7605

• UCREFRP Catalog Number: 7605
• Author: Schaeffer, L.
• Title: Avian Predators at ODFW Hatcheries
• USFW Year: 1992.
• USFW - Doc Type: Their Identification and Control.
• Copyright Material: YES

predation or disease, and so they stock their ponds with a higher
percentage of fish than that allocated for release. The
overstock requires funds for holding and rearing, but until the
fish are larger, the money required is not substantial. Some
hatchery managers consider the overstock a non-game contribution
that literally "raises" birds like osprey, which attract and
delight visitors. Installation of physical barriers can be
costly and should be weighed against the loss attributed to
predation. When losses are high or valuable fish are lost,
expensive measures to control that loss are justified.

Lethal Solution

The most effective way to control predation on fish is to
kill the predators. In the past, fish eating birds were harassed
or killed by private citizens. Some of this persecution was
legal because all cormorants, common and hooded mergansers, and
kingfishers could be killed legally through 1958. Further,
belted kingfishers and double-crested cormorants could be killed
legally in Oregon until 1972 (Bayer 1989). However, killing
these birds is not an acceptable solution at present. Since
1972, all migratory birds have been protected, but this does not
mean that none were killed.

The U.S. Fish and Wildlife Service issues permits to kill
offending birds only if they". . . cause or threaten to cause
serious damage. Permits to take birds at aquaculture facilities
are issued only after scare techniques, physical barriers, or
both, have been used correctly and qualified u.s. Fish and
wildlife Service personnel certify that these methods have been
ineffective" (Salmon and Conti 1981). Species that are listed as
threatened or endangered by the federal government cannot be
harassed legally in any way.

Similarly, the State of Oregon does not issue kill permits
except under certain conditions. Some species may be killed
during hunting season if they are a game species and all hunting
regulations are observed. Oregon does require that a state
permit be obtained by the landowner to haze or harass wildlife on
private property, but only. when it is necessary to avoid damage
to the property. No hazing on public lands is allowed.

SUMMARY

Responses to two questionnaires about avian predation on
fish and measures to control predation sent to 43 managers of
fish rearing facilities showed that 17 species of birds were
responsible for the predation. Two species of heron, however
accounted for most of the damage. Control measures consist of
frightening devices that scare birds and physical devices that
prevent birds from seizing prey. Frightening devices are
effective only when they are used at random intervals and are

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