494 BULLETIN OF THE BUREAU OF FISHERIES. 
western Atlantic. He believes that in those places a profitable fishery merely 
awaits the time when the exhaustion of the older fisheries will force their 
exploitation. ? 
I have been informed by a Greek of wide experience on both sides of the 
Atlantic that in the shallow waters about the Canary Islands there is a sponge 
closely resembling the coarser qualities of the yellow sponge, though the shape 
is flatter. 
Several sponges are reported from the Madeiras and the Bermudas, those 
of the latter islands resembling those of the North American coast and including 
the grass, sheepswool, and possibly the velvet. The velvet sponge is also 
recorded from Fernando de Noronha, off the Brazilian coast, indicating the 
probable extension of the American commercial sponges along the mainland 
south of the equator. 
VII. CONDITIONS AND EFFECTS OF THE SPONGE FISHERIES. 
DEPLETION OF THE BEDS. 
Wherever the sponge fisheries have been prosecuted with vigor for a long 
period, there has resulted a more or less definite depletion of the beds, or a well- 
grounded fear of the approach of that condition. The commercial sponges can 
never be actually exterminated by the agency of man. It is an impossibility 
to denude the grounds so completely as to leave none for reproduction, and, 
moreover, as soon as the beds become so depleted as to reduce the earnings of 
the spongers to a bare living wage, the economic result is a reduction in the number 
of fishers and the establishment of an approximate equilibrium between pro- 
ductiveness and catch. The point at which this equilibrium is established will 
vary with economic conditions, becoming lower with an increase in the value of 
the product and higher with an increase in the cost of living of the fishermen. 
More men, gathering in the aggregate a somewhat larger quantity of sponges, 
though the catch of each individual may be less, can be supported when the 
price is high than when it is low, and this results in increasing the fishery, in 
a further reduction in the productiveness of the beds, in profits, and eventually 
in the number of fishermen, the equilibrium being again established on a somie- 
what lower plane of productiveness. Thus, while the sponges are never actually 
exterminated there results an approximate commercial extermination, never 
quite complete for the reason that were the fishery entirely abandoned the beds 
would soon recuperate and again become commercially productive. 
This is well illustrated in a number of cases. In the Adriatic, sponges were 
formerly much more abundant, but the fishery has been nearly stationary for a 
number of years. In the A¥gean and on the Syrian coast there is said to have 
been a material decrease during the past thirty years, but the conditions of the 
