Table Sc^'Tlne (In seconds) and oatch (In nmbers of fish) 

 during control and test conditions when testing 

 Inedible lures, lure arrays, and edible lures 

 (for explanation see text) 



Discussion 



Failure to attract and hold the schools of tuna with non-motile edible 

 lures perhaps was to be expected in view of the fact that present fishing methods 

 (for skipjack) depend on the use of live rather than dead bait. However, In view 

 of the success In pond tests, it was hoped that the fish at sea would respond, to 

 some extent at least, to the extract-Impregnated lures* This hope was not rea- 

 lized. Possibly sane response of interest might be noted if the experiments with 

 direct chumming (without the preliminary use of live bait) were repeated under 

 more favorable circumstances, e.g., during the regular summer fishing season when 

 skipjack schools are plentiful and when they respond well to live bait* 



There is the possibility that tuna in other parts of the world, parti- 

 cularly those species which will take dead bait on longline gear, might respond 

 to the macaroni or agar preparations* Dr. W. M. Chapman, Director of Research of 

 the American Tunaboat Association, has informed us (verbally) that in the Califor- 

 nia fishery yellowfln have responded to plain cooked macaroni on occasion* With 

 fish such as these, a positive and consistent response might be obtained if the 

 extract-impregnated, silver- colored macaroni or agar preparations wei^ used* 



SUMMARY AND APPRAISAL OP RESULTS 



The main object of this investigation has been to study the response of 

 tuna to chemical and visual stimuli in the hope that the information so gained can 

 be utilized in developing a substitute for live bait* 



In the past 2 years nianerous experiments 1 ave been conducted on the res- 

 ponse of captive little tunny to chemical stimuli. A screening of over 100 known 

 chemical compounds ranging from simple inorganic to complex organic materials and 

 including several reputed fish attractants has been undertaken. Apart from an ap- 

 parent sensing of some of the strong-smelling aromatics and an avoidance of some 

 of the highly-colored dyes, the results have been negative. It seems unlikely 

 that fiirther screening of chemicals will produce any worthwhile information* 



18 



