An invasive species has escaped into the River Faughan following the floods last week prompting the Loughs Agency to issue an urgent ‘kill on sight’ appeal.
There have also been several sightings of the foreign intruder in both the Strule and Mourne this week.
On Friday the Loughs Agency confirmed a number of Rainbow Trout - native only to the North Pacific area of North America - had escaped into rivers within the Foyle Catchment during the floods last week.
Officers explained how the Rainbow Trout is a non-native species that has been farmed all over Ireland for several decades.
The agency has asked anglers to remove and kill all Rainbow Trout caught; note the time, date and place of capture; and, if possible, leave samples of Rainbow Trout caught into the Loughs Agency Headquarters, Prehen or contact a Fishery Officer and ask him/her to transport these samples to Prehen for further evaluation and analysis.
Rainbow Trout (Oncorhynchus mykiss) and Brown Trout (Salmo trutta) are of the same family (the Salmonidae) but are different species.
They have the same ancestors but divided into two groups around 15-20 million years ago. Oncorhynchus became isolated in the North Pacific and Salmo in the North Atlantic.
Rainbow Trout can have a pink stripe running down either side of the fish. However Rainbow Trout are often muted in color and thus they sometimes appear more silver than pink.
Rainbow Trout do not have leading, white, edges on their Pectoral, Pelvic, and Anal fins and they do not have light colored halos around the dots on their sides.
Also, when the pink color is muted, they will often display a faint pattern of diamonds placed adjacent to each other running down each side of their body.