Table 5. — Niimber of tows and size distri- 

 butions from which shrimp were discarded 

 and not discarded 



22 2S 28 31 34 37 40 43 4e 49 92 

 CARAPACE LENGTH IN MM, 



Figure 20. — Size frequency distribution of the total catch of 

 pink shrimp and those discarded. 



in which shrimp less than 26 mm. were 

 discarded and not discarded. In discard- 

 ing tows, the mean percentage (obtained 

 by averaging the percentages of all 

 samples) was higher (58.1 percent of 

 shrimp were 26 mm. or less) than for 

 the no-discard tows (33.7 percent). On 

 some tows when no discarding took place, 

 as high as 93 percent of the shrimp 

 were 26 mm. or below. 



When large numbers of small shrimp 

 (under 26 mm.) first appeared on the 

 grounds in September 1958, discarding 

 occurred. When it becanne apparent that 

 the small shrimp were in great abun- 

 dance, they were retained. During the 

 study period dealers indicated that all 

 sizes of shrimp could be marketed. In 

 September, samples taken from trash 

 in two heading houses produced no whole 

 discarded shrimp that were not soft or 

 damaged. Average size of two samples 

 were 22.9 mm. and 22.2 mm. carapace 

 length, the smallest individuals measured 

 about 18 mm. 



SUMMARY 



1. This report contains observations 

 on the relation between the size of Tor- 

 tugas pink shrimp and the depth of water 

 where they occur, on fleet concentrations, 

 on the grounds, and on the discards of 

 small pink shrimp. 



2. Data on these aspects were gathered 

 from September 1957 to November 1958. 

 Two cruises per month were made each 

 month except June, October, and Novem- 

 ber 1958 to observe fleet activities and 

 to collect samples of shrinnp. Seven 

 flights were made over the grounds to 

 observe fleet concentrations. Additional 

 information on fishing effort was obtained 

 from logbooks. 



3. The average carapace length of both 

 male and female shrimp taken during the 

 year increased with depth; however, a 

 size gradient irrespective of depth was 

 also apparent in a northerly direction 

 from the Keys. Whether the size-depth 

 relation was a function of seasonal dis- 

 persion of shrimp as they increased in 

 size, could not be determined. 



During the period from Jvme through 

 November 1958, logbook reports from 

 14 boat& indicate that very little discard 

 took place. Data from approximately 645 

 tows (on the basis of three tows per 

 night) show discard occurring on only 

 17 tows, for an estimated total weight 

 of 138 pounds. Apparently small shrimp 

 are discarded only when few are caught, 

 and it is not worth the effort or expense 

 to ice them separately from the rest of 

 the catch. 



4. The small shrimp first occurred on 

 the eastern and southeastern portions 

 of the grounds. Small shrimp were most 

 widely distributed on the grounds during 

 September through May 1958. 



5. The highest catches, based on try- 

 net data, were made December 1957- 

 January 1958, and during March to June 

 1958. The highest catches were made 

 on the southern and eastern areas of 

 the grounds, generally in shallow water. 



22 



