Dear editor:
This letter addresses comments made by Mike Baranowski (“Fishing is for the birds”–July 19), Lyle Armstrong (“Cormorants cause headaches for area cottagers”–July 19), and Allan Kielczewski (letter to the editor–July 26).
First, each one claimed cormorants consume large quantities of sport fish. Studies have repeatedly shown, however, that cormorants feed primarily on small, largely non-commercial, shallow-water fish.
Cormorants consume about one pound of fish flesh per day. They do not, as Mike Baranowski stated, eat their weight in fish each day. And, only two-three percent of the cormorant diet is large, major sport fish.
So 4,000 adult cormorants, for instance, eat only 80-120 pounds per day of large sport fish such as walleye and northern pike. An insignificant amount indeed. And, they only visit local waters for about 140 days of the year.
Incidentally, there are no population surveys that support Allan Kielczewski’s claim that 4,000 cormorants inhabit Rainy Lake.
Secondly, all three claimed cormorants consume large quantities of prey fish, and thereby indirectly impact sport fish populations.
Again, a population of 4,000 adult cormorants would consume about 3,900 pounds of small prey fish per day. While this may seem significant, studies repeatedly have shown that cormorants consume about 0.5 percent of all prey fish available–which is insignificant when compared to the more than 13 percent taken by sport fish.
All the scientific evidence, therefore, proves cormorants are not impacting large desirable fish. Suspicions to the contrary are entirely unfounded.
Mike Baranowski and Allan Kielczewski both expressed concern about the impact the cormorants has on perch–the number-one commercial fishery and single-largest component of the cormorant diet. Here the impact of the cormorant is less clear than its impact on sport and other prey fish.
Nevertheless, cormorants eat about 20 times less perch than the amount taken by predator fish. And there is no evidence predator fish populations are declining because food is scarce. Indeed, local predator fish populations are now higher than they have been in decades.
If, however, perch populations do decline in the future it could be, in part, because of increased cormorant populations.
Mike Baranowski also misled his readers when he suggested fish-eating birds are responsible for walleye catch limits being dropped from six to four and then to two. It was overfishing by anglers and commercial harvesters, not cormorants, that first caused historic declines in predator fish populations, which then led to the introduction of angler catch limits.
Similarly, in the 1940s and 1950s, overfishing-induced fluctuations in fish predator-prey populations, coupled with ecological ignorance, led to cormorant control measures.
Incidentally, Allan Kielczewski does not mention whether his control attempts were government-sanctioned or not. Regardless, his method of persecution likely only slowed their population growth because after the nest and eggs were destroyed, the breeding birds would have simply laid another clutch elsewhere in a more secretive location.
The cause which appreciably reduced fish-eating bird numbers was not intentional; instead, it came with the wide-spread usage of the insecticide DDT and other persistent toxic chemicals.
Allan Kielczewski cites the example of Asian fisherman using cormorants to catch fish for human consumption as the basis for his argument that cormorants are non-selective feeders. Similarly, after watching a documentary about Asian cormorants, Lyle Armstrong is convinced the Double-crested cormorant (DCC) is harming local fish populations.
They’re both wrong. The findings of the Lake of the Woods diet study is supported by each and every one of numerous other existing studies conducted on the DCC in North America. One contrary television documentary should not form the basis for an intelligent argument against scientific study after scientific study.
Moreover, the DCC are not to be compared with cormorants in Asia.
There are 37 species of cormorants in the world. Of the six found in North America and northern Mexico, the Double-crested cormorant is the only species that frequents freshwater lakes and rivers. DCCs are native to the area, not Asian imports, with archaeological bone evidence establishing their presence on Lake of the Woods back as far as the 1790s.
Their appearance over the past 20-30 years into locations in which they have not existed in recent memory likely represents recolonization of areas in which they occupied in the past.
Increases in population are a result of contaminant levels having decreased, an increase in the food supply of fish, and legislation which now protects cormorants.
Mike Baranowski, Lyle Armstrong, and Allan Kielczewski got some things right. The islands on which the DCC nest are stripped of their natural vegetation, and give off a foul odour from an accumulation of excrement and dead birds. And the birds’ feces do contribute to poor water quality.
If, however, the vegetation is not of local, regional, or provincial significance, they should not be concerned. And all surface water obtained for drinking should be treated regardless of proximity to nesting sites. Area lakes support a wide variety of organisms that can be directly or indirectly harmful to human health.
After all, we would not accept our town water if it was not treated.
As for Allan Kielczewski’s suggestion that the increase in cormorant numbers is not good for our ecosystem, most of your readers are bright enough to answer for themselves the question “you mean species richness (number of individuals within a population) and biological diversity (number of naturally occurring different organisms ) is not indicative of a healthy ecosystem?”
Finally, I will comment on the caption which appeared below Jennifer Battler’s photo of cormorants fleeing an oncoming boat (Aug. 2) which read, “Cormorants have been a point of contention between anglers and naturalists . . . .”
Anglers and naturalists are not, and never will be, mutually exclusive groups. That is, many anglers are naturalists and vice versa.
Sincerely,
Gordon Earle
Fort Frances, Ont.
Fort Frances Times
Local News from Across the Rainy River District
