Yellowfin NOo 2 was i^x..., odu^ea on August 22s 1951* started 

 feeding 3 days later, but Jumped from the tank and died on Septem- 

 ber ks 1951 » It we-; in excellent condition during its short life 

 in captivityo Its estimated weight was about 6 roo^ids. 



The five tunny were introduced between August 27}i 1951 ^"^^o. 

 September 2, 1951 j and started feeding witiiin 1 to 3 days, t^ey 

 were in excellent condition until the end of October j fcilowing 

 which thej"- gradually became listless and fed only occasionally« 

 Three died on or about November 12, one i-n Dacamber 6, apd the 

 last one on December 8, l?>.o During tb.sir moribund condition they 

 lost their bright coloration but otherwise (apart from their beha- 

 "jlor) seemed normal in appaaran.ce,. Tb-e reason for the sickness and 

 subsequent mortality is unknown^ it followed a period of cold, wet 

 weather o During their period of confinement, the tunny increased 

 from an initial weight of about 2 pou3.ds to a final weight of 3 to 

 k pounds o 



Except prior to experiments en chemoreception, the tuna ware fed 

 regularly once a dayo Notes on their feeding aR.d schooling beha^/ior 

 are included In the reports which folloWo 



It was planned to study the reaction of tuna in large Pond Koo 5 

 (Tester 195'2) to light and sound stim^ili during J?;.nuary 1952. using 

 one yellowfin and one tunny. These were the sur-i-jors of a mortality 

 which occujred, as in the concrete tank, during Kcrembero Ihe sur%'-5~ 

 vors were f eliding ,. and were apparently in good condition during 

 December and the first part of January. A few experiments with sound 

 were ner^ormed but, unfortunately, before the series could be complet,;: 

 the tunny disappeared (about January 22, 1952) and the yellowfin 

 died (about January 30, 1952), again following a period of cold, wet 

 weather. No experiments with light were conducted in Pond No. 5= 



SUMI«IARY OF RESULTS 



Dro P. Bo van Weel, studying cnenorecption in tuna, found uiat 

 both tl-i.e yellowfin and tunny have a well -developed sense of Suiell or 

 taste whereby they may be attracted to certain food substancea. Tr -^ 

 were strongly attracted to clear, colorless extracts of tuna flesh « 

 Moreover, it was fcund that the attractant was contained in the 

 "protein" ratter than in the "fat" fraction of the clear extracts In 

 general,, the reactions of the . t-.mny were t^re pronounced than those of 

 the yellowfino Cn the other hand, "r.here was no positive reaction of 

 either species to "conditioned" water in rhich baitfish had been living, 

 nor to extracts of either baitfish or squido Tvtc chemicrl-s, otl';sr 

 than food substances, were tried — asparagine, a possible^ at-':.r£-jtant9 

 and copper acetate, a known shark repellent o ^ne fcrmsr did not 

 prove to be an attractant. The latter was a repellent to tuna, al- 

 thou'^h its effect was not as pronounced as on fish of other species 



