The Double Crested Cormorant is a voracious fish eater. These strange looking water birds can weigh up to five and a half pounds. They have a long, sharp, hooked beak and are strong swimmers with webbed feet and powerful legs. They are very quick and mobile underwater, and are capable of diving to at least twenty five feet.

It has been estimated that cormorants can consume up to half of their body weight in fish and crustaceans each day. That body-weight to fish-consumption ratio is even higher among immature birds. The preponderance of that diet is composed of small fish.

Cormorants are extraordinarily efficient fishers. They consume most small fish that they catch while diving underwater. They only bring the larger fish to the surface where they toss the fish in the air and then swallow it head first.

The largest colony of nesting Double Crested Cormorants in the Western United States and Canada is located at the mouth of the Columbia River. This colony numbers about 13,000 breeding pairs plus immature birds.

On their migration out to sea, young salmon smolts become disoriented when they encounter saltwater for the first time in the River estuary. These temporarily stupefied fish are easy prey for the cormorants. The U.S. Army Corp of Engineers estimates that cormorants kill and consume about twenty million salmon smolts each year in the Columbia River estuary.

These federally protected migratory birds are found nesting all along the Pacific Coast and on inland waterways as well. Another very large nesting colony is found at the mouth of the Klamath River where they prey on out-migrating Klamath River Chinook and Coho salmon smolts in that estuary. Government agencies have no estimate of how many smolts are killed by cormorants in the Klamath River.

Under the protection of the international migratory bird treaties, cormorants have been increasing in population about three percent per year, for the last several decades. They are so tightly protected that biologists have generally been unable to even take enough birds to confirm estimates of their rates of depredation.

Cormorants do spit up the undigested bones that they have consumed in small pill-like balls. Biologists are able to get a rough idea of what the cormorants are eating by analyzing these regurgitated bones.

Cormorants readily and efficiently feed on fresh water fish. Oregon Coastal lakes have been known for their exceptional bass fisheries for decades. Many believe that the influx of cormorants has virtually eliminated natural reproduction among bass in these fresh water lakes because they are only able to find either newly hatched or large bass in those coastal lakes. The cormorants appear to fish so efficiently that they kill and eat almost all of the young bass in these lakes before the fish can mature.

So, why am I talking about coastal cormorants, salmon and bass?

What is NOT commonly known is that the second largest nesting colony of Double Crested Cormorants in the Western United States and Canada is located on Upper Klamath Lake. There may be as many as six thousand breeding pairs of these birds reproducing in the Upper Klamath Basin.

Cormorants prefer to nest in trees. Unfortunately, their fecal accumulations on and under the trees often cause the trees to die. This is likely what has caused the death of many trees adjacent to water bodies including the stately old pine trees where the cormorants nest along the banks of the Lost River near Olene.

These Upper Klamath Basin cormorants also feed primarily on fresh water fish. We can be certain that the birds are not feeding on salmon smolts in Upper Klamath Lake. So what are the Cormorants eating?

The Lost River and Short Nosed Suckers are listed as endangered in the Upper Klamath Basin. They continue to be listed primarily because the young fish are disappearing from the reproduction cycle even though the early recruitment of suckers appears to be phenomenally successful. It appears that tens of millions of sucker eggs successfully hatch each year.

But biologists tell us that the yearling sucker fish simply disappear from the system. They are only able to find very young suckers or mature sucker fish. This is eerily similar to what has happened to the young bass in Oregon’s coastal lakes.

Are we overlooking the obvious? Except for at the mouth of the Columbia River, Upper Klamath Lake has more Cormorants than any other place in the entire Western United States and Canada.

It would seem that cormorants would be super-efficient fishers in a lake as shallow as Upper Klamath Lake. Is sucker predation, by the ever increasing number of federally protected cormorants, responsible for the unexplained loss of yearling suckers?

Biological science is too often based on false premises. Federal, State and Tribal biologists have assumed that the reduction in the numbers of endangered suckers is the result of man-caused changes in their habitat. Hundreds of millions of taxpayer dollars have been spent on studies and restoration activities designed to improve that sucker habitat.

The Biological Opinion that requires the maintenance of artificially high Upper Klamath Lake levels is based upon improving sucker habitat. This Opinion has persisted in spite of the fact that the National Academy of Sciences determined that these elevated lake levels would not help the suckers and might even harm them. Enforcement of that Biological Opinion deprives the Klamath Project irrigators of much of the water that is stored for the irrigation of their land.

Most of the Tribal science used in determining the Upper Klamath Lake Total Maximum Daily Load was gathered for and was predicated upon restoring sucker habitat. That science generally assumed that man-caused ecological changes have resulted in water quality degradation that is causing the demise of the suckers.

Yet after all these studies and related management modifications, virtually no positive change has occurred as measured by either adult sucker fish recovery or water quality improvement. What has changes is that irrigated agriculture in the Upper Klamath River Basin is being irreparably harmed.

Isn’t it time for the biologists to start questioning their own assumptions? Isn’t it time for them to expand their hypotheses to include other potential causes for reduction in sucker numbers?

I am neither a bird nor a fish biologist. However, during nearly thirty years of veterinary practice, I always remembered and attempted to apply the advice of one old veterinary college professor. Doctor Koger began every lecture by telling our class that we should never overlook the obvious.

When will the biologists look to see if the immense population of Double Crested Cormorants living in the Upper Klamath Basin may be simply eating the young endangered suckers?

Please remember, if we do not stand up for rural Oregon no one will.

Best Regards,

Doug