13 



St. James. A typical case, of which the following notes were 

 taken at the time, may be quoted : — On the 4th August, 1905, 

 an unusually large number of Harders {Mugil capito), together 

 with Bamboo-fish {Box salpa), were found in the rock-pools. 

 Though small Harders are frequently found in such pools, 

 those that appeared at this time were larger and more numerous 

 than usual, and the Bamboo-fish, which are fairly large (about 12 

 inches), are never found normally in these places. There had 

 been little or no change of temperature either before or after 

 the occurrence. A very large number of sea birds, however, 

 were fishing in crowds close inshore, and it seemed probable 

 that the fish were driven ashore in their endeavour to escape 

 from their pursuers. These birds were exclusively the common 

 Duiker, which, particularly in a strong N.W. wind, as in this 

 instance, come close inshore, perhaps to find shelter under the 

 lee of the mountain. On another occasion a number of large 

 Sardines {Clupea sagax) were found in the rock-pools, where 

 they never normally occur. Some of the Bamboo-fish and 

 Sardines were caught and placed in the tank at the Marine 

 Laboratory. They showed no signs of injury or illness and 

 lived for many months afterwards in the tanks. 



There are, however, certain other considerations which may 

 have some value in deciding to what an extent this destruction 

 of fish-life takes place. It has been observed at various times 

 by those in charge of the guano islands that there has been an 

 unaccountable mortahty amongst sea birds. Some time ago 

 I was fortunate enough to have the opportunity of observing 

 such an occurrence on " Seal Island," one of the islands 

 situated off the coast of German S.W. Africa. I was informed 

 by Mr. Muller, British Consul, stationed at Luderitzbucht, 

 that the Duikers were dying off in large numbers on this island, 

 and we visited it with the purpose of ascertaining the cause 

 of such an occurrence. In the crevices of the rocks were 

 numbers of dead birds, chiefly young, and here and there were 

 others in a dying condition. The bodies of both dead and 

 dying were in an emaciated condition, but there was no 

 evidence of any disease. At a later date I was informed by 

 Mr. Muller that it had been found that the cause of the mor- 

 tality was the great scarcity of fish, which was known to have 

 occurred at this time. It is not unlikely that similar occur- 

 rences observed on other islands on the West coast are due to 

 this cause. While the scarcity of fish may not have been due 

 to the excessive increase of these sea birds, it is obvious that 

 such an increase, which could bring about a marked decrease 

 of fish, would react in such a way as to bring the number of 

 sea birds back to their normal numbers. In other words, the 



[C.P. 6— '14.] 



