NATURE: Cormorants remain plentiful on Mayo’s inland waters

The words of poet Robert Southey’s 1801 epic, ‘Thalaba the Destroyer’, come to mind: ‘The cormorant stands upon the shoals / His black and dripping wings / Half open to the wind’.
Two full centuries later cormorants stand guard over the small bay into which my favourite stream flows. I counted five that morning, every one of them standing with wings spread, either as an aid to digestion or to let their feathers dry, depending on which book you read.
Low-slung bellies drooped upon cold rock. Yellow mandibles hung agape; cold, blue, disc-eyes blinked from the exertion of preventing each bulging crop from throwing up that last, most recent meal. When they finally flew at the approach of the boat, they found themselves unable to rise more than a few feet under their own weight, but struggled landward over low waves.
Why are they in attendance here? There can be only one reason. Last autumn trout ascended the stream to spawn, and then, with their business complete, those spawned out and weary fish made their way back to the lake where they now make easy pickings.
Nobody would withhold from the cormorant his means of living, if only he wouldn’t insist upon making a party of every occasion. We rarely see him on his own. No, look! Five birds here, half a dozen beyond the next headland and more dotted around every lake in the country, each one more than capable of consuming three or four adult trout every day.
There are two ways of looking at this. One, we begrudge the birds their meal – after all, we want those same fish for ourselves, either to catch them and eat them or to catch them and let them go again, just for the rather dubious fun of it. The cormorant thus becomes our competitor, and because he is more skilled than we ourselves could ever hope to be, he becomes our enemy.
Thus ill will festers in the breast. It is not our own ineptitude that sees us off the lake with another empty creel, but that bird, that ruinous glutton, the one Milton deemed fit to use as a metaphor for the devil himself: “On the tree of life / the middle tree, the highest there that grew / Sat like a cormorant”, an image to which even the thinking angler gives a nod, who is responsible.
Such thoughts are nothing new, for cormorants have been persecuted for centuries, even in Ireland. Until such a late date as 1976 there was a bounty on these birds, with up to half a crown being paid for each head presented to the authorities. Between 1973 and the passing of protective legislation more than 3,500 cormorant bounties were claimed.
The Wildlife Act of 1976 put an end to that, but still, despite each bay of every trout-holding lake having its own itinerant population, the cormorant has joined the Amber List of Birds of Conservation Concern.
This fact hasn’t helped to elevate the bird in the eyes of many. In 2020 the UK government rejected calls from the Angling Trust for a structured cull of the cormorant population there, prompting then Head of Policy Martin Slater to comment: “Whilst the Angling Trust has won plenty of campaigns of late for the benefit of fish and fishing, it’s a matter of extreme frustration for us that governments of all persuasions seem reluctant to acknowledge the damage these invasive birds can do to some of our vulnerable native fish species.”
In this country, the go-to document on the matter is the excellent report commissioned by Inland Fisheries Ireland which, despite the rather daunting title (‘A preliminary assessment of the potential impacts of Cormorant Phalacrocorax carbo predation on salmonids in four selected river systems’) makes very interesting and surprisingly accessible reading.
Back in the United Kingdom, the Moran Committee was established in 1997 to investigate further on this matter. Among the suggestions made were the use of ‘scarecrows, bird-scaring kites, reflectors and flashing lights, as well as noise-generating deterrents such as pyrotechnics, screamers and gas canons’ in order to disturb the birds and disrupt their feeding, at least in the short term.
That sounds just the business. Imagine that quiet evening afloat in search of a trout already swallowed by a cormorant, faced by an army of gun-toting caricature scarecrows, screaming fireworks and fake explosions. Count me in!
On the positive side, predators only congregate where prey species abound. If prey is scarce, predators will disperse. Perhaps the abundance of cormorants on inland waters is more a good sign than a bad one.

Michael Kingdon, a naturalist and keen fisherman, lives on the shores of Mayo’s Lough Carra, the best example of a shallow marl lake in western Europe and therefore an SAC of enormous ecological and conservation importance.