Commercial fishing, trawl operation in 

 particular, could likewise profit from 

 closer scrutiny at the level where reaction 

 of the fish to the gear can mean the differ- 

 ence between success and failure of the 

 operation. Increased knowledge of other- 

 wise undisturbed behavior of the fish can 

 lead to greater efficiency in both protection 

 and utilization of fish resources. 



Summary 



Observation of fish behavior in the dark 

 is possible through the employment of infra- 

 red radiation. The literature does not 

 suggest that the visible spectrum of other 

 animals extends further into the infrared 

 wavelengths than that of man. 



The reaction of fingerling silver salmon 

 ( Oncorhynchus kisutch) to infrared radiation 

 was investigated with respect to attraction 

 and avoidance, orientation, and fright . The 

 experiments failed to yield evidence that 

 the fish tested could perceive, or were af- 

 fected by, infrared radiation. 



Acknowledgments 



Dr. Gerald B. Collins provided sugges- 

 tions as the work progressed and reviewed 

 the manuscript; Kenneth H. Mosher and 

 Howard L. Raymond assisted with the photo- 

 graphs; Paul T. Macy aided in the literature 

 survey; Sueto Murai aided in preparation of 

 the diagrams; and Charles D. Volz and Karl 

 A» Hampton aided in technical problems 

 connected with the equipment. The viewer 

 and power supply used in the experiment 

 were loaned by the U.S. Navy, the infrared 

 source by the U.S. Army. 



LITERATURE CITED 



BRACKETT, F. S. 



1932 Graphic correlation of radia- 



tion and biological data . 

 Smithsonian Mi sc . Collections, 

 87(8), (Publication 3170). 7p. 



DICE, LEE R , 



1945 Minimum intensities of illum- 

 ination under which owls can 

 find dead prey by sight . 

 Amer. Nat., 79(784): 385- 

 416. Sept. -Oct. 



EWING. MAURICE, ALLYN VINE, AND 

 J. L. WORZEL. 



1946 Photography of the ocean 

 bottom . J . Opt . Soc . Amer . , 

 36(6): 307-321. June. 



GRIFFIN, DONALD R., RUTH HUBBARD, 

 AND GEORGE WALD. 



1947 The sensitivity of the human 

 eye to infrared radiation. 



J. Opt. Soc. Amer., 37(7): 

 546-554. July. 



GUNTER, RALPH. 



1951 Sensitivity of the cat's eye to 



infrared radiations. Nature, 

 167(4261): 1062-1063 . June 30. 



HECHT, SELIG, AND MAURICE HENRI 

 PIRENNE . 



1940 The sensibility of the nocturnal 



long-eared owl in the spectrum. 



J. Gen. Physiol., 23(6): 709- 



717. July -20. 



JENKINS, F.A., ANDI.S. BOWEN. 



1946 Transparency of ocean water. 



J. Opt. Soc. Amer., ^(11): 

 617-623. November. 



15 



