few Florida and Texas ports where statistical agents, with the full coopera- 

 tion of the fishing industry, have devised effort and catch accounting methods 

 so effective that statistics of United States fleet operations in the Gulf of Cam- 

 peche may be included among the most accurate of all statistics describing 

 the Gulf shrimp fishery. 



Commercial yield After reaching a high of about 33 million pounds in 1953, 



annual landings of Campeche pink shrimp by United States fishermen stabil- 

 ized at 24 to 25 million pounds over the period 1954-1956. Thereafter (1957- 

 1960), they steadily declined to a low of 13.4 million pounds in 1958 but then 

 began to climb again, reaching 18. 5 million pounds in I960. The lowest an- 

 nual take recorded prior to 1958 was 8 to 9 million pounds in 1951, early in 

 the fishery's development. 



In contrast to seasonal catch patterns in most Gulf of Mexico 

 shrimp-producing areas, the 1956-1960 pattern for pink shrimp on the Cam- 

 peche flats showed relatively steady year-round production (see figure. A). 

 Greatest month-to-month variation occurred during midwinter with the high- 

 est monthly production in December and (until summer and fall catches 

 dropped below "normal" in 1958-1960) the lowest in January, This sharp 

 drop is believed to reflect intensification of adverse fishing conditions rather 

 than marked seasonal changes in shrimp abundance. 



Fishable biomass The "fishable biomass" is defined as that fraction (in 



terms of weight) of a commercial fish or shellfish population, which com- 

 prises those individuals susceptible to capture by the gear commonly used in 

 the fishery. An index thereto is provided by the ratio of catch to fishing in- 

 tensity, such an index being calculated for each of reasonably small tinae in- 

 crements, in this instance, periods of 1 month. Fishing intensity is defined 

 as the quantity of fishing effort expended per unit area of the population's geo- 

 graphical range. 



However, in the Campeche pink shrimp fishery as in the Texas 

 brown shrimp fishery, all segments of the fishable biomass are not repre- 

 sented in the commercial landings despite the fact that the gear employed is 

 essentially the same as that used throughout the Gulf. This is due to the 

 rather rigid restrictions concerning the sizes of shrimp landed that the fish- 

 ery imposes upon itself. The United States fleet fishing the Campeche shrimp 

 populations is, perhaps, the most selective of any comparable unit operating 

 in Gulf waters. Rarely are Cannpeche landings composed of shrimp predom- 

 inantly smaller than 19-24 heads-on (31-40 heads-off) count size. And only 

 in recent years has the average size fallen below 16-18 "whole" (26-30 "head- 

 less") shrimp to the pound. The task of maintaining quality control, i. e. , 

 sorting the decreasing numbers of large shrimp from increasing catches of 

 small shrimp, is reportedly becoming more and more difficult. The conse- 

 quence of such practices is that landings are not representative of that portion 



23 



