useful conclusions that can be drawn are that available quantities of premium 

 pink shrimp on the Campeche flats reached a seasonal peak during late fall, 

 and over the 5-year study period experienced a significant decline. The steady 

 rise in annual mean bionnass since 1958 does, however, offer some hope for 

 recovery in the near future. 



Population characteristics Little information on population age structure 



could be obtained by plotting weight-frequency modes of monthly Campeche 

 landings. As intimated earlier, weight-composition curves were almost ex- 

 clusively unimodal with large shrimp predominating at all times (see figure, 

 C). Conclusive evidence of more than one period of heightened spawning per 

 year is lacking, but bimodal weight -frequency curves for spring landings in 

 1959, and winter and midsummer landings in I960, suggest that two peaks in 

 annual spawning activity are characteristic of the Campeche pink shrimp 

 population. 



Summary of 5-year status Accurate but restrictive statistics give only a 



vague picture of conditions in the Campeche pink shrimp population. Com- 

 posed primarily of large-size shrimp, yields to United States fishermen de- 

 clined over the period 1956-1958, but increased measurably during the ensu- 

 ing 2 years. Of significance was the drop in apparent abundance of large 

 shrimp commencing in 1958 and sustained through I960. Whether this was 

 caused by excessive fishing alone, or by a combination of fishing and adverse 

 environmental conditions, will always remain problematical. The Campeche 

 fishery serves as a good example of a situation where lack of all-inclusive 

 yield data (i. e. , landings plus discards) inhibits proper population analysis. 

 If landings statistics truly represented what was actually caught, further 

 investigation of the Campeche population's dynamics would be justified. 



25 



