30 



DEPARTMEXr OF THE XATAL SERVICE 



The average temperature for the whole eight months was 2-3°C (4-2°F) lower 

 in 1915-16 than in 1914-15. 



No record has been made of the maximum and minimum temperatures of the 

 surface water daily and hence the average in the same sense in which it is applied 

 in connection with the air temperatures is not obtainable, but as there is so much 

 less daily variation in the water temperature this is not of so much moment. The 

 water temperature was taken at or near eight o'clock each morning at the landing 

 float of the Station wharf, Departure bay, and from these records, average, maximum 

 and minimum figures for the months above referred to, were obtained. 



WATER TEMPERATURE. 



CENTIGRADE. 



FAHRENHEIT. 



Average . 

 Maximum 

 Minimum . 



1914-15 

 1915-16 

 1914-15 

 1915-16 

 1914-15 

 1915-16 



54-5 

 520 

 57-0 

 55-6 

 49-8 

 46-4 



This shows that the surface water although not going to the same extremes as 

 the air temperature, is yet very materially dependent upon it. In fact, taking the 

 two seasons into consideration, there is almost as great a difference in the average 

 water temperature for the eight months, viz., 1-9°C (3.4F) as there was in t\ie 

 average air temperature. 



It is not probable that this difference in temperature is so great as to be beymid' 

 the power of accommodation in the larger species, food fishes for example, but these 

 all. directly or indirectly, live on much more minute forms that ave more readily 

 ailected by changes that act as stimuli, than are the larger forms. Dur'ng the 

 months of December, January and February, the greater portion of th? minute 

 animal fcod consists of crustaceans, copciwds predominating. On account of the 

 rough sefis or of the cold surface waters or from the fact that the diatoms on which 

 thr^v feed are influenced by these, copepods were extremely scarce during the past 

 season and hence many larger forms remained at depth as well. During the winter 

 of 1914-15 there was scarcely a day that the fishermen, using a troll and spoon, and 

 fishing near the surface, were unsuccessful in obtaining spring salmon. In 1915-16. 

 when they did venture out, very few salmon were to be obtained and those that were 

 caught, were caught at depth. 



In the Xanaimo district herring are usually caught with purse seines and in such 

 a method of fishing it is necessary to be able to see the schools of fish near the surface 

 before the net cap be cast successfully. Last season the seine fishing was a failure 

 until very late as no herring could be seen. Doubtless they were there as usual as the 

 gill net fishermen at Pender harbour on the other side of the strait found a good 

 supply during the surface scarcity. When the herring did come into shallow water 

 towards the end of February and early in March, the copepods were plentiful again. 

 The herring spawning season was someAvhat later than it was the previous year but 

 not very much so, and possibly the weather had nothing to do with it. 



