PART II 



OBSERVATIONS ON THE CHEMORECEPTION OF TUNAi/ 



by 



Po Bo van Weel 

 Professor of Zoology 

 University of Hawaii 



INmODUCTION 



The ejqjeriments to be described in this paper were undertaken 

 during the summer and autumn of 19^1 at the Hawaii Marine Laboratoryo 

 The author undertook to determine v^hether tuna have a sense of taste 

 or smell whereby they might be attracted (or repelled) by food sub- 

 stances in suspension or solution o It was hoped to find some con5)on" 

 ent of the food of the fish which acted as an attractantj and which 

 might possibly be prepared in large quantity from some cheap sourcGo 

 If soj it might replace or supplement the live bait which is present- 

 ly needed for pole and line fishing (June 1951) and which is in short 

 supply in the Central Pacific area. 



Originally it was not planned to investigate the reaction of 

 tuna to selected chendcalso However, two such substances were tried 

 at the suggestion of others g asparagine., a possible attractantj and 

 copper acetate s a known shark repellent o 



I am very much indebted to DTo Ao Lo Tester for his critique and 

 kind help in preparing this paper,, 



MATERIAL, IffilHODS AND TECHNI(|JE 



The experiments were conducted on one or more of two yellowfin 

 (Neothunnus macropterus ) and five little timny ( Euthynnus yaito ) which 

 were established in a concrete tank (figo I) at the Hawaii Marine 

 Laboratoryo Normally the tuna were fed a daily ration of tuna flesh 

 from skipjack (Katsuwonus pelamis ), yellowfin^ or tunny, which they 

 accepted greedily,, They also accepted live baitfish (Pranesus insula- 

 rum), the heads of which had been pinched so that they floundered in 

 the water, Ihey were not observed to feed on a school of baitfish 

 Tirtiich was present in the tank, probably because they could not develop 



£/ Contribution No„ 23 of the Hawaii Marine Laboratory, University 

 of Hawaii 



