at least 140 men working full time are required 

 merely to gather the sponges. On the basis of 

 manpower alone, therefore, it would only re- 

 quire 8 to 10 men to produce as many sponges 

 by cultivation as 35 or more men harvesting 

 naturally growing sponges at the present rate 

 of production once the plantation was in full 

 production. 



Establishing sponge plantations along the 

 coast of Florida presents several additional 

 problems that would be less serious in an area 

 such as the Bahamas. 



1. Turbidity of the water along the Florida 

 coast is much greater than in the Baha- 

 mian water because of greater land drain- 

 age and differences in the type of soil. 

 Poorer underwater visibility would in- 

 crease the difficulty of planting and 

 gathering the sponges. There is also the 

 danger of periodic mortality due to fresh- 

 water runoff. 



2. Heavier water traffic over potential plan- 

 tation areas would require closer super- 

 vision of the grounds. 



3. On the west coast of Florida the diving 

 boat crews find that the water is suf- 

 ficiently calm and clear enough for work 

 only about 100 days each year. On the 

 shallow larger banks of the Bahamas, 

 where the water is crystal clear, the 

 number of work days would be expected 

 to be considerably higher. 



From the standpoint of quality the logical 

 choice for a sponge plantation off Florida would 

 be in the Rock Island area, probably in the 

 region of the Econfina flats off the Econfina 

 River. From the standpoints of faster growth 

 and availability of quantities of natural sponges 

 the area off Cape Sable would be the most 

 profitable. In the northern part of the area, 

 the winter weather is rather severe for water 

 work and in addition, there is the constant 

 danger of freshening of the sea water. In the 

 southern area off Cape Sable there are rela- 

 tively few days when the water is sufficiently 

 clear for work of any kind underwater. 



Some parts of the Florida Bay area in the 

 vicinity of the lower keys would appear to be 



a practical area for a plantation. Much would 

 depend on the quality of sponges that could be 

 produced there. 



DISTRffiUTION 



Determination of Distribution 



Distribution of the commercial sponges in 

 the Gulf was determined on three survey trips. 

 On the first two trips, 1 did the diving; on the 

 third trip, two regular sponge divers did the 

 surveying. The first trip was made with a small 

 pleasure craft in September 1955. This cruise 

 surveyed the area from Tarpon Springs to St. 

 Marks in water depths from 6 to 60 feet. The 

 second trip was made aboard a regular diving 

 boat in November 1955 when the area from 

 Tarpon Springs southward to the Ten Thousand 

 Islands was explored. The third field trip, 

 again aboard a regular diving boat (Ellni), was 

 made in July 1956 and covered the area from 

 Tampa Bay to Carrabelle. This trip was made 

 to survey the bottom at depths from 50 to 100 

 feet to establish the outer limits of commercial 

 sponge distribution. 



In the three field trips, 88 diving stations 

 were established in the area between Tampa 

 Bay and Carrabelle, with well over 100 dives 

 being made (fig. 10). Nine stations were south 

 of Tampa Bay, but these did little more than 

 verify the scarcity of sponges between Tampa 

 Bay and the area seaward of Everglades City. 

 A careful survey of sponging areas from Plan- 

 tation Key to Key Largo was made on the 

 Florida east coast from chartered small open 

 boats; my assistant, Robert Work, and I made 

 about 40 dives on 11 stations in this survey. 



From the information obtained on the field 

 trips plus additional information from the 

 spongers themselves it has been possible to 

 construct a diagram of the present distribution 

 of the commercial sponges (fig. 11). This dis- 

 tribution diagram represents only the areas 

 where commercial sponges are found at the 

 present time (1958) in the upper Gulf and does 

 not indicate the density of the population. 



Concentration of ^onges and Extent 

 of Sponging Area 



Density of the sponge population on the bars 

 is important economically as well as 



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