A Remote Controlled Underwater 

 Photographic Surveillance System 



by 

 Paul J. Kruse, Jr. 



ABSTRACT 



An underwater motion picture camera system has been developed and used to 

 study midwater trawling operations. The photographic equipment is handled by re- 

 mote control from the vessel deck and records both trawl mechanics and fish escape 

 reactions. The equipment has been tested and placed in operation in studies in the 

 Gulf of Mexico. 



INTRODUCTION 



During the past 5 years, the Bureau of Com- 

 mercial Fisheries Exploratory Fishing and 

 Gear Research Base, Pascagoula, Miss., has 

 been investigating the pelagic school fishes of 

 the northern Gulf of Mexico. The U.S. Fish and 

 Wildlife Service exploratory fishing vessel 

 Oregon has been assigned to the investigation. 

 In the first year, effort was devoted largely to 

 sampling and qualitatively surveying the re- 

 source (Thompson, 1959). In subsequent years, 

 attention was turned to assessing the abundance 

 and availability to trawling gear of the fish 

 species involved. 



As the work progressed, several difficulties 

 became evident (Bullis, 1961). Calculations of 

 abundance and availability are dependent on a 

 knowledge of the effectiveness of the sampling 

 device being used. The effectiveness of sam- 

 pling in this study was difficult to assess, how- 

 ever, as the sampling device was out of sight, at 

 the end of hundreds of feet of cable, and 

 beneath several hundred feet of water. 



Visual observation appeared to offer the best 

 overall synchronous study of the many different, 

 but related, events taking place during midwater 

 trawling operations. Films made by diver pho- 

 tographers would have been preferred, how- 

 ever, the physical conditions encountered dur- 

 ing field trawling operations made this approach 

 impractical. A special remote controlled mo- 

 tion picture camera system was subsequently 

 developed, at the Pascagoula Base, to overcome 

 the limitations of divers and permit visual 

 recordings of midwater trawling operations. 



REMOTE CONTROLLED PHOTOGRAPHIC 

 SYSTEM AND ACCESSORIES 



The remote controlled photographic systenn 

 permitted cameras to be mounted on the mid- 

 water trawl itself, and yet be controlled by 

 an operator on board the Oregon. The system 



Note. — Paul J. Kruse, Jr., Fishery Biologist, Bureau of 

 Commercial Fisheries Exploratory Fishing and Gear Re- 

 search Base, Pascagoula, Miss. 



can also be synchronized with data received 

 from a trawl headrope transducer. The cameras 

 are compact and rugged enough to operate 

 under any conditions that permit trawling. 



The photographic system (fig. 1) consists 

 of three electrically driven motion picture 

 canneras in underwater housings that are 

 fastened to the trawl (fig. 2). The cameras 

 are connected to the towing vessel by an 

 electrical cable that is plugged into a master 

 control box (fig. 3), connected to a shipboard 

 110-volt a.c. outlet. Camera operation is con- 

 trolled by a switch on the control box. Con- 

 verters in each underwater housing change 

 the 110-volt a.c. current to the 24-volt d.c. 

 required for the camera motors. 



Basic Camera Modifications 



The N-9 GSAP U.S. Air Force gun camera 

 (also known as TKB-3A) is the basic unit for 

 this system. It was chosen because of its com- 

 pact size, ruggedness, availability, adjustable 

 shutter opening, rapid film loading, and choice 

 of 50- or 100-foot film magazines. The three 

 film speeds available on the standard cameras 

 are 16, 32, and 64 frames per second (f.p.s.). 

 Other frame rates are available as special 

 conversions. The basic canneras are modi- 

 fied as follows: 



1. The 0- to 3- second overrun mechanism 

 is removed. 



2. The small disk tension spring in the film 

 magazine clamp, located at the rear of the 

 camera body, is removed to assure a more 

 positive connection between the film magazine 

 and the camera body. 



3. The remote shutter adjusting mechanism 

 is not used. This reduces the nunnber of con- 

 ductors necessary in the underwater cable. 



Film Magazines and Modifications 



Two sizes of underwater cameras were used 

 for the nnidwater trawl studies and offered 

 greater flexibility than if only one were used. 

 A 400-foot film capacity camera permits 8 

 minutes running time, at 32 f.p.s. It is used 



