which were also present in the tank„ Future research should be 

 directed at identifying the particxLar "protein" substance in the 

 clear extract of tune, flesh which ^cts as the attractanto If this 

 can be isolated an . prepared in large quantities, it oould be used 

 in attempting to attract tuna to the stern of a fishing boat at sea. 



Dr. Sidney Co Hsiao studied the reaction of the tuna ti -.rtificial 

 light generated from an arc larap;, a prcjsotion lantern^ and electric 

 light bulbs o liis experiments were performed after dark, wi r.h the 

 tank illuminated constantly by tirfo 60-watt bulbs o He found that 

 both yellcwfin and t'onny were attracted t,o continuous: white light 

 over a range of moderate intensity (about 70 to UBC foot candies )o 

 Hov/everj they were not attracted by a light of weaker intensity, and 

 tiiey were repelled by a light of stronger inter.oit;-o Both species 

 vrf-ere attracted to colored lights of moderate intensity, but to no 

 greater extent than to white light,, Similar results were obtained 

 with interrupted white light o There appeared to be no relationship 

 between the strength of the reaction ^zid the fre'^uercy c:l ini.9rr--i.'- 

 tion of the lighto It was noted that although tLa tana apprc-f-ched an 

 interrupted light of moderate intensity, they were repelled frcrr. tlie 

 near vicinity at the instant tlrie light flashed either on or ofl » 

 Future research might be directed profitably at determining the react- 

 ion of tuna to reflected light of different quantity and quality 

 originating from moving objects during daylight hours o 



Professor Iwao liiyake attempted xo discover (l) if tuna proiuced 

 any sound, and (2) if they could be attracted or repelled by sounds 

 of various frequencies. Using a listening frequencj'' which ranged 

 from about 100 cycles to 70 kilocycles per second, he vras able to 

 identify low frequency sounds produced by the sudden movement of the 

 tail of the yellowfin in the tanko This might hve some significance 

 in respect to the mechanism of school forraationo No sounds produced 

 by the tuna at moderate, high, and supersonic frequencies were detect- 

 ed. In attempting to attract or repel tuna by continuous sound stimu- 

 li, sounds were produced at many freqiiencies within the IOC c^ole to 

 70 kilocycle ra-:ii3. No positive res^olts were obtainedo Ho^e-rer, 

 there were seve. .J: indications tJ-^^t ths "uuna might react pocitiveiy 

 to complex sou-ids :n* lov,- frequency. These, and also interrupts' 

 sound stimuli over the entire frequency range, might be invs.:- 'i-^T' ted 

 in the future,. 



The writer attempted to extend the observations: made by Morgan 

 (1951) on the reacticn of the ahole h.^e to interrupted direct current 

 in a small wooden tank of s'jawiixero It ^f^s found t.hat by progressive 

 shortening of the on-fraction of ." cycle at h frequency of 15 cycles 

 per second the downyfai'd trend in average current necessary to attract 

 the fish, demonstrated by Morgan, was continued. Ths relaticnsni- 

 betv/een source voltage and electrode siae was also clarifiedo .n.ddi- 

 tional vj-ork on the reaction of this species in a small tank of yeawater 



