Avian Predation of Fish Populations – Is It a Problem, How Do We Know, and What Do We Do About It?

Symposium
ROOM: RSCC, A10
SESSION NUMBER: 8123
 
Increasing abundance and range expansions of piscivorous birds, in particular Double-crested Cormorants and American White Pelicans, have created new and complex resource management challenges for state and federal fish and wildlife agencies. These biological and social challenges are a function of interactions of piscivorous birds with fish populations of high recreational, economic, and/or conservation value. This symposium will examine: the current scope of bird- and fish-related conflicts, (including native/non-native, game/nongame, and stocked/wild populations); the status of available science, including relevant case histories; methods of assessing effects of piscivorous birds on important fish populations; management alternatives, including case studies of effectively managed conflicts; complexities involved in defining free-swimming fish; and challenges of establishing management goals for both bird and fish populations. Ultimately, the symposium is intended to provide a better understanding of the issue to avian ecologists and fishery managers, and acknowledge the need to develop shared objectives for viable fish populations and secure, viable, and socially-acceptable piscivorous bird populations.

8:00AM Avian Predation of Fish Populations – Scoping the Problem, Assessing Science and Values, and Bringing Professional Disciplines Together for Conflict Resolution
  Craig Bonds, David Cobb
Co-presenters will provide a high-level overview of bird- and fish-related conflicts across the United States. Topics will include nuances of regional differences in the issue’s scope by water-body type, bird species of concern, and fisheries resources involved. Co-presenters will discuss challenges associated with addressing natural resource issues that cross-cut professional disciplines exhibiting both shared and conflicting resource values and management objectives. A preview of subsequent presentations in the symposium will be given, along with a brief description of the nexus with a complimentary and closely-related symposium.
8:40AM Migratory Bird Treaty Act 101
  Eric Kershner
Four international Migratory Bird Treaties and the implementing Migratory Bird Treaty Act (MBTA) provide a framework for the conservation and management of migratory birds. The U.S. Fish and Wildlife Service is responsible for the implementation of the MBTA and its regulations. The Service carries out its mission to conserve migratory birds through communication and coordination with other federal agencies, states, tribes, non-governmental organizations, local agencies, businesses, and private citizens. The Service works with its partners on a variety of levels to conserve migratory birds. Bird conservation actions include: (1) complying with the MBTA, (2) protecting birds and their habitats to minimize long-term population-level impacts, and (3) implementing landscape-scale practices that benefit birds. More recently, certain bird conflicts have emerged and the Service must work with partners to resolve these conflicts within the MBTA framework and its regulations. To find effective and efficient solutions to bird conflicts, we must explore and understand the MBTA regulatory toolbox that is available.
9:00AM Species Conflict Framework — a Decision Making Tool
  Laurel Barnhill
As human and bird populations expand, conflicts with human interests (e.g., agriculture, development, conservation of threatened and endangered species), and, at times, with other species, increase. Conflicts occur across social, economic, environmental, and regulatory contexts, and each can be unique in terms of species biology, stakeholders involved, extent of damage, and additional factors. Conflicts can range from minimal, such as a minor nuisance, to potentially significant economic and ecological damages, or risks to human health and safety. To better address situations where a protected migratory bird species is negatively affecting a resource to the extent that intervention is necessary to reduce the effects, the USFWS Migratory Bird Program has developed a systematic approach to promote consistency and coordination with stakeholders in identifying and implementing management solutions. The approach is a conceptual framework of step-wise guidance to identify management options that could be implemented to resolve conflicts, including identifying whether lethal take is necessary, and, if so, to identify the appropriate level of lethal take to reduce the conflict. This process is designed to be biologically defensible and to promote efficiency, effectiveness, and transparency.
9:20AM Managing American White Pelican Predation on Native Yellowstone Cutthroat Trout in the Blackfoot River Drainage, Idaho.
  Jeff Dillon
The Blackfoot River and Blackfoot Reservoir in southeastern Idaho historically produced a trophy-class fishery for native adfluvial Yellowstone Cutthroat Trout (YCT). American white pelicans (AWPE) began nesting on islands in Blackfoot Reservoir in 1992 and the colony quickly expanded to a peak of over 3,400 breeding birds by 2007; concurrently, the YCT spawning population plummeted to just 16 fish in 2005. Subsequent research demonstrated that AWPE were consuming up to 60% of adult YCT spawners and 40% of juvenile outmigrants. Since 2010, active management at Blackfoot has included non-lethal hazing and dissuasion along the river and on nesting islands. Following extensive coordination between IDFG and the U.S. Fish and Wildlife Service, IDFG acquired a depredation permit to allow limited lethal take of adult birds on the river and limited nest destruction on the breeding colony. Predation rates on YCT have declined in recent years, but the staff time and cost of this program exemplify the challenge of managing localized impacts on free-swimming fish by migratory piscivorous birds.
09:40AM Break
1:10PM Managing Recreational Fisheries in Private Impoundments in the Presence of Avian Predation
  John Jones, Lee Schoech
Privately-owned ponds and lakes are ubiquitous features across the Texas landscape and can offer landowners and their guests’ hours of recreational enjoyment. Financial investments in the development and implementation of fisheries management objectives can vary widely but are often substantial. Management activities include purchasing of sport- and forage fish for stocking, habitat enhancements, water quality improvements, invasive aquatic plant control and providing annual reports to illustrate progress. Presenter will discuss observations of the most prevalent avian predators visiting private ponds and lakes, as well as history of utility and successes for both lethal and non-lethal bird-control techniques. Bird depredation affects, both biological and economical, on private fisheries resources will be presented. Potential solutions for resolving bird-and fish-related conflicts with private pond and lake owners will be discussed.
1:30PM An Assessment of Arizona’s Cormorant Populations, Their Impacts on Fish, and Potential Management Strategies to Reduce Impacts
  Larisa Harding, Jacob I Mesler
Little is known of cormorant (Phalacrocorax spp.) habits and population dynamics in the southwestern USA. In Arizona, neotropic (P. brasilianus) and double-crested (P. auritus) cormorants have increased in number and distribution, particularly in metropolitan areas, subsequently increasing anxiety over their potential impacts on aquatic resources. To evaluate their impacts, and to provide empirical data to inform management actions in addressing impacts, we conducted a study with three primary objectives. We first estimated seasonal minimum abundance for both cormorant species in Arizona. Second, we sought to characterize seasonal spatial distributions of both species and investigate bird movements. Third, we explored cormorant feeding habits and environmental factors that likely put fish at risk of predation from cormorants in community fishing waters. To aid efforts, we recruited >100 volunteers to help conduct seasonal bird counts and feeding observations. We also trapped and tagged cormorants and sampled stomach contents from cormorants to document size and shape characteristics of fish prey. To identify key habitat characteristics that influenced cormorant predation on fish, we correlated environmental variables to observed bird numbers at metropolitan fishing waters. We expect these empirical data will help inform management decisions related to cormorant population dynamics, fish stocking, and habitat enhancement practices.
1:50PM Where Does Conflict Come from? Habitat Use Overlap By Humans, Piscivorous Birds, and Sport Fish on High-Use Lakes on the Northern Great Plains.
  Michelle Chupik, Christopher Somers
Human perception of conflict between piscivorous birds and anglers may be a more important management issue than the actual consumption of fish. The perception of conflict can intensify in areas with limited aquatic habitat that is used intensively by humans. Our research addresses aquatic habitat use overlap by humans, piscivorous birds (Double-crested Cormorant, American-white Pelican, and Western Grebe), and important sport fish (Walleye, Northern Pike, and Burbot) on high-use lakes in Southern Saskatchewan, Canada. Acoustic telemetry revealed large-scale movements and broad lake use by fish over multiple time-scales (e.g., > 6 km per day), with an uncertain relationship to human activities. Cormorants and pelicans selected areas of lakes that did not overlap extensively with human activity and developed shorelines. However, Western grebes were abundant in our study area and found in all types of habitat assessed. This was surprising because this species is of conservation concern and considered disturbance-sensitive. The finding that the more common subjects of fisheries complaints, cormorants and pelicans, avoid humans and do not overlap extensively with human lake use raises questions about the origin of conflict.
2:10PM Avian Predation of Fish Populations- Yes, Know, Maybe
  James Farquhar
Concern related to avian predation on fish stocks dates back decades or longer. Recent inquiry quantifying bird/fish interactions along with corresponding human dimensions research provide evidence of both biological and social impacts. While these impacts do not exist everywhere, nor do all factors converge in every case, examples of conflict exist. Published accounts of Double-crested Cormorant, Great Cormorant and American White Pelican interactions with fish resources can be used to illustrate the range of conflict. Complicating the discussion are the complexities of aquatic systems, the nature of fish/bird interactions, and environmental and anthropogenic variables. These factors challenge a “cookbook” approach to definitive assessments in lesser studied systems. In addition, competing values among stakeholders, perspectives on allocation of fishery resources and varied acceptance of risk influence social discourse. The issue of “what we do about it?” remains a thorny public policy matter in that biological and social certainty in choosing an action is generally not possible. Nonetheless, management decisions must be made. Establishing sustainable goals for both fish and birds, performing a credible assessment of risk to each, and articulating well defined monitoring, evaluation and reporting criteria can aid decision-making and overcome anxiety over identified uncertainties.
2:30PM The Best Laid Plans of Mice and Managers: Lessons from Recent Avian Management to Benefit ESA-Listed Salmonids in the Columbia River Basin
  James Lawonn
Predation of juvenile salmonids by Caspian terns and double-crested cormorants is considered to limit the recovery of several ESA-listed runs in the Columbia River Basin. Recent federal management of both of these waterbird species, however, has yielded uncertain benefits. Specifically, recently implemented management plans have resulted in the redistribution of terns and cormorants to unmanaged colony sites within the Columbia Basin and increased nesting density at an existing colony site. Consequently, salmonid survival is unlikely to have improved as anticipated. Efforts at adaptive management have been frustrated by: 1) the willingness of birds to colonize new areas outside the jurisdictional reach of managers, 2) constraints associated with federal policy, 3) the involvement of multiple governmental entities with differing mandates. Additionally, future monitoring related to the plans remains uncertain or appears inadequate to quantify anticipated benefits for salmonids. Effective management of avian colonies can be difficult to implement, especially when potential nesting habitat lies within a mosaic of jurisdictions. When designing avian plans, managers should emphasize long-term adaptive management and monitoring strategies. Finally, managers should consider measuring the success of avian predation management based on long-term monitoring of fish survival, and not on location-specific bird abundance.
2:50PM Refreshment Break
3:20PM Efficacy and Implementation of Non-Lethal Techniques to Manage Conflicts Associated with Cormorants and Other Migratory Birds
  John McConnell, Laurel Barnhill
EFFICACY AND IMPLEMENTATION OF NON-LETHAL TECHNIQUES TO MANAGE CONFLICTS ASSICIATED WITH CORMORANTS AND OTHER MIGRATORY BIRDS. John E. McConnell and Laurel Barnhill USDA, APHIS, Wildlife Services 920 Main Campus Drive Raleigh, NC 27606 John.e.mcconnell@aphis.usda.gov United States Fish and Wildlife Service Migratory Bird Program, Southeast Region 1875 Century Blvd. Atlanta, GA 30345 Laurel_Barnhill@fws.gov Over the past 40 years a significant rise the double-crested-cormorant population (Phala-crocorax auritus) a long-lived fish eating bird has led to cormorant-society conflicts associated with commercial and natural resources such as aquaculture, property and fisheries. Mitigating these conflicts involves an Integrated Wildlife Damage Management approach that incorporates a diverse and adaptive non-lethal program. Damage scale, intensity, resources impacted and migratory bird species involved are variables considered when selecting the appropriate non-lethal methods and technologies. The various types of historic and emerging visual, auditory and exclusionary harassment techniques will be presented including and assessment of tool selectivity, efficacy, and cost effectiveness. Emerging technologies to protect an evolving aquaculture industry and select non-lethal harassment projects targeting fisheries and natural resources protection will be discussed. Migratory birds can cause significant economic damage and management can reduce losses. Non-lethal technique types, effectiveness, limiting factors and tool selection process to mitigate various damage types will be presented.
3:40PM Approaches to Scaling Cormorant – Fish Interactions from Local Conflicts to Regional Goals
  Randall M. Claramunt
The Great Lakes supports several important fisheries including commercial, recreational, and tribal, which are highly valued resources that are jointly managed through comprehensive efforts by all levels of government. There is a long history of the cormorant-fish conflict in the Great Lakes region. However, the conflict is often at the local scale, whereas management objectives are set at the inter-basin scale, and population goals at the region or basin-wide scale. Stakeholders view the conflict only at the local scale and want management actions at that level. Strategies need to be effective at the local level, but also designed to be scaled up to meet basin and regional fisheries and cormorant population goals. Approaches for managing the cormorant-fish conflict in the Great Lakes region range from an Avian Predator Network of volunteers to protect 10 million stocked trout and salmon to a Great Lakes Regional workgroup and a multidimensional framework for managing cormorant and fish in the Great Lakes.

 
Organizers: Gary Whelan, Jeff Dillon, Craig Bonds, James P. Fredericks, Devin DeMario, David Cobb, Scott Anderson
 
Supported by: AFWA Bird – Fish Conflict Working Group

Symposium
Location: Reno-Sparks CC Date: October 1, 2019 Time: 8:00 am - 5:00 pm