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GLIN==> Cormorant Research Special Edition of JGLR

Posted on behalf of Gerald Matisoff <editor@iaglr.org>

June 25, 2002

Cormorant Research Special Edition
Journal of Great Lakes Research 28(2) International Association of Great
Lakes Research 2002

The common cormorant or shag
lays eggs inside a paper bag
the reason you will see, no doubt,
It is to keep the lightning out.

But what these unobservant birds
have never noticed is that herds
of wandering bears may come with buns
and steal the bags to hold the crumbs

ANN ARBOR, Mich. -- For a long time, humans have viewed cormorants as
competitors for fish stocks. In 1998, concern over loss of fish to
cormorants erupted into violence with an illegal attempt at cormorant
population control that occurred on islands in eastern Lake Ontario.

A special edition of the Journal of Great Lakes Research includes a set of
eight scientific papers that report the results of research on cormorants,
their use of habitat, and diet in the Great Lakes.

Extensive new results relating to the impacts of cormorants on various Great
Lakes fish populations and herons can be found alongside reviews of the
state of scientific knowledge regarding related management issues such as
the detrimental effect of cormorants on rare native Carolinian vegetation
(their acidic guano is rich in nitrogen and phosphorus) and on other
colonial nesting birds. This work should help guide development of sound
management strategies that will protect both the fishery and these
interesting birds.

In general, research indicates that the effects of cormorants on fish are
likely to be localized to areas close to nesting sites. Where a local
cormorant population is high, and an easy supply of fish is available (for
example in small enclosures such as aquaculture lagoons and small ponds),
there can be significant economic losses. In the shallow waters around the
shores of the islands in Lake Erie, close to their nesting sites, cormorants
may be removing more fish than the anglers and commercial boats. Removal of
small spawning fish or young fish of significant species (including yellow
perch and smallmouth bass) has had broader impacts in several specific

Cormorants tend to fish in shallower water (less than 10 meters), and avoid
the deeper waters, whereas much of the commercial fishing occurs in more
open areas. It is difficult to assess the relative effect of cormorants on
the Great Lakes Fishery; more accurate estimates of the total fish
populations are needed. Cormorant preference for coastal areas brings them
into significant contact with boaters, particularly recreational boaters who
also concentrate in the nearshore areas. Public perception of cormorants may
reflect the fact that cormorants and boaters use the same shallow water
areas, so they tend to see a lot of each other!


For more information about this study contact Dr. Martin A. Stapanian, U.S.
Geological Survey, Lake Erie Biological Station, 6100 Columbus Ave.,
Sandusky, Ohio; Martin_Stapanian@usgs.gov; (419) 625-1976.

For more information about the Journal of Great Lakes Research contact
Gerald Matisoff, Editor, Journal of Great Lakes Research; Professor and
Chair, Department of Geological Sciences, Case Western Reserve University,
Cleveland, Ohio; editor@iaglr.org; (216) 368-3677.

Journal of Great Lakes Research: http://www.iaglr.org/jglr/journal.html

IAGLR Web Site: http://www.iaglr.org


Since 1967, IAGLR has served as the focal point for compiling and
disseminating multidisciplinary knowledge on North America's Laurentian
Great Lakes and other large lakes of the world. IAGLR communicates this
knowledge through publication of the Journal of Great Lakes Research
(established in 1975) and sponsorship of an annual conference on Great Lakes
research (begun in 1953).

The association's membership has grown from 225 scientists in 1968 to nearly
700 scientists, policy makers, engineers, resource managers, and graduate
students from the United States, Canada, and 20 other countries in 2002. In
addition, IAGLR's membership includes more than 250 libraries throughout the
world. IAGLR is a nonprofit organization supported primarily by membership
dues, private donations and income generated from its annual conferences.

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