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Cormorant: A fish-eating scapegoat?

by Barry Kent MacKay

One of the strangest things about the double-crested cormorant is its apparent ability to generate irrational hatred in humans.

The double-crested is one of 39 living (and one recently extinct) species belonging to a family of aquatic birds known by the tongue-torturing name, Phalacrocoracidae, more popularly called cormorants or shags. They are found on every continent and are related to pelicans and gannets.

People think they know a great deal about the super-abundant double-crested cormorant, the only species to nest in Ontario. But much of what they know is myth. Along with many other species of fish-eating wildlife, cormorants are a scapegoat fishermen love to blame for any real or imagined depletion of fish stocks. I have challenged everyone who hates cormorants to name one naturally occurring fish stock, anywhere in the world that has been wiped out by any cormorant species, anywhere, any time. None have.

Double-crested cormorants do eat fish, to the tune of about one pound per day per adult bird, and obviously are a factor in fish population numbers. But study after study has demonstrated double-crested cormorants do not seriously affect fish stocks. They mostly eat species of fish of no commercial value and not favoured by sporting anglers. They also do not take fish that feed "desirable" game and commercial fish species except in highly contrived circumstances (for example, on a fish farm, or in a small bay or behind a dam). Cormorants certainly can cause temporary shortages of fish at the local level, but any more than that, and the cormorants, themselves, would die. They don't have alternative food sources.

They eat so few commercial fish compared to their population it usually makes little or no statistical difference to the numbers of fish available to anglers. As one study put it, "…no study reviewed convincingly demonstrated double-crested cormorants' negative impact (on) sport or commercial fisheries." There are collapses in once robust fisheries reported from around the world, whether cormorants of any kind are present or not, but it is a large suite of factors that have caused those fishery collapses, and primary among them is overfishing by humans.

Still, a lot of fishermen hate the highly visible cormorants. Unlike factors that have truly profound impacts on population sizes of any given species of fish-from zebra mussels to changes in water temperature to introduced non-native salmon species with voracious appetites for native fish.

And, here in Ontario, they are seen as a new creature in our midst. Fishermen remembering (accurately or otherwise) lots of big fish from a childhood in which cormorants were rare or absent, now worry that there are fewer fish. Cormorants are now common and increasingly apparent. This begs the question-steeped in the most basic laws of physics-of how a species, dependent on a finite food supply, can exponentially increase, while its food decreases; the belief is that the double-crested cormorant is a recent invader and our native fish have not evolved defences against the marauder.

But like so much that is believed about this bird, it simply is not true. Ironically, the double-crested cormorant is playing a positive role in terms of protecting native fish stocks, feeding on invasive fish species whose presence is deleterious to human interests.

One of the most frustrated scientists I've ever chatted with is Linda R. Wires, of the University of Minnesota. She has studied cormorants for years, authored many peer-reviewed papers, and cannot understand how both the general public and wildlife managers manage to ignore the facts science produces. She spoke to me as she and a colleague were preparing a paper on the history of the double-crested cormorant in the Great Lakes region.

It is an endemic North American bird (with a small population in the West Indies) that has, within all recorded history, ranged from the extreme northwest of the continent to the east coast. It is inconceivable to think that it has, until recently, somehow avoided the largest fresh water system in the world-the Great Lakes and the complex and vast pattern of post glacial-lakes and rivers covering most of the province of Ontario.

Linda Wires points out that, in 1886, the newly formed American Ornithologists Union began the compilation of bird species of North America in a frequently renewed annotated checklist, popularly known as the "AOU Checklist." It is considered the definitive reference on bird distribution in North America, and is still published periodically as new information becomes available. That first edition, in 1886, gave the Great Lakes as part of the range of the double-crested cormorants. Then, as now, the AOU included the top ornithologists in the continent, and they clearly recognized the species as inhabiting the Great Lakes.

So, too, did Philo Louis Hatch, M.D., (1823-1904) in his pioneering state bird book, Birds of Minnesota, published in 1892, and the Hamilton-based, noted pioneer Ontario ornithologist, Thomas McIlwraith (1824-1903) in our very first provincial bird book, Birds of Ontario in 1886.

In my personal library, I found that The Natural History of the Toronto Region, Ontario, Canada, edited by J. H. Faull, Associated Professor of Botany, University of Toronto, 1913, and the noted Toronto-based ornithologist, J.H. Fleming, listed the double-crested cormorant as occurring in Toronto as rare migrant. I checked other old books I own. In Birds of America, whose Editor-in-Chief was T. Gilbert Pearson, 1917, (and still in print), we read under the species account of the double-crested cormorant, "Distribution-Eastern North America; breeds from Central Saskatchewan, southern Keewatin, northeastern Quebec and Newfoundland…" and also in the U.S.

There are numerous other such early descriptions of the double-crested cormorant's range, all including the Great Lakes, where they either nested, or visited during migration to and from the northern lakes.

Here in Ontario, not too far from the North Channel-where locals consider the species invasive and the Ontario Ministry of Natural Resources is oiling eggs-the Ojibwa people, as reported in 1893, named a rock that is part of a cliff face, "Kakakeshiwishtagwaning", which translates to "cormorant's head." They must have been familiar with cormorants.

My old friend, the late James L. Baillie, (1904-1970) spent most of his career in the department of ornithology of the Royal Ontario Museum, where he was an assiduous chronicler of distribution patterns of birds in Ontario, working in the field most summers through the middle decades of the 20th century with other museum staff, to document bird distribution in Ontario at that time. Even then, in a paper published in 1947, when the decline in this native species was at its height, he recorded it as having been found at Carney Rocks, Black Bay, on the northwestern shore of Lake Superior, reviewing material from "about 1920."

Jim Baillie also noted a report by fishermen (who, then as now, persecuted the species relentlessly) that cormorants nested in the general region of the Mink Islands, in Lake Huron, in 1919. While no actual verification, in the form of preserved specimens or photographs, was obtained (hardly a surprise), Baillie, who was extremely conservative about such matters, was inclined to believe the report was accurate.

The double-crested cormorant was also noted by American ornithologists to be breeding in Agawa Bay of Lake Superior's eastern shore in 1926, where the residents noted that "the cormorants had nested there for years." This suggests they were there prior to the 1920s, although by then, egging and persecution by fishermen had done most of the damage to our Great Lakes population-damage that the application of DDT would virtually complete. (However, there is apparently no time in recorded history when double-crested cormorants were totally absent from the Great Lakes).

Cormorants are generally considered inedible, so one does not expect to find cormorant bones in archeological digs of kitchen middens-bone piles from meat consumed by early people-but in fact they were found at a site Brent County, on the Niagara Peninsula, that dates back to the 16th century.

The myth that the cormorant is alien to our waters seems to stem from the lack of preserved specimens of nests or newly hatched young. In the old days of ornithology, all sightings of bird species were considered, at best, "hypothetical" if they were not backed up by preserved specimens (later clearly identifiable photographs became acceptable). And by this criterion, although the double-crested cormorant was reliably recorded at the Lake of the Woods in the 1790s, it did not become "official" until 1924, when nests were formally collected and recorded on an island in Lake Nipigon.

It is probable there are more cormorants in Ontario now, than ever before. No one can say for sure that there are, but if we go far back in time, we find that the conditions were probably less favourable for the kinds of fish cormorants eat, in the centuries following the retreat of the very ice age that left this province with its immense legacy of lakes, including the Great Lakes system. But they were here, and as colonial nesters, it is likely that there were large populations wherever suitable populations of fish existed.

Nature, even when left alone, is not static. Add human activity, and there is a rapid dynamic that sees many changes in relatively short time spans. This is particularly true of such mobile species of wildlife as birds and fish. One would be hard put to find a species of bird that exists in Ontario now, in essentially the same numbers and in the same locations, as it did one, two, three or nine hundred years ago.

The landscape has changed, and so has the mix of flora and fauna that share our space. Humans have either accidentally or intentionally been responsible for the introduction of hundreds of species of plants and animals that would otherwise be absent from Ontario. And species like the northern cardinal, once unknown in Ontario, have moved north in response to warmer winters and the increased availability of food, thanks to humans.

But the double-crested cormorant has been here all along. Like the wolf, hawk, owl and other predators, the cormorant is often seen as a competitor for game, maligned and hated. But like those species, it is part of our natural environment, a native member of our wildlife heritage.

This is an original story, first published in The Country Connection Magazine, Issue 47, Summer/Autumn 2004. Copyright Barry Kent MacKay.



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