greatest amount of pink shrimp around south Florida where the 

 salinities are almost oceanic. In nature most postlarval P_. aztecus 

 are exposed to lower and more fluctuating estuarine temperatures 

 than those encountered by white shrimp. Aldrich et al . (1968) ob- 

 served in the laboratory that the temperature optima of the two 

 species differed. The variations in the environmental requirements 

 of the three species indicate that they should be studied separately. 



Despite their commercial importance brown shrimp, or for that 

 matter any one of the penaeid species, failed to attract the atten- 

 tion of physiological ecologists until recently. Widespread studies 

 on the general biology of the North American white shrimp were initi- 

 ated in 1930 by Weymouth, Lindner and Anderson (1933) . At that time, 

 95% of the total shrimp catch consisted of white shrimp. The main 

 emphasis of those studies was to learn about the life history 

 (spawning, embryology, larval history, growth and longevity) , the 

 migratory pattern, the effect of fishing, and the abundance of the 

 species in relation to salinity and temperature conditions. Experi- 

 ments with tagging techniques revealed data relating to the growth 

 and seasonal migration. Among other investigators who originally 

 supplied information on the biology of American penaeid shrimp, 

 work of the following should be noted: Spaulding (1908), Viosca 

 (1920), Burkenroad (1934, 1939), Pearson (1939), Anderson et al. 

 (1949) and Gunter (1950). 



Among early workers Burkenroad (1934, 1939) gave the most ex- 

 tensive data on brown shrimp. His information related partly on the 

 salinity preference of this species as being different from the white 

 shrimp. He showed that brown shrimp are less abundant in less sa- 

 line and more abundant in more saline coastal waters. Gunter (1950) 

 confirmed this point and added specific data. Burkenroad also 

 pointed out that the sexually mature adult brown shrimp in Louisiana 

 waters are found beyond the inner littoral zone. Gunter (1967) ranked 

 white shrimp, brown shrimp, and pink shrimp in order of their 



24 



