THE COMMERCIAL SPONGES AND THE SPONGE FISHERIES. 431 
and as known in 1905 covered an area of about 290 square miles. At that 
time the depth in which the sponges were found extended from about 4 or 5 
fathoms to about 8 to ro fathoms; but the divers have since then taken large 
quantities in from 10 to 15 fathoms, and a few boats are said to have worked 
as deep as 18 fathoms. There are a few small patches of bar in waters as shoal 
as 2 or 3 fathoms on the Buoy grounds, in the channel south of Anclote Key 
and near the north end of Hog Island. The Buoy grounds are noted for their 
rapid recuperation. The deeper waters produce a fine grade of sheepswool 
sponges, and both yellow and grass are also found in considerable quantities. 
Highlands region.—This, the southern limit of the Bay grounds, stretches 
from Big Pass to Johns Pass, the known distribution of sponges in 1905 cover- 
ing an area of about 300 square miles. Owing to the absence of streams dis- 
charging fresh water, the sponges extend much closer to shore than in the 
regions to the northward, but they range offshore to about the same depths 
as in the Anclote region, though, owing to the steeper slope of the bottom, the 
hookers never worked so far from shore. 
KEY GROUNDS. 
The Key grounds, though for many years the only source of supply of 
Florida sponges, are now comparatively exhausted and of reduced value. 
During the past few years they have produced about 30,000 pounds of sheeps- 
wool sponges per annum, while in 1900, an exceptionally good year for these 
grounds, the catch was 58,294 pounds. The production of all kinds averaged 
79,487 pounds in the years 1906, 1907, and 1908, while in 1899 and 1900 the 
average was 139,458 pounds. 
Between the keys and the mainland the grounds extend from Boca Grande 
Key and Cape Sable as far as the Cowpens, off Long Island, and from the 
lower end of Cards Sound to Cape Florida. In Hawk Channel there are 
patches of sponge-bearing bottom along the line of reefs forming its outer 
margin, and at intervals close to the keys which define it on the landward 
side, from near Key West as far as Hillsboro Inlet; but, though at one time 
fished throughout the entire distance, it is only between Knights Key Channel 
and Soldier Key that these patches now attract the attention of spongers. 
The interruption in the distribution of sponges inside the line of keys 
from Long Island to Cards Sound, mentioned above, is due to the low salinity 
of the water. For nearly 30 miles Key Largo imposes an unbroken barrier 
against the interchange of waters between the inside bay and Hawk Channel, 
with the result that the drainage of the Everglades is impounded and the 
salinity reduced below the degree which inhibits sponge growth. On two 
occasions I have run a line of salinity observations through this barren area 
