pink shrimp. The number of spines for each 

 species generally increases with increasing 

 size, and for shrimp of a given length, the 

 number of spines differs little between species. 



W. Lee Trent, Project Leader 



EVALUATION OF ESTUARINE DATA 



Estuarine Atlas 



The need for aninventory of estuarine areas, 

 such as the one being planned and coordinated 

 by the ETCC (Estuarine Technical Coordinating 

 Committee) of the Gulf States Marine Fisheries 

 Commission is emphasized by competition for 

 these coastal waters by fish and wildlife re- 

 sources on one hand and industrial, commer- 

 cial, residential, and agricultural interests 

 on the other. Documentation of the biological 

 value of estuaries for perpetuating fish and 

 wildlife resources is needed if the integrity 

 of our estuaries is to be maintained. 



The ETCC intends to standardize field 

 methods for collecting estuarine data and 

 formats for recording all "atlas" data. These 

 methods and formats are to be used by the 

 participating States and agencies. Alabama, 

 Mississippi, and Louisiana receive financial 

 assistance from Public Law 88-309 funds to 

 inventory their estuarine area; the Gulf coast 

 of Florida will be inventoried by the Bureau of 

 Commercial Fisheries; and Texas will par- 

 ticipate to the extent funds and staff can be 

 made available. 



Assistance was provided an ETCC subcom- 

 mittee in preparing an outline for "Area 

 Description." It was reviewed by the full com- 

 mittee, and several changes were suggested. 

 The final version, which includes a listing of 

 priority items and standardized tables for re- 

 cording data, was drafted in cooperation with 

 the Bureau of Commercial Fisheries Biological 

 Laboratory, St. Petersburg Beach, Fla., and 

 adopted by the ETCC for the Estuarine Atlas. 



Assistance with the review of formats for 

 the "Biology" and "Hydrology" phases of the 

 Atlas was also provided to the respective ETCC 

 subcomnnittees. The fornnat for "Hydrology" 

 has been adopted by the ETCC, butthe "Biology" 

 format is being revised and the "Sedimentology" 

 format is being drafted by their respective 

 subcommittees. 



Fish Food Study 



Clear Lake, a brackish bay on the western 

 side of Galveston Bay, has long been known as 

 a valuable nursery area for commercially im- 

 portant fish and crustaceans. The area has 

 been subjected to considerable investigation 

 by personnel from Federal and State con- 

 servation agencies. Much of this effort, how- 

 ever, was restricted in scope, being linnited to 



studies on the relative abundance and sea- 

 sonal distribution of several selected species. 

 Therefore, a study on the food of fish from 

 Clear Lake was begun as an additional con- 

 tribution to the biology of the lake. 



A total of 228 samples containing 5,016 fish 

 was collected with a small trawl from 10 loca- 

 tions in Clear Lake. Of the 40 species in the 

 samples, 8 contributed 4,628 specimens and 

 nnay be classified as "dominants"; the remain- 

 ing 388 specimens were distributed among 32 

 species. 



The Atlantic croaker ( Micropogon undulai:us ) 

 and the sand seatrout ( Cynoscion arenarius ) 

 were most numerous with 2,342 and 1,041 spec- 

 imens, respectively. Ninety-one percent of the 

 croaker stomachs and 85 percent of the sand 

 seatrout stomachs contained food. 



Mysidacea, copepods, plant nnaterial, fish, 

 organic detritus, and annelids occurred most 

 frequently in the stomachs of croakers; 

 mysidacea, palaemonid shrimp, and fish made 

 up the bulk of the diet of the seatrout (table 8). 



Table 8. --Percentage frequency of occurrence of different food 

 items in stomachs of 2,131 MleropoRon undulatus and Cynoscion 

 arenarius taken from Clear Lake, Tex. 



Food item 



Foraminifera 



Bryozoa 



Annelids 



Crustacea; 



Unidentified remains 



Branchiopoda 



Copepoda 



Ostracoda 



Cirripedia 



f^sidacea 



Amphipoda 



Isopoda 



Stoma topoda 



Penaeid shrimp 



Palaemonid shrimp 



Crangonid shrimp 



Crabs 



Spiders 



Insects 



Clams 



Squid 



Fish 



Plant debris 



Unidentified organic debris 

 Mud and sand 



0.0 

 0.0 

 0.3 



1.8 



0.0 

 4.0 

 0.0 

 0.0 



67.2 

 2.5 

 0.4 

 0.1 

 4.4 



29.8 

 0.0 

 2.0 

 0.0 

 0.1 



0.0 



0.0 



24.8 



4.9 



2.0 

 1.5 



1/ 23-160 mm. total length. 

 2/ 10-165 mm. total length. 

 3/ Items with less than 0.1-percent frequency occurrence. 



27 



