The data suggest that a* pH c the shorter the period be- 

 tween preparation and testing the greater the responseo Agdin^ how- 

 everj the difference is not statistically significanto Moreover^ an 

 even greater difference in the opposite' direction is present at the 

 neutral pH 1 ,, AIsOj of course^ any^ diiierences due to time may be 

 confounded with possible differences between observers o 



The experiment provided no proof that differences in 

 either pH or in tiine lag at various pH s caused differences m re- 

 ponseo Rather^ it emphasized the great vairiability of the response 

 --a factor which doubtless contributed mostly to the erratic results 

 encountered after the nniddle of December 1952o In view of this^ 

 further attempts at isolaiion and identification of the attractant were 

 abandonedo 



SUMMARY AND DISCUSSION 



General 



The present investigation^ conducted from June 1„ 1952 

 to May 31i, 195 3j, is a study of the response oi captive tunny to ex- 

 tracts of fish flesh, viscerap etCo and to certaon chemicals in solu- 

 tion or suspensioHo 



The tunaSj caught by trolling^ were transported to shore 

 and established in a small concrete tank and a large pond at the 

 Hawaii Marine LaboratorVp Coconut Island^ OahUo For the most 

 partj they were fed strips of tuna flesh 3 or 4 times a week andj on 

 this dietp more than tripled their weight during the course oi the yearc 

 The two tunny estiblished in the t^nk during the summ<=r of 19^2 sur- 

 vived until the following summero The population o^ 1 3 tunny^ estab- 

 lished in the pondj waS decimated in two periods of mortality during 

 the fall and winter; two fish survived to the following sunnmero 



Test substances were introduced into the tarik or pond 

 through a continuous stream of water supplied by an electric pump. 

 When and where possible;, precautions were taken to avoid distrac 

 tion of the fish by e>tr ^r-eous audio or visual stimullo 



When certain test substances such as clear aqueous or 

 alcohol extracts of tuna flesh were introduced into the tank or pondg 

 a response was obtainedo This took the form of a feeding reaction 

 and included one or all of the following components^ speeding or 

 acceleration of the swimming ratCp a return to the area of distribu- 

 tion of the substanceo surfacing^, fanning-out and eventually ^ break <» 

 down of school fcrmationo circltngi, splashing^ and bitmg at incident- 

 al objects on the surface of the wa+ero 



S7 



