354 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



per pound, with eight or nine "size-count" 

 categories in common use along the Gulf coast. 

 Notwithstanding the possible influence of biases 

 noted in the foregoing section, any conversion of 

 landings within size-count categories would neces- 

 sitate a corresponding change in the size-count 

 scale. Size-count notation for headless and cor- 

 responding whole shrimp is given in table 2. 



Table 2. — Numbers per pound of headless and corresponding 

 whole shrimp. A constant ratio of 1.68 between total 

 and "tail" weight is assumed 



GULF OP MEXICO 



DZ 150- 



3 



1 O 



1 1 r I 



- COMMEfiCIAL LANDINGS 



- EFFORT EXPENDED 



Figure 7. — Effort expenditure and total commercial 

 landings by the United States shrimp fleet, Gulf of 

 Mexico, 1956-59. 



FISHING EFFORT AND TOTAL SHRIMP 

 YIELD, 1956-59 



For the years 1956-59, annual fishing effort on 

 Gulf of Mexico shrimp grounds deviated only 

 slightly from an average of 169 thousand days 

 (fig. 7, table 3). Corresponding shrimp harvests 



exhibited no startling trend, fluctuating between 

 167 and 193 million pounds with a ma.xirnum 

 deviation from the 4-year mean of only 8 percent. 

 EfTort expended in and catches from foreign 

 Gulf waters averaged 23 and 22 percent, respec- 

 tively, of overall Gulf of Mexico totals (tables 

 3 and 4). 



Another look at overall effort and catch data 

 after they are separated into their spatial and 



Table 3. — Fishing efort expended by United States com- 

 mercial shrimp trawlers in the Gulf of Mexico, 1956-59 ' 



[24-hour units] 







1 Breakdown of fishing effort according to amounts expended seasonally 

 inshore and offshore waters is made in appendix table 1. 



