Introduction |
Taxonomy |
Morphology |
Distribution |
Diet |
Size |
Aging |
Spawning |
Predation |
Extinction |

The Arctic Char, Salvelinus alpinus, in Ireland

Food and Feeding
Fundamentally arctic char are, like most salmonids, opportunistic feeders, but their diet is often constrained by what is available. Many landlocked populations are planktiverous. Planktiverous char are most frequently encountered in lakes where they co-exist with trout. In lakes where they exist on their own they occupy a feeding niche largely similar to that of brown trout, feeding on aquatic and terrestrial invertebrates and small fish.

However, where trout and char co-exist the char are often forced to utilise the less productive zones of the lake by the more aggressive behaviour of their less well bred cousins. These include the benthic portions of the lake where productivity is low due to lack of sun light and the deep (>5m) unproductive pelagic zone. Where food is abundant trout and char may have similar feeding habitats, but where it is scarce there is nearly always segregation. Char exhibit a high degree of development in the gill rakers, which are finer than those of trout, and it is thought that for this reason they can exploit a food niche unavailable to larger trout. The finer gill rakers are thought to make the char more efficient at straining the plankters from the water.

The char of landlocked populations in Ireland are therefore most often found feeding benthically or on the zooplankton of the lake. However, in some lakes they are known to segregate according to feeding behaviour. This leads to separate populations of char which feed almost exclusively on plankton, on benthic organisms or on fish. All populations of char in Ireland either feed benthically, on the plankton or on a mixture of both. On warm summer evenings char may be seen dimpling the surface, feeding on cladocera, a planktonic organism which migrates up through the water column in the evenings, and on tiny emerging flies at the surface. At this time they may be caught by the more careful angler.

In some Irish lakes where char are present, the productivity is so low that the standing crop of phytoplankton does not support sufficient numbers of zooplankton to provide the char with a substantive food source and under these conditions the char will be found to feed where ever there is more food.

Typical components of Char diet in Ireland.