Currents on the Continental Shelf of the Northwestern Gulf of Mexico 



JUNE 14-15, 1961 



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TIDE 

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J. Bruce Kimsey and Robert F. Temple 



The three commercially important species of shrimp, i.e., brown 

 (Penaeus aztecus ), white (P. setiferus) , and pink (P. duorarum ), all spawn 

 offshore where the eggs hatch. This may occur at distances ranging from a 

 few miles to as much as 150 miles offshore and at depths down to 60 fathoms. 

 The larvae move shoreward while passing through a series of developnnental 

 stages, arriving at the passes into the bays and estuaries as postlarvae. It 

 is not known whether the shoreward migration is aided by water currents or 

 the larvae arrive under their own power with no outside aid. 



A study to determ.ine the role water currents play in the movenaent 

 of larvae from offshore spawning grounds to the inshore nursery grounds has 

 been a part of the Shrimp Fishery Program since 1961 when the Savonius 



rotor current meter was first used. 



Analysis of cur- 

 rent data collected with 

 this current meter during 

 April through October 1961 

 has been completed. The 

 data were obtained by tak- 

 ing instantaneous readings 

 every 3 weeks at 1 1 sta- 

 tions in waters adjacent 

 to Galveston. Station 

 depth ranged from Tg 

 to 45 fathoms. At each 

 station, current observa- 

 tions were made at 10 feet 

 below the surface, mid- 

 depth, and 10 feet from the 

 bottom. To complement 

 these data, three 24-hour 

 current studies were under- 

 taken at one 15 -fathom sta- 

 tion (Station "H"). 



In an attempt to 

 obtain a generalized cur» 

 rent pattern fronn the in- 

 stajitaneous monthly ob- 

 servations, current roses 

 were constructed for each 

 station and depth. Although 

 the results are not con- 

 clusive, indications are 



Progressive vector analysis of 24 -hour 

 current observations made at a 15-fathom 

 station off Galveston, Tex. 



23 



JULY 20-21, 1961 



TIDE 

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