during each year of the study (fig. 2). The greatest 

 numbers occurred in the spring; usually peak abun- 

 dance was reached between mid-March and mid- 

 April. Following the spring peak, comparatively 

 few postlar\-ae were caught until about mid-June. 

 Thereafter, the number of postlarvae in the collec- 

 tions increased through July and reached a second 

 peak in August or September. In each year, the 

 numbers of brown shrimp postlarvae present at 

 Galveston Entrance diminished rapidly after the 

 second peak and remained low throughout the win- 

 ter. During 1961, peak abundance appeared to 

 develop in late April and earlj' May, but because 

 sampling was suspended from May 8 to August 11, 

 the actual time of the peak for that year is unknown. 

 The first postlarval white shrimp, P. setifcnis 

 (Linnaeus), were taken in early May of each year at 

 Galveston Entrance (fig. 2). Seasonal distribution 

 of postlarval white shrimp suggests that two peaks 

 in abundance may occur each summer and that the 

 relative strength of these peaks is variable. 



GALVESTON ISLAND BEACH 



Trends in seasonal occurrence of postlarval brown 

 and white shrimp at Galveston Island beach stations 

 were similar to those at Galveston Entrance stations 

 (table 1). Brown shrimp postlarvae were numerous 

 in mid-April 1960, from late June through August, 

 and again during April 1961. In contrast to Gal- 

 veston Entrance, a few brown shrimp postlarvae 

 were present along the beach during late December 

 and January. In 1961 brown postlarvae did not 

 appear in significant numbers until early March. 

 Postlar\al white shrimp were caught in beach sam- 

 ples from mid-May through November 1960 and 

 were most abundant from late June through July. 

 None was taken from December 1960 through April 

 1961. 



Samples of postlarvae were collected along Gal- 

 veston Island beach to determine if young shrimp 

 use the littoral zone along beaches as nursery areas. 

 Should they use this zone, advanced stages of post- 

 larval shrimp could be expected in collections from 

 beach stations. Agreement as to general size of 

 postlar\'ae from the beach and from Galveston En- 

 trance (table 2), indicates, however, that postlarvae 

 spend little time in the beach area. Repeated tows 

 with a fine-mesh seine at beach stations caught no 

 shrimp larger than those taken in the beam trawl. 



Table 1. — Average monthly densities of postlarval shrimp at 

 Galveston Entrance and Galveston Island beach stations, 

 April 1960-61 



IFigures represent the average number of postlarvae per 100 m.' of bottom 

 in 7 to 12 collections each month] 



Table 2. — Mean total lengths of postlarral shrimp collected 

 concurrently along the Galveston Island beach and in Galveston 

 Entrance, 1960-61 



(Figures in parentheses indicate number of specimens me^ured] 



IDENTIFICATION AND SEASONAL 

 SIZE DISTRIBUTION 



Of the three commercially important species of 

 the genus Penaeus in the northern Gulf of Me.xico, 

 the pink shrimp, P. duorarum, is the least abundant. 

 Small numbers of adult pink shrimp are commonly 

 caught off Galveston Island (15-20 fathoms), but 

 landing data compiled by the Bureau of Commercial 

 Fisheries Branch of Statistics^ included no pink 

 shrimp in landings of 3.7 million pounds taken from 

 Galveston Bay during 1960-63. A few pink shrimp, 

 however, may have been landed and reported as 



' "Gulf Coast Shrimp Catch by .\rea. Depth, Variety, and Size," 

 Annual Summaries, 1960-63. 



DISTRIBUTIOX OF SHRIMP NEAR GALVESTON 



151 



