assumption that the needs of fishing zone enforcement can be met by 



using state-of-the-art techniques and without resort to the kind of 

 high-priority, high-cost, R&D programs used in defense and space explora- 

 tion programs. Should the situation change and a need and justification 

 for a high-priority research program appear, then a much more comprehen- 

 sive and searching examination of remote sensing potential than this 

 brief survey would be in order. 



B. Candidate Techniques 



Table 6 lists the candidate technologies for remote sensing that 

 were examined in the survey, along with some of the characteristics that 

 influence their applicability to functions useful for fishing zone en- 

 forcement. Included in the techniques are those based on electromagnetic, 

 acoustic, and magnetic phenomena. Other theoretically usable phenomena, 

 t;uch as chemical analysis of air or waterborne effluents, gravitational 

 anomalies, or changes in the oxygen content of seawater as a result of 

 vessel or fishing activity were considered and rejected on the basis of 

 lack of sufficient proof of feasibility, gross capability inadequacy, or 

 obviously unacceptable cost. 



Figure 2 shows the kinds of sensors that have been developed for 

 remote sensing using electromagnetic energy and indicates the portions 

 of the electromagnetic spectrum appropriate to the use of various sensor 

 techniques. At the top of the figure is an inset showing the transmis- 

 sibility of the earth's atmosphere in a portion of the visual and infrared 

 spectrum. This simply shows that in many portions of the spectrum low 

 loss transmission of signals necessary for effective remote sensing is 



* 

 Note that the scale of the inset is linear, while that of the main 



figure is logarithmic. 



26 



