Discussion 



The pond tests showed that tunny held In captivity would eat edible 

 preparations such as gelatin capsules, pieces of macaroni, and strips of agar 

 (gelatin, and that these were more avidly consumed If they were made chemically 

 attractive, or palatable, with concentrated extracts of skipjack or anchovy. In 

 some cases, the relative number eaten seemed to depend. In addition, on the 

 visual attractiveness of the lures. 



The pond fish showed a distinct preference to agar preparations over 

 macaroni preparations after the first pair of trials: a learning process seemed 

 to be involved. The reason for the preference is uncertain, but It probably in- 

 volved a difference in smell, taste, or texture of the materials. Although the 

 two preparations were basically different In composition (macaroni is a starch 

 and agar is a sulphuric acid ester of galactan), both were thoroughly Impregnated 

 with the same concentrated extract of skipjack flesh, and presiomably should have 

 had a similar smell or taste. Perhaps the considerable difference in texture 

 between the macaroni and agar preparations was responsible for the choice: the 

 strips of agar were softer, more pliable, and more "jelly-like" than the pieces 

 of macaroni. 



Although there was no assurance that sea fish would respond in a simi- 

 lar manner to the pond fish (which were accustomed to feeding on dead, non-motile 

 food). It was considered worthwhile to conduct sea tests with edible lures. Un- 

 fortunately, attempts to Induce appreciable motility in edible lures have been 

 unsuccessful to date. As will be discussed later, motility may be asi Important 

 factor In the successful use of either edible or inedible lures to attract tiina 

 at sea. 



SEA TESTS WITH EXTRACTS 



Preparation of Material 



For the most part the extracts used in the sea tests were prepared in 

 50-gallon driims by Mr. F. Jerraann of Hawaiian Tuna Packers Ltd. The materials 

 are briefly described as follows: 



(1) Skipjack viscera, groiind, steam-cooked, water added, filtered, pre- 

 served with 2 percent sodium bisulphite (demijohns - 1/20/53). 



(2) Yellowfln flesh, ground, extracted with water, filtered, and preserved 

 with 2 percent sodliim bisulphite (Drum No. 1 - 2/18/53) . 



(3) Yellowfin flesh, as above (Drum No. 2 - 2/24/53). 



(4) Yellowfin flesh, as above (Drum No. 3 - 3/4/53). 



(5) Skipjack viscera, ground, extracted with water, preserved with 2 

 percent sodium bisulphite (Drum No. 4 - 3/13/53) . 



(6) Skipjack viscera, as above (Drum No. 5 - 5/11/53). 



(7) Skipjack viscera, ground, steam-cooked, water added, filtered, and 

 preserved with 2 percent sodium bisulphite (Drum No. 6 - 6/20/53). 



(8) Sllpjack viscera, ground, frozen into 5-pound blocks (various dates). 



All materials were tested on the captive tunny in the pond, in some 

 cases both before and after sea testa. The responses In the pond were generally 

 weak and variable due to the unresponsive condition of the two surviving tunny 

 during the late winter and spring of 1953. However, all substances did produce 

 a response in at least one out of several tests (Tester et al. 1954). 



13 



