, AR, FL, GA, KY, LA, MS, NC, SC, TN) 140 

5 (CT, DE, MA, MD, ME, NH, NJ, NY, PA, RI, VA, 

VT, WV ) 

5 

6 (CO, KS, MT, ND, NE, SD, UT, WY) 14 

Currently, egg oiling activities are conducted at Lake Champlain, Vermont; Eastern Lake 

Ontario, New York; and Oneida Lake, New York. In recent years, the New York State 

Department of Environmental Conservation has oiled DCCO eggs on islands in eastern 

Lake Ontario [19,862 DCCO eggs (1999); 15,118 (2000); 14,620 (2001); and 13,977 

(2002)]. The project has continued in 2003. The Vermont Department of Fish and 

Wildlife oiled 9,569 eggs on islands in Lake Champlain in 1999 and 4,595 eggs there in 

2000. It continued to oil DCCO eggs in 2001, 2002, and 2003. 

Johnson et al. (2000a) found egg oiling to be “an effective technique to reduce the 

reproductive success of [DCCOs]” on Little Galloo Island in Lake Ontario and estimated 

that, due to egg oiling efforts, 8,300 fewer chicks were produced there in 1999. Farquhar 

et al. (2001) concluded that two years of intensive egg oiling on Little Galloo Island 

resulted in an estimated 98 percent reduction in DCCO reproductive success. However, 

Weseloh et al. (2002) observed that this success was probably highly localized. They 

pointed out that during the same time period that DCCO nest numbers declined at Little 

Galloo Island, the population on High Bluff Island (110 km to the northwest) increased 

from 2,442 pairs to 8,105 pairs and the entire Lake Ontario DCCO population increased 

from 17,066 to 24,344 pairs. Indeed, data collected by the Service (based on annual 

reports prepared by NYSDEC biologists) confirm this. It appears that while numbers on 

managed islands in New York have generally decreased, total numbers for the Eastern 

Basin and Upper St. Lawrence River area have remained steady. USFWS (2003) 

concluded that “declines from reduced reproductive output on Little Galloo Island are not 

yet affecting the area population.” 

Managers at Oneida Lake, New York, have been engaged in intensive DCCO harassment 

efforts each fall since 1998. Cormorant numbers were reduced by 61 to 98 percent in 

1998 and 80 to 98 percent in 1999-2001 compared to lakewide population estimates 

conducted during 1995-1997. Local biologists believe that the hazed DCCOs continued 

further south in their migration in reaction to the harassment (NYSDEC press release). In 

Lake Champlain, Vermont (USFWS 1999b), and eastern Lake Ontario, New York 

(USFWS 1999a), the goal of preventing colonization on specific islands by DCCOs was 

achieved through nest removal activities. 
54 – Chapter 4 

Night roost harassment is a common technique for managing DCCO depredation at 

catfish farms. Tobin et al. (2002) found that only 11 percent of harassed DCCOs returned 

to the same roost within 48 hours, compared with an 81 percent rate of return for 

unharassed DCCOs. Glahn et al. (2000a) observed that, while roost dispersal programs 

continue to shift DCCOs away from areas of high catfish concentration, such results are 

“temporary at best.” The number of known night roosts within the Mississippi Delta 

region has increased recently, making monitoring and harassment more difficult 

(Aderman and Hill 1995, Tobin et al. 2002). 

Conclusion: Current management practices (shooting, egg oiling, and harassment) have 

had no significant impact on regional or continental DCCO populations. 

Alternative B: Non-lethal Management 

The main population effects of non-lethal management efforts would be spatial (i.e., 

moving birds to different areas where they may be more or less of a problem). Nest 

removal activities, as noted above, can prove effective at preventing the establishment of 

breeding birds or, at sites where birds have previously nested, can be used to lower 

reproductive success. In the case of harassment, birds may be prevented from 

reproducing during a specific breeding season or may suffer reduced reproductive 

success because of time and energy expenditures involved in finding new nesting areas, 

but this technique is generally believed to have negligible impacts on local populations 

when practiced on a relatively small scale (USFWS 1999a,b). If prevention of 

colonization is practiced intensely, annually, and over a large enough area, it may be 

effective at managing regional populations (Bregnballe et al. 1997). 

Conclusion: An entirely non-lethal approach to cormorant damage management would 

not significantly affect DCCO populations on a regional or national scale. 

Alternative C: Increased Local Damage Control Alternative 

The main difference between management activities conducted under Alternatives C, D, 

and E would be the degree to which and by whom they are conducted. Under Alternative 

C, we estimate that depredation permit issuance would increase by no more than 30 

percent, leading to mortality of approximately 15,400 adult and/or juvenile DCCOs 

annually (the average take under depredation permits for 1998-2000 = <11,800; 30 

percent increase in mortality = 15,400). 

Egg mortality might also increase. The majority of breeding pairs in the Interior and 

Atlantic populations (73 and 59 percent, respectively) will be exempt from egg oiling 

under this alternative because they nest in Canada (Hatch 1995, USFWS 1998b). Under 

this alternative, the goal of egg oiling efforts would be to decrease DCCO production on 

a very localized (i.e., colony) scale. Thus, it is unlikely that increased egg oiling efforts 

would have any significant impact on continental or regional DCCO populations. 

Under this alternative, shooting at winter roosts would be authorized. Glahn et al. (1999) 

proposed that, in order to maximize the effectiveness of shooting DCCOs at reducing 

depredation damage, shooting birds at winter roosts should be allowed. Anecdotal 
55 – Chapter 4 

evidence indicates that DCCOs are wary birds and are difficult to kill at aquaculture 

facilities (Hanebrink and Byrd 1989; Conniff 1991; Price and Nickum 1995). Empirical 

evidence has confirmed this. At two aquaculture facilities in the Mississippi Delta, 

during 3,000 total hours of effort in which maximum take was not limited, only 290 

DCCOs (12 percent of the 2,500 authorized) were killed over a 19-week period (Hess 

1994). Glahn (2000) also found that, despite deploying skilled marksmen to shoot 

DCCOs in winter roosts, only a relatively small number of DCCOs (<5% of the roosting 

population) were killed, mainly due to the dispersal effects of shooting at them. This 

effect has been observed elsewhere, as reported by Aderman and Hill (1995): 

Collecting efforts to assess the diets of roosting [DCCOs] (Glahn et al. 1995) also were a source of 

harassment. For example, after the initial shotgun blasts at Goose Pond roost, all the cormorants present (c. 

1,000) departed and did not return. Roost counts five days after collection revealed that such disturbance 

usually caused a decrease in numbers of cormorants at a site. Efforts at night to capture cormorants at 

roosts also reduced bird numbers. Mott et al. (1990) also noted a decrease in the numbers of roosting 

[DCCOs] following nighttime harassment activities. 

For these reasons, Glahn (2000) concluded that allowing DCCOs to be shot at roosts is 

“unlikely to result in a large number of birds killed.” We estimate that take under the 

expanded aquaculture depredation order would increase by 25 percent, leading to about 

44,875 adult and/or juvenile DCCOs being killed under the aquaculture depredation order 

each year (average annual take under depredation order for 1998-2000 = <35,900; adding 

25 percent comes to <44,875). 

In their analysis of various management strategies for Great Cormorants in Europe, 

Bregnballe et al. (1997) observed that, since the outcome depends on the extent of 

competition in the population and the degree of density-dependence working within the 

population, it is difficult to predict quantitative impacts on cormorant population size. 

Even for species, such as mallards, for which there is a highly structured annual system 

of resource monitoring and data analyses, certainty in predicting the population effects of 

management actions has remained elusive (USFWS 2000c). In total, we predict DCCO 

take under this alternative would be <60,275 (~44,875 + 15,400) birds per year, or 3.0 

percent of the estimated continental population. 

Conclusion: Given the current population growth parameters and overall population 

status of DCCOs, it is very unlikely that the increased mortality associated with this 

alternative would significantly impact regional or continental DCCO populations. This 

alternative would be somewhat more effective than the No Action alternative in 

addressing impacts. It would probably resolve some localized problems, but it would not 

enhance the flexibility of other agencies to manage DCCOs. 

PROPOSED ACTION Alternative D: Public Resource Depredation Order 

Relative to the No Action alternative, a public resource depredation order would likely 

result in a marked increase in the annual mortality of adult and/or juvenile DCCOs. In 24 

States, 137 agencies (24 State fish and wildlife agencies, 89 Federally-recognized Tribes, 

and 24 APHIS/WS state programs) will be eligible to participate in the public resource 
56 – Chapter 4 

depredation order, although not all agencies are expected to participate (since 

participation is strictly voluntary). 

To estimate how many birds will be taken per State we used historic data and factored in 

any other special considerations. For example, from 1998 to 2000 the total annual take of 

DCCOs in the contiguous U.S. for depredation control purposes averaged 47,662 birds 

(2.4 percent of the estimated continental population of 2 million birds). This figure 

largely represents take at aquaculture facilities in the southern U.S. Since agencies that 

participate will be able to shoot DCCOs with greater efficiency than aquaculture 

producers (e.g., they will have more resources to expend and will be able to focus their 

activities in areas in which cormorants are concentrated in greatest abundance) we 

increased this figure. Thus, compared to take under the aquaculture depredation order 

(average of 2,760 birds killed annually per participating State from 1998-2000 [total 

estimated take under depredation order divided by 13]), we assume that 150 percent more 

DCCOs would be killed annually in each participating State under this alternative, or 

about 4,140 per State. Multiplying the figure of 4,140 by 24 (the number of States where 

the public resource depredation order applies) amounts to an estimated annual take of 

99,360 adult and juvenile DCCOs. 

Assuming that take under the public resource depredation order will be additive to the 

60,275 birds estimated to be taken under depredation permits and the expanded 

aquaculture depredation order, the estimated total mortality under this alternative would 

be 159,635 birds, or roughly 8.0 percent of the continental population. 

Table 13. Estimated Take Under Proposed Action 

Depredation permits and expanded Aquaculture 

Depredation Order 

60,275 

Public Resource Depredation Order 99,360 

TOTAL 159,635 

Adoption of this alternative could also result in moderate reductions in annual 

recruitment of DCCOs at some colonies by means of egg oiling, egg destruction, or nest 

destruction. In the last few years, just two States have conducted intensive egg oiling 

under the authority of depredation permits but more would likely do so under the public 

resource depredation order. Since DCCOs are relatively long-lived birds, egg oiling 

would have to be conducted repeatedly over a period of many years before any effect on 

adult populations would be evident. Without extensive regional coordination of efforts, 

the overall impact of egg oiling on continental and regional DCCO populations would 

likely be minimal. 

The majority of breeding pairs in the Interior and Atlantic DCCO populations (73 and 59 

percent, respectively, which amounts to approximately 60 percent of total breeding birds) 

will be exempt from control activities carried out during the breeding season under this 

alternative because they nest in Canada (Hatch 1995, USFWS 1998b). Most of the 

breeding birds that will be affected by increased mortality under this alternative will be 
57 – Chapter 4 

from the U.S. portion of the Interior population. DCCOs affected by winter control or 

shot during migration will be mostly from the Interior and Atlantic populations. 

In general, we can predict that under this alternative, one of 3 things will happen when 

lethal control of birds (not eggs) is implemented: (1) shooting will serve as more of a 

harassment tool than an effective means of culling and birds will simply relocate; (2) 

birds in the local population will be killed and the population reduced as a result; or (3) 

birds in the local population will be killed without the population being reduced overall 

because turnover is high (shot birds are replaced by new birds) or because increased 

mortality stimulates density-dependent compensation. 

Conclusion: We predict that this alternative has a much greater likelihood of successfully 

minimizing conflicts with DCCOs than the No Action alternative. It will enhance the 

flexibility of other agencies such that they will be able to conduct control activities more 

readily where necessary; at the same time, it has sufficient reporting and monitoring 

requirements and other restrictions to ensure the long-term conservation of DCCO 

populations. 

Alternative E: Regional Population Reduction 

According to demographics information (section 3.2.1), DCCO populations are thriving 

and have, for the most part, steadily increased over the past 20 years. It is unlikely that 

the long-term sustainability of continental DCCO populations would be threatened 

significantly by efforts to reduce local and regional populations, if done in a controlled 

and coordinated manner. 

Veldkamp (1997) commented that, with respect to population-level control measures, 

since cormorants have “remarkable reproductive skills,” only massive long-term and 

large scale measures are likely to result in a significant population reduction. Reduction 

of regional DCCO populations would be carried out via extensive localized control 

efforts. Glahn et al. (2000b) suggested that DCCO populations be managed on a 

“flyway” basis, using a goal-oriented population model to guide management decisions. 

The objective would be to reduce localized conflicts by managing regional cormorant 

populations. While no consensus on the biological and/or social carrying capacities for 

DCCOs currently exists (and thus we cannot realistically state population objectives at 

this time), insights from population modeling and resource economics, in addition to 

dialogue among interested agencies and organizations, could contribute to the 

development of biologically and socially acceptable population goals (Glahn et al. 

2000b). As stated in the analysis of the No Action alternative, current damage control 

efforts help to reduce cormorant depredations but apparently have little overall effect on 

regional populations (Belant et al. 2000, Glahn et al. 2000a, Mott et al. 1998). Therefore, 

methods of control such as shooting, egg oiling, and nest destruction would need to be 

implemented at a greater level, with the likelihood that some local populations of DCCOs 

would be significantly reduced or eliminated. 

The difficulty with attempting to reduce populations as a means of alleviating wildlife 

damage is overcoming the population’s ability to compensate for increased mortality. In 
58 – Chapter 4 

fact, in Resolving Human-Wildlife Conflicts: The Science of Wildlife Damage 

Management, Conover (2002) wrote, “it usually is very difficult to suppress wildlife 

populations to a low enough level where the population cannot recover within a short 

period.” This is because increased mortality reduces intraspecific competition and thus 

increases birth rates and immigration (because increased mortality provides transient 

individuals a better opportunity to move into the area). Both of these factors help nullify 

any population reduction caused by lethal control. Nonetheless, Bregnballe et al. (1997) 

concluded that control measures did lead to populations stabilizing at lower levels. 

Conclusion: The development of regional DCCO population objectives and 

implementation of large-scale (as opposed to local) population reduction efforts could 

prove an effective means of managing this species. However, the achievement of these 

objectives will require levels of management intensity, agency coordination, financial 

commitment, and research and monitoring efforts much greater than those which 

currently exist. 

Alternative F: Regulated Hunting Season 

The number of DCCOs killed by hunters would depend on the length and timing of the 

hunting season, hunter success, and the number of States participating. The number of 

hunters participating in a DCCO hunting season would probably be low compared to 

other game species because of two key factors. First, many hunters would not be 

interested in killing a non-traditional species such as cormorants. Due to the aquatic 

nature of DCCO habitat, it is expected that, in addition to those interested in only hunting 

DCCOs (e.g., for depredation control purposes), other participants would largely be 

waterfowl hunters. Bédard et al. (1999) commented that cormorants do not inspire respect 

among waterfowl hunters and would likely not be used as “real game.” Second, most 

hunters would not wish to consume DCCOs because of low palatability and/or because 

they carry high contaminant loads. 

Hunting of DCCOs could take place at any area open for legal waterfowl hunting. In 

particular, DCCOs would be hunted in open water feeding and loafing areas and at 

roosting locations. To maximize participation, hunting seasons could follow similar 

seasons as waterfowl and take place during the fall, winter, and migration months with 

juvenile and adult birds of both sexes being harvested, although males would probably be 

taken at a higher rate than females (Campo et al. 1993, Glahn et al. 1995, Glahn et 

al.1999). Since hunters would not need a depredation permit to hunt DCCOs, we expect 

that more DCCOs would be killed than under the No Action alternative. Hunter 

avoidance behavior exhibited by DCCOs would limit the total number of DCCOs 

harvested (Glahn et al. 2000a, Bregnballe et al. 1997). As noted above, DCCOs are 

notoriously difficult to shoot. However, decoys and blinds have been used to 

successfully lure DCCOs into shooting range (Bur et al. 1999, Glahn et al. 1995) and 

could increase the success of hunting DCCOs (USFWS 1998b). 

Conover (2001) wrote that hunting is one of the “few human activities that reinforces an 

animal’s fear of humans.” Bregnballe et al. (1997) predicted that hunting would lead to 

increased shyness toward humans and would more greatly restrict cormorants’ choices of 
59 – Chapter 4 

breeding and feeding areas and loafing and roosting sites. As a result, more individuals 

would stay in safe (i.e., non-hunted) areas and competition would increase for available 

resources. This could lead to increased density-dependent effects on populations. 

Take under this alternative would include the number of DCCOs killed under the No 

Action alternative in addition to the number of birds harvested under a hunting season. 

Annual DCCO mortality (hunters + permits + aquaculture depredation order) is expected 

to be no more than 10 percent (~200,000 birds) of the estimated continental DCCO 

population. Because of the buffering effect of density-dependence, the relationship 

between hunting pressure and population size is not linear and thus the actual effects on 

populations cannot be predicted with high accuracy (Bregnballe et al. 1997). 

Nonetheless, model predictions by Bregnballe et al. (1997) showed that hunting 

cormorants in the fall would lead to a lower overall population and to a lower breeding 

population; these effects will be more pronounced the higher hunting mortality is and the 

weaker density-dependent winter mortality is. Thus, we can conclude that the increased 

mortality caused by hunting could, depending on the length of the season and hunter 

interest in shooting cormorants, be an important tool in reducing the overall size of the 

cormorant population. 

Conclusion: We predict that a hunting season would have a greater impact on DCCO 

populations than the No Action alternative. From a cost effectiveness standpoint this 

alternative has many advantages as hunters would shoulder much of the cost rather than 

agencies. However, there are serious administrative, legal, and ethical challenges 

associated with this option. 

4.2.2 Impacts to Fish 

Alternative A: No Action 

Determining the effect of predation on the dynamics of prey populations is neither a 

simple nor a straightforward task (Banks 2000, Krebs 1995). The information necessary 

for determining impact, or lack of impact, in even the simplest cormorant-fishery systems 

is complex and difficult to acquire (Wires et al. 2002). For example, the findings of a 

study that examined the relationship between Great Cormorants and fish populations in 

England were deemed “uncertain” by the authors because of the complex nature of such 

systems and the difficulties inherent in relating cormorant predation to changes in fishery 

performance and in separating the effects of piscivorous birds from other factors affecting 

fish populations (Davies et al. 2001). 

In addition to predation pressure, many other environmental and human-induced factors 

affect fish populations. These can be classified as biological/biotic (overexploitation, 

exotic species, etc.), chemical (water quality, nutrient and contaminant loading, etc.) or 

physical/abiotic (dredging, dam construction, hydropower operation, siltation, etc.). Such 

factors may lead to changes in species density, diversity, and/or composition due to direct 

effects on fish year class strength, recruitment, spawning success, spawning or nursery 

habitat, and/or competition (USFWS 1995). It is beyond the scope of this document to 

examine these factors in relation to DCCO predation at every place of interest. 
60 – Chapter 4 

Based on a review of the DCCO diet literature, Trapp et al. (1999) concluded that, 

relative to other biotic and abiotic factors, DCCOs have a minor overall impact on sport 

fisheries, with localized exceptions. The management implication of this conclusion is 

that it would not be biologically-justified to make the general assumption that DCCOs 

cause negative impacts to fisheries in all or even most of the places where they forage. 

However, as they stated (and as has become increasingly clear since that time), 

exceptions occur, and it is also not biologically-justified to assume that DCCOs have no 

negative impacts on local fisheries. 

Russell et al. (2002) found that the proportion of trout in the diet of Great Cormorants on 

river trout fisheries, one in northwestern England and another in southeastern England, 

varied considerably. In the former, trout represented 85 percent of the diet by weight; in 

the other, trout represented only one percent of the diet by weight. They concluded that 

there is a “need to assess potential impact on a case by case basis.” In the U.S., Derby 

and Lovvorn (1997) found that the percentage of sport and commercial fish in the diets of 

DCCOs in a Wyoming river varied widely, from 0.6 percent to 93 percent, and appeared 

to depend on local food availability. Although they were unable to determine whether 

cormorant predation rates were compensatory or additive, they acknowledged that, 

“piscivorous birds can substantially affect fish stocks, depending on bird densities and 

availability of alternative prey.” While these studies were inconclusive about the actual 

impacts on fish stocks, they highlight the importance of continuing research on 

cormorant-fish interactions. 

In order to fully understand fisheries impacts related to predation, DCCO diet must be 

evaluated in terms of the number of DCCOs in the area, the length of their residence in 

the area, and the size of the fish population of concern (Weseloh et al. 2002). While 

most, but not all, studies of cormorant diet have indicated that sport or other humanvalued fish species do not make up high percentages of DCCO diet, conclusions about 

actual fisheries impacts cannot be based on diet studies alone. Nisbet (1995) referred to 

this as the “body-count” approach (i.e., counting the numbers of prey taken rather than 

examining the effects on prey populations) and noted that it is necessary to also “consider 

functional relationships between predation and output parameters.” Stapanian (2002) 

also noted that “in order to quantify the effects of cormorant piscivory, reliable estimates 

of the fishery in question are needed.” 

Stapanian (2002) observed that “Rigorous, quantitative studies suggest that the effects of 

cormorants on specific fisheries appear to be due in part to scale and stocks of available 

prey.” Indeed, negative impacts are typically very site-specific and thus DCCO-fish 

conflicts are most likely to occur on a localized scale. Even early cormorant researcher 

H.F. Lewis recognized that cormorants could be a local problem at some fishing areas 

(Milton et al. 1995). In sum, the following statements about DCCO feeding habits and 

fisheries impacts can be concluded with confidence from the available science: 

(1) DCCOs are a generalist predator whose diet varies considerably between seasons and 

locations and tends to reflect fish species composition. 
61 – Chapter 4 

(2) The present composition of cormorant diet appears to have been strongly influenced 

by human-induced changes in the natural balance of fish stocks. 

(3) “Impact” can occur at different scales, such that ecological effects on fish populations 

are not necessarily the same as effects on recreational or commercial catches, or vice 

versa. 

(4) Cormorant impact is generally most significant in artificial, highly-managed 

situations. 

(5) Because environmental and other conditions vary locally, the degree of conflicts with 

cormorants will vary locally. 

To illustrate number four above, the following example was sent to us by the Idaho Fish 

and Game Regional Fishery Manager (D. Scully, pers. comm.): 

The best quantitative information from the Southeast Region that we have on negative impacts of 

piscivorous birds on sport fisheries is from 66-acre [27 ha] Springfield Reservoir. In 1994 we found that 

although we stocked 129 catchable size (9-inches) rainbow trout per acre the first week of May, almost 

none of these fish were observed in a subsequent creel survey. Angry Memorial Day weekend anglers 

accused the Department of lying and not stocking any trout. We stocked an additional 8,500 trout and 

made daily observations on bird activities at the reservoir. We found that on the day of stocking few 

piscivorous birds were present. However by the fourth day after stocking over 200 cormorants were 

observed at a given time. A week later, gillnet and electrofishing surveys found very few trout, but did 

catch large numbers of Utah chubs of the same size as the stocked trout. The naive newly stocked trout 

were quickly removed whereas the cautious chubs survived. Or possibly there was a preference by the 

birds for the trout. No matter what the reason, it became obvious that we could no longer sustain a trout 

fishery at Springfield Reservoir based on 9-inch long or smaller trout. 

Moreover, in Europe, direct effects associated with Great Cormorant predation have been 

reported in fish ponds or in rivers or small, artificially-stocked lakes where high densities 

of fish are raised (van Eerden et al. 1995). 

Local variability of DCCO conflicts is demonstrated by our examination of DCCO-fish 

interactions for four specific areas (and one region) where information is sufficient to 

analyze potential interactions: Oneida Lake, New York; eastern Lake Ontario, New York; 

Les Cheneaux Islands, Lake Huron, Michigan; Lake of the Woods, Minnesota; and 

southeastern lakes, ponds, and reservoirs. In this section, we present conclusions; further 

details on these specific areas can be found in Appendix 6. 

Oneida Lake, New York. DCCOs are an important fish predator in Oneida Lake with the 

potential to alter the lake’s fish populations (L. Rudstam, Cornell Univ., pers. comm.). 

Cormorants consume older yellow perch and walleye targeted by anglers, intermediate 

size or pre-recruitment perch and walleye, and smaller age-0 to age-1 perch and walleye. 

Cornell University biologists Rudstam and Adams (cited in Wires et al. 2001) based their 

conclusion of effect on perch and walleye on the following: 1) the timing of the 

disappearing adults coincides with the increase in DCCOs; 2) the size of the fish eaten by 

DCCOs coincides with the size of the fish that have increased mortality; and 3) at least 

for walleye, the number of fish missing is comparable to the number estimated to be 

consumed by DCCOs . VanDeValk et al. (2002) found that while DCCO consumption of 
62 – Chapter 4 

adult percids has little effect on angler harvest, consumption of subadults is likely to 

reduce future angler harvest of yellow perch and, to a lesser extent, walleyes. 

Eastern Lake Ontario, New York. In 1999, the New York State Department of 

Environmental Conservation’s Bureau of Fisheries and the USGS Biological Resources 

Division prepared an extensive report assessing the impact of DCCO predation on 

smallmouth bass and other fishes of the eastern basin of Lake Ontario. They found that, 

based on gill net sampling, dramatic declines in smallmouth bass abundance have 

occurred there since the early 1990s. The main results reported by Lantry et al. (1999) in 

this report were: 1) the mortality of age-3 to 5 smallmouth bass increased substantially 

after 1988; 2) loss rates of this magnitude could severely limit numbers of adult 

smallmouth bass recruited to the fishery; and 3) DCCO predation on 3-5 year old bass 

was significant enough to cause the observed declines in the smallmouth bass population. 

Lantry et al. (2002), examining the relationship between smallmouth bass and DCCOs in 

the eastern basin of Lake Ontario, found that after the number of DCCOs nesting on 

Little Galloo Island in New York exceeded 3,500 pairs in 1989, survival of young 

smallmouth bass began to decline. The authors wrote: 

Despite production of strong year classes in 1987 and 1988, abundance of smallmouth bass measured from 

gill net surveys declined to its lowest level by 1995 and remained there through 1998. Stable or increasing 

catch and harvest rates in other local fisheries along the U.S. shore suggested that declines in smallmouth 

bass abundance in the eastern basin were not related to water quality. Stable or increasing growth rates for 

smallmouth bass age 2 and older since the 1980s further indicated that food resource limitation was also not 

the cause for declines in abundance. Comparisons of estimates of size and age-specific predation on 

smallmouth bass by cormorants with projected smallmouth bass population size indicated that much of the 

increased mortality on young smallmouth bass could be explained by cormorant predation. 

Burnett et al. (2002) analyzed DCCO predation on yellow perch in the eastern basin of 

Lake Ontario and concluded that “cormorant predation had the potential to play an 

important role in regulating perch population levels in the eastern basin during the 1990s” 

while noting that increased abundance of walleye could have contributed to the observed 

increases in mortality of young yellow perch. 

Les Cheneaux Islands, Lake Huron, Michigan. Fisheries investigations carried out 

concurrently with DCCO diet investigations in the Les Cheneaux Islands area found that 

DCCOs removed only 2.3 percent of the available yellow perch biomass and accounted 

for less than 20 percent of the total annual mortality of perch. Overall, cormorants 

accounted for 0.8 percent of the mortality of legal-sized perch, whereas summer sport 

fishing accounted for 2.5 percent. The conclusion was that DCCOs had minimal impact 

on the local yellow perch population (Belyea et al. 1999).

Lake of the Woods, Minnesota. For the last decade, there has been no clear upward or 

downward trend in year class strength for either walleye or sauger. Preliminary evidence 

from Minnesota Department of Natural Resources fisheries reports does not indicate that 

DCCOs are impacting game fish populations, as various population indices have 

indicated strong populations of walleye, sauger, perch, and northern pike in the lake. 

However, specific modeling that factors all types of juvenile fish predation, including 

DCCOs, has not yet been done in this lake (K. Haws, MDNR, pers. comm.). 
63 – Chapter 4 

Southeastern lakes, ponds, and reservoirs. Two of the studies examined (Glahn et al. 

1998, Campo et al. 1993) did not find evidence of significant impact to fisheries caused 

by DCCO predation. A third study (Simmonds et al. 2000), using modeling, found that at 

particularly high levels of predation, fisheries could be negatively impacted. It is difficult 

to make broad conclusions about the impacts of DCCOs on fisheries at ponds, lakes, and 

reservoirs across such a broad geographical area. Generally, the lower availability of 

prey refugia often found in smaller waterbodies, especially manmade ones, will make 

prey more susceptible to predation. Additionally, at any pond or reservoir within the 

geographical range of DCCOs where sport fish are managed at levels intended to 

maximize recreational catch, it is highly likely that these areas will be utilized for 

foraging by DCCOs. 

Estimations of the beneficial effects on fisheries associated with DCCO control efforts 

have been made using information on average DCCO consumption and estimations of the 

amount of fish that were not consumed due to management actions. However, without 

associated DCCO foraging data and fisheries data, it is difficult to accurately predict the 

long-term impacts to specific fish populations. Johnson et al. (2000a) determined that 

DCCOs from the Little Galloo Island (Lake Ontario, New York) colony consumed 

approximately 13.25 million fewer fish in 1999, the first year of extensive egg oiling 

activities, than in 1998. They estimated that 8,300 fewer DCCO chicks were produced 

on the island in 1999, which reduced fish consumption by 348,000 kg (766,000 lbs). Two 

species, alewife and smallmouth bass, were believed to have benefited the most since 

their contribution in the diet was known to be substantially greater during the chickfeeding period than during the pre-chick feeding period. Additionally, they found that 

fish consumption in 1999 was only 45 percent by number and 58 percent by weight of the 

mean of the previous seven years for Little Galloo Island DCCOs. 

Conclusion: Currently, conflicts with sport fisheries are a significant cause of concern

associated with abundant DCCO populations, but only in a few places have negative 

impacts been empirically confirmed. In at least one area (Little Galloo Island, New 

York) control activities (egg oiling) being carried out to protect other resources are 

believed to also be beneficial to local fisheries. 

Alternative B: Non-lethal Management 

Non-lethal management techniques to benefit fisheries involve temporarily moving 

DCCOs away from a specific fishery (e.g., harassment and/or nest removal), altering fish 

release practices, or physically separating DCCOs from fish. Techniques such as altered 

stocking practices have proven useful in reducing cormorant depredation at least 

temporarily. Moore (2001) noted that increasing the size of trout stocked and varying the 

timing of stocking were effective in improving angler success and reducing the 

proportion of fish taken by Great Cormorants at two still-water trout fisheries in the 

United Kingdom. In 1996, to address concerns over DCCOs feeding on stocked fish, the 

New York State Department of Environmental Conservation altered stocking methods to 

include stocking fish further offshore, stocking streams earlier in the spring before 

DCCOs return from wintering areas, and stocking nearshore areas at night so that fish can 
64 – Chapter 4 

disperse before daylight. These efforts were considered to be effective in reducing 

predation on recently-stocked fish (J. Farquhar, NYSDEC, pers. comm.). 

Van Dam and Asbirk (1997) predicted that continuous roost disturbance and efforts to 

prevent the establishment of new breeding colonies could benefit local fisheries in the 

vicinity, especially at inland sites, but this would likely require highly intensive 

harassment efforts. Disturbance efforts on Oneida Lake, New York, involving limiting 

the number of successful DCCO nests to 100 in the spring and then hazing migrating 

birds in the fall, have been estimated to reduce predation on walleye by about 45 percent 

(NYSDEC press release). In the first year of implementation, the program was roughly 

estimated to have reduced DCCO consumption by 30,000 walleye and 90,000 perch 

(USDA-APHIS 1998). The long-term impact of this reduced DCCO fish consumption on 

fish populations has not been examined. 

Conclusion: Non-lethal control efforts can, if carried out intensively, reduce DCCO 

predation in the short-term at the site-specific level. Some important setbacks of this 

approach are that it moves birds to other areas where they are likely to continue to come 

into conflict with other resources, it limits management flexibility in cases where lethal 

control might be the most appropriate option, and it can lead to habituation in which the 

birds are no longer frightened by the techniques. Thus, overall, it is considered to be less 

effective than the No Action alternative. 

Alternative C: Increased Local Damage Control Alternative 

Under this alternative, shooting, egg oiling or destruction, nest destruction, and 

harassment would be used somewhat more frequently than under the No Action 

alternative. Shooting birds may benefit fish by reducing DCCO predation through the 

immediate effect of removing depredating birds and the secondary effects of scaring 

away other birds and reinforcing non-lethal harassment efforts. Additionally, killing 

birds, as opposed to harassing them, avoids the problem of merely moving DCCOs to 

another area where they could potentially cause damage. However, if shooting is 

attempted in a systematic way for a given area, its benefits will be limited when the 

area’s turnover rate is high (i.e., DCCOs killed are quickly replaced by new birds moving 

through). Responses of DCCOs to localized control efforts will vary from site to site 

depending on the movements of birds to and from the particular area. 

A key factor for determining effects on fish populations is whether or not overall 

predation levels are actually reduced as a result of DCCO control efforts. Egg oiling has 

been shown to help reduce predation levels on local fish populations, as described under 

the No Action alternative. 

Control efforts will be most effective at reducing predation when multiple management 

actions are coordinated across a large area or where the “source” of depredating birds is 

concentrated (such as at a colony or roost) and localized control is targeted toward these 

birds. The specific effects on fish populations and/or the likelihood of recovery of the 

fishery are difficult to predict when there is uncertainty about the role of DCCO predation 

relative to other factors limiting fish populations. 
65 – Chapter 4 

Conclusion: This alternative would require other agencies to seek Service approval 

before initiating control activities (similar to the No Action) but in cases where strong 

evidence for openwater fishery impacts caused by DCCOs exists, the Service would issue 

depredation permits. Thus, this alternative would be more effective at reducing impacts 

than the No Action alternative. 

PROPOSED ACTION Alternative D: Public Resource Depredation Order 

This alternative would give States, Tribes, and APHIS/WS more flexibility in deciding 

when to carry out control efforts to protect fish from DCCO depredation. As stated 

above, the main factor that determines effects on fish populations is whether or not 

overall predation is actually reduced as a result of DCCO control efforts and how that 

relates to other factors limiting the fishery. The discussion under Alternatives B and C, 

above, are equally applicable here. 

Conclusion: Because agencies would be able to implement control measures more readily 

and would have the opportunity to engage in preventive measures and limited localized 

population control measures, this alternative will be more effective at alleviating DCCOfish conflicts than the No Action alternative. 

Alternative E: Regional Population Reduction 

As described under the No Action alternative, localized population control efforts have 

been shown to reduce predation levels on local fish populations. It is likely that regional 

reductions in DCCO numbers would further reduce predation levels and in the long-term 

could benefit fisheries even more than localized control efforts. 

Conclusion: Reducing regional populations of DCCOs would be more likely to alleviate 

cormorant-fish conflicts than the No Action alternative. However, based on fishery 

impacts alone, largescale population reduction is not a biologically justified option at this 

time. 

Alternative F: Regulated Hunting Season 

The impact of hunting on DCCO populations would be variable based upon hunter 

participation and success. The effects of any hunting-induced population changes would 

depend on similar factors as those discussed in the alternatives above (population 

turnover rates, environmental factors, etc.). 

Conclusion: Since hunters would be able to target DCCOs in areas where they are 

causing fish depredation problems (assuming they had landowner permission), it is more 

likely that hunting would have positive impacts on fisheries than the No Action 

alternative. As previously mentioned, there are legal, administrative, and ethical 

challenges pertinent to this option. 
66 – Chapter 4 

4.2.3 Impacts to Other Birds 

Alternative A: No Action 

As stated in Chapter 3, numerous concerns about DCCOs causing negative impacts to 

other birds have been expressed to the Service. While “concern” about impacts does not 

equate to scientific proof as such, one would expect that the likelihood of observations 

and concerns actually reflecting reality increases as the number of concerns increases, 

especially when the observers are trained resource professionals. Here are a few 

examples of the concerns that have been raised: 

• The Ohio Department of Natural Resources stated that increases in DCCO 

numbers “have caused extensive damage to terrestrial island habitats in Lake Erie 

that are important to several species of rare Ohio birds” and noted that the “habitat 

alteration/competition problem [from DCCOs] is quite discouraging given the 

lack of alternative nesting sites for colonial waterbirds.” 

• The Vermont Department of Fish and Wildlife expressed concern that habitat on 

Young Island in Lake Champlain, which was “once a mix of trees and herbaceous 

vegetation that supported breeding populations of black-crowned night-heron, 

cattle egret, snowy egret, black duck, mallard, goldeneye, and common 

merganser,” had been completely destroyed by cormorants (and gulls) so that the 

other species had left. 

• The New York State Department of Environmental Conservation commented, 

during public scoping, that they are concerned about “the impacts that cormorants 

have on other colonial-nesting species [such as Common Terns, a State-listed 

threatened species].” 

• An independent researcher noted that “The disastrous effects of the cormorant 

colony on Home Pond [Gardiner’s Island, New York] are unequivocal. 

Cormorants and their profuse guano...have denied the ‘right to life’ of a 

heron/egret/ibis colony of several species; eight-plus pairs of nesting ospreys; 

nesting black ducks and gadwall...” (P. Spitzer, pers. comm.). 

• The decision to carry out an intensive DCCO population reduction program in the 

St. Lawrence River estuary in Québec was made to “protect unique insular plant 

communities whose destruction was affecting colonies of great blue herons, 

[black crowned night-herons], and common eiders” (Bédard et al. 1999). 

Based on their observations in the Great Lakes, Weseloh et al. (2002) suspected that 

cormorant nesting could affect other colonial waterbirds in at least three ways: (1) if the 

nesting island is small, an increase in the number of DCCO nests could reduce the 

amount of space available for nest construction by other species; (2) on islands where 

night-herons or egrets nest in trees or shrubs, DCCOs may take over these nests or the 

shrubs; and (3) where DCCOs nest in tall trees with small herons nesting below them, 

falling guano and nesting material may be enough to lead to herons abandoning their 

nests. Ludwig et al. (1995) noted that DCCOs “may have significant competitive 

advantages over the other species with which they compete for nest sites” in Great Lakes 

ecosystems. 
67 – Chapter 4 

DCCOs almost always nest in close association with other species of colonially-nesting 

birds, both ground- and tree-nesters. In the United States Great Lakes, for example, 97 

percent of all active DCCO colonies (between 1976 and 1999) were associated with other 

species of colonial waterbirds (Scharf and Shugart 1998, USFWS unpubl. data). To 

examine the question of whether there is evidence to suggest that increases in recent 

years in the number of nesting DCCOs at multiple-species breeding colonies have had a 

direct effect on the numbers of other colonially-nesting waterbirds, we analyzed data 

from the U.S. Great Lakes for three time periods: 1976-1977, 1989-1991 (Scharf and 

Shugart 1998), and 1997-1999 (USFWS unpubl. data). 

Herons and Egrets. Impacts to egret species are a concern. Blokpoel and Weseloh 

(CWS, unpubl. data) stated that Great Egrets “may suffer from nest site competition, or 

takeover, from cormorants, especially on East Sister Island (Lake Erie) and Chantry and 

Nottawasaga Islands (Lake Huron).” Localized concern about displacement of Snowy 

Egrets by DCCOs has led to the issuance of depredation permits to authorize egg oiling 

activities for enhancing avian diversity in New York and Vermont. 

Suspected impacts to heron species have raised concerns as well. The Great Blue Heron 

is a frequent nest associate of the DCCO. Over the approximately 25 years that 

comprehensive surveys of the U.S. Great Lakes have been conducted, Great Blue Herons 

are known to have nested at 26 colony-sites. The number of colony-sites known to have 

been occupied by herons increased from 13 (1976-1977), to 18 (1989-1991), to 19 (1997-

1999). Over the same time periods, the mean number of heron nesting pairs per occupied 

colony-site increased slightly: 27, 30, and 34. Analysis by Cuthbert et al. (2002) 

indicated that on a regional scale Great Blue Heron colony trend is independent of 

cormorant presence (Χ2

 = .45, df = 1, p > 0.5). 

An examination of site-specific observations between DCCOs and Great Blue Herons 

reveals that there were 29 site-specific instances in which cormorants nesting in 

association with Great Blue Herons increased between adjacent time periods. Trends of 

Great Blue Herons with respect to cormorant increases were about equally mixed: in 16 

instances Great Blue Herons also increased (mean of 16 pairs), while in 13 instances they 

declined (mean of eight pairs). The mean net changes per colony-site in these 29 

instances were gains of 261 pairs of cormorants and two pairs of Great Blue Herons. 

Nesting populations of Great Blue Herons were not correlated with nesting populations of 

DCCOs, nor were changes in populations between adjacent time periods correlated with 

increasing populations of cormorants. 

The Black-crowned Night-Heron has frequently been mentioned as a species that is 

negatively affected by DCCOs in the Great Lakes (Jarvie et al. 1999, Shieldcastle and 

Martin 1999, Cuthbert et al. 2002, Weseloh et al. 2002). Night-herons are known to have 

nested at 26 colony-sites in the Great Lakes. The number of colony-sites known to have 

been occupied increased from 12 (1976-1977), to 15 (1989-1991), to 23 (1997-1999). 

Over the same time periods, the mean number of nesting pairs per occupied colony-site 

declined steadily: 24, 18, and 13. Analysis by Cuthbert et al. (2002) indicated that on a 
68 – Chapter 4 

regional scale night-heron colony trend is influenced by cormorant presence (Χ2 = 4.97, 

df = 1, p > 0.025). 

An examination of site-specific observations between DCCOs and night-herons reveals 

that there were 29 site-specific instances in which cormorants nesting in association with 

night-herons were documented to increase between adjacent time periods. In 12 of those 

instances, night-herons also increased (mean of seven pairs), and in 17 instances they 

declined (mean of 11 pairs). The mean net change per colony-site was a gain of 677 pairs 

of DCCOs and a loss of four pairs of night-herons. Nesting populations of Blackcrowned Night-Herons were not correlated with nesting populations of cormorants, nor 

were population changes between adjacent time periods correlated with increasing 

populations of cormorants. 

A New York State Department of Environmental Conservation biologist provided 

evidence of direct displacement of Black-crowned Night-Herons by DCCOs at the local 

level on Gull Island, a one acre site situated on the edge of Henderson Bay, within the 

greater eastern basin of Lake Ontario. Black-crowned Night-Herons have been 

sporadically documented as a nesting species on Gull Island. A more “permanent” 

presence began to develop in the late 1980s, presumably from birds displaced from Little 

Galloo Island, where DCCO numbers were increasing. By 1993, 30 pairs of night-herons 

were breeding on the island. In 1993, DCCOs also established an arboreal colony of 

about 150 nests there. Larger trees were removed from the island late in 1993 to deter 

DCCO from maintaining the newly established colony in future years. Since 1994, the 

NYSDEC has annually removed DCCO nests from the island in order to maintain 

shrubby vegetation for use by night-herons. Count data for night-herons from 1995-1999 

have revealed a stable number of nests ranging from 41-46 each year. In 2000, DCCOs 

re-established a breeding colony on the island beginning in late April. Attempts to 

displace the cormorants did not begin, however until 15 May, at which time 478 nests 

were occupied (and removed). One hundred and ten (110) of the nests were arboreal, 

either in box elder or directly above night-heron nests in the tops of dogwood shrubs. 

Night-heron nest numbers dropped by about half under these conditions, and remained at 

this level through the breeding season in spite of cormorant removal. Based on field 

observations and professional judgment, it was hypothesized that direct guano deposition 

by DCCOs resulted in the observed abandonment by night-herons. Although Gull Island 

was apparently partially abandoned by Black-crowned Night-Herons due to the direct 

effects of DCCOs, suitable nest sites were utilized on nearby Bass Island, where numbers 

increased from 6-12 annual nests over the past three years (1997-99) to 35 in 2000. On 

Bass Island, DCCO usage was not in proximity to night-heron nesting sites (J. Farquhar, 

NYSDEC, unpubl. data). 

Weseloh et al. (2002) reported that the displacement of night-herons from their colony 

site after DCCOs began to nest there “may have occurred” at 7 sites in Lake Ontario: Pier 

27 (Hamilton Harbour), Tommy Thompson Park (Toronto), and at Scotch Bonnet, 

Pigeon, West Brother’s, Snake, and Little Galloo Islands. In 2000, 28 percent of nightheron sites visited had been abandoned “in light of increasing cormorant numbers or were 

in imminent danger of being overrun by cormorants” (Weseloh and Havelka, CWS, 
69 – Chapter 4 

unpubl. data). They concluded that night-herons may be leaving historical nesting areas 

and establishing new colonies because of DCCOs. Observations by Cuthbert et al. 

(2002) of nesting DCCOs and Black-crowned Night-Herons at Epoufette and Green 

Islands, Lake Michigan, noted no direct interactions between the two species. There was 

some overlap in tree species used for nest sites between DCCOs and night-herons; 

however, they appeared to separate themselves spatially when utilizing the same tree 

(Cuthbert et al. 2002). The authors noted that “cormorant impact on great blues and 

black-crowns may be greatest on small forested islands where cormorant fecal material 

kills all woody vegetation and eliminates nest habitat for these species” (Cuthbert et al. 

2002). 

Gulls and Terns. The impact of DCCOs on ground-nesting terns and gulls appear to be 

minimal, at least in the Great Lakes (USFWS 1999a). Herring Gulls are the most 

ubiquitous of the colonial waterbirds nesting in the U.S. Great Lakes, where they are 

known to have nested at 74 colony-sites. The number of colony-sites known to have 

been occupied increased from 56 (1976-1977), to 63 (1989-1991), to 70 (1997-1999), 

while the mean number of nesting pairs per occupied colony-site varied over these same 

time periods: 148, 247, and 114. There were 88 site-specific instances in which DCCOs 

nesting in association with Herring Gulls increased between adjacent time periods. 

Changes in Herring Gull numbers in relation to cormorant increases were about equally 

mixed: in 42 instances they increased (mean of 172 pairs) and in 46 instances they 

declined (mean of 54 pairs). The mean net changes per colony-site in these 88 instances 

was a gain of 253 pairs of cormorants and a loss of 4 pairs of Herring Gulls. 

Ring-billed Gulls are known to have nested at 30 colony-sites in the U.S. Great Lakes. 

The number of colony-sites known to have been occupied increased from 15 (1976-

1977), to 20 (1989-1991), to 22 (1997-1999), and the mean number of nesting pairs per 

occupied colony-site increased over these same time periods: 374, 1328, and 1786. There 

were 35 site-specific instances in which DCCOs nesting in association with Ring-billed 

Gulls increased between adjacent time periods. In 18 of those instances, Ring-billed 

Gulls also increased (mean of 343 pairs), and in 16 instances they declined (mean of 598 

pairs). The mean net changes per colony-site in these 35 instances were gains of 338 

pairs of cormorants and 18 pairs of Ring-billed Gulls. Nesting populations of Ring-billed 

Gulls were positively correlated with nesting populations of cormorants, but population 

changes between adjacent time periods were not correlated with increasing DCCO 

populations. 

Caspian Terns are known to have nested at nine colony-sites in the U.S. Great Lakes. 

The number of colony-sites known to have been occupied increased from 3 (1976-1977), 

to 5 (1989-1991), to 7 (1997-1999), and the mean number of nesting pairs per occupied 

colony-site remained fairly stable over these same time periods: 537, 437, and 566. 

There were 11 site-specific instances in which DCCOs nesting in association with 

Caspian Terns increased between adjacent time periods. In eight of those instances, 

Caspian Terns also increased (mean of 198 pairs), and in three instances they declined 

(mean of 249 pairs). The mean net changes per colony-site in these 11 instances were 

gains of 1,440 pairs of DCCOs and 27 pairs of Caspian Terns. Nesting populations of 
70 – Chapter 4 

Caspian Terns were positively correlated with nesting populations of DCCOs, and 

population changes between adjacent time periods were likewise positively correlated 

with population increases of DCCOs. 

Numbers of Caspian Terns on Little Galloo Island, eastern Lake Ontario, New York, 

were higher in 2001 than in previous years, after three years of intensive DCCO egg 

oiling activities. Great Black-backed Gull numbers on Little Galloo Island had increased 

in 2001 compared to previous years. Ring-billed Gull and Herring Gull numbers had 

declined somewhat but this was not believed to be associated with recent egg oiling 

efforts on the island since the egg oiling activity was removed from most of the gull 

nesting areas and since declines in these two species had apparently started before the egg 

oiling program began in 1999 (J. Farquhar, NYSDEC, unpubl. data). 

The Common Tern is considered to be endangered, threatened, or a species of special 

concern in six Great Lakes States and Ontario, as well as being a USFWS species of 

management concern in the U.S. Great Lakes. Competition with Ring-billed Gulls is 

considered a major factor in their decline in the Great Lakes (Scharf et al. 1992) although 

displacement by DCCOs may also occur (USFWS 1999a). 

Cormorants and Anhingas. Along the Pacific Coast, the DCCO’s range overlaps broadly 

with those of the Pelagic Cormorant and Brandt's Cormorant. Populations of Pelagic and 

Brandt’s Cormorants, species which nest in association with DCCOs on the Pacific coast 

have fluctuated in response to El Niño conditions but, overall, their numbers have 

remained stable or increased (Carter et al. 1995a). 

Great Cormorant populations in North America appear to have increased dramatically 

and expanded their range southward in recent decades (Kaufman 1996). Populations of 

Neotropic Cormorants appear to be increasing and spreading geographically (C. Hunter, 

FWS, pers. comm.). Populations of Anhingas appear to be stable except for a decline in 

Texas numbers (BBS trend for 1990-1998 was a statistically significant mean annual 

decline of 17.98 percent). Under the aquaculture depredation order, some incidental take 

of Neotropic Cormorants and Anhingas may occur in southern States (where their range 

overlaps with that of DCCOs). In particular, it can be difficult to distinguish juvenile 

DCCOs from Neotropic Cormorants, while Anhingas are more distinguishable because of 

their bill structure. The declining trend for Anhingas in Texas started well before the 

depredation order came into effect and is not believed to be related to by-kill. There is no 

evidence that incidental take is a threat to populations of other cormorant species or 

Anhingas. See Appendix 7 for guidelines on distinguishing DCCOs from Anhingas and 

Neotropic Cormorants. 

Food Competition. A review of the vast literature on DCCO food habits and foraging 

behavior revealed little information about potential food competition with other birds. 

DCCOs are opportunistic in their foraging habits, feeding on a large variety of fish 

species. In any given situation, individual DCCOs can be expected to prey on those 

species that are most abundant and most easily captured (Trapp et al. 1999, Wires et al. 

2001). 
71 – Chapter 4 

The DCCO is one of at least 73 bird species found in freshwater or saltwater habitats of 

the United States whose diet consists primarily of fish. Food competition between these 

species is reduced by differences in foraging techniques and the substrates in which prey 

are hunted. By defining specific foraging techniques and substrates, DeGraaf et al. 

(1985) categorized these 73 species into no fewer than 17 different foraging guilds or 

categories. DCCOs and six other species were placed in the “water diver” guild (species 

that dive from the surface to pursue underwater prey, and that forage in brackish, 

freshwater, and saltwater habitats). The most likely food competitors of the DCCO are 

loons, grebes, pelicans, other species of cormorants, and mergansers, although there is 

currently no evidence to show that competition for food has negatively impacted these 

species. 

Ainley et al. (1981) compared and contrasted the diets and feeding habitats of DCCOs 

and Pelagic and Brandt’s Cormorants. They found that DCCOs fed primarily on 

schooling fish (66-67 percent compared to 22-60 percent for Pelagic and Brandt's) that 

occurred at relatively shallow depths (22-33 percent ranged from the water surface to 

mid-depths compared to 11-14 percent in that range for Pelagic and Brandt's) over flat 

bottoms (63-67 percent compared to 20-38 percent for Pelagic and Brandt's). 

Kirsch (1995) concluded that DCCOs were not competing for food with herons and 

egrets along the Upper Mississippi River where forage fish (especially gizzard shad) were 

not limited. Cormorants forage differently and in different habitats than herons and 

egrets, further reducing the potential for competition. 

Ecological differences and limited geographic overlap between DCCOs and Neotropic 

Cormorants helps restrict foraging competition between the two species (Johnsgard 

1993). Limited foraging competition may exist between Anhingas and DCCOs in areas 

where they both occur, such as in Florida, but this is poorly documented. Owre (1967 in

Johnsgard 1993) suggested that different fish-catching strategies of the two species in 

southern Florida may reduce competition for food, even though both fed on slowswimming centrarchids. 

Densities of DCCO prey fish (winter flounder; American plaice; and grubbies) were 

measured in four Prince Edward Island bays located at varying distances from two large 

cormorant colonies (Birt et al. 1987). Fish densities were significantly (83 percent) lower 

in two bays used by cormorants for feeding than in two bays outside their foraging range 

(i.e., 3.6 versus 21.0 fish/transect). These findings provide evidence of prey depletion, 

and suggest the possibility of prey competition between DCCOs and other fish-eating 

diving birds. 

Disease Transmission. The disease most often associated with DCCOs is Newcastle 

disease, which is chiefly a disease of the central nervous system and is caused by 

infection with a type of avian paramyxovirus. Newcastle disease was first identified as a 

source of mortality in DCCOs in Québec in 1975 (Kuiken et al. 1998). Some of the 

largest epizootics of Newcastle disease occurred in western Canada in 1990, when at least 
72 – Chapter 4 

5,000 DCCOs died, and in 1992 in western Canada, the Great Lakes area, and the north 

central U.S., when some 20,000 DCCOs died. In all cases, most, if not all, of the dead 

birds were juveniles (Kuiken 1999, Kuiken et al. 1998, Glaser et al. 1999). A 1995 

epidemic in Saskatchewan, Canada, led to a 32-64 percent mortality rate among juvenile 

DCCOs (Kuiken et al. 1998). In 1997, Newcastle disease was diagnosed in juvenile 

DCCOs from breeding colonies at Salton Sea (CA), the Columbia River estuary (OR), 

and Great Salt Lake (UT) by the National Wildlife Health Center. Mortality of juveniles 

varied from “not abnormal” to greater than 90 percent (Kuiken 1999). 

In a survey conducted by Wires et al. (2001), two out of 49 respondents reported 

documented cases of disease transmission involving DCCOs. This involved the outbreak 

of Newcastle disease in Michigan in 1992 (mentioned above). While Newcastle disease 

is considered a serious threat to poultry, there has been only one reported incident in ten 

years directly linking DCCOs to an outbreak of the disease in domestic poultry (Mixson 

and Pearson 1992, Kuiken 1999). Evidence suggests that Newcastle disease is not an 

important cause of mortality in other wild bird species that nest in close association with 

DCCOs (Kuiken et al. 1998, Kuiken 1999). 

Disturbance Caused by Management Actions. There is no evidence that current 

management practices are a threat to the population viability of any bird species. The 

intensive egg oiling efforts on Little Galloo Island, New York have not impacted other 

nesting waterbirds on the island (USFWS 2003). Carney and Sydeman (1999) noted that 

nesting colonial waterbirds, when disturbed by humans, often flush from their nests, 

during which time nest contents can be spilled, exposed to predation, or harmed by 

exposure to the elements. Nest abandonment may also occur. These authors emphasized 

“the varied responses of individual species and populations to...disturbance,” while also 

noting that in many cases “significant impacts on reproductive performance of colonial 

waterbirds” may occur. 

In general, the extent of impacts to other birds varies by species, time of year, and 

location. Risks to other birds from DCCO management vary depending on the level of 

cohabitation and the degree of disturbance (van Dam and Asbirk 1997). Harassment 

activities aimed at preventing DCCOs from nesting, roosting, or feeding at particular sites 

can clearly lead to indirect impacts on other bird species, with the greatest risk of impacts 

involving actions that occur at multi-species breeding colonies. 

Bayer (2000) noted that DCCO harassment efforts at various estuaries along the northern 

Oregon Coast caused disturbance to “waterfowl,” “herons,” and Black Brant but no 

biological impacts associated with this disturbance were noted. In the final 

Environmental Assessment for the take of cormorants and gulls on Lake Champlain 

Islands, Vermont (USFWS 1999b), non-lethal management techniques were considered 

very likely to disrupt other nesting species. In particular, it was believed that 

“pyrotechnics...would frighten non-target species sharing islands with cormorants, and 

could result in abandonment by gulls and common terns.” For this reason, the 

requirement that non-lethal management techniques be used before the authorized egg 

oiling and nest/egg destruction activities was waived. Hazing activities conducted at 
73 – Chapter 4 

Oneida Lake, New York, did not negatively impact Common Terns, largely because the 

timing and specific location of DCCO harassment efforts took into consideration the 

presence of terns (NYSDEC press release). 

Benefits to Other Species. Depredation permits have been issued to the States of New 

York and Vermont for the purpose of enhancing avian diversity, including Blackcrowned Night-Herons. The USFWS Environmental Assessment for the take of 

cormorants on Lake Ontario Islands, New York predicted that night-herons would benefit 

from reduced DCCO recruitment caused by egg oiling (USFWS 1999a). Habitat 

manipulation and DCCO nest removal efforts on Gull and Bass Islands in eastern Lake 

Ontario are presumed to have contributed to the stable night-heron population on that site 

(NYSDEC 2000, USFWS 2003). 

Gull species that nest in association with DCCOs may benefit from the presence of 

cormorants due to the increased availability of food on the islands, including fish remains 

and chick regurgitates. Gulls also routinely prey on cormorant eggs and young nestlings 

when nests are left unattended (J. Trapp, FWS, pers. comm.). Given the abundant, and 

sometimes nuisance, status of certain gull populations, this may or may not be desirable 

from a management perspective. In the Great Lakes, habitat has been created for 

American White Pelicans on islands denuded by DCCO guano (S. Lewis, USFWS, pers. 

comm.). 

It is believed that the Common Tern could benefit from reduced DCCO recruitment 

where suitable island nesting sites are otherwise limited. Thus, from 1995-1999, the 

Service issued a permit to Vermont to destroy DCCO nests and eggs on five islands in 

Lake Champlain, in order to reduce competition with Common Terns. Additionally, 

permits have been issued since 1999 to Vermont and New York to oil DCCO eggs and 

destroy nests to benefit Common Terns. 

Conclusion: The significance of DCCO-related impacts to other birds is a matter of scale. 

Large-scale impacts on regional or continental populations of other colonial waterbirds 

have not been documented (Cuthbert et al. 2002), but evidence is strong that DCCOs 

have had negative impacts on other bird species at a localized level (Weseloh et al. 2002). 

DCCO control efforts carried out in the vicinity of other birds, especially at nesting 

colonies, must be done so with caution in order to minimize incidental negative impacts.

Alternative B: Non-lethal Management 

Under this alternative, while the risk of birds being killed directly is minimal, the threat 

of disturbance caused by DCCO harassment efforts is considerable. When carried out on 

a limited and localized level, non-lethal activities are unlikely to threaten populations of 

colonial waterbirds. However, if practiced on a broader level (such as might be required 

to enhance the effectiveness of an entirely non-lethal management regime) and at multispecies colonies, negative population impacts could occur as a result of repeated nest 

failures. 
74 – Chapter 4 

Conclusion: This alternative would be less effective than the No Action alternative at 

addressing DCCO impacts on other birds and could potentially cause serious disturbance 

to other species. 

Alternative C: Increased Local Damage Control 

In addition to harassment activities, this alternative authorizes shooting, egg oiling, and 

nest destruction, all of which could lead to increased human disturbance of mixed species 

breeding colonies but this can be mitigated to insignificance as shown in control efforts 

on Little Galloo Island, New York (USFWS 2003). Increased shooting authority could 

lead to greater incidental take, especially for look-alike species, but this is not likely since 

the shooting would be carried out mainly by trained resource professionals and because 

the Service would be cautious in its issuance of depredation permits in areas with high 

numbers of look-alike species. Under the expanded aquaculture depredation order, the 

likelihood of incidental take of look-alike species at roosts would increase slightly. See 

Appendix 7 for guidelines on distinguishing DCCOs from Neotropic Cormorants and 

Anhingas. 

Conclusion: By permitting control actions in specific situations where DCCOs are having 

negative impacts, this alternative is more likely to benefit other birds than the No Action 

alternative. 

PROPOSED ACTION Alternative D: Public Resource Depredation Order 

We anticipate that more DCCO control actions will occur under this alternative than the 

No Action alternative. This increases the risk of incidental take or disturbance to nontarget species. At some mixed species colonies, it would not be advisable to conduct 

DCCO control at all because of the risk of disturbing other breeding birds; at other sites, 

careful planning would reduce the likelihood of significant disturbance. 

In the DEIS we reported that increased incidental take of look-alike species such as 

Anhingas, Neotropic Cormorants, Great Cormorants, Pelagic Cormorants, and Brandt’s 

Cormorants may occur. Because of subsequent geographic limitations on the public 

resource depredation order, the risk of incidental take now only applies to Anhingas and 

Neotropic Cormorants. See Appendix 7. 

Conclusion: This alternative has a high likelihood of allowing agencies to effectively 

manage DCCOs to reduce impacts to other birds. Caution must be exercised to 

minimized disturbance to non-target species, especially during the nesting season. 

Alternative E: Regional Population Reduction 

The relationship between reduced regional populations of DCCOs and effects on local 

populations of other birds is not completely clear. Local management of DCCO colonies 

to benefit other birds would continue under this alternative. However, because of the 

need for intensive management to attain reduced regional population objectives, this 

alternative could result in considerably increased disturbance of bird species that feed, 

nest, or roost in association with DCCOs and increased incidental take of look-alike 

species (especially other cormorant species). 
75 – Chapter 4 

Conclusion: Relative to the No Action alternative, the direct and indirect negative impacts of 

DCCOs on other birds are more likely to be reduced under this alternative. Increased 

disturbance to non-target species would likely result. 

Alternative F: Regulated Hunting Season 

If this alternative served to reduce regional or continental DCCO populations it could 

help reduce direct and indirect negative impacts to other bird species. If it had no effect 

on populations its effectiveness at reducing these impacts would be limited since most of 

the conflicts between DCCOs and other birds occur during the breeding season and 

hunting would take place outside of the breeding season. By-kill, especially of look-alike 

species such as Great Cormorants, Neotropic Cormorants, and Anhingas, would occur 

more frequently than under the No Action alternative. For example, in the Canadian 

province of Prince Edward Island, legal hunting of DCCOs reduced local Great 

Cormorant populations by 50 percent (Korfanty et al. 1997). However, geographic 

restrictions and identification guides could help reduce the risk of incidental take. 

Conclusion: Hunting is no more likely than the No Action alternative to effectively 

reduce negative impacts on other bird populations unless it had the effect of reducing 

DCCO populations overall. Increased disturbance to non-target species would likely 

result. 

4.2.4 Impacts to Vegetation 

Alternative A: No Action 

DCCOs destroy their nest trees by both chemical and physical means, due to 

accumulation of guano, which is highly acidic, and removal of foliage for nesting 

material (Palmer 1962, McNeil and Leger 1987, Scharf and Shugart 1981, Weseloh and 

Ewins 1994, Weseloh and Collier 1995). Cormorant guano, or excrement, disturbs the 

ionic equilibrium in forest soils (Haynes and Goh 1978), thus killing ground vegetation 

and eventually the nest trees. Furthermore, DCCOs damage vegetation by stripping the 

leaves from trees and even breaking branches due to the combined weight of the birds 

and their nests (Weseloh and Ewins 1994). 

Some specific examples of damage caused by DCCOs to vegetation/habitat include: 

• Weseloh and Ewins (1994) observed that, up until 1980, all DCCO nests on 

eastern Lake Ontario’s Little Galloo Island were in trees. They noted that several 

large willow and hackberry trees, which were “alive and in relatively good health 

in 1978-79, have simply died or crumbled.” Consequently, the number of ground 

nests on Little Galloo Island increased significantly after the early 1980s 

(Weseloh and Ewins 1994). 

• Moore et al. (1995) reported that DCCOs began nesting in cottonwood trees at 

Hamilton Harbor, Lake Ontario in 1986, and that since that time the trees have 

gradually died, with only 24 percent remaining alive by 1993. 

• Lemmon et al. (1994) observed extensive damage to trees containing DCCO nests 

on the Norwalk Islands off the coast of Connecticut. They noted that, “branches 
76 – Chapter 4 

above and within a six to eight foot radius of cormorant nests were stripped of 

their foliage... [while]... lower limbs extending beyond the nests had normal 

foliage... [and]... the ground cover and lower sections of the trees below the 

cormorant nests were whitewashed with guano.” 

• The State of Michigan expressed concern about “the impact of large cormorant 

nesting colonies on the underlying vegetation” and noted that “many wellvegetated Great Lakes islands have been drastically impacted by these cormorant 

colonies, often reducing them to barren landscapes.” 

• Shieldcastle and Martin (1999) reported that the Ohio Division of Wildlife and the 

Service are concerned, biologically and aesthetically, about the arrival of nesting 

DCCOs on West Sister Island National Wildlife Refuge and other islands in Lake 

Erie because of their potential impacts on vegetation. 

• Korfanty et al. (1999) also noted that DCCO-induced habitat destruction on 

Carolinian islands in western Lake Erie is a major problem and that DCCO 

colonies have killed trees and shrubs on several islands in Lake Ontario, Lake 

Huron and at Lake of the Woods. 

• On Pilot Island in Lake Michigan’s Green Bay, evidence exists of DCCOs 

colonizing and killing all of the white cedars there (as well as displacing the 

herons that were using the trees). These islands experienced a “major loss of 

mature trees” due to guano accumulation and defoliation caused by nesting and 

roosting DCCOs (Shieldcastle and Martin 1999). 

• Vegetation on other Great Lakes islands (Hat and Spider Islands in Lake 

Michigan, for example), some of which are managed as National Wildlife 

Refuges, has also been changed significantly by DCCOs (S. Lewis, USFWS, pers. 

comm.). 

• In Rhode Island, a DCCO nesting area on an Audubon Society of Rhode Island 

preserve in the upper Sakonnet River, which once constituted a mature deciduous 

forest of beech, oak, and hickory, has been observed to be “rapidly losing all its 

tall vegetation and may eventually become unsuitable for wading birds” (M. 

Lapisky, pers. comm.). 

• In Canada, damage to island vegetation in the St. Lawrence River estuary of 

Québec was described by Bédard et al. (1995) as “severe, ecologically measurable 

and aesthetically real” and led the Québec Ministère de l’environnement et de la 

faune to initiate a DCCO population control program. 

• In the first study to quantitatively examine the impact of DCCOs on plant 

communities in the Great Lakes, Weseloh et al. (2002 Waterbird Society Annual 

Meeting abstract) assessed forest cover on East Sister and Middle Islands in Lake 

Erie and determined that DCCO nest density was negatively correlated with 

canopy cover in parts of Canada’s last remaining Carolinian vegetation. They 

observed that from 1995-2001 DCCOs were “rapidly affecting island vegetation.” 

Depredation permits have been issued to the States of Vermont and New York for the 

purposes of enhancing habitats on islands in Lake Champlain and the eastern basin of 

Lake Ontario. On Gull and Bass Islands, removal of DCCO nests has minimized 

encroachment of cormorants into the shrubby vegetation (box elder and dogwood) used 

by Black-crowned Night-Herons (Farquhar 2002). 
77 – Chapter 4 

Alternative B: Non-lethal Management 

Harassment and nest removal can be effective at protecting vegetation where used to 

prevent the establishment of DCCOs. Where they are already established but irreversible 

damage has not yet occurred, non-lethal techniques will be limited in effectiveness 

(because, for example, habituation occurs more quickly). This alternative would be less 

effective than the No Action alternative because it does not allow the use of the full range 

of available techniques. 

Alternative C: Increased Local Damage Control 

Impacts to vegetation would be dealt with more effectively than under the No Action 

alternative since permit issuance practices would be less stringent. To the extent that 

control activities under this alternative prevent the establishment of DCCOs, vegetation at 

specific locations will be protected. If permits are issued for aggressive management of 

specific DCCOs that are affecting specific areas, then it is possible that established birds 

could be removed. Where vegetative damage has already occurred, recovery will be slow 

or non-existent, depending on the particular habitat type and thus it may be fruitless to 

conduct DCCO control for the purpose of enhancing vegetation. 

PROPOSED ACTION Alternative D: Public Resource Depredation Order 

In areas where irreversible damage has not occurred, impacts to vegetation will be 

minimized since agencies will be able to control DCCOs more readily. To the extent that 

control activities prevent the establishment of DCCOs, vegetation at specific locations 

will be protected. Some agencies may engage in aggressive management of specific 

DCCOs affecting specific areas and this should help alleviate damage to vegetation. 

Where vegetative damage has already occurred, recovery will be slow or non-existent, 

depending on the particular habitat type and thus it may be fruitless to conduct DCCO 

control for the purpose of enhancing vegetation. 

Alternative E: Regional Population Reduction 

Impacts to vegetation would be dealt with more effectively than under the No Action 

alternative since the ability to control DCCOs causing such problems would be enhanced 

and, eventually, there would be fewer DCCOs. With population reductions originating at 

the local level and objectives focusing on reducing damage, control activities carried out 

under this alternative should help alleviate significant damage to vegetation. Where 

vegetative damage has already occurred, recovery will be slow or non-existent, 

depending on the particular habitat type. 

Alternative F: Regulated Hunting Season 

Impacts to vegetation would most likely be reduced more effectively than under the No 

Action alternative. In some cases, people would be able to target specific DCCOs 

damaging vegetation, although it should be noted that hunting would not be allowed 

during the breeding season and this is when DCCOs are the most destructive. If the 

establishment of hunting seasons across the U.S. led to lower regional populations of 

DCCOs, this would be helpful in alleviating vegetation damages. 
78 – Chapter 4 

4.2.5 Impacts to Federally-listed Species 

Alternative A: No Action 

Under the No Action alternative, there are two potential levels of relationship to species 

protected under the Endangered Species Act. The first is impacts associated with DCCOs 

themselves and the second is impacts associated with DCCO control actions. In the case 

of the former, the best studied impacts are those to listed salmonids in the Pacific 

Northwest and in Maine. With regard to Pacific salmonids, multi-disciplinary science 

reviews have found no compelling scientific evidence that predation has been a primary

cause for recent declines (USFWS 2000b), although that does not mean that they are an 

insignificant part of overall mortality on salmonid smolts. While the role of avian 

predation and the relationship of increasing survival of listed salmonid smolts in the 

estuary to numbers of adult returns is relatively unknown, numerous initiatives are 

underway throughout the Columbia River Basin to decrease in-river smolt mortality as a 

means to aid the recovery of listed salmonid stocks. These include control of predatory 

northern pikeminnows (a native fish known to prey on salmonid smolts), relocation of a 

large Caspian Tern colony to a new location at the mouth of the estuary, and 

modifications of extensive systems of estuary pile dikes to preclude use by DCCOs as 

foraging platforms. Management actions to reduce avian predation, primarily focused on 

Caspian Terns, have resulted in substantial reductions in smolt losses to avian predation 

in the estuary (Collis et al. 2000). Research and monitoring activities are continuing to 

further refine estimates of DCCO smolt consumption and to determine the need for 

further management actions (BPA 2001). 

With regard to Atlantic Salmon in Maine, loss of smolts to DCCOs foraging on New 

England rivers is believed by some biologists to be a potential limiting factor to the 

recovery of Atlantic salmon populations (Moring 1987 and Moring et al. 1995 in 

Blackwell et al. 1997). However, there is currently no scientific evidence to substantiate 

this claim. Milton et al. (1995) wrote: “information on river-specific salmon stocks and 

environmental and habitat factors affecting these stocks is insufficient to consider 

cormorants a factor affecting their survival or limiting their growth at this time.” 

Currently, there is no evidence that DCCO management actions have led to the take of 

any Threatened or Endangered species or that DCCO control efforts are having 

significant impacts on these species. 

Alternative B: Non-lethal Management 

Bayer (2000) found that hazing of cormorants on a few northern Oregon Coast estuaries 

was not correlated with improved hatchery returns of salmonids. Nor have average 

spawning ground counts of wild coho salmon, winter steelhead, and fall chinook 

increased since hazing began. Bayer observed that “Returns may not have increased with 

hazing because it was ineffective in substantially reducing predation, because smolts 

saved by hazing died anyway, or because other factors such as unfavorable ocean 

conditions may have been much more important in affecting smolt survival than hazing.” 

Without incorporating proper mitigation measures, harassment activities associated with 

this alternative could have deleterious effects on listed species that occur in association 
79 – Chapter 4 

with DCCOs. Overall, impacts to Threatened and Endangered species would probably be 

similar to the No Action alternative. 

Alternative C: Increased Local Damage Control Alternative 

Impacts to Threatened and Endangered species would be the same as under the No 

Action alternative. 

PROPOSED ACTION Alternative D: Public Resource Depredation Order 

Consultation under the Endangered Species Act was completed between the Division of 

Migratory Bird Management and the Division of Consultations, HCPs, Recovery and 

State Grants. Based on information from the DCCO proposed rule and an intra-Service 

Biological Evaluation (to request a copy of this BE, contact the Division of Migratory 

Bird Management), incorporating the following conservation measures would avoid 

adverse effects on the bald eagle, interior least tern, wood stork, and piping plover: 

All control activities [under the aquaculture depredation order] are allowed if the activities occur more than 

1500 feet from active wood stork nesting colonies, more than 1000 feet from active wood stork roost sites, 

and more than 750 feet from feeding wood storks, and if they occur more than 750 feet from active bald 

eagle nests. 

At their discretion, landowners, operators, and tenants may contact the Regional Migratory Bird Permit 

Office to request modification of the above measures. Such modification can occur only if, on the basis of 

coordination between the Regional Migratory Bird Permit Office and the Endangered Species Field Office, 

it is determined that wood storks and bald eagles will not be adversely affected. If adverse effects are 

anticipated from the control activities, either during the intra-Service coordination discussions described 

above or at any other time, the Regional Migratory Bird Permit Office will initiate consultation with the 

Endangered Species Field Offices. 

[Under the public resource depredation order,]: 

(i) discharge/use of firearms to kill or harass double-crested cormorants or use of other harassment methods 

are allowed if the control activities occur more than 1000 feet from active piping plover or interior least 

tern nests or colonies; occur more than 1500 feet from active wood stork nesting colonies, more than 1000 

feet from active wood stork roost sites, and more than 750 feet from feeding wood storks; or occur more 

than 750 feet from active bald eagle nests; 

(ii) other control activities such as egg oiling, cervical dislocation, CO2 asphyxiation, egg destruction, or 

nest destruction are allowed if these activities occur more than 500 feet from active piping plover or interior 

least tern nests or colonies; occur more than 1500 feet from active wood stork nesting colonies, more than 

1000 feet from active wood stork roost sites, and more than 750 feet from feeding wood storks; or occur 

more than 750 feet from active bald eagle nests; and 

(iii) to ensure adequate protection of piping plovers, any Agency or their agents who plan to implement 

control activities that may affect areas designated as piping plover critical habitat in the Great Lakes 

Region are to make contact with the appropriate Regional Migratory Bird Permit Office prior to 

implementing control activities. The Regional Migratory Bird Permit Office will then coordinate with the 

Endangered Species Field Office staff to determine if the above measures are adequate. 

At their discretion, agencies or their agents may contact the Regional Migratory Bird Permit Office to 

request modification of the above measures. Such modification can occur only if, on the basis of 

coordination between the Regional Migratory Bird Permit Office and the Endangered Species Field Office, 

it is determined that no adverse effects to any of the four listed species will occur. If adverse effects are 

anticipated from the control activities, either during the intra-Service coordination discussions described 

above or at any other time, the Regional Migratory Bird Permit Office will initiate consultation with the 

Endangered Species Field Offices. 
80 – Chapter 4 

Alternative E: Regional Population Reduction 

It is unclear what the actual effects of this alternative on Threatened and Endangered 

species would be. Without incorporating proper mitigation measures, control activities 

associated with this alternative could have deleterious effects on some listed species that 

occur in association with DCCOs. Reductions of DCCO populations could alleviate 

impacts on listed species if these are occurring. 

Alternative F: Regulated Hunting Season 

It is unclear what the actual effects of this alternative on Threatened and Endangered 

species would be. Without incorporating proper mitigation measures, control activities 

associated with this alternative could have deleterious effects on some listed species that 

occur in association with DCCOs. Localized reductions of DCCO populations associated 

with hunting could alleviate impacts on listed species if these are occurring. 

4.2.6 Impacts to Water Quality and Human Health 

Alternative A: No Action 

Currently, depredation permits have only been issued for the control of DCCOs that are a 

direct source of water pollution (e.g., birds roosting over a water storage area). None 

have been issued for indirect pollution of groundwater, since it can be difficult to show a 

direct relationship between DCCOs and compromised water quality. The organochlorine 

contaminants found in many fish and birds were (and many continue to be) introduced 

into the environment by human activities. There is little scientific discussion of the 

relationship between bird abundance, contamination of ground water, and associated 

human health impacts. We were unable to locate any references in the literature or 

elsewhere of elevated bacterial counts or contaminant levels caused by DCCOs 

threatening human health. 

Clearly, DCCOs, by virtue of being a top predator, harbor contaminants that are found in 

the Great Lakes ecosystem and convey these to the waters that they inhabit. While there 

is a great deal of literature examining the levels and effects of various contaminants in 

DCCOs (cf. Elliott et al. 1989, Bishop et al. 1992a, Powell et al. 1997, Rattner et al. 

1999, etc.), there is no documentation of effects on humans caused by direct 

contamination from DCCO excrement, feathers, or carcasses. In 1999, testing by a New 

York State-accredited environmental laboratory (Chopra-Lee, Inc.) found no chemical 

contaminants in either of two residential groundwater wells near Little Galloo Island 

(home of a large DCCO colony in eastern Lake Ontario) that were sampled, although 

elevated bacterial counts were measured (Anon. 1999). 

DCCOs are not considered to be a significant threat to groundwater supplies in general, 

although they may be a direct source of contamination in cases where they nest or roost 

near water supplies (however, examples of this are uncommon). 

Alternative B: Non-lethal Management 

Where impacts are directly related to the presence of specific birds, harassment may help 

alleviate these conflicts (e.g., where birds only needed to be moved away). However, 
81 – Chapter 4 

since lethal control is useful for enhancing harassment efforts, this alternative would be 

less effective than the No Action alternative. 

Alternative C: Increased Local Damage Control Alternative 

Controlling DCCOs in localized situations would likely not eliminate, or necessarily even 

alleviate, human health risks associated with contaminants due to the effects of other 

piscivorous birds, the persistence of organochlorine chemicals in Great Lakes waters, and 

bioaccumulation of those chemicals from fish to humans. Where DCCOs are a direct 

source of bacterial contamination, this alternative would allow for as effective control as 

the No Action alternative. 

PROPOSED ACTION Alternative D: Public Resource Depredation Order 

Relative to the No Action alternative, local water quality–to the extent that it is impacted 

by DCCOs–would be expected to improve under this alternative. Concentrations of 

pathogens (e.g., E. coli) in local water bodies might decline proportionally to reductions 

in the number of DCCOs associated with actions to protect public resources. Since 

DCCOs are merely a means by which chemical contaminants may be distributed within 

aquatic ecosystems, not a direct source of the contaminants themselves, reductions in 

cormorant numbers are not expected to reduce overall contaminant levels. 

Alternative E: Regional Population Reduction 

Similar to the discussion under the previous alternative, local water quality would be 

expected to improve relative to the No Action alternative, to the extent that it is impacted 

by DCCOs. Since DCCOs are merely a means by which chemical contaminants may be 

distributed within aquatic ecosystems, not a direct source of the contaminants themselves, 

reductions in cormorant numbers are not expected to reduce overall contaminant levels. 

Alternative F: Regulated Hunting Season 

Similar to previous conclusions, local water quality–to the extent that it is impacted by 

DCCOs–would be expected to improve under this alternative relative to the No Action 

alternative. Since DCCOs are merely a means by which chemical contaminants may be 

distributed within aquatic ecosystems, not a direct source of the contaminants themselves, 

reductions in cormorant numbers are not expected to reduce overall contaminant levels. 

The human consumption of DCCOs would, for health reasons, not be advisable due to 

high contaminant loads. Statewide advisories are commonly issued to warn the public of 

the potential for widespread contamination of certain species of fish or certain species of 

wildlife. Mercury, PCBs, chlordane, dioxins, and DDT (DDE and DDD) were at least 

partly responsible for 99 percent of all fish consumption advisories in effect in 1999 

(EPA 1999a). All waters of the Great Lakes and their connecting waters are under 

advisory for restricted consumption of fish or certain wildlife coming from these waters 

(EPA 1999a). Seventeen States (Alabama, Connecticut, Florida, Indiana, Louisiana, 

Maine, Massachusetts, Michigan, Missouri, New Hampshire, New Jersey, New York, 

North Carolina, Ohio, Rhode Island, Texas, and Vermont) and Washington, D.C. 

currently have statewide advisories in effect. In any State where there is a statewide 

advisory against the consumption of fish, DCCOs should not be consumed. 
82 – Chapter 4 

4.2.7 Economic Environment (Aquaculture, Recreational Fishing Economies, and 

Commercial Fishing) 

Alternative A: No Action 

Aquaculture

As stated by Curtis et al. (1996), “predation problems are to be expected when 

aquaculture facilities are constructed on known migratory routes or in areas where fisheating birds are known to congregate.” This appears to be precisely the case with the 

southern aquaculture industry, especially that of the Mississippi Delta region. This is 

noted merely as biological fact; it should be added that early fish farmers could not have 

foreseen the DCCO population explosion or the extent to which these birds would alter 

their migration routes in response to new food sources such as fish farms. Curtis et al. 

(1996) advised that such areas should be avoided or the presence of fish-eating birds 

should be taken into consideration when designing aquaculture facilities. However, for 

many aquaculture producers it is either too late to take these factors into consideration or 

the costs of doing so are prohibitive. See Appendix 8 for an overview of aquaculture 

production and estimated control expenses in the 13 States included in the aquaculture 

depredation order. 

The actual magnitude of DCCO-related economic impacts to the aquaculture industry 

depends on many different variables, including the value of the fish stock, the time of 

year the predation is taking place, and the number of depredating birds present. The 

frequency of occurrence of DCCOs at a given aquaculture facility can be a function of 

many interacting factors, including: (1) size of the regional cormorant population; (2) the 

number, size, and distribution of ponds; (3) the size distribution, density, health, and 

species composition of fish populations in the ponds; (4) the number, size, and 

distribution of “natural” wetlands in the immediate environs; (5) the size distribution, 

density, health, and species composition of “natural” fish populations in the surrounding 

landscape; (6) the number, size, and distribution of suitable roosting habitat; and (7) the 

variety, intensity, and distribution of local damage abatement activities. 

Glahn et al. (1999) found that as much as 75 percent of the diet of DCCOs in certain 

roosting areas of the Mississippi Delta consisted of catfish and, according to bioenergetic 

models, cormorants can exploit as much as 940 metric tons of catfish per winter. Price 

and Nickum (1995) noted that the aquaculture industry has small profit margins so that 

even a small percentage reduction in the farmgate value due to predation is economically 

important. Stickley et al. (1992) estimated that in a 9-hour foraging day with birds 

feeding at an average rate, 100 DCCOs could cause a loss of approximately $400 to a 

Mississippi fish farmer. Bioenergetics modeling on DCCOs estimated that losses to the 

Mississippi Delta catfish industry over the winters of 1989-90 and 1990-91 approximated 

20 million and 19 million fingerlings, respectively. This was equivalent to approximately 

4 percent of the fingerling class, representing approximately $2 million in fish losses 

(Glahn and Brugger 1995). Glahn et al. (2000) used this same model to predict current 

predation rates on fingerling catfish in the Delta region based upon the recent doubling in 

the wintering DCCO population, with estimated losses resulting in the removal of 49 

million fingerlings valued at $5 million. 
83 – Chapter 4 

Controlled experiments by Glahn et al. (2002) investigating predation losses by DCCOs 

confirm previous estimates of cormorant damage and have started to examine output 

parameters at harvest with and without predation. Using sampling weights of fish 

inventoried from captive cormorant trials, they calculated a 19.6 percent biomass 

production loss from DCCO predation. At the commercial pond scale this level of 

predation corresponds to a loss of 6,800 kg (15,000 lbs) valued at $10,500 or almost 5 

times the value of the fingerlings lost. Using this ratio, catfish production losses to 

Mississippi Delta catfish farmers may currently approach $25 million or 8.6 percent of all 

catfish sales in Mississippi. Furthermore, they examined the economic effects of 

cormorant predation on net returns in an enterprise budget for an average 130 hectare 

catfish farm using data collected from captive cormorant trials and standard budgeting 

techniques. Enterprise budgets resulted in a 111 percent loss of profits based upon a 20 

percent production loss observed at harvest from simulating 30 DCCOs feeding at a 6 

hectare catfish pond for 100 days (Glahn et al. 2002). 

Because DCCOs are adept at seeking out the most favorable foraging and roosting sites, 

they are rarely distributed evenly over a given region, but rather tend to be highly 

clumped or localized. In the Mississippi Delta, the number and location of roost sites are 

dynamic, and depredations have been found to be “temporarily highly concentrated on 

ponds in close proximity to active roost sites” (USDA 2000). Thus, it is not uncommon 

for some fish farmers in a region to suffer little or no economic damage from DCCOs, 

while others experience exceptionally high losses. 

Much of the bird depredation to baitfish and the tropical fish industries have been 

associated with wading birds rather than DCCOs (Avery et al. 1999; Hoy 1994; Hoy 

1989; USDA-APHIS 1997a). Impacts of cormorants on baitfish and tropical fish are not 

well known (Brugger 1995). Similar wading bird impacts are seen within the crayfish 

industry with White Ibis, Yellow-crowned Night-Herons, and Great Egrets being the 

main predatory bird species (Price and Nickum 1995). Cormorants have been 

documented eating crayfish on their northern breeding grounds (Blackwell et al 1997; 

Lewis 1929; Ludwig et al. 1989; Neuman et al. 1997; Weseloh and Collier 1995) and 

depredation has been observed on crayfish farms in Louisiana (USDA-APHIS 1997a; 

Huner and Jeske 2001). Based on available scientific studies the impacts of cormorants 

on commercial crayfish production are unclear (Huner and Jeske 2001). 

Under the No Action alternative, a combination of lethal and non-lethal control 

techniques is used to reduce economic impacts to aquaculture producers. See the 

discussion of Alternative B in this section for discussions of non-lethal techniques. No 

control tool is 100 percent effective against predation losses (OTA 1995), however 

depredations on aquacultural stock are less than they would be without lethal control 

(Glahn et al. 2000a). Shooting to kill birds is commonly used by producers to control 

DCCO depredation at commercial freshwater aquaculture facilities. The 1998 

aquaculture depredation order authorized the unlimited take of depredating DCCOs at 

aquaculture facilities in 13 States (Alabama, Arkansas, Florida, Georgia, Kentucky, 

Louisiana, Minnesota, Mississippi, North Carolina, Oklahoma, South Carolina, 
84 – Chapter 4 

Tennessee, and Texas). In other States, depredation permits are issued by the Service 

Regional Migratory Bird Permit Offices for significant economic impacts to aquaculture 

producers. Glahn et al. (2000a) estimated that without such lethal damage control 

programs, the impact of DCCO depredation on the catfish industry would likely have 

more than doubled in the late 1990s compared to earlier years. 

A report from the head of the aquaculture program at Langston University in Oklahoma 

shows the usefulness of variety in depredation control techniques (C. Kleinholz, pers. 

comm.): 

[The university] applied for its first depredation permit when a group of approximately 400 cormorants 

were suddenly observed on 2, one-acre catfish/trout ponds during late 1984. Within the 30 days that 

elapsed to obtain an expedited permit, approximately 900 rainbow trout and 3000 channel catfish 

fingerlings were eaten by the cormorants, despite daily hazing. Our management strategy from that time 

has been to shoot all birds legally permitted, as soon as they appear at the pond site(s). Since, 1996, we 

have also used 15’ x 15’ grids of synthetic baling twine suspended over the ponds to discourage cormorants 

from landing in the ponds, which appears to have reduced visitation to both facilities.... We are very 

fortunate to be included in the current depredation order for cormorants. The cyclic nature of cormorant 

occurrence at our facilities would have resulted in severe depredation without the order, since our 

depredation permit allowed the take of only 25 birds annually. In 1998, shortly after the [aquaculture] 

depredation order was issued, we had a very large fall flight of cormorants that stayed in the area for almost 

three months. We killed 85 birds and hazed several thousand more during that period. 

Recreational Fishing Economies 

Depredation permits have not been authorized for the take of DCCOs to benefit 

communities whose economies are closely coupled with the quality of recreational 

fishing. This is because (1) the Service does not issue permits for this reason and (2) the 

relationship between increased DCCO abundance (and predation) and subsequent 

declines in angler participation and spending is undocumented. Trapp et al. (1999) 

surveyed the States asking, “Is there documented evidence that increased DCCO 

populations have affected local economies associated with the sport fishing or tourism 

industries?” Of the 12 responding States, none reported any documented evidence that 

DCCOs had affected local economies associated with the sport fishing or tourism 

industry. 

We do not doubt the reality or disregard the importance of the economic changes 

occurring in communities whose economic health is closely tied to recreational fishing. 

However, analyzing the relationship between DCCO predation, fishery impacts, angler 

participation, and economic effects is very complex and, at this point, is limited to 

qualitative predictions. The Oregon Department of Fish and Wildlife, in reply to the 

survey conducted by Trapp et al. (1999), commented that, 

[while] we can document the economic effect of decreased salmon populations through closure of 

commercial fisheries and formerly popular sport charter fisheries, and declining sales of salmon harvest 

tags...we believe that DCCO predation is only one of a number of causative factors which in total are 

responsible. 

In areas where the evidence shows that DCCOs are impacting fisheries and associated 

recreational catch (e.g., eastern Lake Ontario and Oneida Lake, New York), it is easier to 
85 – Chapter 4 

assume that they may be having negative impacts on the economies of surrounding 

communities. As stated in chapter 3, a report on the economic impacts of sport fishery 

declines in eastern Lake Ontario found that a number of businesses that depend heavily 

on eastern basin sport fisheries experienced declines in business throughout the 1990s 

(Brown et al. 2002). The authors stated that, “we feel reasonably confident that we have 

documented at the correct order of magnitude a large decline in coastal fishing and 

boating-related activity over the 13-year period between 1988 and 2001,” but also noted 

that, “putting a dollar value on the portion of the decline that is attributable to cormorants 

is impossible” (Brown et al. 2002). The declines that they documented include fewer 

boat trips (lakewide), fewer charter boats (lakewide), lower angler expenditures (in 

Jefferson and Oswego counties), and economic losses to marinas and charter and guide 

services. Overall, they estimated that the total impact of the decline in expenditures 

across the two-county (Jefferson and Oswego) economy was $10.9 million. The authors 

correlated this information with the evidence from NYSDEC biological data showing that 

DCCOs are negatively impacting the eastern Lake Ontario smallmouth bass fishery and 

concluded that there is a high likelihood that DCCO depredation is contributing to these 

economic impacts while noting that “additional factors may also be operating” (Brown et 

al. 2002). 

Commercial Fishing 

Historically, impacts to open water commercial fish stocks were one of the more 

important problems associated with DCCOs (cf. Mendall 1936). Today, concerns about 

declines in openwater commercial fisheries are shadowed by concerns about negative 

impacts to recreational fisheries and aquacultural stocks, although they do still exist. For 

example, in a March 2000 letter, the State of Maine Department of Marine Resources 

stated that, “During the past 20 years, alewife runs have declined dramatically. Of the 34 

rivers and streams that have supported commercial alewife fisheries, only eight continue 

to support commercial harvests. The remainder have been closed to harvest for almost a 

decade to allow rebuilding of the runs. In spite of closures, these runs continue to remain 

at low levels. Every spring, large concentrations of cormorants are observed in the upper 

estuaries of rivers that support alewife runs. We believe that cormorant predation on 

these low level spawning runs is very high and may be having significant impacts on the 

ability of these stocks to recover to former levels of historical abundance.” 

Additionally, the States of Maine, New York, and Rhode Island each expressed concern 

about potential impacts to the commercial winter flounder fishery by DCCOs. For 

example, the Rhode Island Division of Fish and Wildlife stated that, “significant 

anecdotal information exists regarding severe predation of juvenile winter flounder in 

coastal salt ponds and all near-shore marine waters of the state.” 

Blackwell et al. (1995) noted that examinations of DCCO diet in a variety of habitats 

have shown that primary prey species are fish of little or no commercial value and cited 

several studies that confirm this notion. They pointed out that commercial groundfish 

populations (Gadidae, Bothidae, and Pleuronectidae) in the Gulf of Maine have declined 

drastically, probably due to increasing exploitation since the 1960s (Blackwell et al. 

1995) and that, as groundfish populations have decreased, cartilaginous fishes (Squalidae 
86 – Chapter 4 

and Rajidae) have filled their ecological niches, thereby adding competition to the other 

factors threatening their numbers. Thus, groundfish species such as flounders and 

Atlantic cod, which were present in Mendall’s (1934, 1936) DCCO diet data in the same 

area (Penobscot Bay), were noticeably absent from Blackwell et al.’s (1995) list of 

highest ranking prey species. 

Commercial fish generally do not appear to make up a significant part of DCCO diet, as 

the following studies suggest: 

• Ludwig et al. (1989) examined 8,512 regurgitated DCCO food items from Lakes 

Huron, Michigan, and Superior and did not find any lake trout or common 

whitefish, two commercially important species. Fish species of local commercial 

importance constituted 12 percent by number (34 percent by weight) of these food 

items, including yellow perch (13 percent by weight), smelt (8 percent by weight), 

and sucker (7 percent by weight). 

• In the Apostle Islands of Lake Superior, Wisconsin, there was a concern in the 

mid-1980s that DCCOs were feeding heavily on commercially valuable whitefish. 

A subsequent study showed that the diet consisted primarily of forage fish such as 

sticklebacks, burbot, sculpins, and chubs. No more than 3 percent of the fish eaten 

by DCCOs were whitefish (Craven and Lev 1987). 

• A study conducted in western Lake Erie found that DCCO diet primarily 

consisted of gizzard shad, emerald shiner, and freshwater drum, suggesting that 

impacts of DCCOs at current population levels were not detrimental to sport and 

commercial fishing (Bur et al. 1999). 

Work with the Great Cormorant in Europe has not found evidence of significant impacts 

to commercial fisheries. On a lake in southern Germany, Keller (1995) found that the 

total catch of whitefish by Great Cormorants amounted to just 3.2 percent of the total 

commercial catch of this species. Larger consumption rates were found for other 

commercial species such as eel (22.3 percent) and pike (6.2 percent). It was estimated 

that cormorants took 3.3 percent of total annual fish production, while commercial 

fishermen took 28 percent. Just as with recreational fisheries, however, examinations of 

impacts to commercial fisheries should be evaluated on a site-by-site basis whenever 

possible. We were unable to find any documented evidence of significant impacts to 

commercial fisheries caused by DCCOs. 

In Sweden, Great Cormorants are viewed as a problem by commercial fishermen, mainly 

because they injure or consume fish in fishing gears (Engström 1998). In studies carried 

out on six lakes and one coastal area, Engström (1998) found that fishermen may 

encounter, at most, an average of 8 percent (by weight) of fish damaged by cormorant 

predation. How much fish was removed from the fishing gear by cormorants was not 

known, but it was determined to be most likely that such predation affected smaller fish 

species of lesser economic value. Engström (2000) also found that commercially 

important species such as eel and pikeperch were absent or made up only a very small 

part (0.2 percent) of the diet of cormorants in a lake in south-central Sweden and that, for 

pikeperch, there was no evidence showing that such small out take would have a negative 
87 – Chapter 4 

impact on commercial yields. Examples of DCCO-induced damage to commercial 

catches in the Great Lakes also exist. One commercial fishermen reported that he no 

longer fishes his pound nets in the spring because DCCOs chase the whitefish in the pots 

and spear many of them, lowering the market quality of the catch. Trap net fishers also 

experience DCCO damage to fish in the pot, but to a much lesser degree since the pot is 

submerged (S. Lewis, USFWS, pers. comm.). 

Wires et al. (2001) noted that “Where cormorants are consuming commercial fishes, 

isolating the role of cormorant predation relative to other sources of mortality is difficult. 

Thus the magnitude of impact due to cormorant predation is often unknown.” Under the 

No Action alternative, no depredation permits have been issued in recent years to 

alleviate DCCO damages to openwater commercial fisheries. 

Alternative B: Non-lethal Management 

Aquaculture 

Surveys of aquaculturists reveal that harassment patrols are commonly utilized, despite 

the fact that few producers consider them very effective. Stickley and Andrews (1989) 

reported that 60 percent of respondents who reported using harassment techniques used 

vehicle patrols combined with shooting to repel (not to kill) birds; of these, 13 percent 

found this combination to be very effective, 47 percent somewhat effective, and 40 

percent not effective. Of these same respondents, 9 percent utilized pyrotechnics 

regularly; of these, 24 percent found pyrotechnics to be very effective, 57 percent 

somewhat effective, and 19 percent not effective. Catfish producers implementing roost 

dispersal activities may reduce depredation to fish stocks for a period of time, but only 

temporarily (Glahn et al. 2000; Glahn et al. 1996; Mott et al. 1998; Tobin et al. 2002). 

Damage abatement activities typically shift bird activities from one area to another, 

thereby reducing damage at one site while often increasing it at another (Aderman and 

Hill 1995; Mott et al. 1998; Reinhold and Sloan 1999; Tobin et al. 2002). Nisbet (1995) 

referred to harassment as a “negative-sum game” because, “in most cases, it merely 

moves [DCCOs] to other ponds, where more harassment is needed, which moves them to 

other ponds, and so on, thereby increasing the total burden on the industry.”

The degree to which lethal control is cost efficient will vary with circumstances. See 

Appendix 9 for more information on cost effectiveness of various control techniques. For 

some producers, a harassment program combined with occasional shooting of birds may 

be most cost efficient. For others, it may be more efficient in the long-term to adjust 

management techniques (e.g., stock rates, feeding methods, and/or timing of 

fry/fingerling transplant) and install devices that will physically exclude fish-eating birds. 

In Arkansas, the use of simple barriers (i.e., twine strung across ponds at 30 m intervals) 

limited the number of DCCOs landing on ponds by 2 to 4 fold (A. Radomski, 

USDA/ARS, unpubl. data). While such techniques hold promise, it would be a mistake 

to assume that such techniques are more effective than lethal techniques. 

Glahn et al. (2002) provide a thorough overview of some of the challenges associated 

with changes in catfish culture practices: 
88 – Chapter 4 

...a number of possible alternatives have been proposed by several authors (Barlow and Bock 1984, 

Moerbeek et al. 1987, Mott and Boyd 1995). These include reducing pond size, delaying stocking and 

reducing stocking rates. Although implementation is seemingly thwarted by tradition, such strategies may 

be simply flawed based on economic risk assessment. For example, reducing pond size would facilitate the 

installation of bird exclusion systems, but pond construction cost, a major capital expenditure, increases as 

pond size decreases (Garrard et al. 1990). Although new ponds being built have decreased slightly in size 

from 6 ha to 4.8 ha (Hanson, unpublished report), there is no information to suggest that these might be 

small enough to make exclusion practical. Delaying stocking of fingerlings until late spring after 

cormorants leave is also often suggested (Glahn et al. 1995, Mott and Boyd 1995, Mott and Brunson 1997). 

However, delaying stocking is not compatible with the multi-batch cropping system and may increase the 

risk of more devastating stress-related disease outbreaks that are prevalent at water temperatures later in the 

spring. 

Night roost harassment is another technique for non-lethal management of DCCO 

depredation. It involves “teams of people [firing] exploding and whistling pyrotechnics at 

birds in roosts and at birds flying into the roosts in the evening” (Tobin et al. 2002). A 

survey of catfish producers in the southern U.S. (Wywialowski 1998, 1999) revealed that 

14 percent reported using night roost harassment, mostly in Mississippi (32 percent of all 

Mississippi catfish producers). Mott et al. (1998) concluded that, although harassment of 

roosts does not eliminate the DCCO predation problem at catfish farms, it does cause 

DCCOs to temporarily shift their roosting activity to locations along the Mississippi 

River, thereby reducing the number of cormorants on or near catfish ponds. Producers in 

the intensely harassed area reported spending less on harassment patrols which saved an 

average of $1,406 and $3,217 per year during the winters of 1993-94 and 1994-95, 

respectively (Mott et al. 1998). Overall, night roost harassment is not considered to be 

sufficient for eliminating the need to practice other forms of DCCO control at 

aquaculture facilities, although it appears to be effective at decreasing losses (Littauer et 

al.1997; Mott et al. 1998; Reinhold and Sloan 1999, Tobin et al. 2002). Mott et al. 

(1998) concluded that, “To be most effective, all roost sites within a large geographic 

area need to be harassed simultaneously, or at least harassed on a weekly basis, to prevent 

cormorants from moving from site to site or reoccupying previously abandoned sites.” 

Recreational Fishing Economies 

The impact of this alternative on local economies that are closely coupled with 

recreational fishing would probably be worse than the No Action alternative. It is 

unlikely that non-lethal methods alone would have significant benefits over the long-term 

to fisheries and economies dependent on recreational fishing. 

Commercial Fishing 

This alternative is no more likely to benefit commercial fishing than the No Action 

alternative. 

Alternative C: Increased Local Damage Control Alternative 

Aquaculture
89 – Chapter 4 

Depredation control methods should be effective, economically practical, and 

environmentally sound (OTA 1995). In their evaluation of lethal methods of depredation 

control at aquaculture facilities, Curtis et al. (1996) stated that: 

The effectiveness of lethal control measures may vary substantially. Lethal methods are most practical and 

successful when limited numbers of birds are involved in the depredation problem. It is important to note 

that many problems that appear to involve a limited number of birds actually involve larger numbers of 

birds than believed due to turnover and replacement. That is, birds that leave a site often are replaced by 

others. When large numbers of birds are involved, lethal methods typically are not effective or cost 

efficient. Lethal techniques are most beneficial when used in an integrated problem bird management 

program to enhance the effectiveness of non-lethal methods. Many operators specifically employ lethal 

methods for removing birds that are not responding to non-lethal techniques. 

Indeed, that is exactly why aquaculture producers in the southern U.S. use an integrated 

approach of both lethal and non-lethal techniques to manage DCCO depredation. 

However, partly because DCCOs are hard to shoot on ponds and partly because of high 

turnover rates at ponds (Tobin et al. 2002), shooting at ponds provides some, but most 

would argue not enough, relief from DCCO depredation. APHIS/Wildlife Services 

biologists are of the opinion that winter roost control will help reduce DCCO depredation 

at aquaculture facilities. The keys for effectiveness are good coordination and adequate 

manpower (T. King, APHIS/WS, pers. comm.). A USDA (2000) report on reducing 

DCCO damage to southern aquaculture notes that “Coordinated and simultaneous 

harassment of cormorants can disperse them from night roosts and reduce damage at 

nearby catfish farms.” It then notes that “Shooting...cormorants reinforces non-lethal 

harassment” and concludes that shooting at roosts “might enable farmers to reduce the 

number of birds on their farms significantly without affecting continental or flyway 

populations.” 

Since DCCOs in the Mississippi Delta were observed to have a tendency to use the same 

roosts (Tobin et al. 2002), if these roosts are targeted it is likely that roost control will 

prove more effective at reducing DCCO damage than shooting DCCOs at ponds alone. 

Roost control efforts will have the result of either dispersing the roost or, if shooting is 

done in a stealthy and targeted manner, may result in a large number of DCCOs being 

killed. 

Recreational Fishing Economies

It is doubtful that the Service will ever make a regular practice of issuing depredation 

permits to benefit local economies. However, this alternative would allow for greater 

responsiveness to concerns about DCCO impacts to fish populations than the No Action 

alternative. In localized situations, this alternative could lead to an improved fishery and 

increased angler participation, and thus benefits to local economies that are closely tied to 

recreational fishing might occur. 

Commercial Fishing 

At this time, there is not sufficient biological evidence to justify controlling DCCOs on a 

national or local level to benefit open water commercial fisheries. If significant sitespecific problems arise in the future, the Service’s practice is, and will continue to be, to 
90 – Chapter 4 

issue depredation permits where lethal control is believed to have a high likelihood of 

alleviating impacts. 

PROPOSED ACTION Alternative D: Public Resource Depredation Order 

Aquaculture 

In addition to winter roost control (discussed under Alternative C, above), control efforts 

associated with the public resource depredation order are likely to have the secondary 

benefit of reducing DCCO depredation at aquaculture facilities. Thus, Alternative D is 

more likely to reduce depredations on aquaculture than either the No Action alternative 

or Alternative C. 

Recreational Fishing Economies

Management actions associated with this alternative, if they lead to positive impacts on 

fisheries and subsequent increases in angler participation, could benefit recreational 

fishing economies relative to the No Action alternative. Local populations of DCCOs 

that are known to be exhibiting high predation pressure on a specific fishery would need 

to be targeted in order to maximize the likelihood of real benefits. 

Commercial Fishing 

This alternative does not specifically address the issue of commercial fishing, but the 

public resource depredation order could have indirect benefits by relieving predation 

pressure on localized commercial fisheries. It is more likely to have positive impacts 

than the No Action alternative. 

Alternative E: Regional Population Reduction 

Aquaculture

Glahn et al. (1999) concluded that currently available DCCO control techniques are “of 

limited effectiveness and are becoming increasingly difficult to implement.” They 

predicted that increases in DCCO population sizes will further reduce the effectiveness of 

these techniques and suggested that effective management of cormorants for reducing 

depredation to southern aquaculture will likely require more intensive control on the 

wintering grounds, control on the breeding grounds, or a combination of both. Reinhold 

and Sloan (1999) also suggested that “management implications should focus more on 

the long term goals of managing DCCO populations.” 

However, in discussion and modeling of management scenarios for European Great 

Cormorants, it has been suggested that reducing the size of the overall population may 

not result in equivalent reductions in the number of cormorants occurring at high quality 

foraging areas, such as aquaculture facilities (Bregnballe et al. 1997; Van Eerden and van 

Rijn 1997 in Wires et al. 2001). Because foraging habitats vary in quality and cormorants 

are efficient at detecting high quality foraging sites, overall population reductions may 

first cause birds to disappear from least preferred or low quality areas, and declines may 

be less marked in high quality areas (Hodges 1989; T. Bregnballe, pers. comm. in Wires 

et al. 2001). Additionally, the scale of damage caused by DCCOs may not be directly 

related to total numbers in local areas (Bregnballe et al. 1997). 
91 – Chapter 4 

Furthermore, the relationship between control activities carried out in one location and 

resource conflicts occurring in another is not a predictable one. In the case of southern 

aquaculture, most of the depredating DCCOs occur for much of the year in northern 

breeding grounds (e.g., the Great Lakes) and then migrate to wintering grounds in another 

region (e.g., the Mississippi Delta). By analyzing band-recovery data, Dolbeer (1991) 

found that birds in the southern Mississippi region originated from breeding areas as far 

west as Alberta and as far east as New England. The data suggest that, while Lakes 

Michigan and Superior were the most important sources of DCCOs wintering in the 

lower Mississippi Valley, significant numbers of DCCOs also came from the region 

between Saskatchewan and eastern Lake Ontario. Hatch (1995), citing Dolbeer (1991), 

stated that “wintering birds that eat a Mississippi farmer’s catfish could come from 

anywhere across the 3000 km breeding range of the populations that winter there.” 

Currently, satellite telemetry is being used to further investigate the migration patterns of 

DCCOs wintering in Alabama, Arkansas, Louisiana, and Mississippi. Preliminary results 

of this research also indicate that birds wintering in the Delta region originate from across 

the Interior population’s breeding range (S. Werner, APHIS/WS, pers. comm.). Based on 

these data, controlling breeding DCCOs to reduce numbers of birds on the wintering 

grounds would likely require a tremendous effort to be successful and would require a 

coordinated effort among the four regions. According to J. Glahn (APHIS/WS, pers. 

comm.), the increase in numbers of DCCOs wintering in the Delta region of Mississippi 

has been proportionally larger than the increase in numbers of catfish ponds in the area. 

Thus, it may be that broad reductions in DCCO populations would not eliminate the need 

to continue local exclusion and harassment efforts; however, lower population levels 

would likely enhance the effectiveness of localized damage control efforts. 

Recreational Fishing Economies 

In areas where there is an actual causal relationship between DCCO predation, declining 

fisheries, and subsequent economic impacts, then the reduction of regional DCCO 

populations would likely be more effective at alleviating economic declines than the No 

Action alternative. 

Commercial Fishing 

Again, in areas where there is an actual causal relationship between DCCO predation and 

negative impacts on commercial fishery harvests, then this alternative would likely be 

more effective at alleviating those impacts than the No Action alternative. 

Alternative F: Regulated Hunting Season 

Aquaculture

Hunting would likely reduce depredation of aquaculture stock more effectively than 

under the No Action alternative, especially if it led to overall reductions in DCCO 

populations. In addition to killing birds, hunting would be an effective supplement to 

roost dispersal programs. Glahn (2000) concluded that shooting with live ammunition is 

at least equally effective as pyrotechnics for dispersing DCCOs from their night roosts. 

Conover (2001) also noted that hunting is likely to increase the effectiveness of nonlethal techniques. 
92 – Chapter 4 

Recreational Fishing Economies 

Hunting would probably not have a considerable influence on local economies 

(especially since the hunting season would not occur while DCCOs were on their 

northern breeding grounds which is where most economic impacts of this nature are 

believed to occur). If a hunting season led to reduced DCCO populations then this 

alternative would likely be more effective than the No Action alternative. 

Commercial Fishing 

Hunting, if it contributed to population reductions, could have localized benefits on 

commercial fisheries (where DCCO predation is actually depressing fish stocks) and 

would be more likely to have these benefits than the No Action alternative. 

4.2.8 Impacts to Hatcheries and Environmental Justice 

Alternative A: No Action 

In a 1990 survey sent to the fisheries chiefs of each State, 33 percent of States reported an 

increase in DCCO predation in hatchery ponds and raceways (Erickson 1990). During 

public scoping, the Illinois Department of Natural Resources wrote that their LaSalle Fish 

Hatchery along the Illinois River has had problems with increasing predation pressure 

from migrating DCCOs in the late summer and fall. They stated that, in 1997, 

“production of muskellunge at this hatchery was severely impacted by cormorant 

predation.” The Georgia Department of Natural Resources also reported that their 

hatchery personnel in southern Georgia “continue to report significant losses of fish to 

cormorant predation, especially in the fall and winter months.” Also during the public 

scoping period, the States of Kansas, Ohio, Texas, and Wyoming indicated that DCCO 

predation on hatchery fish has been a problem. Reported instances of cormorant damage 

to hatchery fish in Texas include the loss of 90 percent of the smallmouth bass 2-year-old 

brood stock and 13,000 rainbow trout at the Jasper facility (Dukes 1987). Texas Parks 

and Wildlife Department fish hatchery managers reported that DCCO depredation at six 

installations increased during 1982-87 and that cormorant depredation had greatest 

impact on largemouth bass brood stock, goldfish brood stock, and rainbow trout rearing 

stock (Thompson et al. 1995). 

DCCO impacts to hatcheries are generally related to predation, stress, disease, and 

financial losses to both hatcheries and recipients of hatchery stock. Hatchery fish are 

stressed by the presence of DCCOs, wounds from strikes, and noisemakers used to scare 

away DCCOs. This stress leads to a decrease in growth factors as feeding intensity 

decreases. Additionally, disease and parasites can be spread more easily by the presence 

of fish-eating birds. For example, some parasites, such as trematodes, complete their life 

cycle only after an infected fish is consumed by the birds (K. Flanery, USFWS, pers. 

comm.). Research from the Czech Republic and Mexico has linked cormorants to fish 

diseases (Moravec et al. 2000, Moravec and Scholz 1994, Vidal Martinez et al. 1994). 

Parkhurst et al. (1987) found that human patrols were considered highly successful or 

better by 30 percent of hatchery managers, of limited success by 60 percent, and not 

successful by 9 percent. Spencer (1996) reported that two State fish hatcheries in 
93 – Chapter 4 

Georgia used whistlers and cracker shells, and both techniques were considered partially 

effective against birds in general at each facility. Neither technique was considered 

effective against “resident” DCCOs however. The manager at Inks Dam National Fish 

Hatchery (Texas) described attempts at controlling DCCO depredation with non-lethal 

harassment alone as follows: 

In years past cormorants have rested on dead limbs of a large cottonwood tree in our picnic area right along 

Lake LBJ. We were unable to shoot birds in this tree because there are houses directly across the lake, a 

distance of about 150 yards. Although we could not shoot these birds, we always tried to keep them scared 

off. At first all we had to do was drive by and the cormorants would fly. After a few days it became 

necessary to drive up to the tree and honk the horn. When this failed to work, I would drive up to the tree in 

a rapid manner, slam on the brakes as I honked the horn. Once the vehicle was stopped, I would step out of 

the vehicle and slam the door as loudly as I could. Once again this only worked for a few days. As a last 

resort, I began to throw rocks and sticks at the cormorants. The cormorants have started roosting in several 

trees along Lake LBJ. I have been driving down there after dark and scaring them with a spotlight. Each 

evening it is getting harder to run them out of the trees. During the daytime these same birds swim up and 

down Lake LBJ. Early in the season they would fly off every time a vehicle drove through the picnic area. 

Now most of them refuse to fly even when they are harassed with cracker shells (R. Lindsey, USFWS, 

pers. comm.). 

Reports of habituation such as this are typical as DCCOs quickly learn to ignore 

noisemakers and other scare tactics. Shooting a few birds, on the other hand, has been 

shown to reinforce harassment efforts. 

Covering ponds and raceways with netting is another management option. This has 

helped reduce depredation at some hatcheries but is not a panacea due to drawbacks such 

as lack of funding to install and maintain nets (e.g., the manager at Inks Dam National 

Fish Hatchery estimated that netting their ponds would cost $400,000) and the fact that it 

makes it considerably more difficult to feed, clean, aerate, and harvest ponds (K. Flanery, 

USFWS, pers. comm.). 

Several managers of National Fish Hatcheries have expressed concern about problems 

with DCCO predation and not being able to use lethal control on birds at Federal 

facilities because of Director’s Order 27, which states that “kill permits will be issued for 

use at public facilities only when it has been demonstrated that an emergency or near 

emergency exists and an [APHIS/WS] official certifies that all other deterrence devices 

and management practices have failed.” For example, the manager at Genoa National 

Fish Hatchery in Wisconsin expressed concern about DCCO predation on largemouth 

bass and walleye that are used as host fish for the endangered Higgins Eye mussel. In 

1999, this facility experienced “complete loss” in their advanced walleye rearing pond 

and 50 percent mortality in their largemouth bass rearing pond due to DCCO predation 

(T. Turner, USFWS, pers. comm.). At Natchitoches National Fish Hatchery in 

Louisiana, 30,000 channel catfish fingerlings were reduced to less than 1,000 in two days 

by a flock of cormorants in the late 1980s (K. Kilpatrick, USFWS, pers. comm.). In 

1996, Tishomingo National Fish Hatchery in Oklahoma lost 140,000 seven-inch catfish 

to approximately 400 cormorants, although they typically lose 5,000-10,000 annually (K. 

Graves, USFWS, pers. comm.). 
94 – Chapter 4 

Additionally, at Inks Dam National Fish Hatchery in Texas, where largemouth bass and 

channel catfish are raised for distribution to Federal and Tribal waters of the 

southwestern U.S., concern has been expressed about depredation problems caused by 

more than 100 resident DCCOs leading to “total loss of production” (N. Kaufman, 

USFWS, pers. comm.). During 1999-2000, Uvalde National Fish Hatchery in Texas 

averaged a 93 percent loss in 3 ponds of channel catfish due to cormorant predation. This 

level of loss caused several last-minute cancellations of scheduled fish deliveries (S. 

Jackson, USFWS, pers. comm.). When hatcheries experience losses of this magnitude, 

they cannot fulfill their trust responsibilities to Native American Tribes. Representatives 

from Service Region 2 (Arizona, New Mexico, Oklahoma, Texas) are concerned that, at 

National Fish Hatcheries in Region 2, excessive losses of fish destined for stocking on 

Tribal lands may result in a significant direct economic impact for Native American 

Tribes. However, this economic impact has not been quantified in any way and no Tribes 

have commented to us that they have been economically impacted by DCCO predation at 

hatcheries. 

Alternative B: Non-lethal Management 

Harassment activities are of limited effectiveness at fish hatcheries and, in many cases, 

exclusion devices are not considered to be cost effective. Thus, depredation at fish 

hatcheries would be dealt with less effectively under this alternative than under the No 

Action alternative. 

Alternative C: Increased Local Damage Control Alternative 

Depredation at hatcheries, especially National Fish Hatcheries, would be more effectively 

reduced than under the No Action alternative since the ability to manage DCCOs causing 

such problems would be enhanced. Where they occur, if at all, impacts to low income 

Native American communities dependent on fish raised at Federal hatcheries would also 

be reduced. 

PROPOSED ACTION Alternative D: Public Resource Depredation Order 

Relative to the No Action alternative, depredation of some stocks of hatchery fish would 

very likely be reduced. Where they occur, if at all, impacts to low income Native 

American communities dependent on fish raised at Federal hatcheries would also be 

reduced. 

 

Alternative E: Regional Population Reduction 

Reducing regional populations of DCCOs would likely help reduce depredation of 

hatchery stocks more effectively than the No Action alternative and would increase the 

effectiveness of localized lethal and non-lethal damage control techniques. Where they 

occur, impacts to low income Native American communities dependent on fish raised at 

Federal hatcheries would also be reduced. 

Alternative F: Regulated Hunting Season 

Hunting would likely help reduce depredation at fish hatcheries more effectively than 

under the No Action alternative, especially if it led to overall population reductions. 
95 – Chapter 4 

Where they occur, if at all, impacts to low income Native American communities 

dependent on fish raised at Federal hatcheries would also be reduced. 

4.2.9 Impacts to Property Losses 

Alternative A: No Action 

The APHIS/WS Management Information System database reveals that, from FY 1995-

2001, losses to property were reported in 19 States with structures, trees and shrubs most 

commonly reported. Respondents to a survey conducted by Wires et al. (2001) reported 

damages to private property in four States: Connecticut, Maine, Massachusetts, and South 

Carolina. For example, in a February 1, 2000, letter to the Service, the Maine 

Department of Inland Fisheries and Wildlife stated that “lower property values at major 

roosts and large nesting colonies” are an important issue in Maine. 

In some cases, the Service has issued depredation permits for DCCOs taking fish from 

privately-owned and stocked fish ponds. For example, the Hiawatha Sportsmen’s Club in 

northern Michigan, has been issued a permit to reduce DCCO predation on trout, walleye, 

and perch in stocked ponds. In Texas and Oklahoma, the Service has also issued permits 

to private stock ponds where DCCOs were having economic impacts. A citizen from 

Texas sent the following comments on the impact of DCCOs at a small, privately owned 

fishing lake west of Fort Worth, Texas: 

I have a forty year history on the same small body of water which in the last ten years has been severely 

impacted by a cormorant problem from mid-November to mid-March of each year. This is a forty acre [16 

ha] fishing lake... During the period 1962 to approximately 1992 it was an excellent lake for bass with 

catch rates of up to 60 for two anglers in a day. It has always been a catch and release lake. I saw the first 

cormorant on the lake in 1984. By 1992, it was an average of 100 birds per day feeding on the lake... 

Fishing success began to decline to the point where in 2001 the most fish caught in a single day was 2! 

...As the food base in this lake is principally gizzard shad I began to suspect that the cormorants were 

devastating the bait fish and small bass population during their...stay each year. This observation was 

further affirmed by numerous catches of bass in the 1990's with cormorant beak scars on their bodies. On 

October 6, 2001 I commissioned an electrofishing survey of the lake by a professional fisheries 

management consultant. The results were stunning... Other than fingerlings from the Spring 2001 hatch, 

one nine inch bass was the only specimen obtained that was less than 18 inches long...the forage base 

which should have been in a ratio of at least 2:1 [shad to bass] was only .5:1... The consultant that I hired 

said I could start a restocking program this spring with an initial outlay of $4,000-$5,000 however it would 

be money thrown away if the feathered predators returned in the fall. If your study requires an economic 

impact and you need a basis for assessing cormorant damage on a small private lake then let me add that a 

few years ago I was offered $5,000 per year to lease the lake to a fishing club. (V. Tinsley, pers. comm.) 

Financial losses to fishing clubs (both in lost revenues and increased stocking expenses) 

related to Great Cormorant predation have also been documented in Britain (M. Read, 

pers. comm.) 

Little attention has been given to complaints of fouling vessels or buildings in the 

literature (Hatch and Weseloh 1999). However, this issue was raised during the public 

scoping process and has been the subject of requests for depredation permits. For 

example, the Massachusetts Division of Fisheries and Wildlife noted problems with 

“small numbers of [DCCOs] perching and defecating on docks and moored boats.” 
96 – Chapter 4 

As discussed in Section 4.2.4, DCCOs are capable of killing trees and other vegetation. 

Lewis (1929) considered the killing of trees by nesting cormorants to be very local and 

limited, with most trees he observed to have no commercial timber value. However, 

vegetation damage may be perceived as a problem if the species is rare, or is aesthetically 

or commercially valued by the landowner (Hatch and Weseloh 1999). Here is the story 

of a landowner in New York: 

I am an island owner who has been pestered with these birds for the past 3 years. We had 18 nests 3 years 

ago, last year over 150. I went out to our Islands [on April 16th, 2003] and...the Cormorants are back... 

These birds are terrible, a nuisance, make a mess, and are quickly destroying our islands... Last December, 

we put a conservation easement on our islands to keep them forever wild and natural. We intend to make a 

wildlife refuge and bird sanctuary. What a mess last spring. [When we returned from our winter residence 

in early May we]...discovered that our islands were taken over and inhabited by [cormorants]. The smell 

and bird droppings were horrendous to say the least. It took mother nature over 3 months to clean up the 

islands. Many trees and vegetation were destroyed when hit by the cormorant’s waste and droppings. 

Alternative B: Non-lethal Management 

Some property losses could be dealt with effectively through non-lethal management 

such as harassment or nest removal. Others would necessitate removal of birds. Thus, 

property losses would be dealt with less effectively under this alternative than under the 

No Action alternative. 

Alternative C: Increased Local Damage Control Alternative

Property losses associated with DCCOs would be controlled as effectively as under the 

No Action alternative. 

PROPOSED ACTION Alternative D: Public Resource Depredation Order 

Relative to the No Action alternative, property losses would be dealt with more 

effectively under this alternative. Although property losses do not receive increased 

consideration under this alternative, control actions associated with the public resource 

depredation order would likely have the secondary impact of reducing property damage. 

Alternative E: Regional Population Reduction 

Relative to the No Action alternative, property losses would be dealt with more 

effectively under this alternative. Although property losses do not receive increased 

consideration under this alternative, per se, reductions in regional populations would 

likely have the secondary impact of reducing property damage. 

Alternative F: Regulated Hunting Season 

Losses to property would be more effectively reduced than under the No Action 

alternative. In some cases, hunting could be used as a tool to directly control damage to 

property. 

4.2.10 Impacts to Existence and Aesthetic Values 

Alternative A: No Action 

Existence Value. To some people, any killing of DCCOs or their eggs represents a loss of 

maximized existence value and therefore anything more than a non-lethal approach 

compromises this value. Under this alternative, however, a very large population of 
97 – Chapter 4 

DCCOs still exists and threats to existence value have not, for the most part, been raised 

as a significant concern. 

Aesthetic Value. While many individuals commented during the public scoping process 

that DCCOs and their colonies are ugly, there are also those to whom the sight of a 

cormorant engaging in natural behaviors is viewed as beautiful. Nonetheless, certain 

species, particularly abundant ones, are more likely to be seen as a nuisance thereby 

losing much of their net aesthetic value (Conover 2002). Several people also indicated 

during the scoping process that DCCOs have turned verdant islands or waterfront areas 

into wastelands through their killing of trees and this has compromised the natural beauty 

of the areas where they live, work, and/or recreate. 

Alternative B: Non-lethal Management 

Existence Value. Existence value would not be compromised under this alternative since 

no DCCOs would be killed. However, it is possible that not effectively managing an 

abundant species such as DCCOs could, ultimately, reduce existence value if a lack of 

management contributed to the species being viewed as a “nuisance” or “pest.” As 

Conover (2001) noted, “[when] a wildlife population increases and the animal becomes 

abundant, negative values may increase faster than positive ones.” 

Aesthetic Value. Effects on aesthetic value would depend on individual perspective. 

Those who find DCCOs aesthetically-pleasing would be slightly negatively affected 

because in many local situations DCCOs would be harassed out of the area and thus 

would not be available for immediate viewing, although it would not be difficult to find 

them in other locations. On the other hand, those who view DCCOs as compromising 

aesthetic values with their presence would appreciate the fact that DCCOs could not be 

viewed. 

Alternative C: Increased Local Damage Control 

Existence Value. More DCCOs would be killed under this alternative than under the No 

Action and thus, to some people, existence value would be compromised. However, 

overall populations of DCCOs would not be significantly reduced, so effects on existence 

value would be minimal. 

Aesthetic Value. Effects on aesthetic value associated with this alternative would vary 

depending on individual perspective. For those who find DCCOs aesthetically 

displeasing, reduced presence associated with control actions carried out under this 

alternative would be viewed positively. For those who appreciate the sight of DCCOs, 

aesthetic value would be somewhat compromised, compared to the No Action alternative. 

PROPOSED ACTION Alternative D: Public Resource Depredation Order 

Existence Value. More DCCOs would be killed under this alternative than under the No 

Action and thus, to some people, existence value would be compromised. However, 

overall populations of DCCOs would not be significantly reduced, so effects on existence 

value would be minimal. 
98 – Chapter 4 

Aesthetic Value. Effects on aesthetic value associated with this alternative would vary 

depending on individual perspective. For those who find DCCOs aesthetically 

displeasing, reduced presence associated with control actions carried out under this 

alternative would be viewed positively. For those who appreciate the sight of DCCOs, 

aesthetic value would be somewhat compromised, compared to the No Action alternative. 

Alternative E: Regional Population Reduction 

Existence Value. More DCCOs would be killed under this alternative than under the No 

Action and thus, to some people, existence value would be compromised. However, 

overall populations of DCCOs would not be significantly reduced, so effects on existence 

value would be minimal. 

Aesthetic Value. Effects on aesthetic value associated with this alternative would vary 

depending on individual perspective. For those who find DCCOs aesthetically 

displeasing, reduced presence associated with control actions carried out under this 

alternative would be viewed positively. For those who appreciate the sight of DCCOs, 

aesthetic value would be somewhat compromised, compared to the No Action alternative. 

Alternative F: Regulated Hunting Season 

Existence Value. More DCCOs would be killed under this alternative than under the No 

Action and thus, to some people, existence value would be compromised. 

Aesthetic Value. Effects on aesthetic value associated with this alternative would vary 

depending on individual perspective. For those who find DCCOs aesthetically 

displeasing, reduced presence associated with control actions carried out under this 

alternative would be viewed positively. For those who appreciate the sight of DCCOs, 

aesthetic value would be somewhat compromised, compared to the No Action alternative.

4.3 Further Discussion of Alternatives 

This section discusses how each alternative compares to other alternatives, particularly 

the preferred alternative. It also explains the anticipated direct, indirect, and cumulative 

effects of each alternative and summarizes the impacts associated with the alternative (as 

outlined in section 4.2), both independently and in relation to the No Action alternative. 

Finally, it describes mitigating measures for minimizing significant negative impacts 

relevant to the proposed action and other alternatives. 

4.3.1 Alternative A: No Action 

Direct, Indirect and Cumulative Effects. Under the No Action alternative, DCCOs will 

continue to have direct effects on the fish they eat (in the wild or in hatcheries), birds 

with which they co-nest, vegetation they destroy, property they damage, fish farmers 

whose stock they consume, and (in limited cases) water quality. The significance of 

these interactions varies at different locations. Direct relationships with commercial 

fisheries are less clear. DCCOs may have indirect effects on recreational fishing 

economies and Tribes that rely on hatchery-raised fish. 
99 – Chapter 4 

Cumulative impacts are those impacts on the environment that result from the 

incremental impact of an action when combined with other past, present, and reasonably 

foreseeable future actions, regardless of who undertakes these other actions. Under the 

No Action alternative, conflicts with other birds would likely increase as more habitat 

was destroyed by DCCOs (although for ground nesting birds this would be beneficial) 

and other factors (such as development). Predation pressure on fish would continue to be 

significant in some areas and would contribute to fishery declines. In addition to 

DCCOs, fish are influenced by chemical, physical, and biological stresses, including 

habitat degradation, imbalances in aquatic communities due to population explosions of 

invading species (in the Great Lakes these include sea lamprey, alewife, white perch, and 

zebra and quagga mussels); reproductive failure; alterations of fish communities and loss 

of biodiversity associated with overfishing and fish stocking practices; and impacts of 

persistent toxic chemicals (Koonce 1995). Furthermore, economic damages to 

aquaculture producers and hatcheries would not be alleviated and might worsen, 

especially if combined with increases in the cost of the fish that are used to stock ponds 

and raceways. 

By continuing under the status quo, we believe that DCCO impacts would continue to 

increase and become more prominent. On the sociopolitical side, serious ramifications of 

continuing to ignore this problem could include the forced (e.g., by Congress) removal of 

DCCOs from protection under the MBTA, delegation of DCCO management authority to 

another agency (e.g., APHIS/WS), and increased frequency of illegal DCCO shootings. 

Biological consequences associated with prolonged continuation of the status quo include 

further progression of impacts to fisheries, vegetation, other birds, and other resources. 
100 – Chapter 4 

Table 14. Cormorant Impacts under Alternative A

Impacts of Cormorants Alternative A: No Action 

DCCO populations N/A 

Other bird populations Suspected conflicts and in some cases confirmed 

conflicts associated with habitat destruction and 

nest site competition; significance localized 

Fish Suspected and in some cases confirmed conflicts; 

significance localized 

Vegetation/habitat Destruction of vegetation confirmed; significance 

localized 

Threatened and endangered species Suspected but not confirmed conflicts with Atlantic 

salmon and various Pacific salmonids; very likely, 

however, that other factors are more important than 

DCCOs in the decline of salmon 

Water quality and human health Accused of being a source of groundwater 

contamination but this is not confirmed; can cause 

direct, open water contamination 

Aquaculture Confirmed economic impacts on aquaculture 

production 

Recreational fishing economies Correlative evidence that DCCOs are a factor 

behind economic declines in communities 

dependent on recreational fishing; not confirmed 

Fish hatcheries and environmental justice Confirmed depredation of hatchery stock with 

significance localized; effect on ability to provide 

hatchery fish to low-income groups not confirmed 

Property losses Confirmed conflicts with some property interests; 

significance localized 

Existence and aesthetic values Effect on values differs with perspective; DCCOs 

may appeal to some individual’s sense of aesthetics, 

while not appealing to others 

4.3.2 Alternative B: Non-lethal Management 

Direct, Indirect and Cumulative Effects. In summary, the chief direct effects (i.e., those 

caused by the action(s) and occurring at the same time and place) associated with this 

alternative would be displacement of nesting, roosting, or feeding DCCO populations and 

disturbance of bird species that nest, roost, or feed with DCCOs. 

Indirect effects (i.e., those caused by the action(s) but occurring later in time or farther in 

distance) include limited positive impacts to fisheries, vegetation, threatened and 

endangered species, water quality and human health, aquaculture, hatcheries, and 

property losses associated with localized displacement of DCCOs. A negative indirect 

effect could be the relocation of nuisance birds to new areas (possibly where they weren’t 

previously a problem). Intensive, long term disturbance of nesting birds associated with 

DCCOs could negatively affect their populations on a local and regional scale. 

Cumulative effects (i.e., those that result from the incremental impact of the action(s) 

when added to other past, present, and reasonably foreseeable future actions) associated 

with this alternative could include even greater abundance of DCCOs, continued 

destruction of habitat, regional declines in some bird populations, continued fisheries 

declines, and continued serious depredation of fish stock at aquaculture and hatchery 

facilities. 
101 – Chapter 4 

Discussion of Alternative. The preferred alternative is preferable to Alternative B because 

it allows for the use of more efficient and effective (i.e., lethal) wildlife damage control 

techniques. Presumably, if more effective techniques are used, resource conflicts will be 

dealt with more effectively. 

Table 15. Management Activity Impacts under Alternative B 

Impacts of Management Actions Alternative B: Non-lethal Management 

DCCO populations No significant impact to regional or continental 

populations; no lethal take 

Other bird populations Considerable localized disturbance possible 

Fish Could help reduce predation in localized situations 

Vegetation/habitat Could help reduce impacts in localized situations 

Threatened and endangered species Localized disturbance possible 

Water quality and human health Could help reduce impacts in localized situations 

Aquaculture Could help reduce depredation in some situations 

Recreational fishing economies Unlikely to benefit 

Fish hatcheries and environmental justice Could help alleviate some conflicts 

Property losses Could help alleviate some conflicts 

Existence and aesthetic values Effects on values differs with perspective 

Table 16. Comparison to No Action Alternative 

Relation to No Action Alternative B: Non-lethal Management 

DCCO populations Fewer birds would be killed (i.e., none) 

Other bird populations Could be somewhat effective, but less effective 

overall 

Fish Less effective 

Vegetation/habitat Could be somewhat effective, but less effective 

overall 

Threatened and endangered species Virtually the same 

Water quality and human health Could be somewhat effective, but less effective 

overall 

Aquaculture Could be somewhat effective, but less effective 

overall 

Recreational fishing economies Virtually the same 

Fish hatcheries and environmental justice Could be somewhat effective, but less effective 

overall 

Property losses Could be somewhat effective, but less effective 

overall 

Existence and aesthetic values Compromises existence value less; effect on 

aesthetics will vary 

4.3.3 Alternative C: Increased Local Damage Control Alternative 

Direct, Indirect and Cumulative Effects. In summary, the chief direct effects (i.e., those 

caused by the action(s) and occurring at the same time and place) associated with this 

alternative would be displacement and limited take of nesting, roosting, or feeding 

DCCOs or their nests or eggs and some displacement of bird species that nest, roost, or 

feed with DCCOs, as well as limited incidental take. These effects would occur at a 

higher rate than under the No Action Alternative but are not predicted to be significant. 
102 – Chapter 4 

Indirect effects (i.e., those caused by the action(s) but occurring later in time or farther in 

distance) associated with this alternative could include positive impacts to fisheries, other 

birds, vegetation, and aquaculture/hatchery production. Long term effects on DCCO 

populations are not anticipated to be significant. Regular population monitoring would 

help ensure this. 

Cumulative effects (i.e., those that result from the incremental impact of the action(s) 

when added to other past, present, and reasonably foreseeable future actions) associated 

with this alternative could include even greater abundance of DCCOs, continued 

destruction of habitat, regional declines in some bird populations, continued fisheries 

declines, and continued serious depredation of fish stock at aquaculture and hatchery 

facilities. 

Discussion of Alternative. The preferred alternative is preferable to Alternative C because 

it allows for greater flexibility in dealing with many types of resource conflicts (i.e., 

agencies experiencing cormorant damages could, in many cases, plan and implement 

management actions more readily) and we believe that it will thus reduce those conflicts 

more effectively. 

Table 17. Management Activity Impacts under Alternative C 

Impacts of Management Actions Alternative C: Increased Local Damage Control 

DCCO populations No significant impact to regional or continental 

populations; estimated annual take of <60,275 

Other bird populations Local disturbance possible, but could be managed 

to avoid significant impacts 

Fish Likely to help reduce predation in localized 

situations 

Vegetation/habitat Could help reduce impacts in localized situations 

Threatened and endangered species No adverse impacts 

Water quality and human health Could help reduce impacts in localized situations 

Aquaculture Would help reduce depredation 

Recreational fishing economies Not likely to benefit 

Fish hatcheries and environmental justice Would help reduce depredation 

Property losses Could help reduce losses 

Existence and aesthetic values Effects on values differs with perspective 

Table 18. Comparison to No Action Alternative 

Relation to No Action Alternative C: Increased Local Damage Control 

DCCO populations More birds would be killed 

Other bird populations Could be more effective 

Fish Could be more effective 

Vegetation/habitat Could be more effective 

Threatened and endangered species Virtually the same 

Water quality and human health About the same 

Aquaculture Expected to be more effective 

Recreational fishing economies Virtually the same 

Fish hatcheries and environmental justice Expected to be more effective 

Property losses Could be more effective 

Existence and aesthetic values Compromises existence value more; effect on 

aesthetics will vary 
103 – Chapter 4 

4.3.4 PROPOSED ACTION Alternative D: Public Resource Depredation Order 

Direct, Indirect and Cumulative Effects. In summary, the chief direct effects (i.e., those 

caused by the action(s) and occurring at the same time and place) associated with this 

alternative would be increased displacement and take of nesting, roosting, or feeding 

DCCOs or their nests or eggs and some incidental displacement of bird species that nest, 

roost, or feed with DCCOs. 

Indirect effects (i.e., those caused by the action(s) but occurring later in time or farther in 

distance) would include, in some but not all situations: reduced predation on some fish 

populations, reduced destruction of vegetation, less competition with other birds, fewer 

property losses, and less depredation at aquaculture and hatchery facilities. We do not 

foresee any significant negative indirect effects associated with this alternative as long as 

mitigation measures are implemented. 

Cumulative effects (i.e., those that result from the incremental impact of the action(s) 

when added to other past, present, and reasonably foreseeable future actions) are very 

difficult to predict at this scale. If combined with other beneficial management actions it 

is possible that, under the proposed action, impacts to all the categories of resources 

discussed in Chapter 3 would be reduced to a level of insignificance. However, impacts 

are unlikely to be eliminated because some of the factors that influence these resources 

are difficult to control (e.g., angler participation rates, growth in the aquaculture industry, 

island development). 

In 2002, the Province of Ontario began ongoing egg oiling efforts at Lake Huron and 

Lake Ontario DCCO colonies. Such actions should increase the effectiveness of 

localized control efforts on the U.S. side of the Great Lakes. It is also possible that 

without significant overall population reduction impacts associated with DCCOs will not 

be effectively alleviated. However, we expect that enhanced management activities 

under the proposed action will be effective. 

Unavoidable Adverse Impacts. This section refers to those adverse effects that cannot be 

avoided as a result of management activities carried out under the proposed action. 

Implementation of the proposed action is intended to move toward an overall improved 

condition, but adverse environmental effects will occur. DCCOs will be killed (and/or 

their nests and eggs will be destroyed) under this alternative, with the possibility that 

some local populations would be reduced or eliminated; however, we do not anticipate 

that impacts would be significant enough to endanger DCCO populations. Disturbance to 

other bird species that nest, roost, or feed in the vicinity of DCCOs is very likely, 

although significant adverse effects are not anticipated if mitigation measures are 

implemented. Aquaculture producers will continue to experience economic losses due to 

DCCO depredation, although to a lesser degree than under the No Action alternative. 

Short-term Effects and Long-term Productivity. The control activities carried out under 

this alternative will, in some cases, lead to short-term disturbance of breeding colonies. 

However, it is anticipated that these actions will lead to increases in long-term 

productivity due to the increased avian biodiversity resulting from reduced DCCO 
104 – Chapter 4 

presence. Additionally, it is anticipated that DCCO control activities will lead to 

increased productivity of specific fisheries and will lessen the overall economic impact of 

DCCO depredation at aquaculture and hatchery facilities. 

Irreversible or Irretrievable Commitments of Resources. Expenditure of funds to 

implement activities in the proposed action would be an irreversible commitment of 

monetary resources. An irreversible commitment of resources is one that results from an 

action that prevents an area or a resource type from returning to its natural condition for 

an extended period of time, or one that utilizes non-renewable resources. The only 

irreversible commitment of resources anticipated under the proposed action would be the 

use of fossil fuels for energy as DCCO management activities are carried out. 

Irretrievable commitments of resources occur when we forego the opportunity to use or 

produce a specific resource for a period of time while favoring the production of another 

resource. The commitments are irretrievable rather than irreversible because the reversal 

of management decisions would allow uses of these resources to occur again. 

Management actions under the proposed action could result in irretrievable commitments 

if they caused any inadvertent damage and subsequent loss of threatened, endangered, or 

otherwise sensitive wildlife and plant species. 

Conflicts between the Proposed Action and Other Federal, Regional, State, Tribal, or 

Local Objectives. Conflicts with the management objectives of other agencies do exist. 

There are some Federal, State, and Tribal entities that would prefer to manage DCCOs 

more aggressively. We did our best to be responsive to the concerns of these entities and 

to enhance their management flexibility as much as we felt reasonable within the context 

of our responsibility to ensure the conservation of DCCO populations. There are also 

States and Tribes that would prefer not to manage DCCOs more aggressively.

 

Table 19. Management Activity Impacts under Proposed Action 

Impacts of Management Actions PROPOSED ACTION Alternative D: Public 

Resource Depredation Order 

DCCO populations No significant impact to regional or continental 

populations; estimated annual take of 159,635 

Other bird populations Local disturbances likely, but can be managed to 

avoid significant impacts; will help overall 

Fish Will help reduce predation in localized situations 

Vegetation/habitat Will help reduce impacts in localized situations 

Threatened and endangered species No adverse impacts with implementation of 

conservation measures 

Water quality and human health Will help reduce impacts in localized situations 

Aquaculture Will help reduce depredation 

Recreational fishing economies Not likely to benefit 

Fish hatcheries and environmental justice Will help reduce depredation 

Property losses Could help to indirectly reduce losses 

Existence and aesthetic values Effects on values differs with perspective 
105 – Chapter 4 

Table 20. Comparison to No Action Alternative

Relation to No Action PROPOSED ACTION Alternative D: Public 

Resource Depredation Order 

DCCO populations More birds would be killed 

Other bird populations Expected to be more effective 

Fish Expected to be more effective 

Vegetation/habitat Expected to be more effective 

Threatened and endangered species About the same 

Water quality and human health About the same 

Aquaculture Expected to be more effective 

Recreational fishing economies Virtually the same 

Fish hatcheries and environmental justice Expected to be more effective 

Property losses Could be more effective 

Existence and aesthetic values Compromises existence value more; effect on 

aesthetics will vary 

4.3.5 Alternative E: Regional Population Reduction 

Direct, Indirect and Cumulative Effects. The chief direct effects (i.e., those caused by the 

action(s) and occurring at the same time and place) associated with this alternative would 

be considerably increased displacement and take of nesting, roosting, or feeding DCCOs 

or their nests or eggs and increased disturbance of bird species that nest, roost, or feed 

with DCCOs. 

Several indirect effects (i.e., those caused by the action(s) but occurring later in time or 

farther in distance) are likely under this alternative. The most significant potential 

negative effect associated with this alternative is that DCCO populations might be 

threatened by successive years of population control. However, this is unlikely because 

the alternative would be conducted in such a way that this risk would be greatly 

minimized (e.g., through the use of population goals and monitoring). Long term 

negative impacts to other birds that would be disturbed or killed by DCCO population 

reduction efforts are an important concern as well but, again, mitigation efforts can be 

taken to reduce the likelihood of such effects. 

Cumulative effects (i.e., those that result from the incremental impact of the action(s) 

when added to other past, present, and reasonably foreseeable future actions) are very 

difficult to predict at this scale but the whole idea behind reducing regional DCCO 

populations is to reduce negative impacts to other resources. If combined with other 

beneficial management actions it is possible that impacts to all the categories of resources 

discussed in Chapter 3 could be reduced to a level of insignificance. 

Discussion of Alternative 

The preferred alternative is preferable to regional population reduction because we are 

still uncertain of the necessity for largescale population management. We believe that an 

interagency and interdisciplinary discussion of the idea of reducing DCCO populations 

needs to take place before we draw a conclusion on its necessity and its effectiveness at 

actually reducing resource conflicts. Additionally, we feel strongly that population 

management will require a much greater commitment of resources for research, 

monitoring, and coordination than currently exists. 
106 – Chapter 4 

Table 21. Management Activity Impacts under Alternative E 

Impacts of Management Actions Alternative E: Regional Population Reduction 

DCCO populations Goal would be to significantly reduce regional 

and/or continental populations to a pre-determined 

level 

Other bird populations Local disturbances very likely, but could be 

managed to avoid significant impacts 

Fish Would help reduce predation 

Vegetation/habitat Would help reduce impacts 

Threatened and endangered species No adverse impacts with implementation of 

conservation measures 

Water quality and human health Could help reduce impacts in localized situations 

Aquaculture Would help reduce depredation 

Recreational fishing economies Might help 

Fish hatcheries and environmental justice Would help reduce depredation 

Property losses Would likely help reduce such losses 

Existence and aesthetic values Effects on values differs with perspective 

Table 22. Comparison to No Action Alternative 

Relation to No Action Alternative E: Regional Population Reduction 

DCCO populations More birds would be killed 

Other bird populations Expected to be more effective 

Fish Expected to be more effective 

Vegetation/habitat Expected to be more effective 

Threatened and endangered species About the same 

Water quality and human health About the same 

Aquaculture Expected to be more effective 

Recreational fishing economies Might be more effective 

Fish hatcheries and environmental justice Expected to be more effective 

Property losses Expected to be more effective 

Existence and aesthetic values Compromises existence value more; effect on 

aesthetics will vary 

4.3.6 Alternative F: Regulated Hunting Season 

Direct, Indirect and Cumulative Effects. In summary, the chief direct effects (i.e., those 

caused by the action(s) and occurring at the same time and place) associated with this 

alternative would be increased displacement and take of nesting, roosting, or feeding 

DCCOs or their nests or eggs and increased disturbance and incidental take of bird 

species that nest, roost, or feed with DCCOs. 

Indirect effects (i.e., those caused by the action(s) but occurring later in time or farther in 

distance) would include, in some but not all situations, positive impacts to fisheries, 

vegetation, threatened and endangered species, property losses, water quality and human 

health, aquaculture, and hatcheries. Because hunting would make DCCOs more wary of 

humans, we anticipate that it will significantly reinforce non-lethal management efforts 

and increase the effectiveness of these techniques. As long as DCCO populations are 

adequately monitored and hunting regulations adjusted accordingly, we anticipate that 

risks to their populations would be minimal. Incidental take of look-alike species would 

occur under this alternative but would probably not be significant. 
107 – Chapter 4 

Cumulative effects (i.e., those that result from the incremental impact of the action(s) 

when added to other past, present, and reasonably foreseeable future actions) are very 

difficult to predict at this scale but we predict that hunting, if combined with other 

beneficial management actions could reduce impacts to all the categories of resources 

discussed in Chapter 3 to a level of insignificance. 

Discussion of Alternative. The proposed action is preferable to hunting largely for ethical 

reasons. From purely biological and economic perspectives, hunting might prove an 

effective way to kill numerous DCCOs at minimal expense to the government. However, 

we have serious reservations about authorizing a non-traditional species to be hunted 

when it cannot be eaten or widely utilized and feel that there are more responsible and 

socially acceptable ways of dealing with migratory bird conflicts.

Table 23. Management Activity Impacts under Alternative F 

Impacts of Management Actions Alternative F: Regulated Hunting 

DCCO populations No significant impact to regional or continental 

populations; estimated annual take of 200,000 

Other bird populations Local disturbance possible 

Fish Might help reduce predation in localized situations 

Vegetation/habitat Might help reduce impacts in localized situations 

Threatened and endangered species No adverse impacts with implementation of 

conservation measures 

Water quality and human health Could help reduce impacts in localized situations 

Aquaculture Likely to help reduce depredation 

Recreational fishing economies Not likely to benefit 

Fish hatcheries and environmental justice Likely to help reduce depredation 

Property losses Likely to help reduce such losses 

Existence and aesthetic values Effects on values differs with perspective 

Table 24. Comparison to No Action Alternative 

Relation to No Action Alternative F: Regulated Hunting 

DCCO populations More birds would be killed 

Other bird populations Might be more effective 

Fish Might be more effective 

Vegetation/habitat Might be more effective 

Threatened and endangered species About the same 

Water quality and human health About the same 

Aquaculture Expected to be more effective 

Recreational fishing economies Virtually the same 

Fish hatcheries and environmental justice Might be more effective 

Property losses Expected to be more effective 

Existence and aesthetic values Compromises existence value more; effect on 

aesthetics will vary 

4.3.7 Mitigating Measures 

One of the purposes of NEPA review is to prescribe mitigation measures to alleviate 

negative environmental effects associated with the proposed action. Above and beyond 

the goal of reducing impacts associated with DCCOs, the Service is responsible for 

conserving migratory bird populations. Therefore, we recognize the importance of 
108 – Chapter 4 

taking measures to ensure the long-term sustainability of populations of DCCOs and 

other migratory birds. The risk of significant negative impacts to migratory bird 

populations will be reduced by exercising the following: 1) prevention, 2) monitoring, 

and 3) evaluation. These are discussed below. 

1) Prevention 

Under NEPA, there are five ways of dealing with significant environmental effects: 

avoiding the impact by not taking certain action or parts of an action; minimizing impacts 

by limiting the degree or magnitude of the action and its implementation; rectifying the 

impact by repairing, rehabilitating, or restoring the affected environment; reducing or 

eliminating the impact over time by preservation and maintenance during the life of the 

action; and compensating for the impact by replacing or providing substitute resources or 

environments. 

The two categories of mitigation most applicable to the current situation are avoidance 

and minimization. These can be incorporated as conditions that responsible agencies 

must abide by in undertaking activities under the depredation order (e.g., requirement to 

use lead shot only, thus mitigating the impacts of lead poisoning on non-target birds and 

other wildlife). The adoption of monitoring programs (including annual reports) and 

adaptive monitoring techniques could also be considered mitigation techniques, as well as 

the provision allowing us to suspend the privilege of agencies to take action under the 

public resource depredation order. 

Carney and Sydeman (1999) noted that techniques such as limiting the number and 

duration of intrusions (to nesting sites), minimizing physical contact with birds, and 

moving slowly while in colonies can serve to minimize negative impacts on most 

colonial waterbird species. They reported that negative impacts to Ring-Billed Gulls 

were “nearly eliminated” when measures such as visiting colonies early in the day to 

avoid thermal stress, avoiding unnecessary chick handling, and moving slowly through 

colonies were carried out. 

On islands with mixed seabird colonies in the St. Lawrence River Estuary, Bédard et al. 

(1999) minimized disturbance to sensitive species such as Razor-billed Auks, Common 

Eiders, and Black-crowned Night-Herons by coordinating control and census efforts into 

a single visit. However, they noted that “it is impossible to census colonies in forested 

sites without killing and disturbing breeding birds at the same time” (Bédard et al. 1995). 

During DCCO management activities on Little Galloo Island, Lake Ontario, New York, 

efforts are made to limit the time spent in close proximity to the Caspian Tern (a sensitive 

species) colony there (NYSDEC 2000). On the other hand, despite extensive DCCO 

harassment efforts on Gull and Bass Islands in eastern Lake Ontario, numbers of Blackcrowned Night-Heron nests have continued to increase (from 60 in 2002 to 83 in 2003; J. 

Farquhar, NYSDEC, unpubl. data). 

Resource managers and wildlife damage professionals must clearly weigh the risks and 

benefits associated with cormorant control activities occurring near other birds and 

exercise caution (or choose not to conduct control) to minimize disturbance of non-target 
109 – Chapter 4 

species. Specific recommendations for minimizing impacts when working in mixedspecies waterbird colonies include: visiting during early morning and late afternoon hours 

to avoid thermal stress to eggs/nestlings; monitoring avian predators and avoiding sites 

with large numbers of predators; focusing efforts on cormorant-dominated colonies; 

avoiding late nesting season visits to reduce nestling nest abandonment; and training 

personnel to monitor control activities at waterbird colonies.

Bédard et al. (1995 and 1999) thoroughly described the process by which they conducted 

DCCO population control in the St. Lawrence River estuary. The population control 

program was initiated by the Province of Québec, “mostly in response to growing 

concern about damage to unique island plant and animal communities and incidental 

destruction of nesting habitat for aquatic species” (1999). After censusing the study area 

to estimate the population, they determined a more appropriate level, and then used 

deterministic modeling to understand how best to achieve the desired population 

reduction. These papers are an excellent resource for any agency considering a 

population reduction effort and contain considerable information on the model 

parameters that were used. 

Blackwell et al. (2002) also offers managers and biologists an excellent overview of the 

development of a population growth model for Lake Ontario DCCOs and will be helpful 

in the evaluation of potential management options. The authors referenced literature 

values for fertility, age at first breeding, and survival and used those parameters to 

develop a deterministic stage-classified matrix model. Additionally, the publication 

“Cormorants and Human Interests” (van Dam and Asbirk, eds. 1997; this document 

comprises the proceedings of the “Workshop towards an International Conservation and 

Management Plan for the Great Cormorant,” which took place in October 1996 in 

Lelystad, the Netherlands) has a useful and insightful chapter on population management 

with sections titled “reducing impacts by reducing overall population size,” “factors 

determining the size of the cormorant population,” “the population model,” “reducing the 

size of the cormorant population,” and “conclusions” (Bregnballe et al. 1997). Each of 

the above referenced papers should be considered required reading for any agency 

contemplating a population control effort and may be obtained by contacting the Division 

of Migratory Bird Management. 

2) Monitoring

Population monitoring provides critical information about population change and tells 

managers the present population status of species (Sauer 2001). Through the North 

American Waterbird Conservation Plan, “a manual of recommended standardized 

breeding season population monitoring methodologies has been produced for use by 

resource agencies and NGOs” has been developed and continues to be updated with new 

information. This document, titled “Breeding Season Population Census Techniques for 

Seabirds and Colonial Waterbirds throughout North America” is available online at: 

http:// http://www.mp2-pwrc.usgs.gov/cwb/manual/. Useful sources of DCCO 

population information are described below. 
110 – Chapter 4 

A. Audubon Christmas Bird Count - The entire CBC database (1900-2000) is 

available online in a searchable format at www.birdsource.org, but detailed analyses of 

the CBC data are generally not provided. Additionally, the Patuxent Wildlife Research 

Center (http://www.mbr.nbs.gov/bbs/cbc.html) has provided an initial analysis of CBC 

data for the period 1959-1988. As a result, the following information is available for 

DCCOs: 

Table of population trends - http://www.mbr.nbs.gov/bbs/cbct/t1200.html 

Graph of annual population indices - http://www.mbr.nbs.gov/bbs/cbcgr/h1200gr.html 

Comparison of BBS and CBC indices - 

http://www.mbr.nbs.gov/bbs/cbccomp/h1200cp.html 

Map of winter spatial abundance/distribution - 

http://www.mbr.nbs.gov/bbs/cbcra/h1200ra.html 

See Appendix 10 for examples of comparison tables that can be produced using CBC 

data. 

B. Band Recovery Analysis - DCCOs were first banded in 1929. In the period 1955-

2000 alone, 179,408 cormorants were banded and 8,974 (5.0%) of them were 

subsequently recovered. This sample of 8,974 banded and recovered cormorants 

provides an opportunity to monitor trends in survivorship over time. Survivorship is one 

of the demographic parameters that could be most useful in tracking the impacts of 

management actions on cormorant populations. Banding data can also be useful for 

determining links between breeding and wintering grounds. A band recovery file for the 

DCCO can be obtained on request from the U.S. Geological Survey’s Bird Banding 

Laboratory (http://www.pwrc.usgs.gov/bbl/default.htm). 

C. Breeding Colony Surveys - The standardized and coordinated inventory and 

monitoring of colonial waterbird colonies in the United States is still in its infancy (see, 

for example, http://www.mp1-pwrc.usgs.gov/birds/othbird.html#cwb). Efforts began in a 

modest way in the early 1970s with development of the Cornell Laboratory of 

Ornithology’s (now defunct) Colonial Waterbird Registry. In the mid-1970s, proposed 

oil and gas exploration and drilling in U.S. coastal waters prompted initiation of the Outer 

Continental Shelf Environmental Assessment Program. OCSEAP efforts resulted in 

extensive inventory of coastal colonial waterbird colonies, with the results published as a 

series of atlases. Since then, monitoring of waterbird colonies has been conducted with 

varying degrees of frequency and intensity by Federal and State agencies, nonprofit 

conservation and environmental organizations, universities, and private individuals. 

Some of this monitoring data has been published, but most has not, hence the need for an 

interactive online colony monitoring database. A prototype monitoring database for the 

West Coast has been developed by the U.S. Geological Survey’s Alaska Biological 

Science Center in conjunction with the Pacific Seabird Group. Similarly, a national 

monitoring database is under development by the U.S. Geological Survey’s Patuxent 

Wildlife Research Center. 
111 – Chapter 4 

D. North American Birds Regional Reports - The seasonal regional reports published 

in North American Birds and its predecessors (Field Notes, National Audubon Society 

Field Notes, American Birds, Audubon Field-Notes, and Bird-Lore) provide a treasure 

trove of qualitative and semi-quantitative information on the status, trends, and 

movements of North American birds. As an example, the Fish and Wildlife Service has 

compiled (unpublished data) statements made about DCCOs that appeared in 1,674 

seasonal reports spanning a 52-year period (fall 1946 to winter 1997-1998). Reading 

these statements in chronological order provides a vivid picture of the changing status of 

this species throughout its range. 

E. North American Breeding Bird Survey - The BBS database is available online in an 

interactive searchable format at http://www.mbr-pwrc.usgs.gov/bbs/bbs.html, and revised 

analyses of population trends are provided annually. The BBS was not expressly 

designed to monitor flocking species such as cormorants, and provides poor coverage of 

the open water and near shore coastal habitats preferred by this species. Nevertheless, the 

BBS does provide some useful trend data for the DCCO, and BBS trends closely mirror 

those derived from the Christmas Bird Count and other sources. 

F. Sea Watches or Coastal Counts - A Sea Watch or Coastal Count can be viewed as 

the equivalent of a Hawk Migration Count. Observations are made from a stationary 

point of all waterbirds moving up or down the coast. Counts are normally made daily 

throughout the spring or fall migration period. The primary object is to document the 

seasonal timing and magnitude of migratory flights of coastal waterbirds. These counts 

are most often conducted by local bird observatories, with some spanning several decades 

(e.g., Avalon, New Jersey). The number and availability of sea watch/coastal count 

databases, and their usefulness for monitoring regional trends in cormorants, has not been 

assessed. 

G. Winter Roost Counts - Aerial counts have been conducted annually in January or 

February by APHIS/WS in the Mississippi Delta region of northern Mississippi. These 

counts provide information on the number, location, and approximate size of cormorant 

night roosts in the vicinity of one of the major catfish producing areas in the nation. 

These counts will continue to be conducted annually. 

H. Reports of DCCOs Killed under Depredation Permits and the Depredation 

Orders – Reporting and/or recordkeeping requirements are associated with depredation 

permits and both the aquaculture depredation order and the public resource depredation 

order. Responsible individuals or agencies are required to report annually the number of 

DCCOs taken. A periodic review and assessment of this information will allow the 

Service to track trends in the number of birds being killed. 

 

In addition to monitoring populations, it will be helpful to monitor trends in resource 

damage levels associated with DCCOs. The Service typically becomes aware of the 

existence and extent of wildlife conflicts via formal and informal communications with 

the public, other affected agencies (e.g., APHIS/WS and States), elected representatives 

(e.g., members of Congress or State legislatures), and Service regional and field offices. 
112 – Chapter 4 

To the extent that our proposed action alleviates damages and conflicts, we anticipate that 

concerns expressed by these groups will decline significantly. In addition, more 

quantitative means of tracking trends in DCCO conflicts include: 

A. APHIS/Wildlife Services Management Information System - This database tracks 

complaints from landowners about damages to private property and agricultural crops 

caused by wildlife, including cormorants. Tracking complaints about DCCOs may yield 

information on the geographic areas in which they are of greatest concern, and may help 

to determine if control actions are having the desired result of reducing conflicts with 

human interests. 

B. Trends in Depredation Permit Issuance - Each Regional Migratory Bird Permit 

Office keeps records of depredation permits issued by year, species, and resource 

category. This information could be tracked to follow trends in permit issuance as new 

management programs are implemented. 

C. Research - The most meaningful information on the effectiveness of damage control 

techniques will come from soundly designed and implemented scientific experiments. 

Unfortunately, carrying out long-term research is the most costly and time-consuming 

means of obtaining this information. In an ideal world, wildlife management activities 

would always be accompanied by a thorough and timely monitoring plan. Research 

needs pertinent to DCCOs have been summarized elsewhere as falling into the categories 

of: distribution information, demographic information, diet, impacts to fisheries and 

aquaculture, impacts to flora and fauna, management techniques, and economic impacts 

(Wires et al. 2001). For our purposes here, we are interested in developing a research 

program that will help us better understand how implementation of the proposed action 

impacts DCCOs and other resources. Some examples of research that the Service and its 

partners such as APHIS/WS, States, Tribes, and universities could carry out, if adequate 

financial resources were available, include: more frequent regional DCCO population 

surveys to better understand population changes and status; color banding and satellite 

transmitter studies to better understand local and regional DCCO movements and 

survival rates in response to management actions; more DCCO diet studies; fish 

population monitoring in areas of DCCO management; public attitude surveys before and 

after implementation of new management strategies. 

3) Evaluation

Evaluation involves analysis of the information collected during monitoring and other 

reporting activities. Each year, under the public resource depredation order, agencies are 

required to provide the appropriate Service Regional Migratory Bird Permit Office with a 

report detailing activities conducted under the order, including a summary of the number 

of DCCOs killed and/or number of nests in which eggs were oiled; a statement of efforts 

being made to minimize incidental take of nontarget species and a report of the number 

and species of migratory birds involved in such take, if any; a description of the impacts 

or anticipated impacts to public resources by DCCOs and a statement of the management 

objectives for the area in question; a description of the evidence supporting the 

hypothesis that DCCOSs are causing or will cause these impacts; a discussion of other 
113 – Chapter 4 

limiting factors affecting the resource (e.g., biological, environmental, and 

socioeconomic); and a discussion of how control efforts are expected to, or actually did, 

alleviate resource impacts. In addition, for actions that are conducted with the intent of 

reducing or eliminating local breeding populations of DCCOs, agencies must evaluate 

effects of management activities on cormorants at the control site and evaluate, by means 

of collecting data or using best available information, effects of management activities on 

the public resources being protected and on non-target species. 

Each year, staff from the Division of Migratory Bird Management will review these 

agency reports in combination with all other relevant sources of information and develop 

a summary report. The goal of the summary report will be to assess the overall impact of 

this program on the long-term conservation of DCCOs and other migratory birds. 
114 – Chapter 5 

CHAPTER 5: LIST OF PREPARERS 

Lead Author: 

Shauna L. Hanisch, Wildlife Biologist, Arlington, VA 

B.S. Wildlife Biology, University of Montana; Master of Public Administration (MPA) 

with emphasis in environmental and natural resource policy, Boise State University. Five 

years of professional experience with the U.S. Fish and Wildlife Service. 

Contributors (USFWS):

Bill Archambault, Region 5, NEPA Coordinator 

Fred Caslick, New York Field Office, Ecological Services 

John Charbonneau, Washington Office, Economics 

Tina Chouinard, Washington Office, Migratory Birds 

Suzanne Fellows, Region 6, Migratory Birds 

Kyle Flanery, Washington Office, Hatcheries 

David Haukos, Region 2, Migratory Birds 

Michael Hay, Washington Office, Economics 

Chuck Hunter, Region 4, Migratory Birds 

Stephanie Jones, Region 6, Migratory Birds 

Rob Kelsey, Region 4, Migratory Birds 

Denny Lassuy, Region 1, Fisheries 

Susan Lawrence, Washington Office, Migratory Birds 

Steve Lewis, Region 3, Migratory Birds 

Roy Lowe, Region 1, Oregon Coast National Wildlife Refuge Complex 

Brian Lubinski, Region 3, Fisheries 

Jerry McClain, Region 3, Fisheries 

Maura Naughton, Region 1, Migratory Birds 

Diane Pence, Region 5, Migratory Birds 

David Perkins, Region 5, Fisheries 

Cyndi Perry, Washington Office, Migratory Birds 

Don Peterson, Washington Office, Federal Program Activities 

Jim Serfis, Washington Office, Endangered Species 

Ken Stromborg, Green Bay Field Office 

Mike Tansy, Seney National Wildlife Refuge 

John Trapp, Washington Office, Migratory Birds 

Robert Willis, Washington Office, Federal Program Activities 

Tara Zimmerman, Region 1, Migratory Birds 

Contributors (State and Other Federal):

Connie Adams, Cornell University 

Jon Anderson, Vermont Department of Fish and Wildlife 

Glenn Belyea, Michigan Department of Natural Resources 

Mike Bur, U.S. Geological Survey 

Jim Farquhar, New York State Department of Environmental Conservation 

Larry Garland, Vermont Department of Fish and Wildlife 

Katie Haws, Minnesota Department of Natural Resources 
115 – Chapter 5 

Shannon Hebert, APHIS/WS 

Carrol Henderson, Minnesota Department of Natural Resources 

Jory Jonas, Michigan Department of Natural Resources 

Russ McCullough, New York State Department of Environmental Conservation 

Noel Myers, APHIS/WS 

Pete Poulos, APHIS/WS 

David Reinhold, APHIS/WS 

Scott Werner, APHIS/WS 

D.V. Chip Weseloh, Canadian Wildlife Service 

Linda Wires, University of Minnesota 
116 – Chapter 6 

CHAPTER 6: CONSULTATION AND COORDINATION WITH THE 

PUBLIC AND OTHER AGENCIES 

6.1 Introduction 

On November 8, 1999, we published a Notice of Intent to prepare an Environmental 

Impact Statement and national management plan for the DCCO in the Federal Register 

(64 FR 60826). The notice solicited public participation in the scoping process. Scoping 

is the initial stage of the EIS process used to identify issues, alternatives, and impacts to 

be addressed in the NEPA analysis. A Notice of Meetings was subsequently published in 

the Federal Register (65 FR 20194) on April 14, 2000, to announce twelve public scoping 

meetings. Public comments were accepted from the date of publication of the Notice of 

Intent on November 8, 1999 until June 30, 2000. Over 900 people attended the public 

scoping meetings (of which 329 gave verbal testimony) and over 1,450 submitted written 

comments, either electronically or by mail. A notice of availability published on 

December 3, 2001 (66 FR 60218) announced completion of the DEIS and its availability 

for public comment. Ten public meetings were held in early 2002 and nearly 1,000 

written comments were received. After publication of the proposed rule on March 17, 

2003 (68 FR 12653), we received nearly 10,000 letters, emails, and faxes during a 60-day 

public comment period. About 85 percent of these comments were opposed to the 

proposed action, the vast majority of which were driven by mass email/letter campaigns 

promoted by various non-governmental organizations. 

6.2 Issues of Concern and Management Options Identified During Scoping 

A scoping report can be found in Appendix 11. NEPA regulations state that only 

“significant” impacts be analyzed. Determination of significance was based on 

interagency discussions, knowledge gained from DCCO research, public involvement, 

and professional judgment. A majority of the public comments expressed concern over 

negative impacts associated with DCCOs, especially those relating to sport fisheries (38.7 

percent). Some individuals suggested that other reasons for fisheries declines should be 

examined instead of “scapegoating” cormorants. 

 

NEPA regulations state that only “reasonable” alternatives be evaluated. Determination 

of reasonableness was based on public involvement, interagency discussions, and 

professional judgment. Management options and suggestions included: controlling 

DCCO populations, removing DCCOs from MBTA protection, hunting DCCOs, focusing 

on non-lethal control, letting States manage DCCOs, changing the depredation permit 

policy, oiling eggs, giving APHIS/WS more authority, basing decisions on the best 

science, using population objectives, and increasing education efforts. 

In addition to citizen input, twenty seven State agencies provided comments during the 

public scoping period. Fourteen States (Connecticut, Georgia, Indiana, Iowa, Nebraska, 

New Hampshire, New York, North Dakota, Ohio, Oklahoma, Rhode Island, Texas, 

Vermont, Wyoming) expressed a desire for increased flexibility/increased State input in 

managing cormorants. Twenty-three States (Arizona, Connecticut, Georgia, Illinois, 

Indiana, Iowa, Louisiana, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New 

Hampshire, North Dakota, New York, Ohio, Oklahoma, Oregon, Rhode Island, Texas, 
117 – Chapter 6 

Vermont, Wisconsin, Wyoming) stated or implied that, under certain conditions (e.g., 

evidence pointing toward a problem, displacement of other colonial nesting birds, 

impacts on natural systems, etc.), increased control should be considered. Five States 

(Arizona, Minnesota, New Hampshire, North Dakota, South Dakota) stated that they 

currently have no real problems with DCCOs. Additionally, we received comments from 

four Canadian agencies whose concerns included potential impacts of management 

actions on Great Cormorant populations (Nova Scotia) and on declining western DCCO 

populations (British Columbia). 

6.3 Public Comments Expressed During the DEIS Comment Period

The DEIS public comment period lasted from November 16, 2001 to February 28, 2002. 

The Service received 994 letters and held 10 public meetings which together reflected 

1,592 different comments. In terms of support for specific management alternatives, 15.4 

percent of the overall comments supported Alternative D (the preferred alternative), 12.4 

percent supported Alternative E (regional population reduction), 8.1 percent supported 

Alternative A (no action), 6.0 percent supported Alternative F (regulated hunting), 5.6 

percent supported Alternative B (non-lethal control). Less than one percent of the 1,592 

comments supported Alternative C (increased local damage control) or some form 

thereof and 7.3 percent supported some combination of alternatives D, E, and F. The 

most common specific comments about the proposed action were criticisms that DCCOs 

were being wrongly blamed (i.e., scapegoated) for fish declines (6.5 percent), that the 

Service was catering to special interests such as aquaculture and sport fishing (7.3 

percent), and that the preferred alternative did not appear to be based on sound science 

(6.0 percent). Figure 1 shows levels of support for the various alternatives in the DEIS. 

Table 25 summarizes the comments of State, Tribal, and Federal agencies. FWS 

responses to all significant comments on the DEIS appear in Chapter 7. 
118 – Chapter 6 

Figure 1. Summary of Support for Alternatives A, B, C, D, E, and F 

A

B

C

D

E

F

0

50

100

150

200

250

DCCO DEIS Public Comments
119 – Chapter 6 

Table 25. Summary of Agency Comments on DEIS 

Arizona Supports Alternative D (proposed action) 

Arkansas Elements of Alt. D, E, and F should be combined into an effective regional 

strategy to reduce DCCO populations 

Florida Final document needs more details on when the action can be conducted and 

on monitoring requirements; concerned about potential disturbance of other 

bird species 

Georgia Supports Alternative D (proposed action) 

Idaho In Idaho, the No Action alternative would be most applicable 

Illinois Agrees with the public resource depredation order if it includes fish in stateowned facilities 

Louisiana No problem with Alternative D (proposed action); ability to designate agents 

is important 

Maine Alternative C best suits conditions in Maine; does not endorse hunting of 

cormorants 

Massachusetts Does not object to the proposed action for states which support the Interior 

population of DCCOs so long as state oversight authority is preserved 

Michigan Final rule must include a full array of management options from local to 

regional population control in the event local measures are not sufficient; 

FWS should be the lead agency and should provide funding and support 

Minnesota Recommends the adoption of Alternative A (No Action) 

Missouri Supports the proposed new public resource depredation order 

Nebraska Supports both the proposed action and Alternative C; more states should be 

included under the aquaculture depredation order 

Nevada Supports Alternative D (proposed action) 

New York Proposed action is the best alternative offered to meet our needs; FWS 

should take an active role in developing regional population goals 

Ohio Proposed action is the most reasonable and responsible approach; ability to 

designate agents is important 

Oklahoma DCCOs should be removed from MBTA protection; supports a combination 

of Alternatives D, E, and F 

Ontario Supports Alternative D (proposed action) 

Rhode Island Supports Alternative D (proposed action) 

Texas Strongly recommends adding an option that would allow agencies to issue 

permits to owners of private fishing waters 

Vermont Supports Alternative D (proposed action) 

Washington Supports Alternative D (proposed action) 

Wisconsin Favors Alternative E; believes FWS should manage DCCOs on a flyway 

basis and provide funding for research and management 

Wyoming Supports Alternative D (proposed action) or E 

Coeur d’Alene Tribe Proposed action has potential for high take of DCCOs and limits should be 

established 

Grand Traverse Band of 

Ottawa and Chippewa 

Indians 

Recommends population reduction and that an interagency task group on 

DCCOs be established 

Sac and Fox Tribe Alternative D is the preferred option 

APHIS/Wildlife Services Supports a population reduction strategy based on scientifically determined 

population levels and social carrying capacity 

6.4 List of Agencies, Organizations, and Individuals to Whom the EIS is Being Sent

We assembled a mailing list for the DEIS. The list includes Federal, Tribal, State, and 

Provincial agencies; organizations; and individuals and was based on the following: 1) 

the mailing list that the Division of Migratory Bird Management uses for its Federal 
120 – Chapter 6 

Register notices; 2) individuals, organizations, and agencies that submitted comments 

during our 1998 aquaculture depredation order Environmental Assessment process; 3) 

individuals, organizations, and agencies that submitted comments in response to our 

Notice of Intent published on November 8, 1999 and in response to the DEIS public 

comment period; and 4) anyone else who has been asked to be placed on our mailing list. 

We also posted the DEIS on our website (http://migratorybirds.fws.gov). The FEIS, the 

Notice of Availability for the FEIS, or another type of notification will be sent to all 

addresses on this mailing list. 
121 – Chapter 7 

CHAPTER 7: PUBLIC COMMENT ON DEIS AND RESPONSE 

1) Why didn’t the USFWS select Alternative A (No Action) as the preferred 

alternative/proposed action? 

In recent years, it has become clear from public and professional feedback that the status 

quo is not adequately resolving DCCO conflicts for many stakeholders. Furthermore, our 

environmental analysis indicated that conflicts were more likely to be resolved under 

other options than under Alternative A. 

2) Why didn’t the USFWS select Alternative B (non-lethal management) as the 

preferred alternative/proposed action? 

In the wildlife management field, the control of birds through the use of humane, but 

lethal, techniques can be an effective means of alleviating resource damages, preventing 

further damages, and/or enhancing non-lethal techniques. It would be unrealistic and 

overly restrictive to limit a resource manager’s damage management methods to nonlethal techniques, even if “non-lethal” included nest destruction and/or egg oiling. Lethal 

control techniques are an important, and in many cases necessary, part of a resource 

manager’s “tool box.” 

3) Why didn’t the USFWS select Alternative C (increased local damage control) as 

the preferred alternative/proposed action? 

Alternative C would still require the issuance of Federal permits before resource 

managers could conduct management actions to protect public resources. The available 

evidence suggests that agencies need greater flexibility and timeliness in their ability to 

manage DCCOs than the permit system allows. Thus, we considered Alternative C to be 

limited in its potential effectiveness. 

4) Why did the USFWS select Alternative D (public resource depredation order) as 

the preferred alternative/proposed action?

Our purpose for the proposed action, as laid out in the DEIS, is to: (1) reduce resource 

conflicts associated with DCCOs in the contiguous United States; (2) enhance the 

flexibility of natural resource agencies in dealing with DCCO-related resource conflicts; 

and (3) ensure the long term conservation of DCCO populations. Based on internal and 

interagency discussions, public comments, and biological information relevant to DCCOs 

and their management, we developed the proposed action, Alternative D, as a strategy 

that would best balance all three aspects of our purpose. 

Specific to the public resource depredation order itself, we believe that since DCCO 

conflicts tend to be of a localized nature and because timeliness is an important factor in 

conducting effective control, it is logical to give more authority, within limits, to the 

agencies that actually deal with the on-the-ground realities of DCCO management. 

5) Why didn’t the USFWS select Alternative E (regional population reduction) as 

the preferred alternative/proposed action? Why doesn’t the USFWS manage 

DCCO overabundance through population reduction? Is the Service planning to 
122 – Chapter 7 

manage DCCOs on a “flyway” basis with the development of regional population 

goals?

Based on public comments received after publication of the DEIS, it is clear that many 

agencies and individuals were supportive of Alternative E because of its coordinated, 

regional approach. FWS understands the logic and appeal of this approach. We manage 

migratory game birds (e.g., waterfowl) in this way, so it only makes sense to do the same 

for other species. The difference is that we have considerably more biological 

information about and resources to conduct monitoring of migratory game birds. 

Intensive management, such as would be required with a cormorant population objectives 

strategy, is expensive. Additionally, while many stakeholders portray cormorant 

conflicts as being a simple overabundance problem whose solution is population 

reduction, the reality is not so clear. That is, it is unclear whether fewer cormorants 

would actually mean fewer problems (since sometimes distribution is as important as 

number in determining impacts), what the necessary scale of control would be, and 

whether or not that scale of control is biologically and socially feasible. Finally, we 

would point out that the proposed action (Alternative D) in no way precludes regional 

coordination, despite being more of a localized damage control approach than a 

population objectives approach. 

6) Why didn’t the USFWS select Alternative F (hunting) as the preferred 

alternative/proposed action? 

While we recognize the validity of hunting as a wildlife management tool, we feel that 

the risks associated with it outweigh any potential benefits. We are gravely concerned 

about the negative public perception that would arise from authorizing hunting of a bird 

with little consumptive (or “table”) value. While it is true that this has been done in the 

past for other species (e.g., crows), public attitudes are different today than they were 

thirty years ago when those decisions were made. Additionally, a number of hunters 

commented that they did not support hunting as a means of cormorant control. 

Therefore, it is our position that hunting is not, on the whole, a suitable technique for 

reducing cormorant damages. 

7) What about choosing a combination, or “hybrid,” of Alternatives D, E, and F as 

the proposed action? 

Our planning and decision making efforts led us to conclude that Alternative D alone, 

and not in combination with any other alternative, is the best option at this time. The 

reasons stated above for not choosing Alternatives E and F are equally applicable when 

considering a hybrid alternative. 

8) In the DEIS, did the USFWS consider a range of reasonable alternatives? 

Yes. We selected the six alternatives in the DEIS based on the public scoping period and 

NEPA requirements. The alternatives adequately reflected the range of public comments 

and represented what FWS considered to be “all reasonable alternatives.” 

9) Will the Service consider an option that allows egg and nest control but not the 

killing of adult or juvenile DCCOs? 
123 – Chapter 7 

No. We see no significant qualitative difference between an entirely “non-lethal” 

alternative, as was analyzed in the EIS, and an alternative that authorizes destruction of 

eggs but not of adult or juvenile DCCOs. 

10) Why didn’t the USFWS more fully consider the option of removing cormorants 

from the list of birds protected under the Migratory Bird Treaty Act? 

In our view, this is not a “reasonable alternative.” DCCOs have been protected under the 

MBTA since a 1972 amendment to the Mexican convention. Removing DCCOs from 

MBTA protection would not only be contrary to the intent and purpose of the original 

treaties, but would require amendment of the original treaties – a lengthy process 

requiring approval of the U.S. Senate and President and subsequent amendments to each 

treaty by each signatory nation. Since DCCOs are protected by family 

(Phalacrocoracidae) rather than by species, the end result could be the loss of protection 

for all North American cormorant species in addition to that of DCCOs. At this time, 

there appears to be adequate leeway for managing cormorant conflicts within the context 

of their MBTA protection and, thus, we believe this approach is neither practical nor in 

the best interest of the migratory bird resource. 

11) Why doesn’t the USFWS implement a cormorant bounty? 

We do not consider bounty hunting to be biologically, economically, or ethically 

appropriate for controlling cormorant damages. Thus, it is not a “reasonable alternative.” 

12) Why doesn’t the USFWS expand the aquaculture depredation order to more 

than 13 States? 

At this time, we do not feel there is sufficient evidence that expansion beyond the original 

13 States is necessary to further protect commercial aquaculture stock. The issuance of 

depredation permits for damage at private fish farms is a high priority and therefore it is 

usually a quick process for aquaculture producers to obtain a depredation permit through 

their Regional Migratory Bird Permit Office. 

13) Why doesn’t the USFWS give producers at saltwater aquaculture facilities the 

authority to control DCCOs under the aquaculture depredation order? 

We have not seen sufficient evidence that an expansion to saltwater facilities is necessary 

to protect commercial aquaculture stock. In some cases, problems at coastal sites could 

be caused by cormorants other than DCCOs and we do not want to greatly increase the 

likelihood of look-alike species being taken. Where significant economic damage has 

occurred, saltwater aquaculture producers can apply for a Federal depredation permit 

through their Regional Migratory Bird Permit Office. 

14) Why doesn’t the USFWS just allow cormorant populations to regulate 

themselves? 

There is a difference between killing limited numbers of birds for localized damage 

management and population regulation. Our proposed action falls into the former 

category, not the latter. Thus, for the most part, we are allowing DCCO populations to 

regulate themselves. 
124 – Chapter 7 

15) Isn’t it possible to control cormorant numbers by impacting their fertility rates? 

There are no technologies currently available that have been shown to limit cormorant 

fertility rates in an economically or logistically effective manner. We can, however, limit 

their productivity rates through egg oiling and destruction and these activities are allowed 

under the proposed action. 

16) Doesn’t the public resource depredation order violate the Migratory Bird 

Treaty Act by abrogating the Federal role in managing migratory birds? 

No. First of all, the PRDO by no means puts an end to the Federal role in migratory bird 

management. The conservation of migratory bird populations is and will remain the 

Service’s responsibility. Second, while the MBTA gives the Federal government (as 

opposed to individual States) the chief responsibility for ensuring the conservation of 

migratory birds, this role does not preclude State involvement in management efforts. 

Bean (1983) described the Federal/State relationship as such (emphases added): 

“It is clear that the Constitution, in its treaty, property, and commerce clauses, contains 

ample support for the development of a comprehensive body of federal wildlife law and 

that, to the extent such law conflicts with state law, it takes precedence over the latter. 

That narrow conclusion, however, does not automatically divest the states of any role in 

the regulation of wildlife or imply any preference for a particular allocation of 

responsibilities between the states and the federal government. It does affirm, however, 

that such an allocation can be designed without serious fear of constitutional hindrance. 

In designing such a system, for reasons of policy, pragmatism, and political comity, it is 

clear that the states will continue to play an important role either as a result of federal 

forbearance or through the creation of opportunities to share in the implementation of 

federal wildlife programs.” 

Nowhere in the MBTA is the implementation of migratory bird management activities 

limited to the Federal government. In fact, the statute specifically gives the Secretary of 

Interior the authority to determine when take of migratory birds may be allowed and to 

adopt regulations for this purpose. Additionally, nothing in the proposed action can be 

construed as being in conflict with the Convention for the Protection of Migratory Birds 

and Game Mammals between the U.S. and Mexico (under which cormorants are 

protected). 

17) Isn’t the concept of a general public resource depredation order foreign to the 

purpose of the MBTA (i.e., to protect migratory birds)? 

No. While the core intent of the MBTA is to protect migratory birds, allowances were 

made in the act itself, the various conventions, and subsequent regulations for dealing 

with resource conflicts associated with migratory birds (e.g., depredation problems). It 

was recognized from the earliest days that there could be instances in which migratory 

birds could conflict with human interests. It would be irresponsible to do nothing but 

“protect” DCCOs when they are having negative impacts on other resources that are 

valued by society. 
125 – Chapter 7 

18) Is the level of analysis conducted in the DEIS sufficient according to the 

requirements of the National Environmental Policy Act? Did the USFWS properly 

evaluate the environmental impacts of the proposed action? 

Yes on both counts. The analysis included, as required by NEPA, a discussion of the 

environmental impacts associated with the various alternatives, unavoidable adverse 

environmental effects associated with the proposed action, the relationship between 

short-term uses and long-term productivity, and any irreversible or irretrievable 

commitments of resources associated with the proposed action. Where new information 

has come out since publication of the DEIS, this was used to augment the discussion in 

the FEIS. 

19) In violation of the National Environmental Policy Act, has the Service 

“arbitrarily limited the scope of the analysis contained in the DEIS, failed to justify 

the purpose and need for action...[and] illegally segmented the action into smaller 

component parts in order to avoid a full analysis of all impacts and issues relevant 

to DCCO management”? 

No, the Service did not arbitrarily limit the scope of the DEIS analysis, nor did it segment 

the action to avoid a full analysis of impacts. The subject of the DEIS is DCCO 

management, so it is only logical that we would focus our analysis on DCCOs. The 

DEIS did not argue that DCCOs alone are to blame for the resource conflicts that they are 

associated with. In keeping with CEQ’s advice to keep EISs “concise...and no longer 

than absolutely necessary to comply with NEPA” (43 CFR 1502.2(c)) we focused the 

scope of the analysis on the most relevant factors. We disagree that the purpose and need 

for the action were not adequately justified. As stated in 43 CFR 1502.1, the purpose of 

an EIS is “to serve as an action-forcing device to insure that the policies and goals 

defined in the Act are infused into the ongoing programs and actions of the Federal 

Government.” We are confident that we fulfilled this purpose in the DEIS and FEIS. 

20) Did the Service fail to disclose or evaluate the environmental impacts of the 

proposed action on threatened or endangered species? 

No. In the DEIS, the Service listed species that “may be affected” by DCCO management 

as a precursor to its completion of the Section 7 consultation. This consultation was 

completed for the FEIS. 

21) Isn’t the public resource depredation order essentially an “unfunded mandate” 

for the States? 

No. The PRDO is not a requirement being forced upon the States (or any other agency) 

by the Federal government. The decision ultimately lies with individual States to choose 

whether or not to use the authority granted to them by the PRDO. It will be up to them to 

decide whether DCCO control is a high enough priority within their budget allocation 

processes. 

22) Were public comments fairly and completely considered? 

Yes. As documented in the public scoping report (Appendix X), all comments, written 

and verbal, received during the scoping period were fully considered in determining the 
126 – Chapter 7 

scope of issues and the range of alternatives addressed in the DEIS. All the comments 

received on the DEIS were also fully considered and responded to here in the FEIS. 

23) Is there sufficient evidence to justify the proposed action? 

What constitutes “sufficient” evidence to justify DCCO control is, to a certain extent, a 

question of values. Among stakeholders concerned with DCCO management we can 

safely say that there is considerable disagreement over whether or not the proposed action 

is justified (with some even arguing that the proposed action does not go far enough). 

FWS and APHIS Wildlife Services, as the lead and cooperating agencies in the EIS 

process, jointly agree that there is sufficient evidence to justify the proposed action. 

24) Shouldn’t the USFWS consider the economic benefits of DCCOs more 

thoroughly in the FEIS? 

Assigning economic value to any wildlife species is difficult, and it is made all the more 

so when that species (such as the DCCO) is of little direct use to humans. However, this 

should not be read to imply that we have no regard for the indirect and intangible values 

of cormorants as a native part of the North American avifauna. As such, we stated 

clearly in the DEIS (p2) that DCCOs “have inherent value regardless of their direct use to 

humans.” While an analysis of the economic benefits associated with DCCOs would be 

interesting, it would be fraught with extrapolation and assumption and would, in the long 

run, add little value to the comparison of alternatives. 

25) Under the public resource depredation order, is the USFWS evading its 

responsibility for managing DCCOs from a national perspective? Will the USFWS 

remain the lead agency in overseeing cormorant control efforts? Doesn’t the PRDO 

fail to coordinate DCCO management at the interstate level? 

We fully understand the necessity of retaining national oversight of DCCO populations 

and therefore of any DCCO management program, especially one that authorizes States 

and other agencies to conduct control without a Federal permit. While the PRDO gives 

States, Tribes, and APHIS Wildlife Services more authority to decide when to conduct 

DCCO control, we will retain our oversight role in order to keep track of DCCO 

management activities from a national perspective. The PRDO is by no means intended 

to inhibit regional or national coordination of DCCO management activities. 

26) Will the public resource depredation order apply to populations of DCCO other 

than the rapidly increasing Interior and Southern populations? 

The PRDO will apply mainly to DCCOs from the increasing Interior and Southern 

populations or States affected by those populations. Thus, it will be applicable to 24 

States. 

27) Will the USFWS provide funding to agencies that carry out cormorant 

management under the Public Resource Depredation Order? 

We currently have no plans to fund other agencies. However, in our Congressional 

budget request, we have asked for increased financial resources to implement the DCCO 

proposed action. This figure specifically includes money that could be used in 
127 – Chapter 7 

cooperative efforts with States and other agencies to conduct cormorant management, 

research, and monitoring. 

28) How will the USFWS ensure that cormorant populations remain healthy and 

sustainable? 

There are a number of methods that, collectively, the Service can use to keep track of the 

status of DCCO populations. Population monitoring is the best means for understanding 

changes in a species population over time. Along with other agencies and universities, 

the Service regularly monitors colonial waterbird populations, including DCCOs. In 

addition, the Service will be able to estimate population trends using a number of 

methods (Christmas Bird Count and Breeding Bird Survey data, for example) and, via 

reporting requirements, will keep track of how many DCCOs are killed under authority of 

the depredation orders. We will also continue to support and be involved in research 

efforts. 

29) What is the USFWS doing to allow for more flexibility in managing cormorants 

that impact private, non-aquacultural resources? 

The proposed action does not authorize actions to benefit private, non-aquacultural 

resources. However, individuals who experience damages to private resources (e.g., tree 

damage or loss of privately-owned fish stocks) should contact their Regional Migratory 

Bird Permit Office about obtaining a depredation permit. 

30) Will the USFWS provide more detail in the FEIS on monitoring and population 

survey requirements? Will the USFWS establish guidelines for agencies to use in 

population monitoring and in evaluating the impacts of management actions? 

No, because we do not feel that this level of detail is necessary. While we understand the 

importance of uniformity in data collection, we have to consider other factors as well. 

We want agencies to thoroughly evaluate the impacts of their management actions on 

DCCOs and, in some cases, other resources but we don’t want the requirements to do so 

to be cost prohibitive. 

31) Will the USFWS provide more detail in the FEIS on the circumstances under 

which agencies may or may not take actions under the public resource depredation 

order? 

No, the purpose of the PRDO is clearly stated in the rule. In order to avoid unduly 

restricting agencies’ flexibility to manage cormorant damages to public resources we do 

not feel that it is necessary to go into considerable detail beyond stating the purpose of 

the order. States, Tribes, and APHIS Wildlife Services have a level of knowledge and 

professionalism sufficient to determine whether actions they take are in accordance with 

the purpose of the order. 

32) How will the USFWS continue to support cormorant research efforts? 

Involvement in research will continue both through financial assistance (as funding 

allows) and through direct research activities (such as color banding work being done in 

Lake Michigan by the USFWS Green Bay Field Office). 
128 – Chapter 7 

33) What does the USFWS plan to do to educate the public about cormorants and 

their role in the ecosystem? 

We have prepared fact sheets for public distribution. Information about DCCOs is 

available at its website http://migratorybirds.fws.gov/issues/cormorant/cormorant.html. 

Our intention is to distribute fact sheets on the depredation orders in the near future. 

Beyond DCCOs, we participate in numerous outreach activities around the nation to 

increase public awareness about the role of migratory birds and other Federal trust 

species. 

34) Under the public resource depredation order, does the definition of “public 

resources” include fish in hatcheries? 

Yes. The PRDO applies to Federal, State, and Tribal hatcheries. 

35) Will agencies acting under the public resource depredation order be authorized 

to designate agents? 

Yes, as long as “agents” abide by the purpose, terms, and conditions of the order. 

36) Will State oversight be preserved under the public resource depredation order? 

Yes, any agency or agent acting under the PRDO must follow all applicable State laws. 

For example, if a State permit is required to authorize a particular control activity, such 

permit must be obtained before that activity can be conducted. 

37) How is the USFWS going to deal with impacts to non-target migratory bird 

species associated with DCCO control activities? Couldn’t cormorant management 

do more harm than good to other colonial waterbirds? 

While the proposed action does not authorize the take of any species of migratory bird 

other than DCCOs, we recognize that “incidental” take may occur and that DCCO control 

activities could greatly disturb other species, especially at breeding colonies. Under the 

terms and conditions of the PRDO, responsible agencies must provide a statement of 

efforts being made to minimize incidental take of non-target species and to evaluate the 

impacts of any control activities on these species. Regular monitoring of colonial 

waterbirds will help us keep track of population changes so that we can address declines 

as necessary. 

38) Will the USFWS more clearly describe allowable control activities in the 

FEIS/final rule? 

Management activities authorized under the proposed action include shooting, egg oiling 

or other means of destroying eggs, nest destruction, CO2 asphyxiation, and cervical 

dislocation. This is clearly stated in the final rule. 

39) Will the USFWS allow depredation permits to be issued for two years instead of 

requiring renewal every year? 

At this time, depredation permits will continue to be issued on an annual basis. 
129 – Chapter 7 

40) Is the Service planning to develop a DCCO working group or technical 

committee? 

The Service has discussed the idea of initiating a cormorant technical committee to 

promote international, interagency, and interdisciplinary involvement in future cormorant 

management. 

41) Will the USFWS clarify the procedures by which an agency’s authority to act 

under the public resource depredation order would be revoked? 

Yes, the final rule reflects this clarification. 

42) How does the USFWS define cormorant population viability? 

We have not explicitly defined population viability for DCCOs. By all accounts, current 

DCCO populations are “viable” (essentially meaning that their long term existence is not 

threatened) and we fully anticipate them remaining so under the proposed action. In the 

future, if we decide to manage DCCOs by population objectives, an important task would 

be to determine more specific levels of population viability. 

43) Shouldn’t APHIS Wildlife Services be included as an agency that can act under 

the public resource depredation order? 

Yes, as the lead federal agency dealing with wildlife damage conflicts it is appropriate for 

APHIS Wildlife Services to be included. This change is reflected in the final rule. 

44) Is the proposed action the most cost effective management alternative? 

Cost effectiveness is only one consideration among many on which the preferred 

alternative decision is based. This is a cost effective alternative, although probably not 

significantly more or less so than other alternatives. 

45) Won’t shooting at winter roosts in aquaculture areas just move the birds 

around? 

The USDA report, “A Science-Based Initiative to Manage Double-Crested Cormorant 

Damage to Southern Aquaculture” notes that “Coordinated and simultaneous harassment 

of cormorants can disperse them from night roosts and reduce damage at nearby catfish 

farms” and cites 3 scientific studies that support this claim. It then concludes that 

shooting at roosts “might enable farmers to reduce the number of birds on their farms 

significantly...” Part of the logic behind this is that studies in the Mississippi Delta have 

shown that, while DCCOs move widely in general, they tend to exhibit high roost 

fidelity. This implies that shooting birds at roosts (where turnover is lower) is likely to 

be more effective at alleviating damages than shooting birds just at ponds (where 

turnover is higher). 

46) Will the proposed action allow for better coordination between USFWS and 

APHIS Wildlife Services? 
130 – Chapter 7 

The proposed action does not specifically require better coordination but that is likely to 

occur since APHIS Wildlife Services, if they choose to, will take on a greater role in 

cormorant management. 

47) Does the proposed action require the use of non-toxic shot? 

Yes, in all cases where shooting by shotgun is authorized, the use of lead shot is 

prohibited. 

48) How can the USFWS be sure that increased control under the proposed action 

will result in alleviation of conflicts? 

No one can predict with 100% accuracy that the proposed action will alleviate all 

conflicts; indeed, we don’t expect the proposed action to alleviate all conflicts. Our 

analysis indicates that the proposed action is highly likely to alleviate many of the 

impacts associated with DCCOs. 

49) How will the USFWS keep track of DCCOs killed under the public resource 

depredation order? 

Reporting requirements are directly tied to the PRDO and ADO (meaning any agency or 

individual acting under authority of the orders must report to us how many birds were 

killed). USFWS will prepare reports on a regular basis summarizing control activities 

under the PRDO. 

50) Does the USFWS have the resources to properly implement the proposed 

action? 

The proposed action is not particularly resource intensive as far as the Service itself is 

concerned. We anticipate that current staff in the migratory bird program will be able to 

handle the increased reporting associated with the proposed action. 

51) Why doesn’t the USFWS amend the aquaculture depredation order to require 

reporting by aquaculture producers who take birds? 

We made this change in the proposed and final rules. 

52) Why doesn’t the USFWS require that States submit annual fish population 

surveys for areas where they carry out control? 

We do not believe that annual fish surveys are necessary or that the outcome would 

justify the extra expense to the States. 

53) Shouldn’t agencies have to prove that DCCOs are having real impacts before 

they can act under the PRDO? 

No. We don’t believe that agencies should have to wait until impacts occur and are 

proven with absolute certainty before they are allowed to manage DCCOs. One of the 

benefits of the PRDO is that agencies in areas where the risks of significant DCCO 

impacts are greatest are given more flexibility in taking action, including preventive 

action. As our partners in the conservation of America’s natural resources, we trust that 

these agencies will act responsibly and in compliance with the purpose of the order. 
131 – Chapter 7 

54) Why did the DEIS analyze “impacts to water quality and human health” when 

there is no substantiated evidence of DCCOs having such impacts? 

There are reports of DCCOs nesting/roosting near open water supplies and violating 

water quality. However, it is true that there is currently no evidence that they are 

responsible for widespread contamination or are a significant threat to human health. But 

since impacts to water quality were a significant concern raised during scoping, we felt 

that it was appropriate to include the issue in the DEIS analysis. 

55) Was the estimate of take in the DEIS accurate? 

Yes, to the best of our knowledge. The estimate has been updated in the FEIS, based on 

new considerations. However, we must emphasize that these numbers are estimates. We 

tried to be liberal in our estimates to increase the likelihood of over-, rather than under-, 

estimating take but we won’t know the actual number of birds taken until the depredation 

orders are implemented. 

56) Has the USFWS based its DCCO management decisions on scientific evidence? 

Does the proposed action have a sound scientific foundation? 

Yes, but not to the degree that all scientists find acceptable. In a perfect world, science 

would shed light on the causes of resource conflicts and then propose ideal solutions; in 

reality this often does not occur, largely for reasons entirely out of the control of 

government agencies. It has long been recognized in the field of natural resource 

conservation that wildlife management possess elements of both art and science. The 

Service’s stance on science-based management recognizes this truth and acknowledges 

that resource science, resource management, and social, political, and economic realities 

all contribute to the Service carrying out its mission to “conserve, protect, and enhance 

fish, wildlife, and plants and their habitats for the continuing benefit of the American 

people.” It is our position that there is sufficient biological and socioeconomic 

justification to support the proposed action. 

57) Shouldn’t the loss of fish caused by fish-eating birds to aquaculture producers 

just be considered a “cost of doing business” and shouldn’t they be responsible for 

developing a more integrated approach to reducing economic damage associated 

with fish-eating birds? Does the USFWS realize that the complete elimination of 

bird predation problems in the aquaculture industry is neither realistic nor 

desirable? 

We realize that the total elimination of bird depredation problems is unrealistic, but 

whether or not it is desirable or whether depredation by migratory birds should be just a 

“cost of doing business” are philosophical issues that are outside the scope of the 

proposed action. While it seems sensible, from an economical and logistical standpoint, 

for the aquaculture industry to work to develop long term solutions to prevent excessive 

losses to depredation (and, in fact, to some extent they are already doing so), it is not 

within the Service’s authority to demand that. 

58) Is there anything inherently “wrong” with the DCCO’s population and range 

expansion? 
132 – Chapter 7 

No. Population and range expansions of certain wild species are environmental 

phenomena that can be either “natural,” directly associated with human activities, or 

indirectly associated with human activities. Cormorant control, whether lethal or nonlethal, is not intended to be a form of punishment, but rather is a means to alleviate 

resource conflicts. 

59) Is the USFWS authorizing greater control just to appease public outcry? 

No, we are authorizing greater control to manage cormorant conflicts more effectively 

and to allow other agencies more flexibility in dealing with cormorant conflicts. 

60) Is it right to kill fish-eating birds that may have come to be a problem due to 

human activities (e.g., fish farming, introduction of exotic species, hatchery stocking 

programs, etc.)? 

Right or wrong, in this case, appears to be a matter of perspective. Most Americans 

would agree that species extinction, especially when caused by human activities, is 

wrong. Attitudes about the ethics of wildlife damage management, however, vary 

widely, often depending on the individual’s proximity to the problem. Our role is to help 

facilitate management of conflicts while ensuring that DCCO populations remain healthy. 

61) Is the role of APHIS Wildlife Services as a “cooperating agency” appropriate? 

Yes. As explained in the EIS, APHIS Wildlife Services plays an important role in the 

management of cormorant damages, especially to southern aquaculture. The Council on 

Environmental Quality NEPA guidelines state that “any other Federal agency which has 

special expertise with respect to any environmental issue...may be a cooperating 

agency.” 

62) Why is the Service reversing its policy of not issuing permits for controlling 

DCCOs feeding in natural environments? 

Our “policy” of not issuing depredation permits for controlling DCCOs feeding in natural 

environments is more accurately described as a “practice.” Technically speaking, the 

policy that guides our process for issuing migratory bird depredation permits lies in the 

regulations found in 50 CFR §21.41. We feel that there is sufficient justification to 

overturn our past management practice for DCCOs and give agencies in 24 States the 

authority to take DCCOs when they are feeding in natural environments. 

63) Isn’t the proposed action merely an attempt on the part of the USFWS to “pass 

the buck” of cormorant management on to the States? 

No. As we were considering options for addressing DCCO conflicts more effectively, it 

became clear that, since many conflicts tend to be localized in nature, a sensible and 

flexible solution was to allow local agencies more authority in deciding when to control 

cormorants. States are major contributors to the conservation of American fish and 

wildlife resources and in most cases they are the agency responsible for managing the 

resources that DCCOs come into conflict with. 

64) Shouldn’t wildlife management rely on sound biological facts instead of the 

opinion of the public, much of which is uninformed? 
133 – Chapter 7 

Yes, to the extent possible within the context of other realities we must consider as a 

public agency. Just as some stakeholders lack an understanding of the ecological 

complexities associated with cormorants, experts in the life sciences often lack an 

understanding of the sociological complexities of natural resource management and the 

realities of living with overabundant DCCO populations. 

65) By controlling DCCOs, isn’t the USFWS dealing with a symptom rather than 

the underlying causes? 

Numerous political, legal, and logistical deterrents prevent us from changing the entire 

American landscape to make it less desirable for DCCOs. It may be true that controlling 

cormorants while their environmental needs (e.g., food and habitat) remain abundant has 

an air of being a “bandage” approach. This is not a significant concern, however, since 

we are not trying to reduce DCCO populations on a large scale but, rather, are focusing 

on alleviation of local damages. 

66) Isn’t the USFWS “scapegoating” cormorants, or blaming them for problems 

that aren’t really their fault? 

This question reflects an inaccurate perception of the proposed action. The Service 

recognizes that DCCOs are a valuable part of our nation’s avifauna. By allowing other 

agencies greater authority to manage cormorants we are not “blaming” them for problems 

but are rather recognizing that they have the potential to cause real conflicts that could be 

addressed more effectively, in some situations, at the local level. We also recognize that 

factors other than DCCOs contribute to resource impacts such as fishery declines. 

However, an exhaustive and comprehensive analysis of these myriad factors is outside 

the scope of the EIS. Our focus is chiefly on addressing conflicts that are associated with 

cormorants and then attempting to manage DCCOs, or the resources themselves, to 

alleviate conflicts. 

67) Isn’t the USFWS putting the needs of special interests (e.g., sport fishing and 

fish farming) ahead of the public interest by controlling cormorants to benefit these 

resources? 

This question reflects an inaccurate perception of the proposed action. At this point, we 

are not engaging in widespread control of cormorants to benefit fisheries, although we are 

authorizing other agencies to carry out limited control where DCCOs have been shown to 

impact fisheries. Moreover, we are not authorizing, under any circumstances, agencies to 

threaten DCCO populations to the extent that their existence as part of America’s native 

avifauna is at risk. Additionally, fish in public waters are a public resource in the same 

way that DCCOs are. Recreational fishing is an important part of our nation’s economic 

base and cultural heritage and is supported by the Federal government in many ways. 

68) Won’t the States and other agencies just cave in to political pressure to control 

DCCOs? 

Political pressure or not, agencies must follow the terms and conditions outlined in the 

public resource depredation order in order to conduct cormorant control activities. These 

conditions were established expressly for the purpose of preventing abuses of the 

authority granted to these agencies under the PRDO. 
134 – Chapter 7 

69) Isn’t it archaic to allow the killing of a species simply because certain people find 

it to be a nuisance? 

That is a matter of opinion. Regardless, we allow killing of DCCOs only when they are 

associated with a specific problem, not just because they’re considered a pest or a 

nuisance. 

70) Isn’t the real problem here humans and therefore it is people who are in need of 

“management,” not cormorants? 

The answer depends on what exactly is meant by “people management.” Certainly, 

among the broad range of stakeholders, there is a need to promote a better understanding 

of the biological and sociological complexities associated with cormorant management. 

71) Does the mission of the USFWS “to conserve, protect, and enhance” allow it to 

adequately deal with the DCCO problem? 

Yes, while “protect” and “enhance” are not terms that many would find conducive to 

controlling birds to alleviate resource damages, “conserve” is generally used to describe a 

more balanced management paradigm somewhere between preservation and 

overutilization. 

72) Isn’t it inefficient and counterproductive for APHIS Wildlife Services employees 

to have to get permission from the USFWS before controlling migratory birds? 

Whether inefficient, counterproductive, or otherwise undesirable, it is plainly illegal 

under current MBTA regulations, based on the interpretation of the court in Humane 

Society v. Glickman (2000), for other Federal agencies to “take” migratory birds without 

a Federal permit. 

73) Is it appropriate for the USFWS to decide when and where DCCOs are 

injurious to public resources that are the legal responsibility of state agencies? 

To some extent, yes. The difficulty that arises when a Federally-managed species (e.g., 

DCCOs) comes into conflict with a State-managed species (e.g., yellow perch) is 

balancing national with local interests. An optimal approach would be responsive to 

local problems while responsible for national interests. We have tried to give agencies as 

much management flexibility as we felt was practicable within the context of our own 

legal responsibilities. 

74) Is the proposed action opening the door to widespread control of other fisheating birds (i.e., setting a precedent)? 

This action does set a specific precedent for more liberal management of overabundant 

cormorants in a specific region, but not for managing fish-eating birds specifically or bird 

depredation in general. The latter authority was clearly established in the original 

language of the MBTA. Some have argued that the proposed action will lead to less 

tolerance of fish-eating birds. However, past experience has shown that if there is a 

perception among stakeholders that nothing is being done about their concerns, 

intolerance also increases. Presently, there is a need to balance responsiveness to 

immediate concerns and management in the long-term. 
135 – Chapter 7 

Actions/Comments R1 R2 R3 R4 R5 R6 Totals 

Alt. F - hunting season 3 13 62 3 15 96 

Alt. E – population reduction 3 24 103 29 36 2 197 

Alt. D - proposed action 2 105 58 6 73 2 246 

Alt. B - non-lethal management 11 10 21 11 33 4 90 

Remove DCCOs from "protected" status 1 7 15 2 2 27 

Private landowners or state-designated 

"agents" should be able to control 

cormorants 

1 11 6 1 19 

Institute a cormorant bounty 2 4 1 7 

Effective monitoring is very important 1 1 3 3 8 16 

APHIS/WS should be more involved in 

control efforts/issuance of permits

2 1 12 2 17 

Stay with No Action alternative 27 18 13 13 56 2 129 

The proposed action could lead to overkill of 

cormorants; need to set a limit on number of 

birds taken under Public Resource DO 

1 1 2 

Expand the Aquaculture DO to include 

additional states 

1 1 1 1 1 5 

Proposed action amounts to an "unfunded 

mandate"; Feds should contribute funding 3 7 2 3 1 16 

Federal, state, and local cooperation is 

necessary (i.e., regional coordination) 

1 1 3 1 3 9 

Need to allow for more flexibility in managing

conflicts with private resources

1 3 3 7 

Agencies should have to report incidental 

take of other birds under Publ. Res. DO; 

there should be more discussion of 

disturbance to other species in the DEIS 

2 4 2 1 9 

More detail should be provided on specific 

plan for population surveys 3 1 4 

Find some way of making DCCOs infertile 1 1 

More research is needed 2 7 8 17 

Hunting or allowing citizens to kill DCCOs 

would be inappropriate, unethical, etc. 

1 0 7 1 5 1 15 

Need to state more specifically the 

parameters under which Agencies will have 

to operate to implement Publ. Res. DO 

1 1 6 2 10 

FWS needs to address/research the "real 

causes" of declining fish populations

(e.g., poor water quality). Cormorants are 

being killed without adequate justification 

(scapegoat) 

18 13 16 6 50 1 104 

FWS needs to increase education to 

counteract the negative public perception of 

cormorants 

4 6 14 24 

NEPA analysis in DEIS is inadequate 6 1 3 6 10 26 

Proposed action violates the MBTA 7 2 8 8 16 1 42 

FWS is putting fishing and farming 

interests ahead of non-consumptive users 

and/or is catering to these "special interests"

21 12 15 10 56 3 117 

Include saltwater facilities under Aquaculture 

Depredation Order 1 1 1 3 
136 – Chapter 7 

Aquaculture DO should be expanded to 

include all effective methods of control both 

at facilities and at nest/roost sites 

1 0 1 2 

A "conservation agreement" rather than a 

Depredation Order is more appropriate for 

giving Tribes more authority 

 1 1 

Alternative C is the best option 1 1 1 3 6 

How was the definition of viable DCCO 

populations (60% of current #s) determined? 

Need to define it more clearly 

 1 2 3 6 

Management decisions in DEIS do not 

appear to be/should be based on sound 

science

15 10 9 8 51 2 95 

Do not allow private landowners to control 

cormorants to protect their property 2 2 

FWS should let DCCO populations regulate 

themselves

1 1 2 

None of the Alternatives will be effective 1 1 

Alternatives D and F Combined 48 1 16 65 

Alternatives E and F Combined 1 3 12 4 2 22 

Alternatives D, E, and F Combined 1 1 1 1 6 1 11 

Alternatives D and E Combined 1 3 2 12 1 19 

Alternative C without the expanded winter 

roost control 

1 2 4 7 

Use $ that would go toward control efforts to 

support ecologically-sound fish farm 

technology 

1 1 2 

Only allow DCCO control on private land 

when a person's livelihood is at stake 

 1 1 2 

Keep No Action alternative for the Pacific 

Northwest 

2 2 

DEIS needs better fisheries analysis 1 2 3 

Use poison to lower DCCO numbers 1 1 2 

Close the sport fishery 1 1 

No comment 1 9 24 3 19 1 57 

Proposed action is an effort on the Service's 

part to evade its responsibility to manage 

DCCOs and to place a burden on States; 

FWS needs to maintain oversight and 

leadership 

 2 2 6 3 13 

Need more details on law enforcement 

elements of proposed action 1 1 1 3 

Concerned about loss of state authority 

under proposed action 

 1 1 

Combine Alternatives C and D with E (local 

damage control with possibility of regional 

population management later) 

 1 1 2 

Utilize an adaptive management approach to 

DCCOs 

 4 1 5 

Monitoring requirements are too burdensome 2 2 1 5 

Involve NABCI, Partners in Flight, NAWCP to 

unite states and provinces in DCCO 

management; proposed action will be difficult 

to coordinate 

 3 1 1 5 
137 – Chapter 7 

Establish a DCCO interagency task group, 

working group, etc. to help in planning 

1 2 1 4 

Management options should allow for 

implementation of preventative actions, not 

only corrective 

 2 2 

Need to ensure consistent interpretation of 

depredation policy across Regions 1 1 

The population model in the DEIS is 

inadequate 2 2 

The issue of protecting publicly owned 

natural resources on private lands is not 

adequately addressed in Alt. D 

 1 1 

Service should subsidize the use of nonlethal technology at fish farms 

 1 1 2 

Support Alternative B, with caveat that eggs 

can be destroyed 

1 1 

Proposed action is punitive not corrective 1 2 1 4 

EIS needs better discussion of economic and 

aesthetic values of cormorants 1 1 2 

States should have to conduct annual fish 

surveys where they control DCCOs 

 2 2 

Change aquaculture depredation order so 

that individuals must report take 2 2 

The FWS has arbitrarily limited the scope of 

the analysis contained in the DEIS, failed to 

justify the purpose and need for the action, 

failed to consider a reasonable range of 

alternatives, failed to fully disclose and 

adequately evaluate the environmental 

impacts of the proposed action and its 

alternatives, and has failed to properly 

disclose the indirect and cumulative impacts 

of the proposal 

 1 1 

USFWS lacks the resources to implement 

the proposed action properly 1 1 

USFWS has no reliable data on DCCOs 

being killed under the aquaculture 

depredation order 

 2 2 

USFWS should provide annual reports to 

Congress detailing the costs of the 

implementation of the proposed action and 

foregone mandated priorities 

 1 1 

It is not appropriate for FWS to decide 

“where DCCs are injurious to public 

resources” that are the legal responsibility of 

other agencies. 

 1 1 2 

DEIS provides evidence of perceived 

conflicts more than real conflicts 1 1 2 

Estimates of numbers of DCCOs that will be 

killed under the proposed action need to be 

revisited 

 1 1 

Why can't feathers and other bird parts be 

sold or given away? 1 1 

Introduce predators to nesting colonies 1 1 

Burn down the cormorant-only rookeries 1 1 

Develop training programs for proper 

instruction of citizens in lethal and non-lethal 

control techniques 

 1 1 
138 – Chapter 7 

Reimburse fish farmers for cormorant 

damages 1 1 

 138 245 440 147 495 22 1592 

Results for letters 1 - 994; and meeting 

transcripts 
139 – Chapter 8 

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Special Acknowledgements: 

Thank you to everyone who took the time to make their voice heard in the matter of 

cormorant conservation and management. Special thanks to all those who have spent 

time in the field to help increase our knowledge of cormorants. I’ll close with a quote 

from Aldo Leopold, a man I deeply respect for being not only a man of science, but a 

man of wisdom. This quote is from Riley et al. 2002: 

One of the anomalies of modern ecology is the creation of two groups, each of which seems barely aware 

of the existence of the other. The one studies the human community, almost as if it were a separate entity, 

and call its findings sociology, economics and history. The other studies the plant and animal community 

and comfortably relegates the hodgepodge of politics to the liberal arts. The inevitable fusion of these two 

lines of thought will, perhaps, constitute the outstanding advance of this century. 
A - 1 

Appendix 1: List of Scientific Names

BIRDS

American Black Duck (Anas rubripes) 

American Crow (Corvus brachyrhynchos) 

American White Pelican (Pelecanus erythrorhynchos) 

Anhinga (Anhinga anhinga) 

Bald Eagle (Haliaetus leucocephalus) 

Black-crowned Night-Heron (Nycticorax nycticorax)

Brandt’s Cormorant (Phalacrocorax penicillatus) 

Brant (Branta bernicla)

California Gull (Larus californicus) 

Canada Goose (Branta canadensis) 

Caspian Tern (Sterna caspia) 

Cattle Egret (Bubulcus ibis) 

Common Eider (Somateria mollissima)

Common Merganser (Mergus merganser) 

Common Raven (Corvus corax) 

Common Tern (Sterna hirundo) 

Double-crested Cormorant (Phalacrocorax auritus) 

Fish Crow (Corvus ossifragus) 

Gadwall (Anas strepera) 

Glaucous-winged Gull (Larus glaucescens) 

Great Black-backed Gull (Larus marinus) 

Great Blue Heron (Ardea herodias)

Great Cormorant (Phalacrocorax carbo)

Great Egret (Casmerodius albus)

Herring Gull (Larus argentatus) 

Least Tern (Sterna antillarum) 

Little Blue Heron (Egretta caerulea)

Mallard (Anas platyrhynchos)

Neotropic Cormorant (Phalacrocorax brasilianus) 

Northwestern Crow (Corvus caurinus) 

Osprey (Pandion haliaetus)

Pelagic Cormorant (Phalacrocorax pelagicus) 

Piping Plover (Charadrius melodus) 

Razor-billed Auk (Alca torda) 

Red-faced Cormorant (Phalacrocorax urile) 

Ring-billed Gull (Larus delawarensis) 

Snowy Egret (Egretta thula)

Western Gull (Larus occidentalis)

White Ibis (Eudocimus albus)

Wood Stork (Mycteria americana) 

Yellow-crowned Night-Heron (Nyctanassa violacea)

FISH 

alewife (Alosa pseudoharengus) 

American plaice (Hippoglossoides platessoides)

American sand lance (Ammodytes americanus)

American shad (Alosa sapidissima)

Arctic char (Salvelinus alpinus)
A - 2 

Arctic grayling (Thymallus arcticus) 

Atlantic cod (Gadus morhua)

Atlantic menhaden (Brevoortia tyrannus) 

Atlantic salmon (Salmo salar) 

blueback herring (Alosa aestivalis) 

bluegill (Lepomis macrochirus)

brook stickleback (Culaea inconstans) 

brown trout (Salmo trutta) 

burbot (Lota lota) 

capelin (Mallotus villosus)

channel catfish (Ictalurus punctatus) 

coho salmon (Oncorhynchus kisutch) 

common carp (Cyprinus carpio)

chinook salmon (Oncorhynchus tshawytscha) 

crappie (Pomoxis spp.)

cunner (Tautogolabrus adspersus) 

emerald shiner (Notropis atherinoides) 

fourspine stickleback (Apeltes quadracus) 

freshwater drum (Aplodinotus grunniens)

gizzard shad (Dorosoma cepedianum)

grubbies (Myoxocephalus aenus)

lake/northern chub (Couesius plumbeus)

lake trout (Salvelinus namaycush) 

lake whitefish (Coregonus clupeaformis)

largemouth bass (Micropterus salmoides) 

ninespine stickleback (Gasterosteus aculeatus) 

northern pike (Esox lucius) 

Pacific salmon (Oncorhynchus spp.) 

Pacific sand lance (Ammodytes hexapterus)

Pacific sardine (Sardinops sagax) 

peamouth (Mylocheilus caurinus)

pumpkinseed (Lepomis gibbosus)

rainbow smelt (Osmerus mordax) 

rainbow trout (Oncorhynchus mykiss) 

rock gunnel (Pholis gunnellus) 

rudd (Scardinius erythrophthalmus) 

ruffe (Gymnocephalus cernuus) 

sauger (Stizostedion canadense)

sea lamprey (Petromyzon marinus) 

shiner perch (Cymatogaster aggregata)

slimy sculpin (Cottus cognatus) 

smallmouth bass (Micropterus dolomieui) 

snake prickleback (Lumpenus sagitta)

starry flounder (Platichthys stellatus)

steelhead (Oncorhynchus mykiss) 

stickleback (Eucalia inconstans)

sunfishes (Lepomis spp.) 

threadfin shad (Dorosoma petenense)

walleye (Stizostedion vitreum) 

white perch (Morone americana) 

winter flounder (Pleuronectes americanus)
A - 3 

wrymouth (Cryptachanthodes maculatus) 

yellow perch (Perca flavescens)

INVERTEBRATES

crawfish (Procambarus clarkii)

sand shrimp (Crangon septemspinosa) 

quagga mussel (Dreissena bugensis) 

zebra mussel (Dreissena polymorpha)

PLANTS

beech (Fagus spp.) 

cottonwood (Populus spp.) 

cypress (Cupressus spp.) 

dogwood (Cornus spp.)

hackberry (Celtis occidentalis) 

hickory (Carya spp.) 

oak (Quercus spp.) 

willow (Salix spp.) 
A - 4 

Appendix 2. Distribution of DCCO Breeding Colonies in North America 1970 – 2000 (From Wires 

et al. 2001) 
A - 5 

Appendix 3: DCCO Foraging Behavior at Aquaculture Facilities 

DCCOs clearly respond in a positive way to the presence of shallow-water ponds stocked with high 

densities of easy-to-capture prey fish. For example, within two weeks of stocking two ponds in Florida 

with fingerling catfish, twelve DCCOs were feeding in the ponds and roosting on nearby poles. A nearby 

pond, stocked with 75,000 fish in August 1980, had attracted thirteen DCCOs by September. These birds 

continued to feed at the pond throughout the fall and winter, and in spring 1981 they nested in a nearby 

cypress dome. By November 1981, about fifty cormorants were feeding in the pond (Schramm et al. 

1984). The positive response of DCCOs to these ponds appears to be a contributing factor to the dramatic 

increase in the wintering population of cormorants in the fish producing regions of the southern U.S. 

(Reinhold and Sloan 1999; Glahn et al. 1999; Jackson and Jackson 1995). 

Daily Movements and Activity Budgets. In the Mississippi Delta, DCCOs fly an average of 16 kilometers 

(10 miles) from their night roosts to feeding sites. Each bird spends about 18 percent of daylight hours 

feeding; 88 percent of their foraging is done at catfish ponds and 12 percent near roost sites. The average 

cormorant forages for 60 minutes each day, but spends just 20 minutes underwater in actual pursuit of fish 

(King et al. 1995). 

Feeding Rates. Feeding rates may be dependent on the size and abundance of the available fish and the 

metabolic demands of the birds, and can be quite variable. Actively feeding DCCOs in commercial 

catfish ponds capture an average of about 5 fish/cormorant/hour (Stickley 1991; Stickley et al. 1992), but 

can vary from 0-28 (Stickley et al. 1992). Partly because of this variability, the rate of 5 

fish/cormorant/hour reported by Stickley et al. (1992) is highly skewed; the median was only 2 

fish/cormorant/hour, and the mean was equaled or exceeded at only 3 (21 percent) of the 14 ponds 

studied. Stickley et al. (1992) did not find a significant relationship between the mean number of DCCOs 

present and the number of catfish consumed, but ponds with 40 or more cormorants generally had a 

feeding rate of 1 or fewer fish/cormorant/hour. Similarly, DCCO feeding rates were not related to the 

density of fingerling catfish, density of all catfish (all size classes combined), or mean length of fish. 

Diet Composition. DCCOs eat a wide variety of fish, and thus there is a great deal of variation in prey 

composition, both geographically and seasonally. Nearly all of the published information on diet 

composition at aquaculture facilities has been gathered in the vicinity of catfish farms in the southeastern 

United States (Bivings et al. 1989; Conniff 1991; Glahn and Stickley 1992; Glahn et al. 1995; Glahn et al. 

1999b; and Glahn and Brugger 1995). These studies show that, among birds taken at winter roosting 

sites, the average proportion of catfish in the winter diet (by number) is most commonly in the range of 

50-55 percent. The proportion varies seasonally from less than 30 percent in October and November to 

more than 80 percent in February, March, and April. 

Prey Size. Although DCCOs are capable of taking catfish up to 42 centimeters (16 inches) in length 

(Campo et al. 1993), studies repeatedly have shown that the vast majority of catfish caught by cormorants 

at commercial facilities are in the range of 7-20 centimeters (3-8 inches), with most averaging about 10-

15 centimeters (4-6 inches) (Schramm et al. 1984; Stickley 1991; Stickley et al. 1992). This range of prey 

sizes is remarkably close to that of prey taken by cormorants in natural freshwater habitats. In such 

studies (Durham 1955; Glahn et al. 1998; Hirsch 1986; Hobson et al. 1989; Campo et al. 1993), prey size 

ranged from 6-21 centimeters (2-8 inches), with a median value of about 12 centimeters (5 inches). 

Prey Preferences. Lacking a precise knowledge of the species composition and size distribution of the 

prey population, it is impossible to make definitive statements about prey preferences. However a few 

tendencies are apparent. For example, the 10-15 centimeter (4-6 inch) fingerling catfish preferred by 

cormorants in one study represented about 64 percent of the catfish (by number) in the ponds (from 

Stickley et al. 1992), suggesting that the birds were merely preying on the most readily available fish. In 
A - 6 

this same study, 1 of the 14 ponds contained gizzard shad in addition to catfish. Nineteen shad were 

consumed for every catfish eaten, even though the pond contained about 5,100 fingerling catfish/hectare. 

The apparent preference for gizzard shad in this instance may be related to their being more easily caught, 

handled, and swallowed by cormorants (the mean handling time for catfish was 6-7 times greater than that 

of gizzard shad). 

Daily Food Consumption Rates. Estimates of daily food consumption rates of DCCOs at or in the 

vicinity of aquaculture facilities in the southeastern United States vary widely, from 208-504 grams (7-17 

ounces, or 0.4-1.1 pounds) (Schramm et al. 1984; Schramm et al. 1987; Bivings et al. 1989; Conniff 

1991; Brugger 1993; Glahn and Brugger 1995). Two separate captive cormorant trials were completed by 

Glahn et al (In Review) in Mississippi, one with out buffer prey and one with buffer prey (golden shiners) 

to help simulate diet composition of DCCOs in the field. In the non-buffered trial cormorants consumed 

between 10.2 and 10.5 catfish /bird/day or 516 and 608 grams/fish/day, which supports the daily food 

demand of 500 grams/fish/bird/day as predicted by the bioenergetics model of Glahn and Brugger (1995). 

In the buffer prey trial cormorants consumed approximately 7 catfish/bird/day closely simulating their 

expected diet composition in the field (Glahn et al. In Review).
A - 7 

Appendix 4: Management Techniques

Wildlife damage control activities generally fall into one of three broad categories: 1) resource 

management, 2) physical exclusion, and 3) wildlife management (USDA-APHIS 1997b). 

1. Resource Management

Cultural methods may include facility location, facility design, and fish management (Gorenzel et al. 

1994) and are carried out by land owners/managers. The physical location, design, and construction of an 

aquaculture facility influence the susceptibility of fish to bird predation, while facility design influences 

success in protecting fish stocks from predation. Fish management may include locating the most 

susceptible fish species and size close to the center of human activity and near buildings that might be 

incorporated in a bird exclusion system, and altering fish stocking dates so that vulnerable fish are not 

stocked when substantial bird numbers are present (Mott and Boyd 1995). 

Environmental/habitat modification can be an integral part of wildlife damage management. Since the 

presence of wildlife is directly related to the type, quality, and quantity of suitable habitat, habitat itself 

can be managed to reduce or eliminate the production or attraction of certain bird species. In most cases, 

the land owner/manager is responsible for implementing habitat modifications. Habitat management is 

most often a primary component of wildlife damage management strategies at or near airports (i.e., to 

reduce bird aircraft strike problems by eliminating bird nesting, roosting, loafing, or feeding sites). 

Generally, many bird problems on airport properties can be minimized through management of vegetation 

and water from areas adjacent to aircraft runways (Godin 1994). 

Nest/tree removal is the removal of nesting materials during the construction phase of the nesting cycle or 

the removal of trees used for nesting/roosting. Nests can be removed or destroyed manually or by use of 

high pressure water to dislodge nests from trees (Chipman et al. In press). Nest/tree removal has been 

used to manage DCCOs locally (to eradicate colonies) and regionally (to reduce populations). The 

technique has been used on both ground and tree nests. Nest destruction on the ground simply involves 

the physical breakup of nest structures. Tree nests present a greater challenge. Entire trees have been 

removed, both in private (Anderson and Hamerstrom 1967) and official control efforts (USFWS 1999a, 

b). 

Nest removal, even when successful at preventing colonization attempts, cannot be considered permanent; 

control must be repeated each time cormorants attempt to nest in areas of concern. It may also eliminate 

nest substrates for other species. Where DCCOs have already made trees unsuitable for nesting by other 

species, this may not be an issue; however, removing nest trees may shift DCCO nesting and move them 

into conflict with other species (Wires et al. 2001). Additionally, because DCCOs frequently nest on the 

ground, tree removal may only be effective where the substrate is inappropriate for nesting or the threat of 

mammalian predation is high (Wires et al. 2001). 

2. Physical Exclusion

Birdproof barriers can be effective but are often cost-prohibitive, particularly because of the aerial 

mobility of birds which requires overhead barriers as well as peripheral fencing or netting. Exclusion 

adequate to stop bird movements can also restrict movements of people, including fish maintenance and 

harvesting operations, and are susceptible to ice and wind damage (Littauer et al. 1997). Barrier systems 

using wire, line, and string in parallel and grid patterns and polyethylene rope with foam floats have been 

used for deterring DCCOs (Mott et al.1995; Littauer et al. 1997). The concept is meant to take advantage 

of the relatively long take-off distance (approximately 30 feet) that DCCOs generally require. Parallel 

wires should be positioned perpendicular to the prevailing wind as cormorants generally take off and land 

into the wind. Colored streamers have been used to increase visibility of the wires and strings. However, 
A - 8 

cormorants have been known to adapt readily to parallel wires so grid patterns are inherently more 

effective (Littauer et al. 1997). 

3. Wildlife Management

A. Non-lethal techniques 

Harassment or animal behavior modification. This refers to tactics that alter the behavior of wildlife to 

reduce damage. Animal behavior modification may involve use of scare tactics to deter or repel animals 

that cause loss or damage (Gorenzel et al.1994; Littauer 1990; Reinhold and Sloan 1999). Numerous 

techniques and devices can be used to frighten DCCOs. Wires et al. 2001 reviewed these non-lethal 

techniques by dividing them into three categories: 1) direct human harassment, in which humans attempt 

to frighten, but not kill, cormorants, 2) simulated human harassment, in which static or animated devices 

frighten cormorants by simulating human threats, and 3) other harassment, in which the negative stimulus 

is not necessarily connected to human activity. Some but not all methods that are included in this category 

are: 

• Electronic guards 

• Propane exploders 

• Pyrotechnics 

• Distress calls and sound producing devices 

• Repellents 

• Scare crows 

• Mylar tape 

• Eye spot balloons 

• Vehicle horn and chase 

• Live ammunition 

These techniques are generally only practical for small areas. Scaring devices such as distress calls, 

helium-filled eye spot balloons, scare crows, effigies and silhouettes, mirrors, and moving disks can be 

effective but usually for only a short time before birds become accustomed and learn to ignore them 

(Mason and Clark 1997; Mastrangelo et al. 1997, Stickley, et al. 1995; Stickley and King 1995; Mott et 

al. 1995; Reinhold and Sloan 1999). Littauer et al. (1997) noted that a scaring program must be 

consistent and aggressive to be successful. Timing is also critical (Mott and Boyd 1995) and therefore 

harassment must begin as soon as it can be economically justified and continued until all undesirable 

birds vacate the area (Reinhold and Sloan 1999). 

Human harassment. As discussed in Wires et al. (2001), the most common form of direct human 

harassment is ground patrol with pyrotechnics. Patrols may occur on foot or in vehicles and may utilize a 

variety of pyrotechnics to frighten DCCOs (and, of course, other birds). Pyrotechnics include various 

shellcrackers, screamers, whistling projectiles, exploding projectiles, bird bangers, flash/detonation 

cartridges and live ammunition (Lagler 1939; Moerbeek et al. 1987; Hanebrink and Byrd 1989; Stickley 

and Andrews 1989; Littauer 1990; Brugger 1995; Mott and Boyd 1995; Pitt and Conover 1996; Spencer 

1996; Littauer et al. 1997; Reinhold and Sloan 1999). Live ammunition is often used because it is cheaper 

and more readily available than pyrotechnics (Littauer 1990; Mott and Boyd 1995; Littauer et al. 1997). 

Cormorants are often frightened from aquaculture ponds simply because of the presence of humans 

(Hanebrink and Byrd 1989; Spencer 1996; and Reinhold and Sloan 1999). Hodges (1989) concluded, for 

example, that the presence of humans at aquaculture facilities during critical periods may be the most 

effective means of keeping DCCOs off ponds. 

Simulated Human Harassment. To reduce labor costs for harassment patrols, various devices, both static 

and animated, have been developed to simulate the threat of human activity near areas of concern, usually 
A - 9 

aquaculture ponds. These devices range from simple wood cutout scarecrows to elaborate contraptions 

that create startling movements, emit numerous noises, and flash lights (Wires et al. 2001). 

Human effigies/scarecrows have long been used against avian predators at many different types of 

agriculture fields, despite their general lack of success at preventing depredations (Lagler 1939; Inglis 

1980). Increasing both realism and level of animation in scarecrows may improve their ability to scare 

birds, and combining scarecrows with automated sound devices may enhance the frightening effect 

(Littauer 1990; Littauer et al. 1997). Stickley et al. (1995) and Stickley and King (1995) tested an 

inflatable effigy called Scarey Man® on catfish farms in Mississippi, as described in Wires et al. (2001). 

For relatively short lengths of time (10-19 days), the device significantly reduced the number of DCCOs 

on the ponds (71-99 percent reduction in number of DCCOs flushed from ponds during ground patrols). 

Compared to replacement cost of catfish consumed (based on mean DCCO consumption rate in Stickley 

et al. 1992), Scarey Man® devices were considered to be economically efficient (Stickley et al. 1995). 

However, evidence of habituation was reported, especially when day roosts were in view of the Scarey 

Man® devices. Stickley and King (1995) suggested that the device be used where DCCO depredations 

are “serious.” 

Another animated scarecrow was described by Conniff (1991). This device was described as a jack-inthe-box scarecrow with inflatable plastic arms, revolving strobe lights, and amplified sounds (130 dB) of 

horns honking, people shouting, shotguns firing, and birds screaming. The device was declared 

“ineffectual,” indicating that “a cormorant can get used to almost anything.” 

Other harassment. As described in Wires et al. (2001), other means to startle birds into flight have been 

developed, and many have been used against DCCOs. These include amplified DCCO distress calls; 

sirens and other electronically generated noises; tin plates, mylar balloons, reflecting tape and other 

reflectors; and eyespot balloons and raptor silhouettes (Lagler 1939; Barlow and Bock 1984; Moerbeek et 

al. 1987; Parkhurst et al. 1987; Stickley and Andrews 1989; Littauer 1990; Brugger 1995; Mott and Boyd 

1995; Price and Nickum 1995; Spencer 1996; Littauer et al. 1997; Reinhold and Sloan 1999.) 

Auditory scaring devices such as propane exploders, pyrotechnics, electronic guards, and audio 

distress/predator vocalizations are effective in many situations for dispersing damage-causing bird 

species. However, birds often habituate to such devices, rendering them ineffective. Using a 

combination of harassment devices prolongs habituation and provides the greatest amount of protection. 

Frequently changing and moving devices further enhances protection (Gorenzel et al. 1994; Reinhold and 

Sloan 1999). 

Visual scaring techniques such as use of mylar tape (highly reflective surface produces flashes of light 

that startles birds), eye-spot balloons (the large eyes supposedly give birds a visual cue that a large 

predator is present), and flags, sometimes are effective in reducing bird damage (Gorenzel et al. 1994; 

Littauer et al. 1997; Stickley et al. 1995; Stickley and King 1995). 

Reviewers have generally found distress calls ineffective against DCCOs for long periods of time (Wires 

et al. 2001). Hanebrink and Byrd (1989) mention that, while APHIS-WS recommended using amplified 

distress calls, the calls merely moved birds to different ponds. Littauer (1990a) listed distress calls among 

other electronically generated noises whose effectiveness was “uncertain,” but did note observations of 

DCCOs apparently being attracted to distress calls. Effectiveness of audio and visual scare tactics 

(specifically distress calls, electronically generated noises, tin plates, mylar ribbon, flash tape, flagging, 

helium balloons, inflatable eyespot balloons and hawk silhouette kites) have generally been found to be 

low when deployed by themselves or over long periods of time (Littauer 1990; Spencer 1996; Reinhold 

and Sloan 1999). 
A - 10 

Various noisemakers to scare DCCOs have been developed, including the rope firecracker, which sets off 

explosions as the rope burns (Littauer 1990) and propane/butane/acetylene cannons, some of which can 

be programmed to go off at varying intervals and variable numbers of times. The effectiveness of cannons 

is itself variable (Wires et al. 2001). Stickley and Andrews (1989) reported that 40 percent of respondents 

used propane cannons. Of these, 60 percent found them to be either somewhat or very effective against 

DCCOs. Brugger (1995) reported initial success with cannons, but with relatively quick habituation. 

Conniff (1991) reported that butane cannons eventually became perches for DCCOs. Individuals using 

propane cannons in Oklahoma and Georgia reported them to be ineffective (Spencer 1996; Simmonds et 

al. 1995a) and Moerbeek et al. (1987) found gas cannons generally ineffective against Great Cormorants 

in the Netherlands. 

Given the general lack of success with harassment techniques used separately (largely due to habituation), 

many investigators have concluded that, to be effective, 1) a variety of techniques must be used, 2) 

techniques should be applied vigorously, 3) location of static and automatic devices should be changed 

frequently, and 4) the combination of techniques should be altered frequently (Moerbeek et al. 1987; 

Littauer 1990; Mott and Boyd 1995; Mott and Brunson 1997; Reinhold and Sloan 1999). The 

recommendation by Littauer (1990a) that use of gas cannons be stopped once habituation begins to occur 

(to prevent a decrease in their utility at a later date) could probably be applied to all forms of non-lethal 

harassment (Wires et al. 2001). 

Non-lethal Dispersal at Night Roosts. Night roost dispersal is used to harass DCCOs from their roosting 

sites in an effort to re-locate birds away from a particular area or region (Mott et al. 1998; Reinhold and 

Sloan 1999). The goal of this approach is to keep DCCOs from roosting in the area at night and 

subsequently to decrease the number of depredating birds within the harassment area during the day. Most 

discussion of this technique has focused on the Mississippi Delta region where it has been practiced since 

1992 (Mott et al. 1998). This type of dispersal program is labor intensive and requires a great deal of 

organization and coordination to be effective (Reinhold and Sloan 1999; Tobin 1998). Electronic noise 

generators, amplified recordings, propane exploders, pyrotechnics, and firecrackers can be used to 

disperse birds. Laser guns can also be used to startle DCCOs in low-light conditions (Wires et al. 2001, 

Hatch and Weseloh 1999). McKay (1999) reported that laser guns have been used effectively against 

Great Cormorants in England, Wales, France, and Italy. This technique effectively reduced numbers of 

birds at night roosts as well as numbers feeding in nearby ponds in England and Wales. However, its 

widespread use is currently cost prohibitive. 

Discussions of the effectiveness of the Mississippi Delta program are limited, but tend to suggest that the 

program may be numerically and economically effective (Wires et al. 2001). Surveys within harassment 

areas during the winter of 1993-94 counted 70 percent fewer birds than the previous winter (1992-93) 

when there was no harassment; surveys from 1994-95 showed a 71 percent decrease from number of birds 

detected in 1992-93 (Mott et al. 1998). Survey data from aquaculturists in 1994 revealed that 62 percent 

within the harassment zone reported fewer problems with DCCOs than in previous years, whereas 38 

percent outside the zone had the same sentiments; data from 1995 revealed little change, with 74 percent 

of aquaculturists within the harassment zone reporting fewer problems and 38 percent outside reporting 

the same (Mott et al. 1998). These perceptions are reflected in the amount of money spent on harassment 

at individual aquaculture facilities: within the harassment zone, aquaculturists reported an average $1,406 

decrease in expenses for harassment at their facilities in 1994, and $3,217 in 1995. Cost of the program 

was $16,757 in 1994 and $32,302 in 1995. If these costs were divided equally among participating 

aquaculturists, each would have paid $419 in 1994 and $557 in 1995. Based on a comparison between 

cost of the night roost harassment program and reductions in harassment expenditures at individual 

aquaculture facilities, the control program was considered economically effective. However, Reinhold 

and Sloan (1999) point out that “ever-increasing numbers” of night roosts can limit the success of 

dispersal programs. 
A - 11 

Prevention of colony establishment. Another important means of limiting the damages caused by DCCOs 

is to prevent birds from establishing colonies in areas of concern. Bregnballe et al. (1997) predicted that 

potential breeders prevented from founding a new colony could be expected to either delay breeding to a 

later year or to join existing colonies. This would likely have two effects: (1) the population would 

stabilize sooner and (2) the population would stabilize at a lower absolute population size because the 

resources available at breeding would be reduced. Without persistent, frequent attempts to harass birds 

away from potential breeding sites, however, or if individuals attempt to nest at sites that have been 

previously used for roosting, it is likely that they would be less willing to abandon nesting attempts. 

Bregnballe et al. (1997) suggested that it might therefore be necessary to shoot some of these individuals 

to prevent colonization. 

B. Lethal techniques 

Egg and nestling destruction. DCCO eggs and nestlings have been destroyed in attempts to reduce 

recruitment into populations and to eliminate colonies at specific locations (in conjunction with other 

forms of harassment). Bregnballe et al. (1997) predicted that the effect of increased egg mortality on 

autumn population size would be buffered by increased density-dependent chick survival. However, if 

repeated egg oiling efforts led to near total clutch failure at ground-nesting colonies, the population would 

be expected to stabilize at lower sizes and the proportion of the foraging area being exploited during 

breeding would decline. Van Dam and Asbirk (1997) predicted no risk to cormorant populations from 

reducing reproductive output if it was carried out “under control.” 

In general, egg and nestling destruction may not be effective at completely eliminating reproduction for 

individual DCCOs during a nesting season because of their tendency to renest after disturbance. As 

reported in Wires et al. (2001), in some instances (Lake Winnipegosis, Manitoba; Lake of the Woods, 

Minnesota and Ontario; St. Lawrence River Estuary, Quebec) local DCCO populations continued to rise 

despite egg and nestling destruction efforts (Hobson et al. 1989; Baillie 1939, 1947; DesGranges and 

Reed 1981). In contrast, some investigators have suggested that egg and nestling destruction on a large 

scale (often in conjunction with killing adults) may have slowed the growth of populations (Weseloh and 

Collier 1995), stabilized populations, or contributed to declines (Ewins and Weseloh 1994; Sheppard 

1994/5; USFWS 1999b). McLeod and Bondar (1954) concluded that consistent destruction of eggs and 

young appeared to reduce the breeding population fairly effectively on Lake Winnipegosis in the 1940s 

and 1950s. The key factor is most likely whether density-dependent mechanisms are sufficiently 

overcome by the specific management actions. 

Effectiveness at causing colony abandonment appears to vary; newly established colonies appear to be 

more easily eliminated than well established ones (Wires et al. 2001). Most recently, egg and nestling 

destruction, in conjunction with nest destruction and sometimes harassment, has been found to be 

effective at preventing renesting for a year or more at newly established colonies (USFWS 1999a, b). 

Egg oiling has essentially the same result as that of killing eggs and nestlings, but with the added benefit 

that DCCOs are less likely to abandon nests and lay replacement clutches, making the technique more 

effective as an annual treatment (Wires et al. 2001). Bédard et al. (1995) report, “None of the eggs in 427 

experimentally treated nests hatched in 1987 and nearly half were still tended by adults 49 to 59 days after 

laying (the remainder having been abandoned and scavenged).” Shonk (1998) reports, “Of the eggs 

treated with oil, 49 percent were incubated past the expected hatching date. The remainder of the eggs 

were lost during the incubation.” Human disturbance during oiling increases predation by gulls (Shonk 

1998), which may cause some DCCOs to renest. 

Egg oiling is a method of suppressing reproduction of nuisance birds by spraying a small quantity of food 

grade vegetable oil or mineral oil on eggs in nests. The oil prevents exchange of gases and causes 
A - 12 

asphyxiation of developing embryos. The method has an advantage over nest or egg destruction in that 

the incubating birds generally continue incubation and do not renest. The EPA has ruled that use of corn 

oil for this purpose is exempt from registration requirements under the Federal Insecticide, Fungicide, and 

Rodenticide Act. To be most effective, the oil should be applied anytime between the fifth day after the 

laying of the last egg in a nest and at least five days before anticipated hatching. This method is 

extremely target specific and is less labor intensive than egg addling. 

Effectiveness at killing embryos is high, with mortality rates approaching 100 percent when the 

oil/solution is applied correctly (Gross 1951; DesGranges and Reed 1981; Blokpoel and Hamilton 1989; 

Christens and Blokpoel 1991; Shonk 1998; Bédard et al. 1999). Although laboratory tests found oiling 

ineffective when applied only to part of an egg (Blokpoel and Hamilton 1989), field tests in which only 

the tops of eggs were sprayed were highly successful, indicating that careful application to the entire egg 

surface may not be necessary (Christens and Blokpoel 1991; Bédard et al. 1999). Egg-rolling activities by 

parents may assist in covering the entire surface (Christens and Blokpoel 1991). 

The effectiveness of egg oiling as a population control method can be quite variable. Because DCCO egg 

laying is not synchronous, only one spraying per summer may not treat enough of the eggs laid that 

nesting season to have a significant impact on the population, and multiple oiling efforts to overcome this 

problem may increase the cost of control beyond acceptable levels. Both problems were cited as reasons 

for the failure of egg oiling efforts in Maine by Dow (1953). If carried out with appropriate intensity, egg 

oiling can be a very effective means of reducing local populations, although the results are more slowly 

seen than with culling or a combination of the two techniques. Modeling of the St. Lawrence River 

Estuary, Québec, DCCO population suggested that egg oiling alone would not be sufficient to bring 

DCCO numbers to target levels within the desired time frame, leading to the selection of a combined 

strategy of egg oiling and shooting adults (Bédard et al. 1995). 

Killing adults. Shooting adults has been a commonly used technique for controlling DCCOs (Matteson 

1983; Hobson et al. 1989; Ewins and Weseloh 1994; Sheppard 1994/5; Carter et al. 1995b; Jackson and 

Jackson 1995; Ludwig and Summer 1995; Weseloh and Collier 1995; USFWS 1999b). Shooting DCCOs 

is believed to reinforce non-lethal harassment (EIFAC 1988, Hess 1994, Littauer 1990, Mastrangelo et al. 

1997, Rodgers 1988 and 1994, Tucker and Robinson 1990, USDA 1994 cited in Glahn et al. 2000b) and 

is highly selective for target species. Shooting is typically conducted with shotguns or rifles and can be 

relatively expensive because of the staff hours sometimes required (USDA 1994). 

The effectiveness of shooting to kill adults may be limited since DCCOs can be wary and difficult to 

shoot (Wires et al. 2001). In cases where large numbers of birds are present, it may be more effective as a 

dispersal technique than as a way to reduce bird densities. A study by Glahn (2000) indicated that 

shooting DCCOs in roosts was as effective as frightening them with pyrotechnics for dispersing them, 

and may not result in habituation. 

Wires et al. (2001) discussed that the killing of adult DCCOs may be a successful technique for 

controlling regional populations, but would likely require that large numbers be killed and that the 

geographic range of the program be sufficiently wide. Killing nesting DCCOs is most likely to be 

successful at reducing population levels when two conditions are met: (1) scale of control is large enough 

to overcome the effects of immigration and (2) the control effort is well coordinated, long-term, and 

sufficiently rigorous to overcome density-dependent compensation mechanisms. The success of a culling 

program is not only limited to the number of birds removed but also the age and sex of the individuals 

being removed (Bédard et al. 1999, Ludwig and Summer 1995, Wires et al. 2001). As a means of 

reducing population levels, it is believed that it is more effective to kill breeding birds than to destroy 

eggs, nestlings, or fledglings because first-year birds frequently have low survival rates and many would 

not have survived to breed anyway (Wires et al. 2001). 
A - 13 

Shooting adults at colonies may have impacts beyond killing individual breeders because of harassment 

effects on survivors. Cairns et al. (1998) observed that the abandonment of a large DCCO colony in 

waters of Prince Edward Island, Canada, seemed to have been caused by shooting and harassment at the 

colony that had taken place when cormorants first returned to the area in the spring. The birds from the 

abandoned Ram Island colony apparently shifted to nearby Little Courtin Island. However, since DCCOs 

usually exhibit strong philopatry and site-fidelity, the displacement was judged to be highly “anomalous.” 

Ewins and Weseloh (1994) reported that the shooting of > 50 adults on Pigeon Island, Lake Ontario, in 

1993 (when the colony had 818 pairs) reduced reproductive output for that year: fledging rates were 0.3 

vs. 1.6 young/nest on a nearby island that was not subject to shooting. Long-term impacts on the colony 

were not reported (Wires et al. 2001). 

Limited data are available on the effectiveness of killing adults on controlling local populations/colonies 

(Wires et al. 2001). Matteson (1983) noted that shooting DCCOs at pound nets by fishermen did not 

prevent the nearby Mink Island, Lake Ontario population from increasing from 40 nests in 1945 to 50 

nests in 1956. Ludwig and Summer (1995) analyzed leg band recovery data for DCCO colonies in the Les 

Cheneaux region of Lake Huron and concluded that, based on the level of immigration into this region, 

lethal control of adults would have to be Great Lakes-wide to be effective at controlling local populations 

(see also Korfanty et al. 1999). 

The St. Lawrence River Estuary, Québec, control program provides an example of a control effort 

intensive and expansive enough to reverse DCCO population growth. The goal of a 5-year control 

program on the St. Lawrence River Estuary, Québec, was to reduce the cormorant population to 10,000 

pairs. Culling was halted after only four years, however, due to quicker than anticipated results believed 

to be caused by the fact that adult male DCCOs were more vulnerable to shooting than adult females (at a 

ratio of 2:1 males to females). Another goal of this program was to discourage tree nesting. In 1989, the 

year the culling program began, 43 percent of all nests were in trees; five years later, in 1993, only 27 

percent of nests were arboreal (Bédard et al. 1999). 

Effectiveness of killing adults relative to other forms of population control are unknown, although it is 

believed that, individual for individual, killing adults that have survived to breed is more effective at 

reducing populations than destroying eggs, nestlings or fledglings. Ludwig and Summer (1995:40) 

estimated that, “From the whole population perspective, killing a young adult just before first nesting will 

have a 3 to 6 fold greater effect on population control than killing fledglings, chicks or eggs.” 

Without adequate knowledge of intercolony migration rates it is difficult to predict the minimum scale of 

control necessary to overcome effects of immigration (Wires et al. 2001). For lethal control to effectively 

reduce predation levels, the mortality rate must be higher than the immigration rate. This level of lethal 

control may be difficult to achieve without extensive control efforts. In Bavaria, Germany, the number of 

Great Cormorants reported shot during the winters of 1995-96 to 1998-99 was approximated at 50 to 100 

percent of the average Bavarian winter cormorant population. Despite this high level of mortality, mean 

winter numbers of cormorants did not substantially decrease. Shooting did not remove birds from water 

bodies that were supposed to be protected, but simply killed migrant birds which were rapidly replaced by 

newly arriving individuals. Because mean winter cormorant numbers did not decrease substantially, 

shooting was considered an inappropriate management tool for reducing overall fish depredation in 

Bavaria (Keller et al. 1998; Keller 1999). 

 
A - 14 

Appendix 5. Methodology for estimating take under the aquaculture depredation order

To estimate take under the aquaculture depredation order we sent out a survey in 2001 to all of the 

aquaculture producers in the 13 relevant States (using data from our SPITS database). This survey led to 

an estimated take per producer of 190 DCCOs per year for the year 2000 (however, since the DEIS was 

written more data came in and the mean take per producer decreased to 159, but we decided to err on the 

“liberal” side and stay with 190). This number is consistent with Glahn et al.’s (2000) finding that 62 

producers in Mississippi killed an average of 154 DCCOs per producer. 

For 1998, to estimate take we multiplied 121 (the estimated number of producers in all depredation order 

States except Arkansas and Minnesota which were excluded because we have reported take data for these 

States and thus didn’t need to estimate) by 154 to come up with an estimate of 18,634 DCCOs killed. We 

multiplied by Glahn et al.’s estimate instead of our estimate of 190 because the latter was an estimate for 

the year 2000. To this estimate we then added the reported take for Arkansas and Minnesota. 

For 1999, we used the same technique except that we had to estimate take for Arkansas this year. So we 

multiplied 154 by 237 (the number of producers excluding those in Minnesota) and came up with an 

estimate of 38,098. To this estimate we then added the reported take for Minnesota. 

For 2000, we multiplied 121 (again, all aquaculture producers except those in Minnesota and Arkansas) 

by 190 (average take per producer based on our survey). This comes to 22,990 to which we added the 

reported take for Arkansas and Minnesota. 

Average annual take under the aquaculture depredation order for the 3-year period equals 35,874. 

Dividing this by 13 gives an average take per State of 2,760 DCCOs per year.
A - 15 

Appendix 6: Discussion of Fishery Impacts

Derby and Lovvorn (1997) stated that to evaluate the effects of bird predation on fish populations, “it is 

best to compare estimated amounts of fish consumed with total populations or production of fish.” 

Furthermore, Cairns (1992b) noted that “the impact of bird predation depends crucially on avian prey size 

selection and the growth and mortality schedules of the fish populations.” Thus, information needs 

include a thorough knowledge of: the diet of DCCOs, either through diet studies and/or bioenergetics 

models that indicate food requirements, and the demographics of the fish population, including mortality 

factors and survival estimates for all segments of the life cycle. However, most research on DCCOfisheries interactions has examined diet alone, often without any estimates of fish population data. Such 

food habit studies, while descriptive of the proportion of a fish species in DCCO diet (e.g., by weight or 

by number), cannot quantify the impacts of DCCO predation on fish populations. As Hatch and Weseloh 

(1999) stated, “cormorant predation and its impacts are not revealed by mere lists of prey or simple 

percentages.” The following sections discuss DCCO-fishery interactions at specific locations where 

DCCOs have been suspected of impacting fish populations. 

Oneida Lake, New York 

Oneida Lake is the largest lake located entirely in New York State and is well-known for its recreational 

fishing. Seventy-four fish species have been identified in Oneida Lake, which is managed intensively to 

optimize recreational fishing opportunities for walleye (Mills et al. 1998). In fact, it has been referred to 

as the “Walleye Lake of New York State” and provides anglers more fish per acre than any other lake in 

the Northeast (Cornell Cooperative Extension of Onondaga County 2000). 

However, the lake’s adult walleye population has decreased during the 1990s from a long term average of 

675,000 (1958-1990) to 215,000 in 1999 (VanDeValk et al. 1999). Walleye recruitment and projected 

stock abundance in Oneida Lake has been estimated by a stock-recruitment relationship model since 

1978. Since 1999, the model has overestimated the actual abundance of adult fish, indicating increased 

mortality of walleye age-1 to 4. For example, this model predicted that 112,000 walleye from the class of 

1995 would reach adult size, but only 32,000 actually did (VanDeValk et al. 1999). In addition to 

increased mortality from age-1 to age 3, walleye mortality has increased during their first year of life 

(from larvae to first fall). This increase in early mortality is likely due to predation by juvenile and adult 

fish in the lake. Predation on young walleye has likely increased because the number of larval perch has 

declined (VanDeValk et al. 1999, Mills et al. 1998). Small yellow perch buffer predation on walleye 

when they are abundant (Forney 1980). Both increased mortality during the first year and increased 

mortality between age-1 and 4 have contributed to the declining walleye population in the lake. 

Yellow perch are a very important panfish in Oneida Lake. They are sought by anglers throughout the 

year, and are the main prey of walleye. The dynamics of perch and walleye populations in Oneida Lake 

are coupled tightly. In the absence of any other dominant forage fish, walleye productivity requires the 

availability of young perch as prey. For example, walleye consumed 58 percent of the estimated 

population of age-0 yellow perch and 47 percent of the age-1 yellow perch in the Lake in 1996 

(VanDeValk et al. 1999). Similar to walleye, the contribution of yellow perch year classes to the adult 

stock at age-3 has been predicted by a stock-recruitment relationship model. However, as with walleye, 

recent forecasts of recruitment have over-estimated year class contributions. These differences between 

predicted and observed estimates of age-3 and older yellow perch are probably a result of increased 

predation between age-1 and 3 (VanDeValk et al. 1999). 

DCCO Status and Diet. Oneida Lake’s cormorant population increased from one nesting pair in 1984, to 

332 nesting pairs in 1998, 339 in 1999, 365 in 2000, and 260 in 2001. Census data of DCCOs 

frequenting the lake during April-May of 1998-99 indicates the population can range between 550 and 

800 birds (J. Coleman and M. Richmond, Cornell University, pers. comm.). However, there has 
A - 16 

historically been a large influx of seasonal migrant birds that stop to feed and roost on the lake. For 

example, there may be as many as 3,000 cormorants on the lake in October (Adams 1999). 

The diet of Oneida Lake’s DCCOs varies from year to year, and seasonally, reflecting the absolute 

abundance of prey species (Adams 1999). Cormorants are known to feed on at least 25 of the 74 fish 

species known to occur in Oneida Lake; they typically feed on up to eight different fish species daily. As 

cormorant populations have increased during the last ten years, walleye and yellow perch have been the 

most abundant fish species consumed, with the heaviest feeding on adult walleye taking place in the fall 

during the influx of birds. In fact, the estimated number of yellow perch and walleye consumed by 

DCCOs is comparable to the number of fish “missing” from model predictions (i.e., the difference 

between the number predicted from the abundance of age-1 fish and the number of age-3 or 4 fish 

observed later in the lake) (VanDeValk et al. 1999). Cormorants are the main predator on these fish sizes. 

Adams (Cornell Univ., unpubl. data) found that in the spring of 1996, DCCOs were estimated to have 

consumed 1,123,800 yellow perch (12.7 percent of the population estimate) and 100,600 walleye (14.4 

percent of the population estimate). 

In 1997, DCCOs were estimated to have consumed about 15 percent of age-3 and older yellow perch and 

7 percent of age-4 and older walleye in 1997. These exploitation rates of adult fish are comparable to the 

angler exploitation rate. It has been calculated that exploitation rates of cormorants were between 12 and 

20 percent of age-1, 2, and 3 walleye (VanDeValk et al. 1999). VanDeValk et al. (2002) found that the 

number of walleye consumed by DCCOs was similar to the number taken by anglers; however, only 

DCCOs consumed subadult walleye (age-3 or younger), and only anglers harvested adults (age-4 or 

older). DCCOs and anglers combined took 7 percent of age 1-3 walleyes and 14 percent of the adult 

walleye population. DCCO consumption of adult yellow perch was similar to angler harvest, but DCCOs 

consumed nearly 10 times as many age-2 yellow perch and only DCCOs harvested age-1 yellow perch. 

DCCOs and anglers together harvested 40 percent of age-1 and age-2 yellow perch and 25 percent of the 

adult yellow perch population. The authors concluded that DCCO predation on adult percids has little 

effect on angler harvest, but consumption of subadults will reduce future angler harvest of yellow perch 

and, to a lesser degree, walleye (VanDeValk et al. 2002). 

Other Factors. Oneida Lake is undergoing biological changes in response to several factors, including 

reduced nutrient loading and exotic species. Zebra mussels have clarified the water to record depths, 

stimulating the growth and distribution of submerged aquatic plants (Mayer et al. 2000). In response, 

walleye populations have redistributed away from shallow reefs, toward the darker water of weed beds 

and deeper locations in the lake. Increased water clarity may be contributing to increased mortality of 

age-0 walleye (a trend revealed since 1992 by index trawl data) by making them more susceptible to 

predation or cannibalism (Mills et al. 1998). Despite zebra mussel infestation, the lake’s zooplankton 

population has not declined, and remains capable of supporting historic populations of yellow perch and 

walleye (Mills et al. 1998). 

Eastern Lake Ontario, New York

Lake Ontario supports a productive sport fishery, albeit one that is changing rapidly (USFWS 1995). Due 

to its shallow and complex morphometry, much of the eastern basin of Lake Ontario supports a 

warmwater fish community (Stone et al. 1954 and Hurley 1986 in Burnett et al. 2002). Salmonids are the 

most popular sport fish in Lake Ontario as a whole but, in the eastern basin, some 48 percent of anglers 

surveyed were fishing specifically for smallmouth bass (McCullough and Einhouse 1999). In fact, 

smallmouth bass remain the most abundant and widespread sport fish in the eastern basin, attracting over 

35,000 directed angler trips in 1998 (NYSDEC 2000). Numerous citizens and the New York State 

Department of Environmental Conservation (NYSDEC) have expressed concern about the impact of 

growing DCCO populations in the eastern basin on the smallmouth bass fishery there. 
A - 17 

The smallmouth bass is a native of the Great Lakes-St. Lawrence River drainage and a key predator 

within the eastern basin of Lake Ontario’s fish community. Their populations in Lake Ontario have 

remained relatively stable over the years (USFWS 1995), but dramatic declines have been documented 

(e.g., through gillnet surveys) in the eastern basin since the early 1990s. For example, the mean catch per 

unit effort (CPUE) from 1995-1997 was over 50 percent lower than that for 1984-1986 (Chrisman and 

Eckert 1999). 

DCCO Status and Diet. DCCOs were first observed nesting on Lake Ontario in 1938. Through the 1960s 

and early 1970s, DCCOs were absent from Lake Ontario but in 1974 they established a colony of 22 pairs 

on Little Galloo Island. In 1999, the number of cormorant nests on Little Galloo Island was 5,681 

(NYSDEC 2000). The Little Galloo Island colony and two other colonies, on Pigeon and Snake Islands, 

represent the three largest DCCO colonies in eastern Lake Ontario (Johnson et al. 2000b). 

Past diet studies indicated that recreationally important species such as salmonids and smallmouth bass 

typically do not make up a large proportion of DCCO diet in eastern Lake Ontario. In the early 1990s, the 

predatory effect of DCCOs was addressed in a report by a special task group of the Lake Ontario 

Committee. Bioenergetic simulations estimated that DCCOs accounted for 2-3 percent of the total annual 

predation of pelagic prey fish and did not appear to be a major contributor to lakewide predation effects at 

that time (USFWS 1995). It should be noted that DCCO populations have increased considerably since 

the early 1990s and, furthermore, the effects of DCCO predation in a large lake such as Lake Ontario are 

more likely to be localized than lakewide, thus warranting examination of potential site-specific 

population impacts. 

A study of cormorant food habits in 1992 revealed that only about 3 out of every 1,000 fish eaten by 

cormorants in the eastern basin was a trout or salmonid. The failure to find coded wire tags (which were 

used to mark released lake trout) in any of the cormorant food samples suggested that cormorants had 

little if any impact on the lake trout stocking program in Lake Ontario. Alewife was found to be the most 

abundant prey species taken, followed by yellow perch and centrarchids (Karwowski 1992). Ross and 

Johnson (1994) found 32 coded wire tags in 176 pellets collected the day after a stocking event in 1993 at 

Stony Point, New York. Ross and Johnson (1995) estimated that 7.6 percent of a 1993 lake trout stocking 

and 8.8 percent of a 1994 stocking were consumed by DCCOs. 

Ross and Johnson (1997) found that smallmouth bass represented 0.7 to 2.1 percent (by number) of 

eastern basin DCCO diet items, with an average estimated annual consumption of 650,000 fish. Johnson 

et al. (1999) used modeling to estimate that 1.3 million smallmouth bass were consumed by DCCOs in 

the eastern basin in 1998. In 1993, 1994, and 1998, it was estimated that smallmouth bass contributed an 

average of 7.2 percent by weight to the diet of Little Galloo Island cormorants. In 1999, Johnson et al. 

(2000a) estimated that smallmouth bass comprised 3.6 percent of the diet of Little Galloo Island 

cormorants, amounting to a consumption of approximately 126,000 lbs (~57,000 kg) of smallmouth bass 

(R. McCullough, NYSDEC, pers. comm.). Yellow perch (28 percent), alewife (27 percent), and cyprinids 

(18 percent) were the major prey items, by number, of cormorants from the Little Galloo Island colony 

(Johnson et al. 2000a). 

Johnson et al. (2000b) determined that yellow perch was the major prey of DCCOs from the Pigeon (38.4 

percent) and Snake (47.7 percent) Island colonies in eastern Lake Ontario, by number. Forage fish, 

including alewife, cyprinids, threespine stickleback, slimy sculpin, etc. made up 50 percent and 39 

percent, respectively, of Pigeon and Snake Island DCCO diets (by number) while smallmouth bass were 

estimated to have contributed, by weight, 5.1 percent (Pigeon) and 1.7 percent (Snake) of DCCO diet. 

Johnson et al. (2002) estimated that fish consumption by DCCOs at the Little Galloo Island colony 

averaged 32.8 million fish per year over the 9-year period from 1992 to 2000. The biomass of fish 
A - 18 

consumed averaged 1.4 million kg per year. Consumption of smallmouth bass averaged 85,300 kg per 

year, compared to an estimated 24,700 kg taken by sport anglers in 1998. The authors noted that 

“substantial temporal variation exists in the diet of [Little Galloo Island DCCOs].” They also pointed out 

that “fish standing stock information for eastern Lake Ontario is not available and, consequently, it is not 

possible to compare these estimates of cormorant fish consumption to stock size.” The authors, however, 

believe that there is sufficient evidence to suggest that DCCOs “may be taking male smallmouth bass off 

of nests, with implications for subsequent recruitment and year-class strength” (Johnson et al. 2002). 

Other Factors. Smallmouth bass populations in the eastern basin of Lake Ontario are dependent on a 

number of factors, including water temperature (cf. Hoyle et al. 1998), year class strength, time of 

spawning, food availability, competition, predation pressure, and fishing mortality. Many changes have 

occurred in the eastern basin of Lake Ontario in recent years that could affect these factors, including 

reduced lake productivity, the introduction of zebra mussels, increased water clarity, and increased 

abundance of two piscivorous species, both DCCOs and walleye. Food web alterations and subsequent 

shifts in nutrient cycling are important changes that may be caused by zebra mussels. However, little is 

known about the actual impacts of these changes on the population dynamics of smallmouth bass 

(Chrisman and Eckert 1999). While factors such as reduced productivity, dreissenid (zebra and quagga) 

mussel abundance and increased water clarity have impacted all of Lake Ontario, smallmouth bass 

populations are thriving outside of the eastern basin (Schneider et al. 1999) and “evidence exists...that 

indicates that these factors [are] not the primary force behind bass stock reductions” (Lantry et al. 2002). 

Les Cheneaux Islands, Lake Huron, Michigan 

Since the late 1970s, the yellow perch fishery in the Les Cheneaux Islands of northern Lake Huron, which 

was economically important to the area for many years, has experienced a marked decline (Lucchesi 1988 

in Belyea et al. 1999). In the mid-1980s, local concern helped lead to a Michigan Department of Natural 

Resources study which revealed that growth overfishing (overharvest to the point that size at harvest 

declines dramatically) may have been at least partially responsible for the decline of the fishery (Lucchesi 

1988 in Belyea et al. 1999). A 175 mm minimum size limit was instituted in 1987 in an effort to reduce 

mortality for smaller fish, but it did not help the fishery as predicted (Schneeberger and Scott 1997 in

Belyea et al. 1999). 

Yellow perch populations have been declining in many areas of the Great Lakes for several decades, most 

likely as a result of repeated recruitment failures (Lucchesi 1988, Haas and Schaeffer 1992). Fisheries 

managers and sport anglers are both concerned that predation pressure from the abundant and growing 

populations of DCCOs will either contribute to the further decline of yellow perch fisheries or prevent 

recovery (Diana et al. 1997). 

DCCO Status and Diet. In 1980, DCCOs naturally reestablished at St. Martins Shoal, just west of the Les 

Cheneaux Islands, after many years of absence. Population surveys in 2001 estimated 4,039 DCCO pairs 

in the Les Cheneaux Islands area (D. Trexel, University of Minnesota, unpubl. data). Since 1980, diet 

studies in the Great Lakes have shown that alewife is the most prominent prey item for DCCOs in nearly 

every location where alewife and cormorants are found together (Belonger 1983, Craven and Lev 1987, 

Karwowski et al. 1992, Ludwig et al. 1989, Ross and Johnson 1994, Weseloh and Ewins 1994). 

A study conducted in 1995 (Belyea et al. 1999) by the Michigan Department of Natural Resources and the 

University of Michigan evaluated cormorant-perch interactions in the Les Cheneaux Islands area and, in 

particular, evaluated population trends in cormorants and yellow perch and determined the effect of 

cormorants foraging on the yellow perch fishery. The study found that yellow perch comprised about 10 

percent of overall DCCO diet with alewives and sticklebacks being the most common prey items, 

although yellow perch represented 48 percent of DCCO diet for a short period in April (Belyea et al. 

1999). It was estimated that the biomass of yellow perch consumed by DCCOs was 7,100 kg during the 
A - 19 

perch spawning season and 4,300 g during the remainder of the year (1995). These biomass estimates 

correspond to a range of 270,000 to 720,000 individual perch consumed, with the best estimate being 

470,000 (Maruca 1997 in Belyea et al. 1999). Approximately 7,000 to 17,000 of these fish consumed 

were figured to be young of the year perch. The authors felt it was a reasonable assumption that removal 

of up to 17,000 young of the year would not have a substantial effect on yellow perch recruitment (Belyea 

et al. 1999). As for legal-size perch, mortality caused by cormorant predation and summer sport fishing 

was low (no more than 3.5 percent) compared to the estimated total annual mortality rate (45 percent). 

The authors concluded that “other sources of mortality, therefore, accounted for the majority of yellow 

perch deaths” (Belyea et al. 1999). 

Other Factors. The waters of the Les Cheneaux Islands comprise a dynamic area of physical and 

biological complexity. Part of the biological complexity results from proximity to open waters of Lake 

Huron and the St. Mary’s River. The Les Cheneaux sport fishery was consistently dominated by yellow 

perch, but catches of perch varied nearly six fold in the period between 1979 and 1995. Yellow perch 

populations vary throughout their range, due in part to differences in year class strength. Sport catches of 

other species (such as northern pike, smallmouth bass, chinook salmon, pink salmon, and lake trout) in 

the Les Cheneauxs vary dramatically and could have considerable influence on the fish community of the 

Les Cheneauxs, whether or not they directly influence yellow perch. Also, white perch were documented 

for the first time in the 1995 creel survey, and if numbers continue to increase, white perch may affect 

yellow perch populations through competition as they have in other waters (Parish and Margraf 1990, 

Prout et al. 1990). 

Lake of the Woods, Minnesota 

Lake of the Woods, located in southeastern Manitoba, southwestern Ontario, and northwestern 

Minnesota, is one of the larger inland lake systems outside of the Great Lakes. The lake is biologically 

diverse with respect to the fish found in the system, containing everything from lake trout in the deep 

Canadian waters, to sturgeon and percids. Lake of the Woods is one of the premier walleye lakes on the 

continent. While there is some commercial fishing, and native subsistence fishing (on the Canadian side), 

the primary harvest of game fish species is by recreational anglers. Currently, the lake is managed to 

optimize recreational opportunities, as well as native fish populations. 

The most relevant statistical data has been gathered by the Minnesota Department of Natural Resources, 

Division of Fisheries, through the large lake sampling program. The primary species of interest are the 

percids. This group of fish is sampled at a variety of life stages through fall gill net sampling, seining, 

and trawling. Several calculations reveal information about relative abundance of fish, although there is 

no lake-wide population estimate for any species (Heinrich 1999). The historical “catch per unit effort” 

(CPUE) as measured by gill net sampling reflects recent trends for each of six fish species. These data 

show that, overall, there has been no general decline in the abundance of any of these species. 

DCCO Status and Diet. Cormorants were historically present at Lake of the Woods, but declined to a 

negligible number in the 1950s and 1960s. The population then started to rebound, beginning in the 

1970s. The nesting population on the American side of Lake of the Woods has fluctuated from 1164 

pairs in 1980, to over 7000 pairs observed in 1990. The population declined following an outbreak of 

Newcastle disease in the early1990s, and then increased to just over 4500 nesting pairs in 1999. 

There is little quantitative information available on diet of cormorants at Lake of the Woods. Sampling of 

bolus regurgitations by chicks of cormorants at Lake of the Woods (K. Haws, Minnesota DNR, pers. 

comm.) has indicated that, of 41 samples taken in 1985, by far the greatest representation by number in 

the samples was yellow perch (72 percent), followed by small amounts of burbot, walleye, and sauger (8 

percent), and white sucker. Other inland studies (e.g., at Lake Winnipegosis, Manitoba) have shown that 

cormorants eat perch, sucker, and cisco (Hobson et al. 1989). Full assessments which include adult food 
A - 20 

habits, and food habits over the entire ice-free season, have not been made. 

Southeastern lakes, ponds, and reservoirs 

Many of the inland lakes in the southeastern U.S. (e.g., Millwood Lake, Arkansas; Lake Livingston, 

Texas, etc.) are reservoirs that were created for purposes such as flood control, water conservation, 

irrigation, and other beneficial uses such as recreational fishing. Concernsamong anglers regarding 

DCCO predation on reservoir fishes in the southern Great Plains and in southeastern States have 

increased in recent years (Simmonds et al. 2000). 

During scoping, for example, the Army Corps of Engineers and the Arkansas Game and Fish Commission 

expressed concerned that cormorants are having a negative impact on fish populations at Millwood Lake, 

Arkansas. Additionally, the Georgia Department of Natural Resources shared the results of surveys 

conducted by their Fisheries Management Section (in 1992 and 1994) which documented “significant fish 

losses” to cormorants at fishing lakes in the southern part of Georgia (while DCCOs in the northern half 

of the State were generally not a problem). 

DCCO Status and Diet. In recent years, both wintering and breeding numbers of DCCOs have increased 

significantly in the southeastern U.S. (Jackson and Jackson 1995, Tyson et al. 1999, Reinhold and Sloan 

1999, Wires et al. 2001). Campo et al. (1993) examined the diets of 420 DCCOs from eight public 

reservoirs in Texas (1986-1987) and found that DCCOs ate fishes that were most abundant in the 

reservoirs. Shad and sunfishes accounted for 90 percent of the total food items by number. Sport fish 

(largemouth and white bass, catfishes, and crappies) made up a significant portion of DCCO food by 

weight, but not by number on some reservoirs. The sport fish taken by DCCOs were much smaller than 

those taken by sport anglers. The authors concluded that, at that time, “consumption of desired sport fish 

in reservoirs was an insignificant portion of cormorant diets in Texas.” 

Glahn et al. (1998) compared percentages of prey species in the diet of DCCOs at Lake Beulah, 

Mississippi and Lake Eufala, Alabama to the percent availability of these prey species in the lakes. They 

found that the only sport fish that occurred in the diet in significant numbers were sunfish species, 

particularly bluegill. They concluded that, with the possible exception of predation on harvestable size 

bluegill, DCCOs do not appear to have a negative impact on fisheries in the two lakes studied. 

Simmonds et al. (2000) stated that “Because cormorants prey on a variety of fish species and sizes and 

because their residency in Oklahoma is seasonal, their ultimate effect on sport fishery characteristics may 

be different from that inferred from simple calculations of consumption.” They modeled effects of 

different levels of DCCO predation on standing crops and yields of reservoir sport and forage fish and 

found that: predation by DCCOs had a moderate or low effect on fish abundances and yields when DCCO 

abundances approximated those found on most reservoirs in Oklahoma (i.e., 2.5 cormorant days/ha), but 

effects on fish abundance and yield were severe when high DCCO abundances were inputted (i.e., 23.4 

cormorant days/ha, a level actually observed on two reservoirs in one year). At this level of predation, 

simulated channel catfish and largemouth bass fisheries collapsed and yields of white crappies were 

greatly reduced. 

On Lake Chicot, an oxbow lake on the Mississippi River in Arkansas, mortality rates of age-0 to age-1 

crappie have been estimated at 90 percent in recent years. While increasing numbers of DCCOs are 

suspected by anglers to be the cause of these high mortality rates, the Arkansas Game and Fish 

Commission reports that an increase in the density of largemouth bass may be having an affect on crappie 

survival. The University of Arkansas is planning to carry out a study examining the diet and potential 

impact of both DCCOs and largemouth bass (Fenech et al. unpubl. data). 
A - 21 

Appendix 7: Guidelines for distinguishing Double-crested Cormorants from Anhingas and 

Neotropic Cormorants

Neotropic Cormorants (Phalacrocorax brasilianus) often occur with DCCOs, particularly in winter, and 

can easily be confused with them. As described in the Birds of North America account (Telfair and 

Morrison 1995*), body size, and shape and color of the throat pouch (“gular pouch”) are the most reliable 

distinguishing marks in the field. The Neotropic Cormorant is smaller in body length (61 vs. 74 cm), 

wingspan (102 vs. 127 cm), and weight (1.4 vs. 2.3 kg). The size, shape, and color of gular pouches also 

differ considerably. The gular pouch of the Neotropic Cormorant resembles a horizontal V (with the apex 

pointed backward); is small, pale yellowish brown, and proportionally <50% the size of the remainder of 

the head; and is bordered behind by a thin white line that outlines the size and shape of the pouch. In 

DCCOs, the pouch is much larger and is rounded rather than V-shaped in posterior profile. It is also 

bright orange-yellow and proportionally about as large as the rest of the head. Additionally, from a 

distance, the tail length of the Neotropic Cormorant is noticeably longer in proportion to body length than 

that of DCCOs (about 0.4 versus 0.2 of total length). Distinguishing juvenile and immature Neotropic 

Cormorants from DCCOs is more difficult however, partly because the gular pouches are duller in color 

at this age. Telfair and Morrison (1995) recommend two references for detailed discussion of this (Clark 

1992 and Patten 1993). The best distinguishing feature in immature birds is the color of the patch of skin 

above the lores, between the eyes and the bill. This area is brighter (yellow-orange) in DCCOs and darker 

in Neotropic Cormorants. 

The Neotropic Cormorant’s range includes South and Central America, Mexico, West Indies, and 

northward to southern New Mexico, north-central Texas, and southwestern Louisiana. In the U.S., 

Neotropic Cormorants are largely resident along the Gulf Coast of the U.S. from southwestern Louisiana 

south through Texas. Breeding is restricted to coasts, lakes, and reservoirs. Most breeding colonies are 

coastal, but since the mid-1970s, colonies have been established in reservoirs, some far into the interior of 

Texas (Telfair and Morrison 1995). 

The Neotropic Cormorant is versatile in climatic and environmental tolerance, inhabiting a wide variety 

of wetlands in fresh, brackish, or salt water. In coastal areas, it remains close inshore in sheltered bays, 

inlets estuaries, lagoons, rock outcrops, and islands. In the U.S., its primary habitats are coastal marshes 

and swamps, as well as inland reservoirs. It nests and roosts primarily in trees (live or dead) but also on 

sea cliffs, rock outcrops, and human-made structures (Telfair and Morrison 1995). 

The Neotropic Cormorant is the only cormorant known to plunge-dive, in which the bird plunges headfirst with wings folded against its body. In Texas, it is mostly a solitary forager (Telfair and Morrison 

1995). 

As described in its Birds Of North America account**, the Anhinga (Anhinga anhinga) is “among the 

most distinctive of North American birds, with long, snakelike neck, straight bill, large fanlike 

tail...corrugations on its central rectrices, and unique swimming, flight, and behavior patterns.” Anhingas 

are a mostly black waterbird about 75-95 cm in length. They are distinctively shaped with a small head; a 

very long, often curved neck; a long daggerlike bill; and a long, fan-shaped tail that can be up to 30% of 

total body length. Their body plumage is entirely black with a patter of silvery to white streaks and spots 

on the upper back, scapulars, and wing-coverts. Cormorants are somewhat similar in structure, plumage, 

and behavior, but Anhingas are easily distinguished by having a much longer neck; a longer, more 

pointed bill (without the distinctive terminal hook found in cormorants); and a longer tail (Frederick and 

Siegel-Causey 2000). 

The Anhinga breeds in the eastern half of Texas, where it is found mainly in the coastal plain and further 

inland. It can also be found in easternmost Oklahoma (locally and irregularly), southern Arkansas (very 
A - 22 

locally), extreme western Tennessee (very locally), central and southern Mississippi, central Alabama, 

southern half of Georgia, lower coastal plains of South Carolina, and North Carolina south to the Gulf 

Coast and southern Florida. In the U.S. breeders usually withdraw south in the winter to coastal South 

Carolina, the southern half of Georgia, southern Alabama, southern Mississippi, southern Louisiana, and 

the coastal plain of Texas (Frederick and Siegel-Causey 2000). 

Their habitat includes shallow, slow-moving sheltered waters with nearby perches and banks available for 

drying and sunning. Anhingas are rarely found out of fresh water, but generally are not found in 

extensive areas of open water, and they usually forage in shallow water (Frederick and Siegel-Causey 

2000). 

Anhingas are often observed swimming, with body submerged and only the head and neck extending out 

of water; perching with wings and tail spread to dry; or in flight with neck extended, tail spread, and 

wings held flat (Frederick and Siegel-Causey 2000). 

*Telfair, R.C. II, and M.L. Morrison. 1995. Neotropic Cormorant (Phalacrocorax brasilianus). In The 

Birds of North America, No. 137 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, 

Philadelphia and The American Ornithologists’ Union, Washington, D.C. 

**Frederick, P.C., and D. Siegel-Causey. 2000. Anhinga (Anhinga anhinga). In The Birds of North 

America, No. 522 (A.Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, and The 

American Ornithologists’ Union, Washington, D.C. 
A - 23 

Appendix 8: Overview of Aquaculture Production in 13 States 

State 

# of 

operations in 

State 

Total production 

acreage in State 

# of producers 

taking DCCOs 

under Depr. 

Order per year 

Estimated 

average annual 

expense to 

control DCCOs 

Alabama 

270 (catfish 

only) 24,400 (9,882 ha) 270 $1,672 

Arkansas 250 75,000 (30,372 ha) 80 

$10,000 -

100,000 

Florida 443 7,585 (3,072 ha) 35 $1,500 - 2,000 

Georgia 406 7,092 (2,872 ha) 50 

Kentucky1 70 400 (162 ha) 15 N/A 

Louisiana 

102 (catfish or 

minnows); 

973 (crawfish) 

14,447 (5,851 

ha)(catfish or 

minnows); 84,635 

(34,277 

ha)(crawfish) 50 $5,000 - 10,000 

Minnesota N/A N/A 35 $1,000 - 2,000 

Mississippi 395 111,500 (45,158 ha) 130 ~$150 per acre 

North Carolina 250 2,820 (1,142 ha) 20 N/A 

Oklahoma 77 900 (365 ha) 77 

South Carolina1 15 520 (211 ha) 9 N/A 

Tennessee 50 800 (324 ha) 20 N/A 

Texas1 34 580 (235 ha) 34 N/A 

1

 = catfish production only; N/A = not available 

Source: survey of APHIS/WS State Directors; NASS Catfish Production Feb. 2002 

 
A - 24 

Appendix 9: Costs of Control Methods and Techniques

Harassment. A typical 5 month harassment program at a 200 hectare farm with high DCCO pressure 

would cost almost $20,000 annually (Littauer et al. 1997). This would include the cost of labor, vehicle 

expenses, pyrotechnics, and live ammunition. If supplemented with propane exploders and scarecrows, 

an additional startup cost of $1,000 to $2,000 would be incurred. 

An observational food habits study conducted by Stickley et al. (1992) concluded, based upon an average 

number of 30.5 DCCOs observed feeding on an eight hectare pond stocked at 51,000 fish per hectare, that 

the fish population would be halved in 30 days if this number of cormorants fed all day. They further 

concluded, based on the cost of bird patrol harassment on a 200 hectare aquaculture facility over a 5 

month period, that costs associated with harassment of DCCOs would be exceeded in 22 days by the 

losses in this one 8 hectare pond. This means that harassment efforts would prove cost-effective after 22 

days at this level of depredation. 

The night roost dispersal program used in the Mississippi Delta to harass DCCOs from the fish producing 

regions during the winters of 1993-95 ranged from $16,757 to $32,302 per year to disperse birds from 30 

to 40 night roosts (Mott et al.1998). Costs to disperse DCCOs from night roost sites averaged $400 to 

$640 per year for each participating farm. Current costs of the roost dispersal program have likely 

increased based upon the doubling of the wintering DCCO population (Reinhold and Sloan 1999; Glahn 

et al. 1999; Glahn et al. 2000) and the increase of night roosting sites to more than 65 in the Delta region 

(Reinhold and Sloan 1999) since the 1995 study was completed. 

Adding the cost of labor and materials necessary to patrol a typical catfish farm to the cost of 

pyrotechnics and live ammunition, Littauer et al. (1997) estimated harassment costs at $132/day. The 

authors calculated that a farm with an average of 100 DCCOs feeding at any time could experience losses 

of $400/day (replacement costs); they concluded that there may be instances in which an aggressive 

harassment program would be cost effective. In a survey of 281 Mississippi catfish farmers, Stickley and 

Andrews (1989) reported an average of 2.6 person-hours of harassment/day for all bird species, at an 

annual cost of $7,400; harassment during the 6 month period when cormorants were present averaged $26 

per day, or approximately $4,700 for the entire six months. Outside harassment zones, expenditures for 

harassment at individual aquaculture facilities increased an average of $845 in 1994 and $741 in 1995, 

suggesting that the harassment program moved DCCOs out of the harassment zone and into surrounding 

areas (Mott et al. 1998). 

Shooting and egg oiling. Bédard et al. (1999) provided a “very rough estimate” for the St. Lawrence River 

Estuary, Québec, control program of $10/adult shot and $3/nest sprayed with oil. Without better 

economic estimates on the costs of DCCO impacts, the cost effectiveness of population control by any 

means can not be determined (Wires et al. 2001). 
A - 25 

Appendix 10: Comparison Tables Using CBC Data 

Comparison of Indices of Abundance of Double-crested Cormorants on Christmas Bird Counts: 2002 

 2002 2001 % 2000-2002 19Flyway/Zone Birds Counts Index Birds Counts Index Change Birds Counts Index Birds Atlantic:  Northern Zone1 591 99 6 559 96 5.8 3 1424 288 4.9 2650  Central Zone2 1719 121 14 4017 126 32 -56 7279 371 18 12964  Southern Zone3 176967 153 1157 126273 155 815 42 457779 461 993 1371283  Sub-Totals 179277 373 481 130849 377 347 39 466482 1120 416 1386897 Mississippi:  Northern Zone4 251 89 2.8 345 90 3.8 -26 701 267 2.6 1104  Central Zone5 730 127 5.7 13930 126 111 -95 15470 379 41 17164  Southern Zone6 199519 84 2375 124037 83 1494 59 473877 249 1903 657222  Sub-Totals 200500 300 668 138312 299 463 44 490048 895 548 675490 Central:  Northern Zone7 5 14 0.36 19 15 1.3 -72 28 43 0.65 32  Central Zone8 90 33 2.6 185 32 5.8 -53 326 99 3.3 1919  Southern Zone9 108241 115 941 225317 110 2048 -54 338230 251 1348 781920  Sub-Totals 108336 162 669 225521 157 1436 -53 338584 393 862 783871 Pacific:  Northern Zone10 4576 48 95 4328 48 90 6 12300 140 88 27877  Central Zone11 12490 73 171 10498 73 144 19 33324 220 151 69731  Southern Zone12 20679 126 164 26762 127 211 -22 74262 378 196 256074  Sub-Totals 37745 247 153 41588 248 168 -9 119886 738 162 353682 GRAND TOTALS 525858 1082 486 536270 1081 496 -2 1415000 3146 450 3199940 
A - 26 

Comparing Frequency of Occurrence of Double-crested Cormorants on Christmas Bird Counts: 

 2002 2001 2000-2002 1990

Flyway/Zone N 

DCCO's 

Present FREQ N 

DCCO's 

Present FREQ 

% 

CHANGE N 

DCCO's 

Present FREQ N 

DCC

Pres

Atlantic:  Northern Zone1 99 55 56 96 56 58 -3 288 157 54 866 42 Central Zone2 121 64 53 126 86 68 -22 371 208 56 1200 63 Southern Zone3 153 128 84 155 142 92 -9 461 397 86 1369 11 Sub-Totals 373 247 66 377 284 75 -12 1120 762 68 3435 216Mississippi:  Northern Zone4 89 19 21 90 41 46 -54 267 78 29 838 24 Central Zone5 127 45 35 126 59 47 -26 379 139 37 1239 46 Southern Zone6 84 71 84 83 71 86 -2 249 206 83 787 64 Sub-Totals 300 135 45 299 171 57 -21 895 423 47 2864 135Central:  Northern Zone7 14 3 21 15 2 13 62 43 7 16 132 2 Central Zone8 33 14 42 32 18 56 -25 99 46 46 301 13 Southern Zone9 115 101 89 110 96 87 2 251 214 85 1042 90 Sub-Totals 162 118 73 157 116 74 -1 393 267 68 1475 106Pacific:  Northern Zone10 48 39 81 48 34 71 14 140 117 83 403 26 Central Zone11 73 60 82 73 54 74 11 220 167 76 629 44 Southern Zone12 126 107 85 127 103 81 5 378 310 82 1120 84 Sub-Totals 247 206 83 248 191 77 8 738 594 80 2152 156GRAND TOTALS 1082 706 68 1081 762 70 -3 3146 2046 65 9926 6151 Atlantic Flyway/Northern Zone includes Connecticut, Maine, Massachusetts, New Brunswick, New Hampshire, Newfoundland, Nova Scotia, Prince Edward Island, 

Quebec, Rhode Island, and Vermont. 

2 Atlantic Flyway/Central Zone includes Delaware, District of Columbia, Maryland, New Jersey, New York, Pennsylvania, and West Virginia. 3 Atlantic Flyway/Southern Zone includes Florida, Georgia, North Carolina, South Carolina, and Virginia. 4 Mississippi Flyway/Northern Zone includes Manitoba, Michigan, Minnesota, Ontario, and Wisconsin. 5 Mississippi Flyway/Central Zone includes Illinois, Indiana, Iowa, Kentucky, Missouri, and Ohio. 6 Mississippi Flyway/Southern Zone includes Alabama, Arkansas, Louisiana, Mississippi, and Tennessee. 
A - 27 

7 Central Flyway/Northern Zone includes Alberta, Montana, North Dakota, South Dakota, and Saskatchewan. 8 Central Flyway/Central Zone includes Colorado, Kansas, Nebraska, and Wyoming. 9 Central Flyway/Southern Zone includes New Mexico, Oklahoma, and Texas. 10 Pacific Flyway/Northern Zone includes Alaska and British Columbia. 11 Pacific Flyway/Central Zone includes Idaho, Oregon, and Washington. 12 Pacific Flyway/Southern Zone includes Arizona, California, Nevada, and Utah. 
A - 28 
A - 29 

Appendix 11. Public Scoping Report 

Executive Summary: On November 8, 1999, the U.S. Fish and Wildlife Service, in cooperation with 

USDA-APHIS-Wildlife Services, published a Notice of Intent to prepare an Environmental Impact 

Statement and national management plan for the double-crested cormorant. This action was in response 

to increasing populations of cormorants, and subsequent growing concern from the public and natural 

resource management agencies that cormorants are negatively impacting or pose a threat to resources 

such as other colonial waterbirds, island vegetation, aquacultural stock, and sport fish populations. 

Public comment on issues of concern and potential management alternatives was solicited. A Notice of 

Meetings was published on April 14, 2000, announcing ten public scoping meetings across the United 

States. Public comments were accepted from the opening of the comment period until June 16, 2000. In 

summary, over 900 people attended the public scoping meetings, with 239 providing oral comments, and 

over 1450 submitted written comments. Analysis of the comments was separated by geographic region 

and into the following groups: private individuals, businesses, non-governmental organizations (NGOs), 

local government agencies and associations, Federal agencies, State agencies, tribes, Canadian agencies, 

and legislative officials. 

Background

On November 8, 1999, the U.S. Fish and Wildlife Service, in cooperation with USDA-APHIS-Wildlife 

Services, published a Notice of Intent (64 FR 60826) to prepare an Environmental Impact Statement and 

national management plan for the double-crested cormorant (DCCO). This action was intended to 

address impacts caused by population and range expansion of the DCCO in the contiguous United States. 

The notice did not identify preliminary alternatives, but rather stated that cormorants have been 

implicated as being responsible for: (1) economic losses at commercial aquaculture facilities; (2) damage 

to trees and other vegetation associated with breeding colonies and roosting sites; (3) impacts to other 

species of migratory birds in the vicinity of cormorant breeding colonies; (4)declines in economic 

revenues associated with outdoor (primarily fishing-related) recreational activities; (5) declines in 

populations of sport fish; and (6) lowering of private property values. 

The November 8 notice stated that comments on issues, alternatives, and impacts to be addressed in the 

EIS are being solicited and, in particular, comments of value would: (1) identify and, where possible, 

quantify impacts caused by increasing cormorant populations; (2) suggest management strategies to 

resolve such conflicts; and (3) identify determining factors in justifying the need for control, if any. 

The notice also stated that the primary issue to be addressed during the scoping phase is to determine 

which alternatives for managing DCCO populations would be analyzed in the EIS. It indicated that we 

would prepare a dicussion of the effects, by alternative, in each of the following resource areas: (1) 

DCCO populations and their habitats; (2) other bird populations and their habitats; (3) effects on other 

species of flora and fauna; and (4) socioeconomic effects. 

Public Scoping Meetings

A subsequent notice was published on April 14, 2000, identifying ten public scoping meeting locations 

(65 FR 20194). The ten public scoping meetings, were held in Washington, D.C.; Portland, OR; 

Burlington, VT; Watertown, NY; Syracuse, NY; Green Bay, WI; Mackinaw City, MI; Hauppage, NY; 

Jackson, MS; and Athens, TX. Over 900 individuals attended the scoping meetings, at which anyone 

who wished to present oral and/or written comments was allowed to do so (239 people provided oral 

comments). A court reporter was present at each meeting in order to provide transcripts of the verbal 

testimony. 
A - 30 

Washington, DC

Approximately 10 people attended the Washington, DC meeting. Representatives from the American 

Bird Conservancy, the Ornithological Council, and the Humane Society of the United States spoke. The 

primary concern was that management decisions be based on sound science. Other concerns/ideas that 

were raised include: fish-eating birds are increasingly being “scapegoated” for fishery declines; DCCOs 

have distinct, regional populations and management options must consider this; other factors, such as 

habitat destruction and modification, contaminants, hatcheries, and hydropower must also be considered 

as factors affecting fish populations; education and outreach are extremely important; the current 

management situation is not necessarily inadequate and the cormorant problem is actually a people 

problem; the Service needs to cooperate with Canada and Mexico as they develop a management plan; 

and an interdisciplinary approach is important. Representatives from USDA-Wildlife Services and 

USFWS Division of Migratory Bird Management and Division of Law Enforcement were present. 

Portland, OR

Approximately 20 people attended the Portland meeting. Four individuals spoke. The primary concern 

was cormorant predation on salmonid smolts, from both a sport fishing and an endangered species 

standpoint. Ideas that were raised included: major reduction in DCCO populations; issuing a permit to 

kill 6-8 DCCOs each week and examine their stomach contents; conducting a predation study in the lower 

Columbia River estuary while smolts are there in the spring; and squirting the birds with ammonia to keep 

them off the breeding grounds. Representatives from the Washington Department of Wildlife, USDAWildlife Services, and USFWS Region 1 and Division of Migratory Bird Management were also present. 

Burlington, Vermont

Approximately 120 people attended the Burlington meeting. Of 32 individuals who spoke, one person 

stated that we need to learn to coexist with DCCOs and should use only non-lethal control methods. 

Others who testified were supportive of more aggressive control. Some speakers suggested removing the 

species from the Migratory Bird Treaty Act, hunting them, or allowing the States to manage them. The 

major concerns expressed were declines in fishing and associated impacts on Vermont’s tourist economy, 

destruction of island vegetation (from a property, aesthetics, and/or biodiversity perspective), water 

contamination caused by DCCO excrement, and impacts to other bird species. Representatives from 

Congressman McHugh’s office and the Vermont Department of Fish and Wildlife testified. Also present 

were representatives from USDA-Wildlife Services and USFWS Region 5 and the Division of Migratory 

Bird Management. 

Watertown, New York

Approximately 175 people attended the Watertown meeting. Of 23 individuals who spoke, all were 

concerned about fishery impacts, economic impacts, and/or human health impacts caused by DCCOs. 

Nearly everyone stated the need for DCCO population reduction, specifically via hunting. 

Representatives from Congressman McHugh’s office and the New York Department of Environmental 

Conservation testified. Also present were representatives from USDA-Wildlife Services and USFWS 

Region 5 and Division of Migratory Bird Management. 

Syracuse, New York

Approximately 50 people attended the Syracuse meeting. Of 18 individuals who spoke, 17 expressed 

concerns that DCCOs are causing an ecological imbalance, are a serious detriment to the sport fishery and 

economy of Oneida Lake, and/or are destroying island vegetation. Most were supportive of controlling, 

even eradicating DCCO populations in the area. One individual stated that the federal government should 
A - 31 

stop protecting special interest groups and leave DCCOs alone. Representatives from USDA-Wildlife 

Services and USFWS Region 5 and Division of Migratory Bird Management were present. 

Hauppauge, New York

Approximately 10 people attended the Long Island meeting and five spoke. Comments included: the 

Service should base their decisions on science and not political pressure; humans should manage 

predators when they are preying on populations that humans depend upon; oiling eggs is the only 

acceptable means of control; and DCCOs are damaging sailboats in harbor marinas. Representatives 

from the New York Department of Environmental Conservation and USFWS Region 5 were present. 

Green Bay, Wisconsin

About 80 people attended the Green Bay meeting. Of 27 individuals who spoke, 26 were in support of 

cormorant control. The crowd was firm in its conviction that cormorants are impacting fishing (especially 

yellow perch) and associated economies, as well as island vegetation and other colonial waterbirds, and 

should be controlled. A cormorant researcher from the University of Wisconsin testified that studies have 

consistently shown that yellow perch make up a very small proportion of what is being consumed by 

DCCOs (he also commented that DCCOs should be kept off certain islands, while acknowledging that it 

is normal for bird populations to change the composition of island vegetation). Representatives from the 

Wisconsin Department of Natural Resources, USDA-Wildlife Services, and USFWS Region 3 and 

Division of Migratory Bird Management were present. 

Mackinaw City, Michigan

Approximately 140 people attended the Mackinaw City meeting. Of 33 individuals who spoke, all were 

anti-cormorant. Some of the points made include the following: concern about cormorant impacts 

(biological and economic) on yellow perch, especially in the spring during spawning, in the Les 

Cheneaux Islands of Lake Huron; concern about the spread of cormorants to inland lakes such as the 

Manistique lakes; concern that tax dollars being spent on fish restoration and stocking are being wasted; 

and concern that anglers are going to Canada because cormorants have decimated the fishing in Michigan. 

A cormorant hunting season was favored by a number of speakers. Representatives from the Michigan 

Department of Natural Resources, USDA-Wildlife Services, and USFWS Region 3 and Division of 

Migratory Bird Management were present. 

Jackson, Mississippi

Approximately 55 people attended the Jackson meeting. Of 18 individuals who spoke, all but 3 were 

associated with the aquaculture industry and expressed concern about serious economic impacts related to 

chasing cormorants off their ponds, in addition to what the birds eat. They stated that the Depredation 

Order (which allows shooting of birds) is not effective in reducing impacts; population level control is 

needed. Other comments that were made include: fish farmers need to be more creative and 

entrepreneurial in finding solutions to reduce DCCO impacts; DCCOs are just doing what comes 

naturally to them; fish farmers should unionize; and roost harassment efforts are an annoyance to 

neighboring landowners. Representatives from USDA-Wildlife Services, USDA Agricultural Research 

Service, Mississippi Department of Fish, Wildlife and Parks, and USFWS Region 4 and Division of 

Migratory Bird Management were present. 

Athens, Texas 

Approximately 120 people attended the Athens meeting. Of 35 individuals who spoke, all but three were 

concerned about economic and recreational impacts of DCCO predation on fish in small, private lakes 

and were in support of increased control, either through removal from the MBTA, a hunting season, or 

delegation of management to the States. Concerns about human health effects of increasing DCCO 
A - 32 

populations were also raised. Other comments included: the EIS and any management actions must be 

based on sound science; the Service must consider not only negative recreational and economic impacts 

but also positive direct and indirect value of DCCOs; DCCO management should not impact the rare 

Neotropic Cormorant and should include education efforts to help people distinguish the two species; and 

the national management plan should have a regional focus and involve Canada and Mexico. 

Representatives from the Oklahoma Department of Wildlife Conservation, Texas Parks and Wildlife, and 

USFWS Region 2 and Division of Migratory Bird Management were present. 

Two additional meetings were held in Little Rock, Arkansas (June 5) and in Angle Inlet (Lake of the 

Woods), Minnesota (June 24), at the request of Congressman Jay Dickey (AR) and Congressman Collin 

Peterson (MN), respectively. 

Little Rock, Arkansas 

Approximately 100 people attended the Little Rock meeting and 35 individuals spoke. All speakers were 

concerned about economic impacts on fish farmers and/or impacts on sport fish populations, and were 

generally supportive of large-scale control. Also raised was the issue of impaired peace of mind to 

farmers caused by the increasing presence of DCCOs. Representatives from USDA-Wildlife Services, 

USFWS Region 4 and the Division of Migratory Bird Management were present. Representatives from 

the Arkansas Game and Fish Commission, the office of Senator Blanche Lincoln, the Arkansas 

Development Finance Authority, and Congressman Jay Dickey testified. 

Angle Inlet, Minnesota

About 20 people attended the Minnesota meeting. Of the 10 individuals who spoke, most were very 

concerned about the impact of DCCOs on local walleye and perch populations and associated economic 

effects on resorts, charter boats, and recreation fishing. They supported some type of localized control 

although several people who spoke in favor of DCCO population reduction did not support hunting as a 

means of accomplishing this. Concern about potential impacts of management actions on colonial 

waterbirds that nest near DCCOs was also expressed. One speaker stated that management activities 

should be based on science and that there is more to the value of Lake of the Woods than fish alone. 

Representatives from the Minnesota Department of Natural Resources (DNR) and USFWS Region 3 and 

Office of Migratory Bird Management were present. DNR fish survey data were presented and they did 

not support the contention that sport fish populations have declined in Lake of the Woods. Congressman 

Collin Peterson testified. 

Written Comments 

Public comments were accepted from the opening of the comment period on November 8, 1999, until 

June 16, 2000. Over 1450 comments were received, either by mail or electronically (via 

cormorant_eis@fws.gov). Analysis of the comments was separated by geographic region (USFWS 

Regions 1-6; no comments were received from Region 7, Alaska) and into the following groups: private 

individuals, businesses, non-governmental organizations (NGOs), local government agencies and 

associations, Federal agencies, State agencies, tribes, Canadian agencies, and legislative officials. 

Comments fell into two categories: (1) issues of concern and (2) suggested management options. Issues 

of concern included impacts on sport fishing, local economies, aquaculture/commercial fishing, bird 

species, ecological balance, vegetation, human health and safety, and private property. Management 

options included population control, leaving DCCOs alone, removing DCCOs from the protection of the 

Migratory Bird Treaty Act, hunting, focusing on non-lethal control, letting States manage DCCOs, 

changing the permit policy, oiling eggs, giving USDA-Wildlife Services more authority, basing decisions 

on the best science, using population objectives, and increasing education efforts. 
A - 33 

SUMMARY OF WRITTEN COMMENTS 

R1 R2 R3 R4 R5 R6 Unkno

wn

Totals

Issues of Concern 

Sport fish impacts 28 213 110 51 147 7 17 573

Economic impacts 0 72 20 16 36 5 149

Vegetation impacts 31 37 1 26 1 96

Destruction/odor caused by DCCO feces 34 22 2 22 2 82

Private property damage 62 6 7 1 76

General concern over 

population increase 

1 52 8 2 8 1 72

Aquaculture/ commercial 

fishery impacts 

3 7 6 30 10 2 58

Human health/safety 29 12 11 52

DCCOs causing ecological imbalance 5 18 3 17 43

Impacts on other bird species 16 1 20 37

DCCOs are non-native 4 6 1 13 24

DCCOs are sacred to Native Americans 1 1

Management Options 

Need to control/reduce 

population 

20 126 97 91 125 2 11 472

Remove from MBTA protection 19 113 7 63 26 1 6 235

Don't blame DCCOs/ leave 

them alone 

22 10 22 14 42 5 103 218

Emphasize non-lethal control 13 8 16 5 44 2 105 193

Have a hunting season 23 18 29 63 42 1 5 181

Let States manage DCCOs 19 144 5 2 7 1 2 180

Base decisions on sound 

science 

13 5 14 11 29 2 55 129

Oil eggs 1 2 9 63 22 1 98

Give USDA/Wildlife Services more 

authority 

3 1 60 1 1 66

Do not allow hunting 1 2 1 3 13 1 25 46

Use population objectives in 

DCCO management 

2 2 2 6 9 4 1 26

Need better information 2 5 3 4 5 19
A - 34 

Change permit policy 6 1 3 6 16

Increase education efforts 1 5 4 3 13

Don't do management plan 1 2 2 3 1 3 12

Expand depredation order to 

other states 

2 2 1 2 2 9

Allow eggs to be gathered for food 1 1

Regional Totals 171 949 479 497 696 32 352 3177

Total # of individual letters/ emails: 1458 

Private Individuals

Over 75% of the written comments came from individuals who wrote to express their own personal 

feelings, ideas, and concerns about the impacts of DCCOs. Although a majority of the letters expressed 

concern about the impacts of DCCOs on sport fisheries and recommended DCCO population reduction, a 

great number of individuals suggested that we stop blaming DCCOs for fishery problems and 

recommended that only non-lethal control efforts be allowed. 

Canadian agencies 

We received comments from four Canadian agencies whose concerns included potential impacts of 

Service management actions on Great Cormorant populations (Nova Scotia) and on declining western 

DCCO populations (British Columbia).

Federal agencies 

The National Marine Fisheries Service expressed concern about the impacts of DCCOs on “fish species 

that are listed under the Endangered Species Act or fish produced to meet Indian treaty trust 

responsibility” and recommended that the scope of the national management plan be expanded to include 

“effects on listed salmonid species and ... impacts on salmon and trout in the inland western states.” 

Biologists from the USDA-APHIS-Wildlife Services National Wildlife Research Center in Mississippi 

stated that the goal of the management plan should be to reduce impacts (on commercial aquaculture 

specifically) and that the best way to accomplish this is through population reduction and science-based 

management efforts. 

State agencies 

Twenty seven States provided comments on the DCCO EIS and national management plan. Fourteen 

States (CT, GA, IN, IA, NE, NH, NY, ND, OH, OK, RI, TX, VT, WY) expressed a desire for increased 

flexibility/increased State input in managing cormorants. Twenty three States (AZ, CT, GA, IL, IN, IA, 

LA, MI, MN, MO, NE, NH, ND, NY, OH, OK, OR, RI, TX, VT, WI, WY, MA) stated or implied that, 

under certain conditions (e.g., evidence pointing toward a problem, displacement of other colonial nesting 

birds, impacts on natural systems, etc.), increased control should be considered. Five States (AZ, NH, 

ND, SD, MN) stated that they currently have no real problems with DCCOs. 

Local government agencies and associations

All of the local government agencies that provided comments expressed concern about impacts of 

DCCOs on sport fish populations, recreational fishing opportunities, sport fish-related economies, and/or 

vegetation and were supportive of control efforts. 
A - 35 

Non-governmental Organizations (NGOs)

Comments from NGOs varied greatly and included animal protection organizations, local fishing clubs, 

scientific organizations, and environmental/conservation groups. Some groups requested that we stop 

scapegoating DCCOs and look into anthropogenic causes for fishery declines; others emphasized the need 

for better science to justify any control efforts; and others requested immediate control actions be put into 

effect to alleviate DCCO impacts. 

 

Businesses

All but 5 of 24 businesses that provided comments were either aquaculture facilities, charter services, or 

other fishing-related businesses. All but one of the businesses expressed concern about the negative 

impacts of DCCOs on their enterprise. The one pro-cormorant business was a 

cosmetics company that does not engage in animal testing. 

Legislative officials

As of July 26, we have received letters from 10 legislative officials (three State and seven Federal) and 

one caucus (Congressional Sportsmen’s Caucus). Each one of these expressed concern about the 

deleterious impacts of DCCOs on sport fisheries and/or the aquaculture industry. 

Tribes

Three tribes sent comments regarding management of DCCOs. One tribe from Arizona (White Mountain 

Apache) stated support for a hunting season on DCCOs. A member of a tribe from Oklahoma (Kiowa) 

stated that waterbirds are sacred to them and that they would like any birds that are killed to be given to 

them for use in native ceremonies. The third tribe (Wampanoag/Aquinnah) expressed concern about the 

possible negative effects of increasing DCCO populations on tribal fishery resources. 

List of Canadian agencies, Federal agencies, State Agencies, Local Governments and Associations, 

Non-governmental Organizations, Businesses, Legislative Officials, and Tribes Providing Scoping 

Comments

Canadian agencies

Alberta Environment, Office of the Deputy Minister 

British Columbia Ministry of Environment, Land and Parks 

New Brunswick Department of Natural Resources and Energy, Fish and Wildlife Branch 

Nova Scotia Department of Natural Resources 

Federal agencies

U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services 

U.S. Department of Commerce, National Oceanic and Atmospheric Association, National Marine 

Fisheries Service 

State agencies

Arizona Game and Fish Department 

Arkansas Game and Fish Commission 

Connecticut Department of Environmental Protection 

Georgia Department of Natural Resources 

Illinois Department of Natural Resources 
A - 36 

Indiana Department of Natural Resources 

Iowa Department of Natural Resources 

Kansas State University 

Kentucky Department of Fish and Wildlife Resources 

Louisiana Department of Wildlife and Fisheries 

Maine Atlantic Salmon Commission 

Maine Department of Inland Fisheries and Wildlife 

Maine Department of Marine Resources 

Massachusetts Division of Fisheries and Wildlife 

Michigan Department of Natural Resources 

Minnesota Department of Natural Resources 

Mississippi State University Extension Service 

Missouri Department of Conservation 

Nebraska Game and Parks Commission 

New Hampshire Fish and Game Department 

New York State Department of Environmental Conservation, Division of Fish, Wildlife & Marine 

Resources 

North Dakota Game and Fish Department 

Ohio Department of Natural Resources, Division of Wildlife 

Oklahoma Department of Wildlife Conservation 

Oregon Department of Fish and Wildlife 

Plattsburgh, State University of New York 

Rhode Island Department of Environmental Management, Division of Fish and Wildlife 

South Dakota Department of Game, Fish and Parks 

Texas Parks and Wildlife Department 

University of Louisiana, Lafayette 

Vermont Department of Fish and Wildlife 

Washington Department of Fish and Wildlife 

Wisconsin Department of Natural Resources 

Wyoming Game and Fish Department 

Local government agencies and associations

Champlain Islands Chamber of Commerce, VT 

Curtis Chamber of Commerce and Manistique Lakes Area Tourism Bureau, MI 

Lake Florida Improvement Association, FL 

Lake Ontario Fisheries Coalition, NY 

Lake Puckaway Protection and Rehabilitation District, WI 

Northwest Angle and Islands Chamber of Commerce, MN 

Oneida Lake Association, NY 

Portage Township, MI 

State of New York Conservation Fund Advisory Board 

Thomas Lake Road Community Association, TX 

Town of Orleans Conservation Commission, MA 

Non-governmental Organizations (NGOs)

Agricultural Council of Arkansas 

American Association of Retired Persons, Inc., Chapter 3876, TX 

American Bird Conservancy 

American Fisheries Society 
A - 37 

Animal Protection Institute, CA 

Association of Northwest Steelheaders, North Fork Nehalem Chapter, OR 

Atlantic States Legal Foundation, Inc., NY 

Audubon Society of Central Arkansas 

BASS, Inc., AL 

Coalition of Louisiana Animal Advocates, LA 

Concerned Citizens for Cormorant Control, AR 

Connecticut Harbor Management Association, CT 

Coon Creek Club, TX 

Dixie Lake Hunting and Fishing Club, TX 

Eastern Lake Ontario Salmon and Trout Association, NY 

Fishers Island Conservancy, Inc., NY 

The Ford Plantation, GA 

Friends of Animals, CT 

Fur Harvester’s Association of Jefferson County, NY 

Great Lakes Sport Fishing Council 

Green Bay Area Great Lakes Sport Fishermen Club, WI 

Green Mountain Animal Defenders, VT 

International Marine Mammal Project of Earth Island, CA 

Lake Champlain International, Inc. 

Lake Champlain Walleye Association, VT 

Lewis County Association of Sportsmen’s Clubs, NY 

Marsh Lake Ducks Unlimited, MN 

Michigan United Conservation Clubs 

National Aquaculture Association 

National Audubon Society 

New York State B.A.S.S. Chapter Federation 

Niagara River Anglers Association Inc., NY 

Onondaga County Federation of Sportsmen’s Clubs, NY 

Pelican Harbor Seabird Station, Inc. 

Rainforest Action Network 

Rochester Birding Association, NY 

Schubert and Associates (on behalf of The Fund for Animals and the Humane Society of the United 

States) 

Society for Animal Protective Legislation 

Straits Area Sportsmen’s Club, MI 

United States Trout Farmers Association 

Vermont Audubon Council 

Wildlife Management Institute 

Wisconsin Wildlife Federation 

Businesses 

After-U Charters, OH 

Beauty Without Cruelty, NY 

Birch View Resort, MN 

Captain’s Cove Motel and Marina, NY 

Danbury Fish Farms, TX 

Fisherman’s Choice Charters, WI 

Fishin’World, TX 
A - 38 

Fish Partners, CA 

Fletcher’s Bait Service, MN 

Flowers Fish Farm, MO 

Foster Management, TX 

Harry Saul Minnow Farm, Inc., AR 

Island Passenger Service of Flag Island, MN 

J-E Fishing Enterprises, WI 

KB Fish Farm, Inc., AR 

Keo Fish Farm, AR 

Kirchner’s Fishing Kamp, NY 

Lake Fork Guide Service, TX 

Niagara Mohawk, NY 

R.E. Palmer, CPA, Inc., OK 

Sea Dog Charters, MI 

Ship to Shore Aquafarm, CA 

Triple Pugh Farms, AR 

West Central Bait, MN 

Wild Woods Charter Service, MN 

Legislative officials

Congressional Sportsmen’s Caucus, U.S. House of Representatives 

U.S. House of Representatives, Marion Berry, Arkansas 

U.S. House of Representatives, Jay Dickey, Arkansas 

U.S. House of Representatives, Jack Quinn, New York 

U.S. House of Representatives, Bart Stupak, Michigan 

U.S. House of Representatives, Don Young, Alaska 

U.S. Senate, Blanche Lincoln, Arkansas 

U.S. Senate, George Voinovich, Ohio 

New York State Assembly, Michael J. Bragman 

New York State Senate, James W. Wright 

State of Arkansas House of Representatives, Sam E. Angel, II 

Tribes 

Kiowa Tribe of the State of Oklahoma 

White Mountain Apache Tribe, Wildlife and Outdoor Recreation Division, AZ 

Wampanoag Tribe of Gay Head (Aquinnah), MA