Summer is here and with it the most exciting angling adventure Japan has to offer — catching dolphinfish. Not to be confused with the sea mammal of the same name, this is the middle-weight champion of offshore angling. These fish have power, speed and will aggressively strike lures, flies or bait.
Dolphinfish (Coryphaena hippuras) are also commonly known by their Hawaiian name, mahi-mahi. In Japanese the name is shiira, but whatever you call it, a raging dolphinfish puts up a battle that won’t soon be forgotten. A magnificent sport-fish and tough hard-fighter, its exceptional endurance can make it extremely challenging to boat a large one. These fish can swim at speeds of 80 kph in short bursts, and when hooked will make long drag screeching runs, dart in one direction and then another, make head-shaking leaps and even tailwalk.
Found throughout tropical seas worldwide, in summer dolphinfish follow the warm currents north to the waters around the main Japanese islands. These fish are voracious feeders, devouring sardines, anchovies, flying fish, squid and even smaller dolphinfish. Under the right conditions they can grow 2 kg a month, and can reach a maximum weight of 40 kg and a length of 1.8 meters. In Japan, a 1-meter-long fish is a respectable catch. This year the season has gotten off to an excellent start with a 145-cm, 14.2-kg lunker having been caught by an angler fishing out of Hitachi in Ibaraki Prefecture.
Dolphinfish are excitingly beautiful in appearance. This is primarily due to the fish’s ability to rapidly change color. When a fish first strikes it is a dazzling iridescent blue. As it tires, its body becomes a golden yellow and the saillike dorsal fin that runs the length of the back becomes an olive-green ribbon, both flecked with neon-blue spots. In death the fish turns uniformly yellow or gray. Another distinguishing characteristic of the species is the hatchet-shaped square blunt head of the male. The female’s head is more rounded.
Normally found offshore near the surface of the open ocean, dolphinfish have a peculiar affinity for floating objects of almost any kind: buoys, masses of seaweed, logs and even dead whales. Anglers exploit this habit. Charter-boat captains will cruise about until they locate such an object and then stop close by, hoping to see the bright blue flashes of a school of dolphinfish. The fishermen cast toward the object and if the fish are interested a hit will come immediately. It can be a wild time with reels screaming and lines crossing as several anglers have fish on simultaneously.
The tackle favored for catching dolphinfish in Japan is quite sporty. Lure fishermen need a spinning reel capable of holding 150 meters of 8-11 kg breaking strength monofilament line and a matching rod 210-270 cm long. The reel needs to have a smooth-as-silk high-quality drag. The drag tension should be set low to about one-third of the line’s advertised breaking strength. Also needed are a 1.5-meter-long shock leader of at least 14-kg strength and a ball-bearing snap-swivel to attach the lure to the leader.
Lures are of three basic types: floating top-water plugs that cause a splashing commotion as they are retrieved; subsurface minnow-type plugs that run a meter or two deep as they are retrieved; and fast sinking metal jigs that are cast into the feeding frenzies caused when a school of predatory fish and seabirds combine forces to rip into schools of helpless baitfish. Lures should approximate baitfish in size and color with bright shiny finishes working best. Use a quick jerking retrieve and keep a firm grip on your rod.
For those who prefer fly tackle, dolphinfish are usually willing to cooperate. Flies will often out-perform lures when you get into a school of peanut-size one to 2-kg fish. Fly outfits should be 10 weight or heavier. A reel with a good strong drag and plenty of backing is a must. Be sure to use a heavy shock leader. A sinking line and weighted flies can work well.
Besides being a top-of-the-line gamefish, many people consider the dolphinfish to be delicious. In Hawaii it is said that people who dine on mahimahi steak risk spoiling themselves for any other island dish. Even though it is hard to beat when deep-fried, here in Japan dolphinfish is not that highly regarded because it makes for less than excellent sashimi.