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Fish Tales


Slow Trolling Threshers


Keith Poe and Chris Bohlman share their conservation-minded approach to tackling California thresher sharks ...

I'm really starting to hate my computer. Last night an e-mail glitch had my inbox frozen up for half the night. But even when she crashes this bad, I'm itching to get reconnected as quickly as possible. For among the hundreds of junks e-mails offering to cure every disease I've never had, and continual stream of all-too-grim memos from the desk of NOAA Fisheries, I'm always searching for that diamond in the rough.

Maybe the thresher sharks have the baitfish pinned down somewhere inside Long Beach Harbor. And just maybe someone is e-mailing to tell me where I can find them.
Though these inshore threshers are for the most part juvenile fish below 100 pounds, they do offer some great light-tackle action for those willing to put forth the effort to find them. However, since these fish are only pups, I believe it is our duty as sport fishermen to release them in the best possible condition so that they can grow large enough to spawn.

Very little is generally known about threshers, and the information we do have is often conflicting. That being said, here are the facts the scientific community seems to agree on. We encounter three species of thresher sharks along the West Coast: the bigeye thresher (Alopias profundis), the pelagic thresher (Alopias pelagicus), and the common thresher (Alopias vulpinus). The bigeye primarily inhabits the deep waters off the shelf and is rarely seen by the likes of sport fishermen, while the latter two species congregate and hunt prey in the inshore waters. In the Pacific, threshers are distributed from British Columbia down to the Baja Peninsula, and everywhere in between. I recently had a tag return of a thresher I originally released off Malibu, Cal., that was recaptured off the Tortugas, nearly 500 nautical miles away!

The most identifiable feature on a thresher is its sickle-like tail, which is usually as long as the rest of its body. Threshers use their tails to herd and then stun baitfish before eating them with their relatively small mouths. Because they dwell in deepwater, we know the bigeye thresher has the ability to feed in total darkness. There is some evidence the other thresher species feed at night, however, every time I have tried to convert our daytime fishing to nighttime, be it slow-trolling or chumming, I have had zero success.

I have caught fish up to 200 pounds inshore and in Long Beach Harbor, but most commonly these threshers range from 30 to 100 pounds. Many scientists believe males reach sexual maturity at 150 pounds and females do so at 200 pounds, yet some recent data indicates males may actually be larger than females when they are first able to reproduce. Threshers have a very low reproductive rate. They are capable of rearing only two pups every year, which makes them extremely susceptible to over-fishing. Fish that have not yet reproduced are considered 'pups,' and these pups make up the majority of the inshore sport and commercial catch. This is why inshore commercial fishing can be so devastating to thresher shark populations'99 percent of what they land has not yet had the chance to breed even once.


Though available year round, thresher action peaks in the fall and spring. We have caught them in water temperatures as low as 58 degrees and as high as 72 degrees, yet we find most threshers in 64-degree water. Water color and quality have always been top topics in sharking circles, but I have witnessed wide-open bites in both trash-laden water emanating from the Los Angles River and red tides. Rather, the presence of baitfish and a place to shoal them seem to be most critical variables in thresher location.

Threshers primarily subsist on baitfish like sardines that they herd in the nearshore waters. Since their location is so dictated by bait movements, they are often here one hour and gone the next. When you find one thresher, there are usually plenty more in the vicinity, and we have spotted as many as 20 threshers one day inside Long Beach Harbor, including any we saw free-jumping. While working with another boat, we have tagged and/or released 10 threshers in Long Beach Harbor one day, and 13 off Malibu on another.

Nearshore waters hold more bait than offshore, and the known hotspots seem to be where the shelf comes in close to shore, providing the sharks with an ample supply of food and place to corner it. For threshers, the farther they can push the bait up onto the beach, the better off they are, as the bait has no place to get away. Certain times of the year, offshore locations like La Jolla, Dana Point, the Hospital, and Newport Canyon attract large threshers, however, most of our efforts are in waters of 100 feet or less.

These fish are always on the move, and without having a good idea of where they're gathering before you leave the dock, you've got a better chance of finding a needle in a haystack. This is why networking plays such a vital role in my thresher strategy. I have a small, tight-knit group of anglers I trade information with. Each is extremely experienced and dedicated, and when they tell me they have, or have not, seen action, I can trust their reports. I also have the cell phone number of almost every bait supplier up and down the coast, and I keep tabs on the commercial halibut fishermen that work inside Long Beach Harbor. I watch the Internet like a hawk, and when the halibut fishermen start talking about a 'mystery' fish that spooled them, I know the threshers are in town. I honestly believe 99 percent of finding is networking, and if you're not giving dope, don't expect to get it back when others locate the fish.


With a general idea of where to find 'em, I hit the water equipped with my pair of Fujinon 14 X 40 stabalizing gyroscopes, constantly scanning the coastline for any fishy signs and watching the meter for bait. Some signs are obvious, like a free-jumping thresher or the black, crane-like grebes diving for baitfish, but others can be as subtle as three inches of thresher tail slicing through the water or a fish oil slick.

To be successful, you first have to understand how threshers feed, and only then can you use this behavior to your advantage. When they encounter a school of bait, these sharks will run the baitfish down in much the same way porpoise do, trying to wear them out and pin them down before actually feeding. When the threshers are really moving in their initial effort to herd bait, it can be almost impossible to get them interested in your hooked offerings.

Eventually, though, the bait will become tired, at which point you can get your boat right on top of the bait ball, and they'll actually stay with the boat in an attempt to find shelter. When that happens, we can dip net all the bait we want and put it in the livewell. I can't stress how important it is to stay right on top of the bait ball once you've found it. Usually, the sharks have the bait pinned down in one little place, and once you mark that spot, that's usually where you'll get all your hits.

Wherever the birds are working, that's where you should be working. If you don't see birds diving, tails sticking up, and fish jumping, you might as well go back home. The bait is constantly on the move, the birds are constantly on the move, and for this reason I choose to slow-troll rather than drift, which would severely limit my ability to stay on top of the fish.


Appropriate tackle for slow-trolling includes Shimano TLD 5's, 10's, and 15's spooled with 20-pound test monofilament. A popular setup among anglers is a 10- to 15-foot, 100- to 120-pound test monofilament leader tied directly to a 2/0 to 4/0 J hook, which is rigged through a sardine's nose. We really don't have a problem with the sharks biting through the monofilament leader, but if you'd rather be safe than sorry, another option is a 10-foot, 60-pound test single-strand wire leader.

To help get the bait down, I'll attach a 1- to 3-ounce torpedo sinker to the leader, about 10 feet up from the sardine, with a rubber band looped through the eye of the sinker, and then around the leader. Hopefully, this rubber band will break once a thresher grabs the bait and takes to the air, leaving you with an unimpeded fight.

Two hookbaits are usually plenty for slow-trolling, and I'll put a sardine 60 to 100 feet back on each side of the boat with the clicker on and a very loose drag. Occasionally, we'll drop a short line up the middle about 20 feet back, and it can be an awesome sight when a fish slams this bait right off the transom! Half the time the thresher will just come up and eat your offering, but the rest of the time it will first slap the bait with its tail in an attempt to stun it before feeding. When this happens, I give them about 30 seconds to come back and finish what they started, and after they've gotten the bait in their jaws, I give them another three to five seconds to munch before putting the reel in gear. Using the above method, I achieve a 90 percent mouth hook-up ratio on these sharks.

Sometimes the shark will hook itself during this initial tail slap. If that happens, you're in for an equally tough battle (minus the jumps of a normal mouth hook-up), but the only way to get them to the boat is to reel them in backwards, basically drowning the shark from the reverse water flow over its gills. On my boat I do everything possible to avoid this scenario since I release all sharks, and it's always preferable to release them alive. Out of the 100 or so threshers I've caught in the past two years, only five have been tail-hooked in this manner. I attribute this to slow trolling speeds of 1-1/2 to 2 knots and loose drag settings, which allow the shark to slap the lure without getting hooked, then still have time to come back and eat. As a bonus, I also get the most bites and have the best hook-up ratio at these speeds. Whenever I've taken the speed above 2 knots, my hook-up ratio decreased by as much as half.

While we're on the subject of tail-hooking, I strongly oppose drag-and-snag fishing where the angler intentionally trolls big, heavy lures or baits rigged with double hooks and the reel engaged in hopes of snagging the shark by the tail on its initial attack. I consider fishing for threshers to be a sport, and I take pride in my hunting and catching abilities. But when you're doing the drag-and-snag, in my opinion, you're not giving yourself very much credit as a fisherman or relying on your skills--you are just being an opportunist.

If you hone your hunting skills, read the water, and present the bait correctly, you give the fish a fair chance. To me, that's what the whole sport is about. In addition, when guys around me are dragging lures, I typically catch seven fish to their one. Why? Because the bait I am using is literally what the threshers are feeding on at the time.


Even if you are planning to release the fish you catch, as we do with most sharks we catch on my boat, there are a few extra steps you can take to ensure the fish you let go will actually live to fight another day.

First, there are two schools of thought regarding light tackle and its impact on a shark's ability to survive post release. Many argue that catching a fish on light tackle wears it out to the point of exhaustion, and thus increases its chances of mortality after you turn it loose. Having experimented both heavy and light tackle, I tend to take the view that heavy tackle is actually worse on the shark since it devastates the fish and allows the angler to bring it in too quickly. Envision the effects of a long, slow jog versus running as fast as you can up a steep hill. Put a shark through the hard sprint with heavy tackle and your chances of that fish going into capture shock increase dramatically.

As far as handling fish boatside, be aware that their gills are extremely sensitive. If you grab a thresher by the gills, or worse yet, hit the gills with the release or tag stick, you could have just killed the fish you were preparing to release. Also be careful not to accidentally place a tag in the shark's color line, which is the area where the brown on their back blends into the white of their bellies (or with makos, blue to white). This is where the fish's main artery is located, and if you accidentally place a tag here, it will bleed to death in a matter of minutes.

Never rush through the tag-and-release or struggle to take a shot while the fish is still going crazy. Have a crewmember grab its tail while the tag man holds onto the leader, and give the fish time to calm down boatside. Heck, I even pet them! With the shark docile and its dorsal fin pointing straight up (never tag a shark that's on its side), I stare at the dorsal and aim to put my tag just below it.
Now it's time to remove the hook, and a release stick works great and is pretty easy to use. If you're using short leaders, you can place the rod in the rod holder, which gives the perfect line angle for removing the hook when you have the release stick properly positioned in the hook bend. As a precaution, try to aim the release stick away from the inside of the fish's mouth so it can't flip and hit its gills or any organs.

Since I've been counting, I have caught close to 100 threshers and 2,000 makos. Thus far I've gotten one return on the threshers, five on blue sharks, and 28 on the makos. I boast a 5 percent tag return rate on mako sharks--compared to the average 1.5 percent return rate--and there is no doubt in my mind this is a direct result of the extra time and care I take with these delicate fish at boatside. Enjoy this great fishery, and let's make sure our children have a chance to enjoy it as much as we do!

Keith Poe, known as the 'Shark Tagger' by fishermen on the West Coast, is a 42-year-old Southern Californian with a passion for sharks. This Redondo Beach resident owns a residential remodeling business in the South Bay area, but when he is not at work, you will find him fishing for sharks. Keith has become renown for promoting responsible fishing and focuses his efforts on reversing the decline in shark populations. Since 1995, he has been one of the top taggers recognized by the in the California Department of Fish and Game, and has also won the AFTCO captain and angler award every year back-to-back for the most threshers and makos tagged in the Pacific. He has leadered the only two IGFA apex predator line class records released alive--the first a 46-pound thresher caught on 6-pound test, and the second a 22-pound mako caught on 4-pound test.

Keith is associate producer for Inside Sportfishing, a member of the West Coast advisory panel for The Billfish Foundation, and an advisor for United Anglers of Southern California. He also speaks at fishing clubs and tackle shop seminars around the state, and he frequently takes fishermen and members of the media fishing to teach the importance of tag-and-release.

Since the termination of the California Department of Fish and Game tagging program, Keith has started up his own tagging program, Tagger International, and currently has 50 taggers enrolled. For free tags or to learn more about the 'Shark Tagger,' visit his website at www.sharktagger.com or e-mail him at sharktgr@gte.net.

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