>From Marty Schlabach:

At the Cayuga Bird Club meeting recently, someone mentioned a study of the
diet of cormorants on Lake Ontario or Oneida Lake. There was concern that
the study, based on 1,200 cormorants, could mean that 1,200 cormorants were
killed to analyze stomach contents.

Following is the text of the article by J. Michael Kelly in The Post
Standard on Sept 8,1993 which indicates that regurgitated food pellets were
analyzed.


"Cormorants have a hardy appetite for fish but appear to eat only a tiny
fraction of the millions of trout and salmon that are stocked annually in
Lake Ontario, experts said Wednesday night.

James Johnson of the National Biological Survey came to that conclusion the
hard way--by picking apart more than 1,200 food pellets regurgitated by
cormorants on Little Galloo Island.

Johnson said various salmonids, mainly lake trout, made up only about 0.5
percent of stomach contents he and associates analyzed. 'The biggest
component of cormorants' diet by far on Lake Ontario are alewives,' Johnson
said.

Alewives, also the favorite food of the lake's salmon and trout, accounted
for 38 percent of cormorants' diet in 1992 and 26 percent in 1993.

Johnson was one of seven speakers at the cormorants workshop held at the
Dulles State Officials Building in Watertown.

The forum was sponsored by New York Sea Grant, Cornell Cooperative
Extension of Jefferson County and Jefferson County Fisheries Advisory
Board.

Cormorants are a hot topic of discussion in Lake Ontario ports. About
12,000 adult double-crested cormorants live on eastern Lake Ontario during
the summer and eat tons of fish. Johnson's best guess is about 2.4 million
pounds.

Many anglers, such as Henderson Harbor guide Ron Ditch, feel the birds are
a threat to the lake's multimillion-dollar sport fishing industry. So far,
research by NBS and the state Department of Environmental Conservation
indicates such worries are unfounded.

'The cormorants eat approximately 5 percent as much fish by weight in Lake
Ontario as are consumed by predatory fish,' said workshop speaker Lee
Harper, a St. Lawrence University Biologist.

Researchers extimate about 2,600 lake trout stocked near Stony Point in May
1993 wound up in cormorants' gullets, but that was only 3.5 percent of the
total number of trout stocked in the area that month, Johnson said.

In response to anglers' concerns, DEC Great Lakes Fisheries Unit leader
Robert Lange said the state has begun stocking lake trout beyond
cormorants' normal feeding ranges.

As recently as the 1960s there were only 125 breeding pairs of cormorants
in the Great Lakes.

Biologists said cormorants came close to being destroyed in the region
because DDT and other pesticides caused reproduction problems for the
birds.

In the 1970s, DDT was banned by the US Environmental Protection Agency and
cormorant numbers began to rise throughout the country.

By 1990, researchers counted more than 4,000 nests on Little Galloo Island
alone. Birds are so thick on little Galloo that trees have been stripped
of vegetation and shorelines are covered with a foot of dung."


Steve Kelling
Applied Physics, Cornell University
Ithaca NY
(607)255-6327 (work) (607)539-7205 (home) stk2 at cornell.edu