The seasonal distribution and abundance vary considerably at the 

 15 -fathom stations from those at the shallower stations. The larvae of one 

 stage or another of the nonexploited shrimp were present throughout the entire 

 year, although in varying degrees of abundance. Two peaks of abundance are 

 noted: one in June and the other in September. Nauplii are most prevalent in 

 March and the first of December. 



The level of abundance of penaeid larvae at 25 fathoms fluctuated 

 radically from February to July. Two peaks of abundance are evident: one in 

 March and another in June. In the ensuing months, August through November, 

 a level of abundance similar to that of March and June was reached and main- 

 tained until November. In December, there was a sharp decline in the abun- 

 dance of larvae. Nauplii were caught sporadically over the entire sampling 

 period with the greatest abundance in March. The overall larval abundance 

 in this depth zone was not as great as at 15 fathonns, however. 



At the 45 -fathom stations the peaks of abundance occurred in April 

 and October. Larvae are less abundant, however, than at shallower stations. 

 The few nauplii taken at this depth were taken in February and September. 



Penaeus larvae of one stage or another were present the entire year 

 at 15-, 25-, and 45-fathom stations. The majority of larvae at Tg-fathom sta- 

 tions, however, were caught between April and November. Indications are that 

 temperatures have a direct effect on the seasonal occurrence of Penaeus larvae 

 at the 7|^-fathom stations. The highest level of abundance was at 25-fathom 

 stations between September and November. 



All larval stages of Penaeus were most abundant at 25-fathom sta- 

 tions. Nauplii at 15- and 25-fathom stations were 3 to 16 times more abun- 

 dant than at either 7|^- or 45-fathom stations. Protozoeae at 25-fathom stations 

 were the most abundant larval stage encountered. It would appear that larvae 

 at 25 fathoms are probably either Penaeus aztecus or P. duorarunn, since P. 

 setiferus, very seldom inhabit these depths. 



Annual catch per standard tow of larvae of exploited shrimp 



25 2.30 15.23 2.13 1.89 



45 .15 4.41 .52 1.45 



21 



