Generally those sponges that are growing in 

 warmer and shallower water have a far greater 

 number of species of animals and numbers of 

 individual animals in the canals and on the sur- 

 face than those found in the more northerly or 

 deeper ranges of the commercial sponges. Be- 

 cause of this difference a far greater proportion 

 of the wool sponges from the northern Gulf are 

 more perfectly formed than those from areas 

 such as Cape Sable. The same is true of sponges 

 from deeper water of 25 to 30 feet, as is shown 

 by comparing sponges taken by hookers with 

 those taken by divers. 



COMMERCIAL SPONGE 

 PRODUCTION 



Production Before and After the 

 1938-39 Sponge Disease 



Table 11 presents the production and value 

 of sponges from 1913-62. For the sake of dis- 

 cussion, table 11 and figure 18 may be divided 

 into two periods, a predisease period from 

 1917-38 and a postdisease period from 1938-56. 

 Without adequate information on the number of 

 boats operating yearly from 1917-35, it is 

 impossible to say with certainty what portion of 

 the variation in productivity is due to the in- 

 tensity of fishing effort during the predisease 

 period. From the data available it would appear 

 that the small changes in the number of fishing 

 boats would not bring about any appreciable 

 change in landings of sponges by individual 

 boats. 



It was important, however, to find some ex- 

 planation for the wide variation in yearly land- 

 ings that took place during the period 1917-35. 

 Yearly take was from 267,000 pounds to 468,000 

 pounds, with an average of about 350,000 

 pounds. According to sponge fishermen, there 

 were few additional areas that were harvested 

 during that period with the exception of the 

 Cape Sable and Everglades areas in 1936 (often 

 referred to by the divers as the Key West 

 area). A considerable portion of the yearly 

 variation undoubtedly was caused by the effects 

 of weather on fishing. Observations made 

 during the past 2 years suggest that some 

 portion of the variation was probably due to 

 mortality of sponges in localized areas, 

 especially in the shallower sponging areas. 



This has already been discussed in the section 

 on disease. 



In the postdisease period (after 1938) pro- 

 ductivity fell within 3 years to two-fifths that 

 of 1938 or about one-half the yearly average. 

 There was a levelling off of the yearly take 

 during the next 5 years despite a 50 percent 

 increase in the number of boats in the spong- 

 ing fleet (fig. 18). According to published re- 

 ports of the Sponge and Chamois Institute, 

 undersized sponges were being taken in- 

 discriminately in large numbers during this 

 5-year period. The rapid increase in the wool 

 sponge price per pound (table 12), from about 

 $2 to almost $30, and the reported failure 

 during the war period to prohibit the taking 

 and/or selling of undersized sponges encour- 

 aged this illegal practice to continue without 

 serious restraint. The effect of taking under- 

 sized sponges before they had an opportunity 

 to mature and produce eggs was possibly a 

 factor in preventing (1) the repopulation of the 

 deep-water sponge beds and (2) an increase 

 in the concentration of sponges in the more 

 limited inshore areas. Had there been a more 

 extensive distribution of small sponges and 

 greater numbers of small sponges during the 

 1947-48 disease period the effect of this disease 

 would probably not have been nearly as great 

 as it was. The fact that the total landings of 

 sponges did not increase appreciably during the 

 5-year period despite greatly increased effort 

 suggests that the sponge beds were being de- 

 pleted. The decline in return per unit of effort 

 also indicates the steady decrease in the con- 

 centration of the sponges that took place. 



Production After the 1947-48 Sponge 

 Disease 



After the disease of 1947-48, which affected 

 the Big Bank grounds (appendix, #10) more 

 than any other, the yearly total of landings 

 once again fell off rapidly. A large part of this 

 recorded drop resulted from the withdrawal of 

 boats from the sponge industry. Return per 

 unit of effort changed little. Within 3 years 

 after the disease began only 57 boats were 

 sponging, and by 1951 only 32 boats remained 

 in the sponging fleet. Of these, only two were 

 diving boats. On the basis of the 1955 and 1956 

 returns, it has been estimated that the return 



51 



