SALMONID^. 61 



they spawn In the -winter. If summer is the spawning time of the charr and trout 

 of the lakes of Southern Austria, it is connected with or owing to the waters at 

 that time being of the temperature best fitted for the purpose, most of these lakes 

 being fed by mountain streams, frozen in the winter, and full in summer from the 

 melting of the snow." In Sweden, Artedi remarked that the salmon spawned in 

 the middle of the summer. Dr. Heysham stated that iu Cumberland salmon at 

 first prefer spawning in the warmer streams, leaving the snow-fed ones until later 

 on. Tarrell considered that " rivers issuing from large lakes afford early salmon, 

 the waters having been purified by deposition in the lakes ; on the other hand, 

 rivers swollen by melting snows in the spring months are later in their season of 

 producing fish, and yield their supply when the lake rivers are beginning to fail." 

 I think that without multiplying instances the fact may be fairly assumed that 

 temperature has some influence in the locality selected by salmon for breeding 

 purposes, the colder and more exposed streams being usually left until somewhat 

 later than the warmer ones, while in very cold regions spawning may be deferred 

 even until the summer months. 



Were the foregoing views correct, and if temperature irrespective of 

 geographical location has a marked influence upon the time these fishes spawn, 

 we ought to be able to observe such among the trout and Aruidnromoiis Salmonoids 

 despatched in the form of ova to Tasmania from this country. Turning to 

 Mr. AUport's account (Proc. Zool. Soc, 1870, p. 25) we find a most marked 

 corroboration of these views. We know the cold season in that portion of the 

 globe corresponds with our summer, and the very first brook t]X)ut which were 

 spawned in Tasmania occurred on July 3, 1866 ; by the 7th of August fourteen 

 females had been stripped, and shortly afterwards five pair of trout were observed 

 constructing redds in the River Plenty. During June, July and August, 1867, the 

 trout were again stripped of their ova artificially. In this country, as observed by 

 Buckland, trout spawn at different periods in different rivers from about September 

 to February. The very first Tasmanian bred trout hatched from English trout 

 eggs have not selected the month for spawning adopted by their ancestors in this 

 hemisphere, but have chosen others which are better suited for their purpose, 

 clearly demonstrating the possibility of trout being capable under changed 

 conditions of varying the period of the breeding season. 



But because temperature exercises a manifest influence as to when and where 

 the eggs of Salmonidce are deposited, it does not follow that it is the temperature 

 of the water which is the sole cause the salmon has under consideration as to the 

 period at which it shall enter certain rivers, some of which are known to possess 

 spring fish, or such as ascend from March until June, whereas in others they more 

 commonly pass up during and after September. 



I will first give an instance of a river which was originally an early one, but was 

 found to become a late one by the Earl of Home, who, in 1837, observed " that 

 in the Tweed a very great change has taken place within these twenty or thirty 

 years ; a considerable portion of the breeding fish not arriving into breeding 

 condition until long after the time they had formerly been in the habit of doing 

 so." But here the question arises whether this had happened consequent upon 

 any changes in the river, or alteration in the natural period of spawning in the 

 fish irrespective of the condition of the waters. The river itself, it is observed, 

 had changed due to the draining of the sheep farms on the hills, the effect 

 produced being that a little summer flood which took a fortnight or three weeks 

 to run off previous to 1795, is now completely run out in eight hours. The bogs 

 on the hill sides, which were the feeders to the river, have the water at once 

 carried off by drains, causing sudden but short floods, which have all run off 

 before the river has had time to clear itself. Sir H. Davy compared the Tweed 

 district as it was prior to these drains, to what it had become subsequent to their 

 construction — to two houses, the one covered with thatch, and the other with 

 slate ; the first dripping for hours after the rain has fallen, the other ceasing when 

 the rain stops. 



If sufficient water for ascent does not exist, if no safe-holding pools are present, 

 as observed by Mr. Brandon, a spring salmon would have but little chance of 



