Canoeists enjoy running rivers in the winter months. Whilst keen to

see sustainable use of waterways, the Loughs Agency urges paddlers

to avoid trampling across gravel at this time as fish eggs are

likely to lie in voids within the material (the Agency is charged with

management and conservation of the fisheries of the Foyle and Carlingford


Salmon and trout deposit their eggs (“spawning”) in the gravel of

swift flowing rivers and streams from November to January. In

spawning, the fish make “nests” (or “redds”) in the gravel using their

tails. Redds form an elliptical profile, with a hollow (or “pot”) upstream

of a slightly raised tail, formed from excavated material. The

eggs take many weeks to mature, meaning that delicate salmon and

trout eggs and fry are likely to be within the gravel from November

to May.

Trout will redd in gravel from 4mm to 65mm in diameter while

salmon can redd in gravel 30mm-80mm in diameter. Although the

eggs are usually deposited some distance below the surface, they

remain susceptible to damage due to compaction and siltation (due

to people walking on the redd material, for instance), processes that

cause a reduction in permeability of the redd material and, hence,

suffocation of the eggs due to reduction in the amount of oxygenated

water running by.

Disturbance of river gravel is likely to have a detrimental effect on

populations of salmon, sea trout and brown trout and the ecology of

the river as a whole.


For further information please contact the Loughs Agency on

Ph: 028 7134 2100.