76 SALMON! DiE OF BRITAIN. 



the last few dorsal rajs, the wire being threaded to a needle, and so readily 

 passed through, the ends being twisted together in a loop. But the aluminium 

 tags became brittle after being a short time in water, and fell off, so platinum wire 

 and tags were substituted, and seem to be durable. 



The subject of "early" and "late" rivers has been already remarked 

 upon, whether these are coincident with the ascent of clean fresh-run fish 

 or the period at which they breed, which latter occurrence generally takes place 

 in Great Britain between the middle or last week in October until the middle of 

 February or even later.* Those eggs deposited early in the cold up]3er waters of 

 rivers would take longer hatching than such as are in warmer affluents lower 

 down and nearer to its mouth. Instances have been adduced (page 63) wherein 

 these fish have been observed going to the redd in March ; but it is not 

 improbable that the progeny from such late breeders would be few, even if any 

 survived, as the redds are often prepared in unsuitable places. For the late 

 migrants are mostly fish which are weakly or have been detained en route, and 

 consequently have to be satisfied with forming their redds in the lower portion of 

 the rivers, where disturbing influences are most prevalent. f The time during 

 which salmon remain in our rivers for spawning purposes is rarely less than three 

 months, but such must be regulated by many causes, as distance to be traversed, 

 accessibility, temperature, &c. ; while there are certain fishes in which abnormal 

 development occurs by having eggs at unusual seasons.^ 



Prior to following out these periods more in detail, several questions in the 

 life-history of these fishes require solution, while others which it is believed have 

 been solved may perhaps be found to be worthy of still further investigation. 

 We have had it proved that salmon eggs deposited in the sea necessarily die from 

 the direct injurious effects of the saline water 5 we know that young salmon or 

 grilse give smaller ova than older and more mature salmon ; while we are also 

 aware that the size of the eggs in the ovary of one of these fishes are not all the 

 same. The age at which tliese fishes first breed has been a disputed point, while 

 the experiments made at Howietoun may be open to discussion as to whether 

 fishes artificially raised, and subsequently retained semi- domesticated in fresh 

 waters without being able to descend to the sea, carry on this function similarly 

 to those in a wild state. Can it be that the breeding in the females under such 

 conditions, it may be asked, is deferred for a season ? but, no data on which to 

 base such a theory actually exist. 



It must be evident that forming conclusions as to age simply from observing 

 fish in rivers at different times of the year, but helieved to be the same brood, 

 would be liable to give rise to more or less error. While, as already observed, 

 marking fish should be done more carefully and systematically than at present to 

 furnish reliable facts. On the other hand when care is taken, as at Howietoun, 

 to segregate the fishes forming the different experiments, data are obtained which 

 must, as a rule, be more or less doubtful among fish in a river. The Howie- 

 toun experiments have shown that young male and female salmon kept in 

 suitable fresh-water ponds^ may develop milt or ova. Some were hatched in 



* In the Tay, spawning is said to usually commence about Martinmas (November lltli) ; but 

 in 1881 fish were not found rijDe by the Stormontfield fish-culturists until December 22nd or 

 23rd ; while in 1883 it was not until December 31st that the hatchery was fully stocked. Teith 

 salmon are said to spawn a little later than those of the Tay; and Mr. Napier, the local 

 superintendent, observed that, as a rule, the period is from November 22nd or 23rd, and lasts 

 until the early part or middle of January. 



f Late fish when forming their redds frequently rout up those which were existing in the 

 same spot, and consequently many ova are carried away down stream. It has been remarked that 

 this procedure permits of any diseased eggs being washed away and not left to contaminate the 

 good ones ; but it does not seem improbable that such treatment is worse than the disease. In 

 some seasons, when the water in the rivers is too low for breeding fish to ascend, they deposit 

 their ova at the mouths or in the sea, occasioning the loss of the year's supply of eggs. For 

 when the ova are ripe for extrusion, the female even by the muscular exertion of swimming or 

 partaking of food, and so distending the abdomen, may cause their expulsion. 



J In The Field of April 30th, 1881, an account was given of one 15 lb. weight with ova the 

 size of No. G shot captured in the Severn above Shrewsbury. 



