key: (NUMBER OF TRAWLERS 

 PER 5 MILE SQUARE) 



CRUISE 23 NOV. 4-7, 1968 



. = 1-7, • =8-14.« =15-21. ■'22-28. % =29-35. ■ =OVER 35. 

 BOUNDARY OF OBSERVATION 



Figure 19.— Distribution of fishing effort on the Tortugas grounds (July-November 1958). 



Table <+. --Number of vessels counted on the fishing grounds and at dock during airplane 



flights, January to November 1958 



count, heads off) were discarded. On 

 certain instances fishermen left small 

 numbers of large shrimp, but these were 

 merely overlooked and were not inten- 

 tionally discarded. Some were also cast 

 aside because they were crushed, or 

 soft, having recently molted. From these 

 data it appears that when discarding 

 occurred, Z6 mm. carapace length was 

 the largest size normally discarded and 

 that at about 20 mm. carapace length 

 all shrimp were discarded. 



The second aspect of this phase of 

 the study was to determine how often 

 discarding took place. Tows containing 

 some shrimp of 26 mm. or less (i.e., 

 sizes which are ordinarily discarded) 

 were observed (table 5). On 23 tows the 

 fishermen intentionally discarded small 

 shrimp and on 177, they did not. The 

 majority of these cruises for which dis- 

 carding took place occurred during mid- 

 winter and fall. Table 5 also shows the 

 range and mean percentages of tows 



21 



