EXPERIMENTS WITH SALMON

Otago Daily Times, Issue 22114, 18 November 1933, Page 17

EXPERIMENTS WITH SALMON

HATCHERIES v. NATURE AN ENCLOSED RIVER. (Feom Ode Own Correspondent.) LONDON, October 13. A special correspondent of the Morning Post reports that an experiment of fear-reaching importance to salmon fisheries throughout Great Britain wU] be started soon on the Hampshire Avon by the zoological department of Southampton University College. It will be the first scientific attempt to discover whether man can aid the breeding of salmon more efficiently than Nature. If he can, the annual catch of salmon in British rivers may be enormously increased without the need of a subsidy. If he cannot, all the money spent on salmon hatcheries may have been thrown away. A Royal Commission recommended a scheme of public experiments im connection with salmon breeding-as far back as 1902. A scheme was framed by the Inter-departmental Committee on artificial propagation last year, only to be abandoned owing to the need for national economy. Now the Southampton University College have taken the matter up, as a result of investigations in the Avon, which they are carrying out for the Hampshire Rivers Board of Conservators. They have found that the Avon is stocked with far more food for salmon than is ever likely to be eaten. Unless they can “ make ” more salmon eggs turn into fry than Nature is allowing, this wealth of food will be wasted. The test, therefore, is: “ Can hatcheries do better than Nature—and how much better ? ” COUNTING THE FRY. The percentage of salmon fry artificially raised from given quantities of salmon eggs in hatcheries is known. The experiment must show what percentage —greater or smaller than the hatcheries —is raised by Nature in the living river—and a new river is being made for the purpose. It will be a “ carrier ” on an ideal site on the Avon offered by an enthusiast to the college for experiments. A “ carrier ” is a waterway from one stretch of river to another, closed at each end by sluice gates, and designed to flood water meadows. , Mr J. Barry and his assistants from the college are turning this channel into a little Avon for salmon pairs to mate in late this autumn. A bed of gravel, ideal for spawning, will be laid down, and the water turned in at right volume and speed. Then two pairs of salmon will be netted in the Avon itself just before mating, hastily measured so that the number of eggs the females will lay can bo calculated, and turned into the “carrier.” When the mating is complete they will be let out through the lower sluice gates and fry proof meshes will bo spread across to prevent the young fry from escaping when they hatch. Much later the water will be turned off, and a census of the fry taken. To I allow for changing factors, the experi--1 ment will be repeated for several years, I when Nature’s best average for hatching ! fry can be compared with that artificially j raised. On this and accompanying experiments the future yields of salmon in the Avon, and British rivers in general, may depend.