transmission within minutes, for immediate 

 interpretation of close-up photography. But 

 images from long-range, high-altitude 

 satellites need more extensive and detailed ex- 

 amination, often requiring several hours or 

 even days by expert photo-interpreters before 

 useful, specific data are developed. Most of the 

 electro-optical systems can provide realtime 

 outputs capable of immediate display and ex- 

 amination in the form of electrical signals 

 readily amenable to interpretation or 

 transmission to a shore-based facility. 



Optical and electro-optical techniques vary 

 widely and the choice of specific systems 

 would depend on the enforcement strategies 

 chosen. 



Electromagnetic Intercept Techniques*' 



Because all ocean-going vessels are already 

 equipped with radio equipment and most 

 with navigational radar, it is possible to detect 

 and classify foreign fishing vessels by inter- 

 cepting and analyzing their radio or radar 

 emissions. 



Two techniques have potential in fisheries 

 enforcement activities: the use of direction 

 finding equipment to determine the position 

 of detected vessels and the use of information 

 from the intercepted transmissions to identify 

 and classify the vessel. 



The technology for both direction-finding 

 and communications interception and 

 analysis is highly developed and numerous 

 systems have been developed for both mili- 

 tary and civilian use. These systems can be 

 operated from shore bases, ships, aircraft, or 

 satellites. At high frequencies intercept is not 

 limited to, but does work best, within line-of- 

 sight of the detected vessel. An aircraft mov- 

 ing at 300 knots could have line-of-sight ac- 

 cess to 200,000 square miles of sea surface per 

 hour. 



In the past, direction-finding equipment 

 was used primarily for location of aircraft and 

 ships in distress. Currently, however, it is in 

 use largely for monitoring and surveillance. 

 The Federal Communications Commission 

 maintains a network to locate illegal radio 

 transmitters and sources of radio interference; 

 the Department of Defense operates several 

 networks for surveillance and intelligence 

 data collection. 



It is possible that some signal intercept in- 

 formation from DOD files can be made availa- 

 ble to the Coast Guard for fishery enforce- 

 ment. However, most of the DOD operations 

 are mission-oriented and are flown in areas of 

 military interest, therefore it is unlikely much 

 time is spent tracking fishing fleets. The 

 feasibility of assigning military aircraft for 

 fishery patrols would be expensive and would 

 have to be worked out with DOD. 



The Coast Guard could supply personnel to 

 sort out fishery information collected by DOD 

 or an entire direction-finding station could be 

 dedicated to Coast Guard fisheries work. 

 Because of the security implications of much 

 of the data handled by DOD facilities, such 

 coordination may prove difficult. 



Magnetic TechniquesS" 



Magnetic anomaly detector systems have 

 been built and used for the detection of sub- 

 marines and there is no reason why they 

 would not be equally successful in detecting 

 fishing vessels. The systems operate by detect- 

 ing local changes in the direction and strength 

 of the earth's magnetic field caused by any ob- 

 ject, such as a steel-hulled vessel, with mag- 



57 



