30 



COMMERCIAL FISHERIES REVIEW 



Vol. 28, No. 7 



trawling system to determine the functioning 

 capabilities, reliability and ruggedness of its 

 components; (2) underwater photography of 

 the electroshrimp trawling system; and (3) 

 photographic recording of the escape reac- 

 tion of electrically-stimulated shrimp from 

 the Tortugas shrimp grounds. 



PHASE II AND PHASE VI- -Gear Studies 

 (February 28-March 16, and April 11-26, 

 1966): A prototype electroshrimp trawling 

 system designed and built by the staff of the 

 Bureau's Gear Research Unit was completed 

 earlier this year. The system is composed 

 of 4 primary components. They are the power 

 control panel aboard the vessel; a cable, sup- 

 plying power from the vessel to the trawl; an 

 electric pulsing unit mounted on one of the trawl 

 doors and an electrode array. Voltage is 

 controlled from a variable transformer and 

 is monitored on a meter in the panel. The 

 power supply cable being used for the initial 

 trials is a neoprene coated, 4 -conductor A- 

 merican Wire Gauge (AWG) No. 12 cable. 

 Two of the conductors are used for the pri- 

 mary power source, and the other 2 conduc- 

 tors are used to monitor voltage readings. 

 The electrical pulser is encased in a water- 

 tight-underwater housing and is attached to one 

 of the trawl doors. The housing is fabricated 

 from polyvinyl -chloride tubing and is design- 

 ed specifically for the electrical pulser. The 

 electrode array is made up of 5 electrodes, 

 equally spaced ahead of the footrope. Each 

 electrode is a heavy-tinned copper braid 

 which has been slipped over a rope core and 

 then connected to a conductor from the elec- 

 trical pulser. 



During field trials, several faulty com- 

 ponents were found and were either replaced 

 immediately or were to be exchanged for 

 parts which were on order. The first ma- 

 terial tested for use as electrode wire was 

 not adequate and was replaced. Another dif- 

 ficulty encountered was that the designed 

 voltage peaks were not obtained on a contin- 

 ual basis, indicating either malfunctioning 

 components or possibly underrated internal 

 components in the electrical pulser. Facili- 

 ties available in the field did not permit the 

 correction of this latter condition and re- 

 pairs were to be effected in the laboratory. 



PHASE IV- -Underwater Trawl Studies 

 (March 22 -April 5, 1966): Turbid water con- 

 ditions which spread uniformly over the Tor- 

 tugas shrimp grounds did not permit the 

 scheduled trawl photography to be carried 

 out. Transmissometer readings indicated 



underwater visibility was limited to only 6 

 feet. This would not have permitted the ef- 

 fective detailed photography necessary. 



Operational testing was carried out on 

 coral reefs adjacent to the Gulf Stream with 

 the new 400 -foot film capacity motion picture 

 camera. The electrically- driven unit with re- 

 flex focusing gives the SCUBA-equipped pho- 

 tographer more flexibility and control than 

 other systems available. Although additional 

 counter -balance weight had to be added to the 

 housing, the unit handled well underwater and 

 800 feet of motion picture footage were taken. 



PHASE VII--Shrimp Behavior Studies 

 (April 26 -May 6, 1966): Results from previ- 

 ous cruises have indicated the escape reac- 

 tion of electrically-stimulated shrimp have 

 varied according to the type of substrate in 

 which they are burrowed. Therefore, as a 

 continuation of the shrimp behavior studies, 

 SCUBA divers recorded photographically the 

 escape reaction of shrimp from a hard clay 

 bottom. The sequences were recorded with 

 900 feet of colored motion picture film. The 

 film will provide information on the electrical 

 stimulation of shrimp on one of the important 

 shrimp grounds in the Gulf of Mexico. Bot- 

 tom samples were taken from the area for 

 laboratory analysis. 



In cooperation with Woods Hole Oceano- 

 graphic Institute, 240 drift bottles were re- 

 leased in 40 locations off the west coast of 

 Florida. _____^_ 



Note: See Commercial Fisheries Review . January 1966 p. 35 and 

 December 1965 p. 33. 



Industrial Fishery Products 



U. S. FISH MEAL, OIL, AND SOLUBLES : 



Production by Areas , April 1966: Prelim- 

 inary data as collected by the Bureau of Com- 



U. S. Productioni/ of Fish Meal, Oil, and Solubles, 

 April 1966 (Preliminary) with Comparisons 



Area 



Meal 



OU 



Solubles 



April 1966: 



Short 

 Tons 



6,017 

 3,578 



1,000 

 Pounds 



4,625 

 481 



Short 

 Tons 



1,980 

 1,944 



East & Gulf Coasts . . 

 West Coast?./ 



Total 



9,595 



5,106 



3,924 



Jan. -Apr. 1966 Total . 



20,036 



6,623 



9,195 



Jan. -Apr. 1965 Total . 



18,962 



11,861 



5,606 



1/Does not include crab meal, shrimp meal, and liver oils. 

 2/Includes American Samoa and Puerto Rico, 



