It may be concluded ...e squid preparation ei trier of 



itself or in combination -witu squid ink or India ink had no attract- 

 ive effect on tlie tuna,, " ■ "''"j, vrhan concentratedj appeared to 

 have a repellent effect ■-:. , olloi'tfinj but thlsvas probably a 



visual reaction. It is imiikeiy that tlie repellent effect could 

 have been produced by sone chemical in the India ink as the carbon 

 particle^ are usually stabilized in suspension by gelatin, aid gelatin 

 has no effect on tlie behavior of the fish as shown by a. control 

 experiment ■'•rith a loO percent solutions * '' 



iv. 



During most of the experiments 'iirLth tuna flesh preparationsj 

 two yellowfin and five tunny were present in the tankj- forming trro 

 distinct schools vdth markedly different crioisins speeds,, Only one 

 individual (not necessarilj the same fish throughout the experiment) 

 of each school vfas timedo The timing tests on each species v/ere 

 conducted alternately o 



A. In the e^qperiment portrayed in fi.giia'e 6 the ".vhols extract 

 of skipjack flesh (200 grams) was used^ vfithout centrifugingo The 

 tunny, in particular, '.vere attracted by the obser^^er^s presence, and 

 did not slow down, and extend their course ever the whole tank for 

 a considerable period of tiraeo '•ftiey appeared to have an exciting 

 effect on the yelloiTfin, the cruising speed of wtdch increased 

 during the preliminary trialso '^Yliile the preparation was being 

 siphoned into the tankj ttiere v^as no reaction during the first fev/ 

 seconds until the tunny naared the inleto Then^ however, the turjiy 

 started railling around the inlet excitedly« ?he yellowfin, also^ 

 soon showed this same reactiono One of the latter actually snaoped 

 at the rubber inlet. All fish took shreds and small pieces of the 

 extracted flesh into tJieir mouths, but invariably spat them out 

 again„ Apparently this material, after extractionj is tasteless 

 and -unpalatable to the fish, even though they normally were fed 

 txna flesh vmile in captivityo Kovrever, other fish in the tank, 

 (a Duffer, Tetrodcn hispidus (?) and a few manini , ( Acanthurus 

 sandvi censi i j" di d eat the extracted materislo Although it 

 required only 3 to 5 JRxnutes to siphcn the 3 liter preparation ^ 

 the general excitement of tlie tuna lasted for seme 10 tc 1^ minutes o 

 The timing (Tests 17 to 2$ for yellcmin and 1,8 to 26 for tunny) 

 was then resumed as liie fish grew calmer and started cruising 

 again. 



Bo A series of experiments -.fas next conducted in -which the 

 tuna flesh preparation vfas fractioned into clear' and rnxn-ky portions „ 

 As these all gave similar results, only one is recorded in detail 

 in figure 7, in v;hich 130 grams of skipjack flesh was usedo 



During the preliminary tests, the speed of the tunny school 

 j^radually decreased, vriiereas tliat of the yellowfin remained fairly 

 constant, V^ien th« clear extract was introduced, there was a difference 

 in behavior of the two species. The tu:nny started milling around the 



10 



c> 



