FISHERY BULLETIN: VOL. 71, NO. 1 



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 March 28, 1969 



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 June 23, 1969 



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Figure 7. — Three different diel distributions of pink shrimp collected with the shrimp sampler. The vary- 

 ing width of each diagram represents the percentage proportion of the catch taken at various distances 

 from the bottom of the sampler. 



seabed. The greatest quantity of shrimp were 

 taken during the day. 



The tows on 23 June presented a valuable 

 opportunity to observe the changes in shrimp 

 vertical distribution accompanying a change in 

 cloud cover. The 2 days preceeding 23 June 

 were sunny. Tows with the shrimp sampler on 

 these days indicated shrimp were concentrated 

 near the seabed during daylight hours. Com- 

 mercial fishermen working near the sample sta- 

 tion were making good catches of shrimp. 



On the evening of 23 June a zone of low baro- 

 metric pressure moved into the area with result- 

 ing cloud cover and rain squalls on 23 June. 

 Catches by commercial fishermen dropped to a 

 fraction of those taken on previous days. The 



vertical distribution sampler indicated shrimp 

 were well off bottom (Figure 7) with reduced 

 shrimp abundance, compared with tows made on 

 previous days. A most interesting situation oc- 

 curred during tows made in twilight and after 

 dark as the catch rates were much higher than 

 in tows made in the preceeding daylight hours. 



MESH SIZE EVALUATIONS 



The effect of mesh size on the movement of 

 shrimp was investigated by placing web of two 

 different sizes on separator panels over the port 

 and starboard vertical columns. A total of six 

 different mesh sizes were evaluated in this man- 

 ner. Two-inch mesh was placed over the center 



248 



