30 



H. C. DANNEVIG. 



is again apparent. But the object of this table is to show 

 how the abundance of fish fluctuates from year to year 

 within the same water, and litte assistance is required to 

 follow the general trend of this evideuce. It is apparent 

 that during the last few years there has been a general 

 decline in the catches, culminating about 1905; about 1901 

 or 1902 there was a general abundance of fish, and again a 

 shortage about 1898. It should here be noted that as all 

 the waters show an almost simultaneous increase and 

 decrease it is useless to suggest that inter-migration from 

 water to water has anything to do with this. 



In order to obtain a still more definite idea as to the 

 evidently periodic fluctuation in the abundance of fish on 

 the coast,'I have reduced this evidence still further by the 

 only two methods possible, Table IV., and Table V., and 

 the result is in both cases the same (Diagram B.). We 

 have before us very conclusive proof of the existence of 

 cycle-like fluctuations embracing numbers of years in each 

 period, and this in itself, is as far as it goes a discovery of 

 wide importance. 



Tables IV. and V.— Showing Average Monthly Catch per Man. 



Waters. 



1897 



1898 



1899 



1900 



1901 



1902 



1903 

 17-7 



1904 

 14*7 



1905 



12-8 



1906 



15-5 



All Waters recorded 



Ei°-ht Waters 













17*6 



15*3 



12-8 



11*1 



133 



Five Waters . 









16'4 



22-0 



20-3 



18-0 



14-6 



12-5 



13-3 



the Three Lake Waters 



17-5 



12-9 



15*5 



15-5 



19-5 



18-6 



18-6 

 27*4 



155 

 22-1 



12-5 

 19*5 



13-3 

 23-5 



Clareuce River and P. Macquarie 



Cape H»wke and Port Stephens 









17 8 



25-7 



23-0 



17*1 



13-1 



12'4 



12-7 



Lakes Macquarie, Tuggemh and 























Illawarra 



17-/) 



12-9 



15-5 



15-5 



19-5 



18-6 



18-6 



15-5 



12-5 



13-3 



Shoalhaven, Clyde, and Pambula 























Rivers 













13'2 



10'9 



9-9 



8-8 



15'6 



The next stage in my inquiry has been to seek a satis- 

 factory explanation of these fluctuations, and primarily to 

 determine whether they are due to natural causes, or more 

 or less to the interference of man. A great deal of work 

 has been expended in connection herewith, and it is only 



