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Great blue heron, Ardea herodias eating a fish at a fish farmBird Damage at Aquaculture Facilities

Fig. 1. Great blue heron, Ardea herodias

 

W. Paul Gorenzel
Staff Research Associate
Department of Wildlife, Fisheries and Conservation Biology
University of California
Davis, California 95616

Fred S. Conte
Aquaculture Extension Specialist
Department of Animal Science
University of California                                                          
Davis, California 95616

Terrell P. Salmon
Wildlife Extension Specialist
Department of Wildlife, Fisheries and Conservation Biology
University of California
Davis, California 9561

Table 1. Bird species reported as predators at aquaculture sites in North America.

Common Name Species Common Name Species
Common loon Gavia immer Red-breasted merganser Mergus serrator
Western grebe Aechmophorus occidentalis Hooded merganser Lophodytes lucullatus
Eared grebe Podiceps nigricollis Bald eagle Haliaeetus leucocephalus
Pied-billed grebe Podilymbus podiceps Osprey Pandion haliaetus
American white pelican Pelecanus erythrorhynchos Red-tailed hawk Buteo jamaicensis
Brown pelican Pelecanus occidentalis Northern goshawk Accipter gentilis
Double-crested cormorant Phalacrocorax auritus Northern harrier Circus cyaneus
Anhinga Anhinga anhinga American coot Fulica americana
Least bittern Ixobrychus exilis yellowlegs Tringa spp.
American bittern Botaurus lentiginosus Franklin's gull Larus pipixcan
Black-crowned night-heron Nycticorax nycticorax Ring-billed gull Larus delawarensis
Yellow-crowned night-heron Nycticorax violaceus California gull Larus californicus
Green-backed heron Butorides striatus Herring gull Larus argentatus
Little blue heron Egretta caerulea Glaucus gull Larus hyperboreus
Great blue heron Ardea herodias Caspian tern Sterna caspia
Cattle egret Bubulcus ibis Common tern Sterna hirundo
Snowy egret Egretta thula Forster's tern Sterna forsteri
Great egret Casmerodius albus Black tern Chlidonias niger
White-faced ibis Plegadis chihi Great horned owl Bubo virginianus
White ibis Eudocimus albus Barred owl Strix varia
Wood stork Mycteria americana Belted kingfisher Ceryle alcyon
Mallard Anas platyrhynchos American crow Corvus brachyrhynchos
Northern pintail Anas acuta Fish crow Corvus ossifragus
Blue-winged teal Anas discors Common raven Corvus corax
Wood duck Aix sponsa Black-billed magpie Pica pica
Redhead Aythya americana American dipper Cinclus mexicanus
Greater scaup Aythya marila European starling Sturnis vulgaris
White-winged scoter Melanitta fusca Common grackle Quiscalus quiscula
Surf scoter Melanitta perspicillata Boat-tailed grackle Quiscalus quiscula
Bufflehead Bucephala albeola Brown-headed cowbird Molothrus ater
Common merganser Mergus merganser

Identification

Reduction of the damage caused by fish-eating birds requires accurate bird identification and some knowledge of avian biology and habits. Responsible bird management requires knowledge of both the problem species and other birds that use the aquatic habitat without harming aquaculture efforts. Not all birds are harmful to production efforts. Birds only become a problem if their activities directly or indirectly result in fish loss. Many species benefit from the association with production facilities without interfering with production efforts.

Table 1 lists 61 species of birds reported as pests at aquaculture sites. Table 2 presents a brief description of the appearance, characteristic feeding habits, and behavior of birds responsible for damage. Although some birds are limited in the way they feed and may be easily deterred by control measures, many birds have a repertoire of feeding behaviors available to overcome various damage reduction schemes. As an example, Table 3 illustrates the variety of feeding behaviors used by six species of herons.

Damage and Damage Identification

The open-water areas and large concentrations of aquatic livestock at aquaculture facilities are natural attractants to many birds. Birds can have a significant economic impact on the culture of aquatic products including fish, shellfish, crustaceans, and other invertebrates. For our purpose here, we will refer to these birds as fish-eating birds, and the aquatic products as fish.

Table 2. Identification and description of the feeding habits and behavior of birds commonly responsible for damage at aquaculture facilities.

great blue heron, black-crowned night-heronHerons

Description:

Feeding and Other Habits:

Cormorants

CormorantDescription:

Feeding and Other Habits:

GULLS

gulls Description:

Feeding and Other Habits:

Terns

Feeding and Other Habits:

MergansersMergansers

Feeding and Other Habits:

blackbirdBlackbirds

Description:

Feeding and Other Habits:

Belted kingfisher