30 SALMON ID^ OF BRITAIN. 



is thus secured in that care can be taken to select these breeders in accordance 

 ■v\'ith their age, for, as has been shown, the size of the eggs increases, up to a 

 certain point, with that of the parent, and from these larger eggs finer and more 

 rapidly growing offspring are pi-oduced. In this manner, and by constant selec- 

 tion, breeds may be improved, as has been proved by Sir James Maitland at 

 Howietoun. Although salmon have not yet been kept in suitable ponds for the 

 purpose of obtaining their eggs and stocking our rivers, muoh has been done in 

 other countries.* 



The mode of how to artificially spawn these fishesf requires time in learning 

 and considerable practice in being an adept at, consequently a skilled manipulator 

 will obtain a larger amount of eggs from one which is rijie than will an inex- 

 perienced or a careless one. Whether a fish captured for this purpose is in a 

 suitable condition may be ascertained by making gentle pressure along its 

 abdominal surface, commencing from the ventral fins and stroking it rather 

 heavily towards the vent. If sufficiently forward eggs from the female or milt 

 from the male will, as a rule, be extruded, but in some cases females will not at 

 first be induced to part with their ova and require a little coaxing or even 

 deferring the operation for a short time. Should the ova not be quite ready, the 

 distended abdomen feels hard and the eggs do not move under pressure as they do 

 in ripe fishes ; force should never be employed, because not only are immature 

 eggs valueless but injury may be occasioned to the spawning fish, especially if 

 some ova mixed with blood are expressed. Sometimes only fish of one sex may 

 be obtainable, and it becomes necessary to retain those which have been captured 

 until some of the other sex have been procured, and this may be done in tubs of 

 water, contiguous pools, or even by fastening a large fish, as a salmon, by means of 

 a cord being affixed around its tail, and thus securing it to a stake on the bank of 

 a river, or placing it in a well-boat. 



amount of the water supply, and should the latter be plentiful, shape is of little consequence ; if, 

 however, it is restricted they should generally be deep and narrow. Some employ planks in 

 forming both inlets and outlets, others prefer brick or stone laid in cement. At the intake a 

 means should exist of entirely shutting off the water when required, while the outlet should allow 

 the passage of all the water at the highest possible flood and making allowance for the screens 

 being clogged. These screens should be placed both at the entrance and outlet of each pond, and 

 may be constructed of perforated zinc, or copper or iron wii'e plates, fixed into wooden frames, 

 which securely block both channels ; and in order to obviate clogging from descending dibris an 

 inverted V-shaped frame may be built out in front of the screens. Capabilities ought to exist 

 enabling the waler from the ponds to be drawn off when it is necessary to repah or clean them. 



The results of experiments made in fish-cultural establishments where segregation is not 

 perfect must always be accepted with the greatest caution. Fishes if allowed the slightest chance 

 will range out of the pond in which they are placed. Irrespective of this, if herons, gulls, or 

 dabchicks are about, the chances are increased of a little admixture being occasioned by their 

 dropping fish from one pond into another as they are flying off with their slippery and struggling 

 prey. 



* In Canada Mr. Wilmot had salmon captured in the sea in May and impounded in a tidal 

 pond, until they became ripe in October or November, when they were artificially spawned. They 

 liave also in the United States been imprisoned in rivers for this purpose with more or less 

 success. As such an undertaking in this country would be costly it is improbable that it will be 

 carried out by private individuals, being, in fact, more of a national than private requirement. 



t An ingenious plan, were it sufficiently successful, has been invented by Mr. Ainsworth, of 

 the United States, in order to induce the trout to naturally spawn in a trap so that the eggs can 

 be readily collected. The channel or race, which supplies water to the pond where the breeders 

 are kept, is left open in order to allow them to ascend, but this they can only do for a certain distance, 

 as it is closely fitted by a wooden framework. This has a floor of perforated zinc raised about a 

 quarter of an inch above the bed of the stream, consequently permitting a circulation of water 

 from below, but the perforations are not sufJiciently large to permit eggs to fall through, any 

 which would find their way there from above being thus unable to escape below. A little above 

 this perforated zinc floor is a second similar tray, thus forming a closed chamber. This is like- 

 wise of perforated zinc, but in it the holes are sufficiently large to allow eggs falling through 

 it into the chamber, which has been formed between these two zinc trays. On the upper surface 

 of this upper tray are placed two inches in depth of coarse gravel, which is too large to drop 

 through, and here the trout spawns, and as it forms its redd with its tail, stirring up the gi'avel, 

 the eggs fall through the perforations in the upper tray, into tlie receiving chamber, and can 

 be removed when required. Mr. A. S. Collins has made an improvement by substituting an 

 endless apron for the lower tray, where by means of a roller which is turned by a handle, 

 the eggs can be received into a pan that is removable at will. (Day, Fisli Culture, 1883, 

 pages 20, 30, plate I, fig. 1, 2, 3.) 



