500 BULLETIN OF THE BUREAU OF FISHERIES. 
owing to their situation in crevices or under ledges. These the divers are able 
to find and obtain and in consequence they leave fewer sponges to furnish the 
young necessary for the recuperation of the beds. Where the divers are work- 
ing on grounds already partially depleted by other methods of sponging, as was 
the case during the first two years of the fishery in the Gulf of Mexico and in 
many places in the Mediterranean, there can be no doubt that the method is 
exhausting to the beds, even if it be conducted without the abuse of gathering 
undersized sponges. When the beds are already worked to or beyond their 
limits of productiveness any method which increases the draft upon them must 
be injurious. 
This was one of the contentions of the opponents of diving in Florida and was 
the reason for the restriction of the divers to depths greater than 50 feet. It 
was hoped by this means to preserve the inshore grounds inviolate for the hookers, 
while permitting the taking of sponges in the deeper waters unattainable by the 
methods previously in use. Concerning the productiveness of these offshore 
grounds we are not yet in possession of data which would warrant an opinion of 
value, but the little that we do know does not indicate that they are more pro- 
ductive mile for mile than were the shoaler waters when first discovered. In 
fact, the bars appear to be fewer and more scattered, and though sponges occur 
on some of them in great numbers, this abundance is due to the fact that they 
are virgin beds and have never before sustained a fishery. There is no doubt 
that in time some, at least, of these will be depleted and the proximity of that 
time will be proportional in some measure to the intensity of the fishery and 
conversely to the area of new grounds developed. 
Assuming that the fishery can be carried on to the 20-fathom curve and that 
the productiveness of this region is proportionately equal to that covered by 
the hookers, an increase of from 250 per cent to 275 per cent in the annual prod- 
uct, making no allowance for the consideration about to be presented, would 
result in approximately the same degree of over-fishing which had gradually 
decreased the catch of the hookers prior to 1905-6. ‘This allowable increase 
was nearly attained in the year ending May 1, 1907, when the value of the 
sheepswool product was over twice the normal of the years immediately pre- 
ceding. Owing to the sudden increase in the supply the price dropped far 
below that of previous years. 
In discussing the effects of the fishery upon the rate of depletion of the inshore 
beds, consideration must be given to the effect upon their recuperative powers 
of the sponges lying in the deeper water, beyond the reach of the hookers but 
now being taken by diving. Undoubtedly a considerable proportion of the 
young sponges on any bed are the offspring of breeding adults in the immediate 
vicinity, either overlooked by the hookers, concealed from sight under ledges, 
or protected from capture by the prevailing turbidity of the water, all factors 
