78 SALMONID^ OF BRITAIN. 



Some auttors iave laid great stress upon the weight of the eggs in these fish 

 at different stages as compared with that of the mother, but very unnecessarily so, 

 for such affords but little, if any, useful information. The eggs up to a given 

 point constantly increase in size and weight, consequently their comparison with 

 that of the body of the parent, which remains the same or even diminishes in 

 weight, must be almost daily changing. 



Salmon are provided with numerous eggs in order to meet the destructive 

 agencies to which the ova and young are subjected, and these are as a rule 

 sufficient to counterbalance natural waste, which, however, must be enormous,* 

 for the number of eggs which each female salmon produces has been estimated at 

 about 900 for every poxmd weight of the parent fish, but they may exceed these, 

 thus one weighing 20 lb. contained 27,850 eggs.f It is very obvious that the 

 number of young reared from fish left to nature is far less than what obtains 

 in those artificially propagated. In the Tay, so soon as artificial propagation 

 commenced, the augmentation was as much as 10 per cent., an increase not 

 apparent in rivers in which this mode of fish cultivation was not carried on. 

 This is now adopted in many rivers where the eggs in their naiTural state prove 

 unequal to the destructive agencies that affect them. While the number 

 removed for this purpose from streams is but a small percentage to what 

 remains.J 



It has already been observed (p. 26) that immaturity of parents may occasion 

 sterility of the eggs or disease, as dropsy, of the offspring, while, although, as I 

 shall have subsequently to observe, it has been stated that the milt of young pars 

 has all the properties of that from adnlfc fish, such is contrary to my experience. § 



Doubtless the prejudices of many persons were formerly in favour of not 

 interfering with nature, and permitting salmon to breed as best they could in our 

 rivers and streams, but some of the latter had already been deprived of these fish 

 through the greed of the fishermen, poisoning of the waters or other causes, and 

 it appeared that if the rivers could not be restored to their pristine condition, 

 artificial attempts at propagation should be attempted. (See pp. 29-36 ante.) 



It has been disputed as to whether salmon are annual breeders, || breed on 

 alternate yearSj or every third year as suggested by Buckland, or merely do so 

 once in their existence. This last proposition may be well dismissed, because if 

 such were so, fertile pars or grilse would be subsequently sterile which is not the 

 case. The young males kept in fresh water having milt for two successive seasons 

 has been observed at Howietoun : while the experiments made on the Penobscot 

 River would seem to show that there at least the fish breed every alternate year, 



* It was calculated by Stoddart and others that if salmon eggs are left to nature the produce 

 is about four or five fish fit for the table for every 30,000 ova deposited, whereas the same number 

 are obtained from every 800 eggs artificially protected. Mr. Ashworth stated it as his opinion, in 

 which Mr. Ffennell coincided, that not above one in 6000 salmon ova deposited naturally in the 

 bed of a river arrives at the grilse or salmon state and becomes marketable. He argued that more 

 than 24,000 fish of various ages annually ascended the river, half being females, or 12,000 fish 

 from 6 lb. to 12 lb., which would give 72,000,000 ova, or one from 6000 ova deposited naturally 

 in the river (Brown, Stormontfield Experiments, p. 85). These figures, however, are founded 

 upon calculations some of which may be fallacious, for instance, if the number of adults left in a 

 river are taken as the basis it was probably computed they breed every year, but if some only do 

 so on alternate years this would considerably alter the number. 



f We are told that a Penobscot salmon, Salmo salar, of about 8 lb. weight does not give more 

 than 5000 or 6000 eggs. 



J Eggs have been found to still retain their vitality in a female salmon that had been dead 

 two hours or even more, having been successfully vivified by the milt from a live male. 



§ As corroborative of the above view that the milt of these young salmon pars was deficient in 

 marital powers, I may mention that on Nov. 29tb, 1883, 1000 eggs of the common brook trout 

 were milted from a Howietoun salmon par which had been dead a few hours. But not a single 

 egg fructified ; only three turned white in December, three in January, and fifteen in February, or 

 a total of twenty-one. On March 12th the remainder were stiU quite clear, but destitute of any 

 sign of a contained embryo. 



II Mr. Buist, writing to The Field, observed, " a few years ago a fine male fish of about 20 lb. 

 was used for spawning purposes at Stormontfield. A mark was put on bim by means of a copper 

 wire, and two years afterwards he was got when nearly 30 lb. weight on the same ford, and at the 

 same season : and after doing duty again, was returned to the river hale and strong, but he was 

 not traced afterwards." 



