JONES and DRAGOVICH: UNITED STATES SHRIMP FISHERY 



CATCH l«bl BY TIME Of FISHING 



EFFORT I"- 1 BY TIME OF FISHING 



40 «0 



PERCENT 



EFFORT CM BY TIME OF FISHING 



6-10 



78 



I I L_ 



20 



40 60 



PERCENT 



PERCENT 



DAY ONIY 



NIGHT ONLY 



DAY & NIGHT 



FIGURE 13. — Distribution of fishing effort (expressed as 

 percentage of total) by time of day and water depth for U.S. 

 vessels in the Guianas-Brazil fishery, July 1972 to December 

 1974. 



ure 14). From 1961 to 1968 the total production 

 from the fishery rose in proportion to the increase 

 in the number of fishing vessels. In 1969 and 1970 

 fishing effort increased, but production remained 

 constant at 27 million pounds. Fishing was re- 

 duced in 1971 and the catch, therefore, declined. 

 After 1971, catch and effort continued upwards at 

 rates similar to those in the early year's of the 

 fishery and a catch of 27 million pounds was again 

 attained in 1973. In 1974 the number of vessels 



DAY ONLY 

 NIGHT ONLY 

 DAY & NIGHT 



FIGURE 12.— Distribution of catch and 

 fishing effort (expressed as percentage 

 of total) by time of day and fishing zone 

 for U.S. vessels in the Guianas-Brazil 

 fishery, July 1972 to December 1974. 



NUMBER OF VESSELS 



FIGURE 14. — Relationship of the average annual landings per 

 vessel (A) and the total production of shrimp (B) to the total 

 estimated fishing effort (average number of vessels operating) 

 for the Guianas-Brazil shrimp fishery. The linear trend line 

 shown was fitted to the data for the years 1965-74; the estimated 

 production curve was derived from the line in A. The exponential 

 trend line was calculated as explained in the text but is not 

 shown in this figure. 



remained high, but the catch declined to 23 mil- 

 lion pounds. 



The variation of the annual catches from those 

 predicted by the model were 53% and 319c in 1961 



713 



