Table U. — Daily take and density of sponges by areas, 1957 



■'■ See appendix A and figure 15 for details of areas. 



2 High concentrations of sponges found only in shallow water. 



than 5 inches (legal-sized sponges). The popu- 

 lation density of wool sponges of all sizes in any 

 area will, therefore, be about four times that 

 given in table 4. 



In areas A and B* the low number of sponges 

 taken per day is in part offset economically by 

 the better quality of sponges taken in these 

 areas and the correspondingly higher price. 

 On the other hand, large number of sponges 

 taken in area F is not as profitable to the 

 sponger, because these sponges are inferior to 

 those from other areas and bring a much lower 

 price. 



In all areas except F the concentration of the 

 wool sponges is not dense enough to expect any 

 sudden increase in the number of sponges 

 through natural propagation. In area F, how- 

 ever, the spongers reported substantial in- 

 creases in the concentration of sponges between 

 1954 and 1957, and this recorded concentration 

 of about 36 legal-sized sponges per acre would 

 appear to be above the level necessary to not 

 only maintain but increase the population of 

 any given area. Because of the increased 

 turbidity, which limits underwater vision, and 

 the higher concentration of sponges, which 

 slows the diver's progress, the density of 

 sponges per acre indicated in table 4 for area 

 F is low. Density per acre may be as much as 

 50 percent greater than shown. 



Distribution of Diving and Hooking 

 Depths 



The data on the landings of sponge from the 

 Tarpon Springs Sponge Exchange enabled us to 



< See appendix and figure 15 for details of areas. 



obtain the distribution of the various commer- 

 cial species of sponges by depth. The diving 

 boats are limited by law to work in water of 

 more than 21 feet (3- 1/2 fathoms). The hooking 

 boats on the other hand usually work in water 

 from a fathom or more to less than 21 feet. 

 By separating the landings of divers and 

 hookers the relative distribution of the sponges 

 in depth can be estimated. The market returns 

 for the years 1955 and 1956 have been analysed 

 on this basis (table 5). 



Table 5 does not give a completely accurate 

 picture of the comparative harvest by divers 

 and hookers. As we shall see later, the aver- 

 age size of sponges landed by the two methods 

 differs quite considerably. Wool sponges taken 

 by diving boat crews are about 50 percent 

 greater in volume than the average size taken 

 by the hooking method. Thus the deeper water 

 area is producing about 50 percent more 

 sponges by weight than indicated when the 

 method of comparison is only by the number 

 of sponges. 



Causes of Short-Term Variations 

 in Landings 



Unfortunately the records of landings for 

 1950-56 are not complete; only 1955 and 1956 

 records are sufficiently accurate for tabula- 

 tion. Although any analysis of the situation 

 based on these 2 years alone is not indicative 

 of trends in productivity of the sponge beds, 

 several observations can be noted from the 

 table above and from available information ob- 

 tained from the sponge fishermen. 



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