SALMONID^. 65 



tteir redds are often the localities where trout have previously deposited their 

 eggs, which now become routed up and carried away down stream to be devoured 

 by every hungry fish. 



The time that salmon eggs may take before they are hatched is subject 

 to variations as great as from 35 to 148 days, which last period occurred 

 at the Crystal Palace in experiments instituted there, and 144 in the Wenham 

 Lake ice vaults. While acting upon previous experience, Mr. Toul succeeded 

 in transmitting salmon eggs to the Antipodes in small boxes packed in ice, 

 and which retarded hatching until the 145th day. Mr. Branden examined a redd 

 that appeared to have been left dry, but on openiag it found that a little water was 

 trickling through the stones and gravel, which was sufficient to keep the ova 

 healthy. Having scraped a hole, he obtained a considerable number of eggs, and 

 these he transferred to a pail of water, where two-thirds hatched within periods 

 varying from five minutes to twenty-four hours. About a week subsequently he 

 returned to the same spot, and had another dig for salmon eggs (no rise having 

 occurred in the river during the interval). He collected more, and putting them 

 into the water, they hatched as the former ones had done. He very fairly 

 advances that this may be a provision to prevent ova deposited in localities 

 where the depth of the stream is liable to considerable fluctuations, from becoming 

 lost or killed, as must occur unless a delay, to obtain a suitable time, could be 

 provided for. Tor as the floods come and sweep up these redds, the imprisoned 

 ova are let loose, at a time when they are ready to burst and the young to emerge. 

 In fact, like the chrysalis, the eggs may be able to abide a suitable time. 



But salmon eggs, even in redds, are not permitted to rest in peace and hatch 

 in security : they have many accidents to escape from and numerous enemies whose 

 vigilance must be avoided. Not only may floods prematurely sweep away redds 

 with their unripe eggs, but during the contiuuanoe of such, spawning fish are 

 unable to avail themselves of their usual breeding grounds because they are too 

 deep in the water. They consequently may have to shed their eggs in the stream, 

 when they will become lost, or covered with mud, or else push higher up to 

 where there wiU be more chance of their redds being left dry, and the ova perishing ; 

 even in their annual spawning grounds, where their eggs may have been deposited, 

 severe seasons of drought m.ay occasion most disastrous results. Irrespective of 

 the seasons, the eggs have numerous water enemies, as the fresh water shrimp, 

 which hunts out the nest, when they are merciless to the eggs, the larva of 

 the may-fly and of the dragon-fly and even some birds as the dabchick. While 

 swans and ducks enjoy nothiug so much as the spawn of fishes, in which taste the 

 vole or water-rat appears to coincide. Due to the many destructive agencies at 

 work an ingenious plan of artificial hatching and rearing has been adopted with 

 great success, while by regulating the water, droughts and floods are prevented, 

 and many enemies are excluded which run riot among fish eggs left in a state of 

 nature in our rivers. 



Supposing some young fish have come forth, it does not follow that the little 

 ones are strong and healthy. The temperature of the water ought to range out of 

 doors about 42° or 46°, nor permitted to sink below 35°, while if it reaches freezing 

 point, such will most probably be fatal. Should it rise to 50° the eggs may 

 become prematurely hatched : the higher the temperature the sooner the young 

 appear, and the more weakly they may be expected to be. Sometimes the jaws 

 are deformed in the fry, or the spinal column is curved, even two fish may be 

 connected together, like the Siamese twins : likewise two or even three heads have 

 been seen fixed to one body. 



When these little fish emerge from the eggs they have a large bag (the umbilical 

 vesicle) attached to their stomachs : this contains the nourishment which is to 

 serve them for several (three to eight) weeks' subsistence, and they do not 

 commonly take in any food by the mouth until it is absorbed. Weighed down by 

 it they lie quietly among the stones at the bottom of the stream and seek 

 concealment from fish larger than themselves, water insects, and other enemies 

 which now commence to feed on them. 



The salmon is rare in our rivers in comparison with the number of fry 



TT 5 



