THE STORY OF A CANADIAN WATER PEST.

Otago Witness, Issue 2528, 27 August 1902, Page 66

THE STORY OF A CANADIAN WATER PEST.

(Fis-hing Gazette )

On many parts of Loch Leven, fishing this season is almost a matter of impossibility owing to the dense growths of Canadian water-weed (Anacharis Alsinastrum), which have choked up the shallows and have converted them into long stretches of sub-aquatic vegetation reaching almost to the surface. The weed has also spread to the moderate depths, the result being thai the anglers who visit the celebrated loch are complaining of the smallness of tLeir catches, owing to the number of fish which, after they are hooked, make their escape by boring down into the nearest bed of anacharis, and thus placing a strain upon the tackle which it is un.ible to withstand. It is satisfactory to learn that every possible endeavoor is being made by systematic cutting and wholesale removal to keep the pest within reasonable limits. Theee efforts have, however, so far been without any permanent effect in checking its growth, and they are likely to- continue so until one thing has happened, when che weed will gradually die away and Loch Leven will know it no more.

Of all the plants which grow in Briti&h waters the anacharis is far and away the most hardy and difficult to eliminate. When once it has established itself in a suitable locality it is> impossible to eradicate it by any artificial means short of draining off the water and burning the soil. As an instance of its tenacity I can cite the case of a founiain with a large concreted basin, in which it grew .vith a too pronounced luxuriance, a.nd which, after being emptied for several weeks, was thoroughly scrubbed out with a hot solution of salt and was then allowed to lie dry for another period before being refilled in the hope of getting rid of it. By the end of the summer it was as thick as ever it had been, and, although the scrubbing and drying operations were repeated several times, the superintendent of the gardens, under whose charge the fountain was, and who has left a name behind him as one of the greatest of our British botanical authors, was forced to own that he was beaten by the quiet persistence of the new Canadian immigrant. The exact manner in which the anacharis reached this country appears to be enveloped in uncertainty. There are writers— but I am inclined to the opinion that they are gentlemen of a veiy imaginative turn of mmd — who assert definitely that it was brought over from Canada or from the northern part of America in a cargo of timber. So far, however, as I have been able to trace its history, I think there is no doubt that a^ some time in the early thirties it was introduced here by an enthusiastic scientist, whose name ' has not been handed down to posterity, a<- a curious and interesting botanical specimen, and a fow sprays were presented to the Botanical Hardens at Kew, Oxford, and Cambridge. As nothing was then known of its habits, it was placed und^r gla&a, and, 'avoured by the high temperature of the houses, it grew at such an abnormal rate that the gardeners, in self-defence, were compelled to trim it down to reasonable limits. Ea<:h of these places are situated on the banks of a river, and the natural inferance is that the clippings, mixed with other rubbish, thus found their way into English waters. This assumption is strengthened by the fact that the appearance of the anacharis was recorded almost simultaneously in the eastern counties and in the Thames Valley, and where, not long afterwards, general consternation was caused by the virulence of its growth, which choked up the ditches and streams in a truly appalling fashion.