Reactions to intermittent white light 



The response of the tuna to intermittent light of various 

 intensities and rates of interruption are s-ommarized in table 

 ^, At lovf and high intensities CU? and 530 foot candles) there 

 was no positive response at any rate of interruption which -was 

 triedc At an intensity of 106 foot candles, there was positive 

 response but there was no clear relationship between its 

 strength and the rate of interruptiono Ihere is, perhaps, a 

 suggestion that the slower rates produced stronger reaction, 

 but this cannot be proven with the present data. Certainly, 

 however, the reactions with interrupted light were no more 

 pronounced than with continuous light „ At 21^ and 32I4 foot 

 candles, the results were erratiCo Although the fish were 

 attracted towards the sourcej, they were scared av/ay at or near 

 the border of the field when the light was switched on or offo 

 This "scared reaction" was not so pronounced with the weaker 

 light 



The results indicate that in attempting to attract tuna at 

 sea, interrupted white light would give no better response than 

 continuous white light, and moreover, that the fish would prob- 

 ably approach less closely to the source o 



Reactions to continuous colored light 



With one exception C-^periment 5y Series v), continuous 

 colored lights of intensity of about I4C foot-candles or less, 

 did not induce a positive reaction from the tuna,, This was also 

 the case with a yellow "insect repellent" light of somewhat 

 higher intensity (6? foot candles) o 



On the other hand, continuous colored lights of higher 

 intensity (about 7C foot candles) evoked about the same response 

 as continuous white light of moderate intensity (70 to about 

 it^C foot candles) o The response was evidently to the intensity 

 rather than to the color There was no evidence that light of 

 any one color was a stronger stimulus than a light of any other 

 color for lights of approximately the same intensityo 



There is no indignation that colored lights of the wave 

 lengths which were used would be of any advantage over white 

 light in attempting to attract tuna at sea^ 



56 



