In the northern hemisphere, this fish is often called a dorado (Spanish for ‘gold’ – but there is also a popular freshwater sportfish of the same name) or a dolphinfish (which can be confused with the marine mammal). Most of the Polynesian languages use the name ‘mahimahi’ or variations thereof, such as masimasi (Samoa) and maimai (Fiji). In the Hawaiian language ‘mahi’ means ‘strong’ so mahimahi translates, loosely, to ‘very strong’.
Many international anglers favour the name ‘mahimahi’ with its lovely Polynesian lilt. Sometimes the name is abbreviated to ‘mahi’, but don’t make this contraction in Tonga or you will get some strange looks. There, ‘mahi’ means ‘underpants’!
A few mahimahi stray into New Zealand waters at the peak of a hot summer, mostly smaller specimens, but generally they are regarded as a tropical species. A blue water, surface-hunting predator, mahimahi have one of the fastest growth rates on the planet. One captive fish was recorded as putting on 24kg in nine months – but that was in an all-you-can-eat situation, where the fish had to do little exercise to get its meals. A 15-year study tagging wild fish turned up a more realistic growth rate of about one kilo per month, meaning an average-sized adult of 12kg is still only a year old.
The males and females of the species are easy to distinguish. The shape of their head is different, with the females (called ‘cows’) having a rounded forehead, while the male (bulls) have a distinct, partly vertical crest that makes the forehead look almost square.
The bulls tend to grow bigger than the cows, and (arguably) fight harder. In New Zealand a mahimahi weighing over 10kg is counted as a good one (although our all-tackle record is 21.36kg), but in many parts of the Pacific Islands a decent bull will crack 20kg, with the girls a little under this. The world all-tackle record, caught off Costa Rica, is just a shade under 40kg.
As a sportfish, I reckon mahimahi have a lot going for them. As their Hawaiian name suggests, they are a very powerful fish for their size, feed voraciously when in the mood (although this is not all the time), and take to the air regularly.
They look gorgeous too, with a range of quickly changing metallic colour schemes. The default, when feeding and swimming free, is flashy silver and bright fluoro-blue with blue spots. ‘Stress’ colours are brilliant green and gold – and this is what most anglers see after hooking a fish. More rarely I have seen purple and bronze tones, or any combination of the above, often overlaid with bright spots. When they die, they go through the silver-blue phase again, then back to a duller green-gold-bronze.
As a final addition to their many attractions, mahimahi are a spectacular eating fish – one of the best on this watery planet. Once, while staying in a back-packers’ hostel in Vava’u, Tonga, I cooked and ate mahimahi and salad for 14 days straight before finally getting sick of it.
These characteristics make mahimahi a spectacular light-to-medium-tackle sportfish, and a much more easily targeted tropical species than marlin for anglers visiting the tropics. On light tackle or fly they are an achievable challenge, having a similar mana in the tropics to catching a kingfish in New Zealand.
Mahimahi is an oceanic species that hunts the surface waters. They largely live on pelagic fish, with flying-fish the most important prey item (by weight), followed by triggerfish and puffer/porcupinefish. However, they will also take any small or larval fish they come across.
They often associate with floating debris such as logs, floating weed, or junk like tangled-up nets etc. We once even caught one that was hanging around an old plastic chair. Naturally these fish are often found around FADs, presumably attracted by the small fish that cluster around these devices for shelter (more on fishing FADs in part two).
Smaller mahimahi can be encountered in decent sized schools, but the biggest specimens are found in smaller groups (often just three or four fish) in the open ocean. Such groupings are often marked by birds, commonly frigate birds, or – especially in Tongan waters – matched pairs of black shearwaters and white terns.
These open-ocean fish are often a welcome by-catch when trolling with billfish as the primary target. With the usual prey items often being adult flying fish, mahimahi have no trouble nailing a marlin lure or a medium-sized rigged bait. In this situation, mahimahi are often hooked on heavy tackle (37-60kg) and can be pulled more or less straight to the boat – although I have seen big bull mahimahi pull 300m of 37kg line against a heavy drag upon getting the bit between their teeth.
Mahimahi have a tendency to stick with their hooked comrades for a while, so pitching in a strip bait and drifting it back immediately after hooking a fish can often mean another bite. In fact, if you keep a hooked fish in the water, several more may be caught. For similar reasons, it’s worth trying to keep track of an open-water mahimahi school, as this can mean opportunities to harvest additional fish. After all, you may only encounter one group in a day, so make the most of the situation.
A system for marking and keeping track of a school of mahimahi in open water involves using a large float with a few metres of fixed line (say 37kg mono) ending with a baited circle hook. Throw it into the water when a group of mahimahi attacks the lures and you can often hook another fish, which will also hold its mates nearby. Then, when you have dealt with the fish on the rods, circle back and pick up the fish on the float line – and, if you are ready with more baits, you can add even further to the tally.
It is a lot more fun to catch mahimahi on lighter gear than standard marlin tackle, but it can be a hazardous practice to blind troll in deep tropical offshore waters with light tackle. The chances are your gear will eventually get bounced by the biggest blue marlin in the district!
If you want to get the fun and sport of catching open-water mahimahi on lighter gear, one answer is to try a technique for these fish that we developed in the waters off Tongatapu about 25 years ago.
First, we would locate the open-ocean roaming mahimahi by the feeding activities of frigate birds or matched pairs of black shearwaters and white terns. The fish (and the birds marking them) are very fast moving and change direction often. To catch up with them, let alone deliberately present a lure or bait to them at normal troll speeds (seven-ish knots) was almost an impossibility, but at higher speeds, the lures would cartwheel and tangle.
Fortunately, we were fishing from an outboard-powered runabout with a fair turn of speed. So when we sighted the appropriate birds, we would pull in the gear and chase the birds (and the associated mahimahi, obviously) at planing speeds. The boat’s pace allowed us to get close to the fish, then we would drop two baits back while still travelling on plane, before throttling back and dropping to troll speed with the baits nicely intersecting the fishes’ line of travel.
Our favourite baits were piper (garfish) rigged on Williamson Bait-O-Matics (part skirted lure, part lead-headed diving bait-mount). I used to take a bin of frozen piper baits up from New Zealand for the purpose, but similar fish are found locally.
Bait-o-Matics are made to take two hooks, with the front hook in the vertical plane, pointy side up, and the tail hook with the point running out the side, at 90 degrees to the first. As mahimahi attack by coming in from the outside of the wake, we maximised hook-up success by running two rigs so each side hook was facing away from the wake, facing the incoming fish.
As mentioned, mahimahi, when in the mood, are not shy about taking big skirted troll lures meant for marlin. They will also take lure sizes right down to the 10cm skirts normally used for catching skipjack. Small, pink-skirted lures have caught plenty of mahimahi (and other species) for me, including a big bull mahimahi on a bungee line – a real handful!
Trolled bibbed and bib-less minnows have also done the job on a regular basis, and offer the advantage of mostly avoiding hooking billfish that often can’t be handled on the tackle used for mahimahi.
Being so surface-oriented, mahimahi can also be taken on surface lures such as stick-baits and poppers. You need to get a lure to the feeding action quickly by making a fast, flat cast, as these fish don’t hang around, but it is great fun. Surface lures can be successfully trolled too, although you don’t get quite the excitement of a surface strike on a cast lure.
For a saltwater-fly fisherman, mahimahi are one of the most fun fish to catch. A small handful have been caught on fly in New Zealand, but none over two kilos are in the record book.
Because of the casting limitations, your best chance of presenting a fly to a mahi’ is around a FAD or other floating debris. I remember Richard ‘Dobbie’ Dobinson managing a little mahi’ off the old Poor Knights FAD while we were contesting the second Orvis SWF Tournament. But with our wealth of natural structure, FADs are seldom used here in New Zealand and you have to be pretty lucky to come across a log holding a bunch of the golden wanderers. It does happen from time to time, though.
I have managed a couple of successful fly-fishing sessions around FADs in Tongan waters. The mahimahi are not always right on the FADs, but will usually be within a kilometre or so of it. They respond well to berley; our method was to drift past the FAD while scraping flakes off a skipjack frame in the same way we would berley while stray-lining with baits. If mahi’s are present and in a feeding mood, they will move in behind the boat, where they can be cast to.
The best result was during a couple of hours on a blustery day (they seem to feed better in sloppy conditions) when the fish were really on the go. We went five-for-seven on fish around 8-10kg, using 10kg tippets and 13-weight rods. They showed a distinct preference for red-and-white streamers.
Each fish jumped 10-20 times, often clearing the surface by three metres. Most fights lasted over half an hour, with the fish making many powerful runs, sometimes several hundred metres into the backing. Fantastic fly-rodding – and then you get to eat them!
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