more common and readily recognizable forms 

 are listed in Table 2. Mortalities related to cap- 

 ture of these larvae were estimated to be less 

 than 10%, while mortalities for subadults and 

 adults were less than 20%. Large specimens 

 of Atlantic cutlassfish, sea catfish, Atlantic 

 croaker, Gulf menhaden, and the blue crab were 

 passed through the pump with little damage. 

 The sorting box was effective in removing all 

 animals and trash larger than 1.5 mm in diam- 

 eter, or about 95% of the larval fishes caught. 

 Postlarvae retained in the trash were less than 

 10% of the total number of postlarvae caught. 

 Larval stages of the blue crab were not eflfective- 

 ly separated, however, and were voracious 

 feeders on postlarvae. 



This system was efficient in capturing and 

 sorting large numbers of postlarval shrimp and, 

 by adjusting the widths of the sorting screens, 

 can be used to catch and sort most small animals 

 as they migrate through tidal passes. The pump 

 and suction cone attachment on the tail of the 

 nets provided a constant free flow of water which 

 eliminated the problem of clogging or fouling as 

 encountered with standard plankton nets. The 

 system is not restricted to use on a boat and 

 could be easily adapted for land-based operations 

 from piers and platforms. 



Table 1. — Estimated number of postlarval brown shrimp 

 caught by date in the Bolivar Roads Tidal Pass, Galves- 

 ton Bay, Tex., 1971. 



Table 2. — Fishes and crustaceans collected during eval- 

 uation of the system; A ^ abundant; = occasional. 



Literature Cited 



Baxter, K. N., and W. C. Renfro. 



1966. Seasonal occurrence and size distribution of 

 postlarval brown and white shrimp near Galves- 

 ton, Texas, with notes on species identification. 

 U.S. Fish Wildl. Serv., Fish. Bull. 66:149-158. 

 Caces-Borja, p., and S. B. Rasalan. 



1968. A review of the culture of sugpo, Penaeus 

 monodon Fabricius, in the Philippines. FAO 

 (Food Agric. Organ. U.N.) Fish. Rep. 57:111-123. 

 DuRONSLET, M. J., J. Lyon, and F. Marullo. 



In press. Vertical distribution of postlarval brown, 

 Penaeus aztecu^, and white, P. setiferus, shrimp 

 during immigration through a tidal pass. Trans. 

 Am. Fish. Soc. 

 Walford, L. a. 



1958. Living resources of the sea: Opportunities 

 for research and expansion. Ronald, N.Y., 321 p. 



C. T. Fontaine 



S. E. P. Gislason 



W. L. Trent 



National Marine Fisheries Service 

 Gulf Coastal Fisheries Center 

 Galveston Laboratory 

 Galveston, TX 77550 



1302 



