52 Part III. — Twenty-sixth Annual Report 



1. Before Planting of Fry. 



Hellefjord, 1903 + 1904 + 2 







Pollack and 



Cod. 



Whiting. 



Saithe. 



426 



1,309 



137 



85 



259 



23 



511 



1,568 



160 



2. After Planting of Fry. 







ollack and 



Cod. 



Whiting. 



Saithe. 



1,328 



1,150 



160 



143 



180 



3 



1,471 



1,330 



163 



While the numbers of young whiting decreased, the number of young cod 

 greatly increased. On the other hand, Mr. Dahl, who also carried on 

 other investigations in other fjords with a different net, and made obser- 

 vations on the hydrograpbical aspects of the problem, comes to the 

 conclusion that the increase of young cod was caused not by the putting 

 in of the larval cod but by general influences which affected other fjords 

 as well. While the result of the joint experiments as they stand 

 clearly shows that an increase in the numbers of young cod in the fjords 

 followed the putting in of cod fry, and might well be due to that 

 factor, the inference from the experiments that will probably be generally 

 drawn is that expressed by Professor Herdman, that the observations are 

 too few to lead to any sure conclusions. When one considers the natural 

 fluctuations that occur, it is evident that the period over which the 

 experiments extended was much too short. The normal natural 

 abundance cannot be determined by observations covering only one or 

 two years, nor would that period suffice to prove the results of artificial 

 interference, whether such interference is caused by the addition of fry to 

 the waters, as in these experiments, or by fishery regulations. For some 

 certainty of result ten years would not be too long a period, and the value 

 of the observations would be greater if two fjords were dealt with in such 

 a way that in the years in which fry were added in the one they were not 

 added in the other, provided that the fjords, while near enough to be 

 under the same general hydrographic and other conditions, were not so 

 near that the fry or young fish would be likely to pass from the one to 

 the other. 



8. The Experiments with Plaice in Lochfyne. 



With the object previously explained, to determine if possible the 

 effect of the liberation of large numbers of the fry of plaice within a 

 restricted area of water, the experiment was begun in 1896 of 

 transporting to Lochfyne a very considerable proportion of the larval fishes 

 produced at the hatchery. This loch was in some respects well adapted for 

 such an experiment. (Plate II.) It is about 36 nautical miles in length, 

 and narrow, the width ranging from about 3| miles to under 1 mile. It 

 is divided into two parts, the lower loch, about 14 miles in length and 

 from 3^ to 1| miles broad, and the upper loch, extending for about 

 22 miles above the narrows at Otter Spit to the head of the loch, and 

 with a width of about \\ to f miles. The water is on the whole deep. 



