Early. Life History of Commercial and Related Shrimps 



William C. Renfro 



STATION PATTERN -SPAWNING GROUND STUDY 



Spawning populations Major objectives of a new sea- sampling project which 



began in January of this year and is scheduled for completion next December 

 are: (1) to delineate penaeid shrimp spawning grounds in the Gulf of Mexico 

 off east Texas; (2) to determine reproductive status in populations of various 

 species with respect to season and area; (3) to study the effects of environ- 

 mental factors (such as temperature, salinity, and bottom composition) on 

 penaeid distribution, abundance, and spawning activities; and (4) to ascertain 

 seasonal and areal distribution of shrimp larvae and the importance of ocean 

 currents in their movement to inshore nursery areas. 



To implement this project, the double- rigged shrimp trawler MISS 

 ANGELA of Freeport, Texas, was chartered through June 1961. A cruise 



pattern to be run at 3- week inter- 

 vals was designed so that as large 

 an area as possible could be cov- 

 ered in a reasonably short inter- 

 val of time (3-4 days). Eleven sta- 

 tions were positioned over an "ef- 

 fective" sampling area of about 

 6, 200 square miles such that two 

 or nnore sets of hydrographic ob- 

 servations and biological collec- 

 tions could be obtained in subareas 

 characterized by depths of 72, 15, 

 25, and 45 fathom.s. 



At each station a "stand- 

 ard" 45-foot flat trawl is towed for 

 1 hour. Since vessel speed is meas- 

 ured during each haul, the resulting 

 biological samples (assuming ratio 

 between ground and surface speed 

 is reasonably constant) may be 

 treated quantitatively. Captured 

 shrimp are identified as to species 

 and sex, measured, and an ovary 

 sample taken and fixed for cytolog- 

 ical examination in the laboratory. 

 During each trawl haul a 20-minute 

 oblique plankton tow is made with 

 a Gulf V sampler. Profiles of tem- 

 perature and salinity are obtained 



NAUTICAL MILES 



Station pattern for shrimp spawning 

 ground survey off east Texas coast. 



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