materials, buoyancy, size, shape, and color to see if there was any preference, 

 but this was not done for fear that if these artificial lures were made suffi- 

 ciently attractive to be taken by the fish they might be eaten and would cause 

 their death. To avoid this possibility edible lures were used. A series of 33 

 pond experiments were conducted over the period from August IS to October 29, 

 1953. These are discussed In the following sections. 



Materials and Methods of Preparation 



In view of the practical problem of attracting tuna to the stern of a 

 fishing vessel, there was need for an edible material which was low in cost, 

 easily prepared, and at the same time both visually and chemically attractive to 

 the fish. In other words it was desired to create a lure which was attractive In 

 shape, size, color, and movement in order to visually attract the fish from a dis- 

 tance, and which at the same time was edible and sufficiently palatable to induce 

 them to want more. Three basic materials were tested: (1) gelatin capsules, 

 (2) macaroni, and (3) agar gelatin. 



The gelatin capsules (Eli Lilly & Co., No. 000) were about 1 inch long 

 when closed, and consisted of two parts, the body (about 7/8 inch) and the cap 

 (about 5/8 Inch). They gradually softened In water, eventually collapsing and 

 dissolving after several minutes. Unsuccessful attempts were made to impart 

 motion to the whole capsule. A slow motion was imparted to the open-ended body 

 or cap when floating on the surface by (a) gluing pellets of calcium carbide in- 

 side the closed end, (b) gluing pellets of Brorao-seltzer" inside the closed end, 

 and (c) stuffing the body or cap loosely with cotton wool (to form an adsorption 

 surface) and filling with 95-percent alcohol (extract of skipjack flesh) before 

 throwing to the surface of the water. The motion of the first two depended on gas 

 production on contact with sea water for the propelling force; that of the third 

 depended on the affinity of alcohol for water. The motion was very slow, of the 

 order of about 6 Inches per second or less. The carbide-filled capsules were not 

 used in the pond for fear of killing the fish. 



Some of the gelatin capsules were coated with a sticky glue (plastic in 

 acetone) and were then dusted with aluminum powder (Slrlus Commercial Aluminum 

 Compound) to make them silvery in appearance. Others were coated with a gummy 

 concentrate of skipjack extract (boiled to a residue) giving them a brownish 

 color. Still others were coated with both the aluminum and the concentrate. They 

 were tested both with and without the motion Imparted by the chemicals. 



The precut macaroni ("Royal" or 'Golden Grain") was cooked In water, in 

 concentrated skipjack extract, and In concentrated anchovy extract. In some cases 

 both with and without preservative (about 2 percent sodium bisulphite). The 

 cooked pieces were about 3/8 Inch in diameter and 1-1/2 inches longo 



The amount of extract used in cooking each small batch was adjusted so 

 that all was absorbed by the time the macaroni was cooked to the right consistency. 

 The pieces were then removed from the pot with a spatula and dried on a screen 

 until they were slightly sticky to the touch. Before being used some were coated 

 with corn starch to keep them from sticking together; others were coated with 

 aluminum powder to give them a silvery appearance. Some were plugged at both ends 

 with glue or with small pieces of cotton wool so that they tended to float when 

 thrown to the surface; others, not plugged, would slowly sink. 



Agar (common Japanese variety) was purchased in long strips (about 11 

 X 1 X 1 Inches). Both "colorless" and red varieties were used. It was boiled 

 with water (300 ml. to one strip), concentrated skipjack extract, and concentrated 

 anchovy extract, both with and without the addition of aluminum powder and both 

 with and without preservative. The boiled solution was poured into flat pans and 

 set In the refrigerator. It was then removed and sliced into strips approximately 

 2 X 1/4 X 1/16 Inches. Strips thicker than 1/16 inch tended to sink too rapidly; 

 those thinner than 1/16 inch tended to float on the surface of the water. 



