Roach a threat to our game fisheries

Outdoor Living

PREFERABLE PERCH Perch might be cannibalistic, but they are preferable to voracious, invasive non-native roach, which are depriving juvenile trout and salmon of the food they need. Pic: John Shelley

Country Sights and Sounds

John Shelley

The fine spring brought something of a bonanza to Carra, in the form of the most prolific spawning of coarse fish I have ever witnessed. Nor is it just here, but the weedy shallows of most waterways are currently thronged with densely packed shoals of tiny fry.
On Lough Carra it is perch that have come to the fore. Other lakes have high populations of non-native fish species, such as roach.
A look over the parapet of Pontoon Bridge is an eye-opener as to the severity of this problem, for there in the narrow cut that connects Loughs Conn and Cullin lie countless thousands of these invasive fish, so many, in fact, that our native species have been driven out, displaced and banished to less favourable stretches of water.
The roach, meanwhile, feed themselves on every living thing the current carries to their ready mouths, whether it be microscopic plankton or larger insect life. In doing so they deprive juvenile trout and salmon of a living. Unless something is done to remedy the situation the reputation of these once world-famous game fisheries will continue to decline.
Inland Fisheries Ireland completed a fish stock survey of Lough Cullin in 2018, at which time roach were already by far the dominant species, despite their only being introduced some time in the 1990s. In that survey, a small number of nets of various types were set in the lake over a period of three nights during the month of August. Among the fish taken were 602 non-native roach compared to a mere 23 native brown trout, the fish that formerly attracted anglers from around the world and supported two local hotels plus numerous ghillies and boatmen.
So where did these undesirable roach come from? It seems likely they were introduced by pike anglers, who had been using imported roach as live bait. (The use of live fish as bait is illegal in this country, as is the unlicensed importation of live fish.) Surplus bait would have been released into the water, and so from the illegal and careless actions of a few we are now witnessing the decline of an extremely valuable resource. It is very difficult to see the situation being reversed.
What can be done?
One potential part-solution would be to establish a commercial net fishery. There is considerable demand for quality coarse fish for restocking fisheries in the United Kingdom. One company there has roach of between eight and ten inches advertised at £3.50 per fish and bream of the same size at £6.50 each, or £9 per pound. One sweep of a net below Pontoon Bridge could prove very lucrative, and the money raised could be used to partially restore the quality of salmon and trout fishing.
Coarse fish spawn during the spring in reasonably well defined areas and could easily be netted in large numbers. Many fish unfit for sale as livestock could be suited for human consumption. Is it only in this country that people turn their noses up at a coarse fish dinner? It wasn’t long ago that such sea fish as pollock and dogfish were barely considered good enough for the cat. Now these are commonly seen on the fishmonger’s slab. Any surplus could be used as fertiliser or pig food. It has to be a winner.

Perch bonanza
But back to the perch on Carra. After intense spawning activity the numbers of resulting perch fry were incredible. All around the shoreline dense shoals of tiny, almost transparent, half-inch fish appeared. By the middle of June the fry had increased in size to an inch or more, and were beginning to be noticed by their parents.
Each evening battalions of larger perch began assembling in various locations. Some of these were composed of many dozens of fish, which would spread out into a long line and advance slowly through the shallows, herding their offspring before them. When I stood motionless in just a few inches of water I was soon surrounded by small fish, which in turn were encircled by the larger ones. Then began the slaughter, as sections of the encircling army took turns to crash into the crowd of terrified prisoners.
In an extraordinary half hour I took over 40 perch of between eight and ten inches with my fly rod and shared the bay with two herons, a pair of great-crested grebes and a large otter, all of which had come to join the feast. I shall go again, of course, while others figure out how to save our trout.