white shrimp these grooves end considerably farther forward, near the 

 beginning of the rostrum. 



The blue and white shrimp are rarely caught in depths greater 

 than 15 fathoms. The brown is taken mostly between the 15- and 30- 

 fathom contours but occasionally is found in shallower and deeper waters. 

 The red shrimp is seldom caught in less than 20 fathoms and is taken in 

 depths to kS fathoms, which is the limit of operations of the shrimp 

 fleet. 



The blue and brown shrimp are found everywhere on the l^^est- 

 coast fishing grounds. The white and red shrimp are not taken along 

 the west coast of Baja California. The blue shrimp is the most abundant 

 species at Salina Cruz, and in all of the fishery north of Mazatlan. 

 The white shrimp is most abundant between Mazatlan and San Bias. 



The market preference is for the blue and white shrimp. As 

 the season progresses and as these tvjo species become scarcer, the boats 

 fish first for brown and later for red shrimp. The blue and white shrimp 

 are caught during the daytime and the brown and red at night. Generally, 

 about 75 percent of the trawl catch of blue and white shrimp runs under 

 20 to the pound, heads-off . The brown shrimp usually are smaller than 

 21-25 to the pound, heads-off, and the red 31-35 or smaller. 



The only area where relatively accurate records of the catch 

 of the various species of shrimp are available is that covered by the 

 Mazatlan travjl fleet. Estimates of the percentage of catch by weight 

 of shrimp made by the biologist studying this fishery are as follows: 



82 



