2. Future benefits . — a. It has been shown in 

 previous sections of this report that a 

 6-inch sponge will produce at least 

 enough larvae to make possible the 

 establishing of one and probably more 

 new sponges. Consequently, with a 6- 

 inch size limit, every sponge har- 

 vested will have produced enough 

 larvae to replace itself. Unless an 

 area were badly affected by disease 

 or adverse ecological conditions, a 6- 

 inch size limit would enable every 

 sponging area not only to maintain the 

 present concentration but, because 

 there will always be a few larger 

 sponges in each area producing large 

 numbers of larvae, the total number 

 of sponges in each area would steadily 

 increase. No area would be depleted 

 by overfishing alone if a 6-inch size 

 limit were adopted. 



b. By the end of the fourth year after 

 the adoption of a 6-inch size limit, a 

 15- to 25-percent increase in catch 

 could be expected as a result of the 

 spawning of those sponges of less than 

 6 inches that were not taken during the 

 first year after the size limit was 

 established. This increase would be a 

 permanent one with a likely further 

 increase of over 15 percent every 4 

 years until an ecological balance is 

 reached. 



c. Food supply is not a factor limiting 

 the density of sponges on the bottom. 

 The two possible factors limiting high 

 concentration on the sponging grounds 

 north of Tampa Bay would be available 

 area for attachment and quantity of re- 

 production. There is much available 

 clean rock with very low competition 

 for space on the plentiful rocky bars 

 in the northern areas formerly 

 densely populated with sponges prior 

 to the disease. Availability of space 

 for attachment and growth of wool 

 sponges is, therefore, not an im- 

 mediate limiting factor. Late matur- 

 ing of the sponges as compared with 

 those further south, combined with the 

 harvesting of large numbers of 



sponges which have never produced 

 eggs, is the only apparent deterrent to 

 increased and heavy concentration. 

 Regrowth from old torn bases and ex- 

 cess of larval production by larger 

 sponges would, it is believed, assure 

 a steady increase in total sponge popu- 

 lation up to the carrying capacity of 

 the bars. 



Improve fishing techniques . — 1. A number 

 of sponge fishermen and scientific 

 workers have suggested that cutting the 

 sponges from the rock would leave a clean 

 base from which a new sponge could grow. 

 It can be calculated that such a method of 

 harvesting could increase production by 

 30 to 50 percent within a 3-year period. 



A number of experiments were carried 

 out to test this possibility. Unfortunately, 

 it was found that more than 50 percent of 

 the sponges were growing on irregular 

 rocky areas and could not be readily cut 

 from the bottom. Instead, after cutting 

 was attempted, the sponges finally had to 

 be torn away, making this type of har- 

 vesting wasteful of time and effort. In 

 about 10 percent of the other cases, the 

 sponge came free of its attachment so 

 easily that it would have been torn loose 

 before it was cut. Harvesting sponges by 

 cutting could be most beneficial but, un- 

 fortunately, is impractical. 



2. Some change should be made in the har- 

 vesting methods used by the hookers. The 

 most practical suggestion for increasing 

 the take by the hookers is the adoption of 

 the tested method used by the Florida Key 

 fishermen. This is the use of a larger 

 power craft and three or four hookers 

 working individually from dinghies. In 

 the present hooking method in the north- 

 ern Gulf, only one man out of two on the 

 smaller boats and only two out of five on 

 the hooking schooners are actually har- 

 vesting sponges. In the Florida Key 

 method as many as four men out of five 

 are taking sponges. Individual income 

 could almost be doubled if this latter 

 method was adopted. 



68 



