POPULATION DYNAMICS OF WHITE 



SHRIMP AND BROWN SHRIMP IN 



VERMILION BAY, LA. 



Investigations of seasonal fluctuations in 

 the abundance of postlarval shrinnp in Ver- 

 nnilion Bay have been underway since Feb- 

 ruary 1963. Infornnation collected to date 

 indicates a possibility for predicting the com- 

 mercial abundance of white shrinnp fronn 

 densities of postlarvae. Attempts to relate 

 the abundance of postlarval brown shrinnp to 

 later commercial catches have been less 

 successful. The reverse of this situation has 

 been found at Galveston, where predictions 

 of brown shrimp abundance appear to be more 

 feasible than those for white shrimp. 



New short-term studies during the summer 

 when classes are not in session were added 

 to the schedule of contract work. Laboratory 

 experiments were undertaken to determine the 

 glycogen and lactic -acid content of shrimp 

 nnuscle tissue, and to develop antisera that 

 may be used to distinguish white and brown 

 shrimp at the postlarval stage. Shrinnp produc- 

 tion in a small portion of Vermilion Bay is 

 being studied by following changes in the size 

 composition of brown and white shrimp. 



Charles W. Caillouet, Jr., Project 

 Leader 



University of Southwestern Louisiana 

 (Contract No, 14- 17-000Z-131) 



ESTUARINE PROGRAAA 



Gulf estuaries, which harbor fishery re- 

 sources that contribute almost one-third of 

 the comnnercial harvest from U.S. coastal 

 waters, are being rearranged, modified, de- 

 stroyed, and polluted at an alarming rate. 

 These valuable ecosystems are natural nutrient 

 "traps" that frequently produce more per 

 hectare than the croplands of our midwest. 

 Nonetheless, those planning construction have 

 given little thought to the present and potential 

 value except as natural features to be con- 

 verted to industrial and residential sites or 

 receptacles for sewage. The short-term gains 

 from these modifications cannot be in the best 

 public interest. 



A major purpose of our Estuarine Progrann, 

 then, is to amass the basic facts needed to 

 document the dependency of fishery resources 

 on estuaries, the specific type of estuarine 

 habitat that is the most productive, and the 

 value of such areas to our national economy 

 in terms of their production of renewable 

 fishery resources. When these facts are docu- 

 mented, the fishery resources can compete 

 in the race to develop our coastal basins for 

 maximum good. 



During the past year we learned much 

 about the specific types of habitat that nnost 

 of the major commercially important species 

 prefer during the estuarine phase of their 

 development. The peripheral "edge" of an 

 estuarine system (exennplified by bordering 

 marshes, small stream or bayou complexes, 

 and protected shorelines) is used more exten- 

 sively by most estuary-dependent species as 

 their primary nursery area than any other part 

 of an estuary. Unfortunately, these valuable 

 edges are being developed and converted to 

 residential and industrial sites faster than 

 other portions of an estuary (fig. l6). They 

 are easily accessible amd often privately 

 owned. 



In an effort to use our manpower resources 

 better and obtain better basic data, we are 



streamlining and mechanizing our field work 

 and emphasizing ADP (automatic data proc- 

 essing) to an ever greater degree. Since 

 most estuary-dependent animals are sensitive 

 to tennperature, we have developed and installed 

 in the field a temperature-recording device 

 (fig. 17) and will soon have salinity-recording 

 instruments for our vessels and for field 

 installation. We hope eventually to record the 

 hydrological regime of an entire estuary with 

 such instruments adapted for ADP. 



Several special studies were started during 

 the year, and one was connpleted. Our first 

 attempt to assess the effect of modifying 

 a natural shoreline zone by bulkheading was 

 successful. We begam a study to determine 

 the effects of pumping hydraulic spoil over 

 a marsh area and nearby submerged grass 

 flats because we needed more information 

 on this increasing type of activity (fig. 16). 

 Our attempt to assess the population of brown 

 shrimp in the tidal passes of the Galveston 

 estuary as they return to the Gulf of Mexico 

 continues in cooperation with the Shrimp 

 Dynamics Program. 



Cooperative research was expanded con- 

 siderably during the year. We exchanged field 

 data, provided technical assistance, or par- 

 ticipated directly in field studies with several 

 universities, private companies. State con- 

 servation and pollution control agencies, and 

 other Federal agencies, including Bureau of 

 Commercial Fisheries Laboratories. One of 

 the more important of these enterprises is a 

 cooperative study with Texas A&M University 

 to survey the fishery resources of the lower 

 Trinity River Delta before a reservoir is 

 built and the area inundated. 



Our review of water-development projects 

 for the Bureau in the western Gulf area 

 continued to require a great amount of time. 

 Private developments in the estuaries in- 

 creased by more than one-third over the 

 previous year, and the larger Federalprojects 



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