The key to catching giant bluefin tuna is finding them; in order to find them, you need to understand their behavior. While it is true that one of the defining characteristics of these fish is their unpredictability, there are certain factors that can help any fisherman be more successful in catching these elusive fish.

While I still have much to learn, I have been working on a harpoon boat since I could walk and have grown up in this fishery. When harpooning, we look for tuna swimming or feeding on the surface, and once we spot them, we try to sneak up behind them. A 40-foot boat with almost 600 horsepower is not the stealthiest craft on the water, but done right, the boat can get remarkably close to the fish. One of us will then run out into the 25-foot-long pulpit on the bow of the boat and attempt to throw a handheld harpoon into the tuna. The pulpit is about twelve feet off the water, and the vessel is moving at around six to eight knots. Coupled with wind and waves, this means the task is often quite difficult. But to me, there is no method of fishing that is more fun or more rewarding than harpooning.

I am sure most On The Water readers use rod and reel gear or handlines, and you may be asking yourself, “What does this stick-boat guy have to offer me?” While in the past I have spent some time catching bluefin with a hook aboard the Cookie Too out of Gloucester, I will not pretend to be an expert with a rod and reel. That’s not my intent here.

As a harpooner, my success relies on finding fish. While some tuna fishermen seem to rely on trolling blindly, the most successful ones all have the important ability to find the fish. So while I can’t offer advice on the best line to use or the best way to tie a mackerel rig, I can offer tips that I hope will help you find the tuna, understand their behavior, and ultimately, catch more. Armed with this knowledge, you will be able to find the general area where the fish are, and can bait to tuna you spot on the surface, instead of relying on blind strikes.

Forage is the Key Factor

The first step in finding giant tuna is finding their food. Bluefin tuna come to the waters off New England for one reason, and one reason only: to eat. And not for mere eating, but gorging. The fish arrive emaciated after swimming thousands of miles from their spawning grounds in the Gulf of Mexico. They are looking to eat as much as they can while expending the least amount of effort before they continue onward and repeat the migratory cycle again.

It is for this reason that forage is the key factor driving the behavior of big bluefin tuna. How forage drives their behavior is dependant upon the type of forage fish and the amount of forage.

Sea Herring

When the tuna arrive in the Gulf of Maine by mid-June, nothing satisfies their hunger like the masses of sea herring that have historically been found off the coast. While there are several forage fishes that big bluefin eat off the coast of New England, the opinion of most successful tuna fishermen is that sea herring is the forage of choice. Whether on Jeffreys Ledge in the summer or in the Great South Channel in the fall, herring have really brought the masses of big bluefin to our part of the ocean.

For harpooners, herring are crucial because of the effect they have on tuna. Herring are loaded with fat and travel in large, dense schools. When tuna corral them into a bait ball on the surface, the feeding tuna are oblivious to anything else – including a harpoon boat. The scene is often chaotic, with fish breaking the surface and rolling through the bait ball, mouths agape, filling up on the high-fat forage. From a distance, a school of tuna feeding on herring appears as a continuous mass of white water. And often, hundreds, or even thousands, of shearwaters, gannets and sea gulls will be diving for the herring as well.

I can recall a spectacular example of this about ten years ago off Mount Desert Rock in Downeast Maine. After a summer of sub-par fishing out of Boothbay Harbor, the sea herring came in thick all along the Maine coast in late July. On the last day of the month, we heard a report of tuna 80 to 100 miles due east, and we made a decision to head offshore.

We arrived at about 7 a.m. to find the mother lode. Large schools of bluefin had finally found masses of five- to eight-inch herring. The first bunch we found included about 150 to 200 fish, each over 500 pounds, feeding in a frenzy on the surface. We were able to get right in the middle of the school without them even realizing we were there; in the chaos, one fish actually ran head-on into the hull of our boat. Even after harpooning that first fish, the school continued feeding. We chased fish all day long, going from bunch to bunch to bunch. There were thousands of shearwaters and thousands of tuna, and only when the wind came up at around 4 p.m. did we realize how great a day we had just had.

Mackerel

Atlantic mackerel are another important forage for tuna in this region. The classic sign of bluefin feeding on mackerel is scattered splashes spread out over large areas – two to three splashes here, two to three there, but nothing really concentrated or lasting for a long time. As harpooners, we are not always happy to try to catch fish feeding on mackerel. Unlike herring, mackerel are very quick and athletic fish, and this means that tuna need to work much harder to get enough to eat. While tuna are slow and lethargic when gorging on herring, when eating mackerel they dart around, often spread out, and are very hard to harpoon.

The same behavior that makes tuna feeding on mackerel difficult to harpoon can make them excellent targets for rod-and-reel fishermen. The scattered conditions of mackerel-eating tuna may favor the fisherman who covers ground by trolling. Different fishermen have different opinions on the best way to target fish feeding on mackerel (or any forage, for that matter). While you would think that mackerel rigs would be ideal in this situation, it is very hard to say for sure ahead of time. Remember, bluefin can be unpredictable; the best method is to carry multiple types of gear and adapt to the situation at hand.

And don’t limit yourself to trolling – there will be times when chunking or live-baiting will be most effective. One method that has worked well in the last few years is live-lining a bluefish using a kite rig. While I haven’t seen it in person, from what I am told, catching a tuna with this type of gear is about as exciting as it gets. Keep in mind that due to the plague of dogfish as of late, the chunking and live baiting can be nearly impossible in many areas during the summer months.

Sand Eels

When tuna feed on sand eels, another important forage species in this region, they do not jump and crash as they do when feeding on herring, and sometimes mackerel. Often the fish are seen swimming rapidly and erratically on the surface, making small wakes and zooming from spot to spot. They are likely feeding a few feet down and then coming up to search for more sand eels. Often the whales and birds will be in the same tight area, and so it is very hard to spot the tuna amidst all the action. Look for a V-wake that is not being made by boats or whales; there’s a good chance you are seeing tuna.

When it comes to sand eels, size matters. Small eels, those that are only a few inches long, are not going to be able to satisfy a fish as large as a giant bluefin. Bluefin only care about putting on fat, and will not stick around if they have to expend more calories catching a meal than they get in return.

When the bait is small sand eels, an area can look completely alive with whales, stripers, birds and juvenile tuna, and yet there will be no big bluefin. This was the case last summer on Stellwagen Bank. At the beginning of the season, there were plenty of larger sand eels over eight inches long. Because of this, large schools of massive bluefin showed up in mid-June and stayed on the grounds for weeks. By mid-July, mostly small eels were left, and it wasn’t a coincidence that the large schools of big tuna were long gone.

Small bluefin require different prey than the big tuna. A 30-pound fish can get by on pencil-sized sand eels, krill or scattered bunker. The same goes for stripers, cod and other life that can be found on Stellwagen Bank late in the season. But giant bluefin are not going to be able to make a living on tiny sand eels; the second-to-last fish we caught on Stellwagen – amidst acres of small sand eels –was full of the bones of stripers and a large dogfish, but not one single eel.

But don’t overlook the potential of catching giant bluefin when they are feeding on large sand eels. If there are enough big eels in an area, there can be massive numbers of fish.

Tuna on the Run

Giant bluefin are easier to find and catch not only when they are actively feeding, but between feedings as well. Tuna that are full from feeding often come to the surface to run, which is the term we use for when they swim up on top. These fish most often swim at around five to six knots, but depending on the situation, they can swim at a crawl or as fast as fifteen knots. Many fishermen believe that the tuna travel through the warm surface waters to digest after gorging in deeper water. This behavior is most commonly seen when the tuna have been feeding on sea herring. For unknown reasons, bluefin appear to become almost intoxicated after gorging on herring.

Sometimes we see similar behavior when the tuna are feeding on large sand eels. I can recall one day about ten years ago, only eight to ten miles off the breakwater in Gloucester, when I saw four or five bunches of over a thousand fish. Earlier the tuna were feeding on the eels, but at the end of the day they were all running on the surface. Some of the bunches were cartwheeling, or swimming in a big circle. While the reason for this behavior is unknown, it appears that the fish are content where they are, and because they need to swim continuously but don’t want to leave the area, they swim in place.

This aspect of tuna behavior is arguably more important to the harpoon fishery, as we rely on the fish coming to the surface. Because the tuna are full and content, they are easier to harpoon. As a hook fisherman, why would you would want to find the fish when they are probably already full?

Well, don’t assume that seeing fish running on the surface means bad news. It means you are where the fish are, so you have already increased your chances of catching them. You never know for sure whether fish on the surface are hungry or not. Some of the best trollers I know thrive on finding fish running on the surface and then slowly and methodically pulling the baits in front of the fish.

Also, if you see tuna running on the surface, there may be others in the area actively feeding. And if the surface-running fish go back into feeding mode, you will be in the position to catch a lot of fish. I remember one day on the Cookie Too when we baited bunches on top all afternoon and only had mixed results. But a few hours later, we moved a short distance toward Stellwagen Bank and started trolling the edge. We had over 50 bites and caught eight or nine fish in about two hours. Had we not seen the fish on the surface a few hours earlier, we probably would have left the area altogether. But since we saw the fish and knew they were there, we put in the time and it paid off.

Tides and Weather

Although finding large numbers of herring, mackerel or big sand eels is key to finding giant bluefin tuna, don’t underestimate the importance of tides and weather. In terms of tides, most people know that slack tide is one of the best times for all bluefin fishermen. Bluefin, especially large bluefin, seem to hate strong tides. The slack tide offers relief, so always be on guard during these periods. There are plenty of days when you will be in an area seemingly devoid of tuna, and then the tide turns and suddenly fish are everywhere. Strong moon tides are usually a bad time for finding tuna, and during these times even the slack may not be enough to bring the fish up. Slack tides during such moons are often short and offer little to no relief for the fish. And finally, while slack tides will often bring fish up, there are always exceptions when it comes to bluefin, and there are times when the turning of the tide inexplicably shuts the fishing off.

As a general rule, bluefin tuna feed heavily early in the morning, and then run offshore in the afternoon. On Jeffreys Ledge, for example, if you find the fish on the ledge in the morning, chances are they will head east or southeast by afternoon. There is no sure bet though, and there will be days when the fish run inshore in the afternoon. The key seems to be that they like to get out into more still waters, and that means getting away from the shallower banks and ledges where the currents and tide run harder.

Weather can also have an effect on giant tuna. Better weather generally means better fishing, which is convenient because most boaters must wait for a day of light winds and clear weather for safety and comfort when fishing offshore. However, large bluefin are notoriously picky when it comes to wind direction, so don’t assume that a nice day with light wind means the fish will be at the surface. The best situation for finding fish on the surface is when you have a north/northwest wind in the morning, and it shifts around to the south in the afternoon. There is no better wind for finding giant tuna than a light southerly. It is impossible to say why, but whatever the reason, the effects can be profound. While southerly winds in the afternoon bring the tuna up, an east wind, even if light, seems to keep the fish down.

One thing to keep in mind is that even if you come across tuna central, these fish are highly mobile and can often disappear for short periods of time. Many times we thought we had the fish dialed in, and were humbled the next day when we got out and there didn’t appear to be a single tuna in the ocean. What makes the fish disappear from time to time is hard to say, but it may just be their way of digesting. Whatever the reason, always be prepared for the “sure thing” to turn out to be a bust; there is no such thing as a sure thing when it comes to bluefin. For example, the day after we got nine tuna off Mount Desert Rock, we came back out and found nothing. Not one single fish. It took four to five days before the fish returned out of nowhere, as if they had been there the whole time.

Finding giant bluefin tuna is a skill that can only be obtained through experience. But if you pay attention to the factors discussed above, you will hopefully be able to put yourself in the right area. With enough time and experience, pursuing giant bluefin tuna can be one of the most rewarding fishing experiences you will find.