(Originally published in the July 2019 issue of Ski-Boat magazine)
By Rob and Scott Naysmith
I CAUGHT my first big eye tuna way back in the early 1980s and, to be honest, at first I didn’t know I had. I thought I’d gone a few rounds with George Foreman when I was booked to fight the local bully. It looked much like a yellowfin tuna, fish we tried to avoid in those days, but there were a few anomalies and the fight was quite different. Only back at the dock did the “fishianados” confirm that it was in fact a big eye, and to prove it they hauled out its liver which is quite distinctive.
In those days catching a big eye was not a common occurrence — a result of a fluke more than skill — and they were hard to identify. But times have changed, and we’ve learned so much about the species, its habits and its beautiful oily steaks that it is now possible to specifically target them. However, I urge everyone reading this article to use this knowledge sparingly and responsibly.
To target any species of fish or animal, the key to success is knowing and understanding your quarry, and the big eye tuna is no exception.
The big eye tuna (Thunnus obesus) is a tuna species spread across all oceans of the world. Preferring cooler waters than the yellowfin and skipjacks, it is more likely to be found where the longfin tuna roam. Rarely found in our waters with a surface temperature over 20°C, it appears that their optimum temperature range is between 10- and 15°C, usually found in depths below 40 metres. That said, an echo-sounder with the ability to show thermoclines becomes an added advantage when you’re hunting big eye.
This tuna species derives its common name from the unusually large eye compared to that of other tuna species. Now that is a vital clue in understanding and targeting these fish. The large eye suggests that the species spends a big portion of its hunting life in the deeper, darker waters, which in turn indicates it can tolerate colder temperatures. Now you’re beginning to understand where the big eye gets its ability to effortlessly empty a reel going straight down, through cold thermoclines all the way to the ground.
In fact, the big eye spends only about 5% of its day feeding in the top 40 metres of water, and that’s predominantly in the early morning and late afternoon.
Another indicator of the amount of time these fish spend down in the cold depths of the ocean, is the high fat content of their flesh. This makes them highly sought after by the sushi market and one of the tastiest eating tuna in the world.
At first glance a big eye looks a lot like a yellowfin, but in younger fish, with their proportionally longer pectoral fins, they can be mistaken for young longfin until you look closely. This pectoral length ratio reduces as they get bigger and the fin reaches between the first and second dorsal in adults.
The dorsal and anal sickle-shaped fins do not get as long as those of a big yellowfin, and the finlets running from the top and bottom fins to the tail are not as bright yellow, but more of a dusty mottled colour. Of course, the eye is disproportionately larger than a yellowfin and it is generally a much more rounded fish, though I have caught some really fat yellowfin as well. The big tell-tale is the liver which is crinkle-cut as opposed to smooth.
Big eye primarily feeds on cephalopods (squid, cuttlefish, etc.), crustaceans (shrimps, crabs, etc.) and almost any fish species it can find. Although fishing methods have become more refined, I still find squid to be their best bait, followed closely by a whole skipjack. However, when we’re not specifically targeting them, most bait-caught fish are taken on pilchards in a chum line while fishing for yellowfin.
The big eye tuna caught in our Cape waters are often of a bigger class than our yellowfin, with fish well over the 100kg mark being not uncommon. Erwin Bursik holds the World and All Africa records for a fish of 156.5kg (right) caught off Ghana, while Donavan Cole regularly catches smaller class big eye on a handline out in the deep off Angola, showing the vast areas these fish roam. The increasing catches of fish over the 120kg mark in Cape waters is an indication of the dedication to learning and understanding the species by the younger generation of anglers.
As a recreational angler I found the most likely time of year to find a big eye was from April through to June, our autumn months when the water was cooling down. In hindsight with what we have learned since those days, this would have been an obvious conclusion. A few of our younger anglers who have followed the progress of their friends and fellow skippers on the tuna line and pole boats have brought us a much better understanding of the species which has resulted in much more refined targeting and more consistent catches.
Now we have learned to start targeting the big eye from late September and early October, through to when the water gets too warm in mid- to late December. I’m sure that if we braved the cold weather and winter seas, we would find them in July and August too.
The period from April to June still stands as a productive time, and as it’s a calm period of year in the Cape it makes big eye fishing much more pleasurable.
Before the introduction of chumming for yellowfin behind longliners and trawlers, we located the tuna by trolling. Our target species was the longfin in preference to yellowfin; yellowfin were a nuisance unless you were in a competition. Now and again you’d hook a big eye and curse until it either came to the boat or broke off.
In years gone by the general observation amongst the more accomplished anglers was that surface lures, predominantly jetheads (before all the new designs came about) in pink or brown were most productive. Diving lures caught a few fish but surface lures were better.
Today I make use of slant faced and flat faced kona-type lures in a pink/dark blue or pink/medium brown colour combination. After dedicating a tanker load of fuel to figuring out what makes these fish tick, I finally discovered that Big T in Plett make the best lures for targeting big eye. We worked closely in refining the lure action of the Smoking Joe 30 over two seasons and it’s deadly. Well there’s one secret gone…
However, the latest trend, and one which was never pursued until recently amongst recreational anglers, is the bait and drift method. Maybe our lust for the big eye wasn’t what it is today and that’s why there were few advancements in this method, but it’s definitely the most productive way to target them. Here is where our young anglers like Scott come to the fore; they practice this method and are way more successful than us older generation anglers ever were.
The constantly rising prices for quality sushi tuna on the world market have led to massive strides forward in catch, production and storage methods through endless studies by some of the top scientists in the field. This brought about a massive refinement in the approach to targeting big eye tuna.
First were the tuna longliners, and then came the trawlers, each taking increasing numbers of fish from the oceans, resulting in international controls being implemented through bodies such as ICCAT which monitors the Atlantic, our fishing ground.
This is where our younger generation in the form of Scott takes over …
As recreational anglers, my friends and I chat with, listen to, watch and learn from our friends and skippers on the commercial boats because their years of record keeping have given them extensive knowledge of when and where to target specific tuna species. From this we’ve learned to make use of baits in preference to lures. We’ve also learned that there are far more big eye down below the thermocline than on the surface and that, at certain times of the year, they prefer certain baits to others.
As discussed earlier, the physical make-up of a big eye tuna gives us a number of clues on how to target them. The large eyed, like those of swordfish, are better suited to hunting in conditions of low light rather than bright sunlight. The fatty flesh is an indication that they spend long periods in cold water temperatures. We know that they love squid and fish at certain times of the year and for the rest they like tiny crayfish type things, but our crayfish don’t last that long.
After assessing all the options we decided that using squid baits drifted just below the thermocline, almost swordfish-style, is the way to go. Big eye show a preference for lolligo squid but will eat a potter.
We’ve refined the traces and use 8/0 to 10/0 Mustad carbon circle hooks because hook-up rates are better and the fish stay on. We use soft mono and don’t bother with fluorocarbon because it’s a waste and it’s hard. Use 1.5mm to 2mm line sanded with 600 grit waterpaper to take the shine off. Balloons are handy so that you can control the distances between baits; as you drop deeper the different currents come into play. Florescence is a big key to attracting fish in the dark depths.
Day fishing is good when there’s nothing else happening, but night time is the most productive, and this is when you could run into either a swordfish or a big eye. They both come closer to the surface at night, depending on the brightness of the moon.
Day fishing requires that you fish deep, often below 60 metres, whereas the fish will almost come to the surface on a dark night. On bright nights you’ll find them from 10- to 30 metres below the surface. Swords and big eye feed deeper on a full moon and shallower on a new moon, so you’ll have to work out the depth accordingly.
Glo-sticks are an advantage during both day and night; green and red are the best colours, but keep them at least two metres away from the baits.
The traces we use are basically an 8/0 or 10/0 circle with a two metre long bite trace to a swivel with the glo-stick and break-away sinker, attached to a four metre long leader to the main line. Then you put the rod in the gunnel and wait…
Big eye have the ability to run from the surface, all the way to digging sea-lice off the ground, deeper than what you’d ever believe you’d have to cope with. I’ve had fish strip a reel while going straight down — 600m before you can blink; it’s crazy.
For the most part the fight is the same as that of the yellowfin which stays deep and makes clockwise circles, but the big eye can run way deeper than a yellowfin and this is usually the first indicator of what you’ve hooked.
They usually give up above 20 metres from the surface as opposed to a yellowfin, and trust me, that’s a Godsend.
Big eye fight deep and know how to stay down there. When the small of your back aches, your muscles burn and your arms stop listening to your brain, you know that you’re getting towards halfway, but how close is the question. The fight can last hours for the uninitiated; you gain line and lose line and eventually believe you’ll never get the fish to the top … and then you begin to wish it would just break off. This is why I admire the determination of all those anglers who have stayed the course to land their big eye.
The only way I’ve found to shorten the fight on these fish is to apply maximum drag after the initial run.
Stand at the gunnel and let the tip of the rod almost touch the water, then lift it level with the reel and wind down hard. You may only get a half turn on the reel but it’s the only way to make progress; you need to keep the fish’s head coming towards you and use its swimming to help. When it can turn its head it will take line, so you need to hang in there and just keep going.
Ease up slightly on the drag when it makes a dash then tighten up immediately when it stops. Remember that the drag on the line is greater when your reel is half full than when you started, and is compounded by the friction of the water.
A good friend Wayne Lauffs landed a record fish of around 75kg on a spinner with 15kg line class, in an epic battle where no quarter was given for what seemed like eternity. I watched him break down to pulp, with no harness and no mercy given. Wayne, I still admire your determination and achievement.
So there you have it … disseminate what we’ve given you, dig deep into this information, become an angler and go and catch yourself a classy big eye tuna. But please, again, I reiterate, only take what you need and then stop targeting, that’s the faith in which we give you this valuable information.
In the next issue Rod and Scott Naysmith will provide further details on the lures and traces they use to catch big eye tuna.