Mounted to the rod is a lightweight but beefy reel, either spinning or conventional. Because you hold the outfit and actively fish it, small reels light enough to be fished all day are essential. On the other hand, because the line and the quarry are anything but ultra-light, powerful, high-ratio gears and substantial drags are equally essential.
Spinning reels need to be able to handle a great deal of torque and pressure to effectively work the jig. You must be able to retrieve line powerfully and quickly. The same goes for conventional reels. A reel that is light enough to jig with and has a high retrieval rate - but still can take heavy drag - is a must.
Both spinning and conventional reels should be filled with braided line. Braid will cast further, sink in a current better, and with minimum or no stretch, let you feel the action of the jig and the immediate strike from a fish. Line sizes from 40- to 80-pound test are standard for tuna.
Fluorocarbon leader material has ultra low visibility, tensile and knot strength, sinks better and is more abrasion-resistant than monofilament. Use a 60- to 80-pound wind-on leader, tied or crimped to a single-hook rig for tuna. Butterfly jigs can be used with a single or double hook rig, attached to the top of the jig, directly to the line. It is a straight pull between the line and the hook. The jig is just swinging free.
Yellowfin and bigeye tuna identification
Some people will try to tell you that bigeye and yellowfin tuna are difficult to tell apart. This statement is completely false and is usually perpetuated by fishery scientists and fishermen who have not seen enough of both species to qualify them to make any statements on fish identification.
The two fish are "similar" in appearance but have several distinguishing internal and external characteristics that will allow the careful observer to identify each species in a range of conditions fresh.
General coloring: Live or fresh yellowfin have a metallic black back with a bright yellow-gold mid-lateral side band running along each side of the body, from the eye to the tail, changing to silvery sides and belly. The dark black back may be separated from the gold band by a thin blue band.
Bigeye have a large blue/black back that blends into a peculiar iridescent cobalt/metallic blue region followed by a golden/yellow side band above silvery gray sides and a white belly. Most of these colors fade soon after death.
The yellowfin body is elongate with a long tail. The body outline is flat between the second dorsal and caudal fin and between the anal and caudal fin. In bigeye, the body is deep, rounded like a football. The body outline is rounded, forming a smooth dorsal and ventral arc between the snout and caudal tail peduncle.
On yellowfin, the pectoral fin is short, extending to the base of the second dorsal fin. The pectoral fin is thicker, straight and stiff, like a wing. The bigeye pectoral fin is long, extending beyond the second dorsal fin base. The pectoral tapers to a thin point, flexible, curving ventrally at the side like a sickle.
For yellowfin, the second dorsal fin and the anal fin, as well as the finlets between those fins and the tail, are bright yellow, giving this fish its common name. The tiny fins (or finlets) run down the top and bottom side of the body, from the second dorsal fin and the anal fin to the tail. The finlets are bordered by a narrow slight black or no color edge. The second dorsal and anal fins can be very long in certain specimens, reaching almost as far back as the tail and giving the appearance of sickles. This particular species is named "Allison" tuna.
In bigeye, the first dorsal fin is deep yellow, while the second dorsal fin and anal fin are pale yellow. The small fins just behind the dorsal and anal fins, called finlets, are bright yellow with a black edge band. The shorter length of the anal fin and the larger eyes of the bigeye tuna, after which it is named, distinguish this species from the similar yellowfin tuna.
The characteristics of yellowfin and bigeye caudal (tail) fins are distinct and can serve as a quick means of identification if the tails are in good condition. This characteristic is most useful when identifying fish larger than 15 pounds. Yellowfin tails are yellow/golden, while bigeye tails are darker in color, being purplish-black, which fades to a dusky black at death.
The central portion of the trailing edge of a yellowfin tail forms a distinctive V- or M-shaped notch. Two raised bumps, or mounds, are apparent on either side of the fin behind the large side keel; these are absent in bigeye. The center of the trailing edge of a bigeye tail has no "V" notch, but forms a flat or slightly crescent-shaped cup. These features are difficult to describe but easy to see if you have a yellowfin and bigeye side-by-side.