Cast caution aside with the fisher king of San Diego

It isn't often you hear a fisherman use the word "gnarly". One of the more recent additions to the sporting lexicon, the adjective is regularly deployed by surfers or mountain bikers, invariably after a run-in with a wave or hill that has attempted to part them from their mental faculties, however few. Roughly, it translates as: "Goodness me, that was close".

So, tripping from the tongue of Conway Bowman, the word sounds a little incongruous. The 39-year-old Californian is the host of In Search of Fly-water, a specialist fishing series that has just finished its second run on the US sports network ESPN.

Describing himself as an "angling adventurer", Bowman uses the show to help with the rather onerous task he has set himself: convincing the world that fishing, and fly fishing in particular, is an extreme sport. And just so we're clear about this, that's extreme sport as in acts of life-threatening bravado, and fly fishing as in J R Hartley.

Bowman is the son of a San Diego schoolteacher, and made his first cast aged three. Having mastered the lakes of southern California, he spent his teenage summers in Idaho, "home to some of the greatest trout creeks in the world. For American fly fishermen, it's hallowed ground," he explains. In his early twenties he bought his first boat and, inspired by the writings of the renowned fishing author Nick Curcione, began exploring the ocean, the "bluewater" that lies just outside San Diego's main harbour. His imagination had been fired by one particular chapter of Curcione's on one particular fish: isurus oxyrinchus, the shortfin mako shark.

In the intervening years, Bowman's travels have taken him around the globe in pursuit of ever more exotic catches - tarpon in Belize, roosterfish in the Gulf of Mexico - but what sets him apart is his ability to catch a potential man-eater on a rod with which most people would struggle to land a trout.

For those unfamiliar with the angler's art, fishing is a complex business. Much like learning to ski or ride a horse, starting young is an advantage, not least because the opportunity to regale late starters with hoary anecdotes increases year on year. And in no angling discipline is this more true than in Bowman's area of expertise. Game fishing is, obviously enough, angling's equivalent of big-game hunting. Instead of lion or buffalo, think big fish, dangerous fish.

Faced with the prospect of battling a 400lb marlin, enthusiasts almost invariably opt for the security of a safety harness, which they bolt to the boat before taking up a rod heavy enough to hook an oil tanker. Bowman's technique is altogether more subtle. With a rod and line designed to catch bass or salmon, he casts his own hand-tied flies on to the ocean and waits.

"Makos are the only sharks recognised by the International Game Fish Association ," he says. Capable of speeds of up to 60mph, the mako is one of the fastest fish in the ocean, eclipsed only by the sailfish (70mph), and one of the most aggressive. So you might think Bowman's vessel of choice, and the one he uses for escorting clients on mako fishing trips, is a touch insubstantial, at just 24 feet and sitting low in the water. "Typically we'll have three or four sharks around the boat, and will size one up for clients depending on their skill level," he says. "You can usually tell what that is by the look on their face - a 200lb shark tends to get a pretty quick reaction."

So how does an expert do it? "The most important thing is to hook them at least 50 feet from the boat," says Bowman. "If you don't, there's a reasonable chance they'll jump in, and then there's very real chance they'll attack.

"Once you hook 'em," he continues, sounding for all the world like Robert Shaw's Quint in Jaws, "you've got to let 'em run, and they'll go for about 200 feet. They're fast, and may well leap out of the water by as much as 20 feet."

Once a mako is hooked, explains Bowman, it is crucial to keep the fish at an angle to the vessel. "If you don't, they'll 'sound' on you," he says, "head straight down for several hundred feet."

Bowman says it is perfectly possible to catch sharks weighing as much as 300lb and around 10ft long on a fly rod. "What separates what we do from the guys who harness up for marlin is the degree of skill involved; we're teasing them into hitting the fly. Makos come in thinking the boat might be a whale or a pod of tuna, which they prey on. They also eat sea lions and porpoises. I've even seen a 150lb mako attack a 400lb sea lion; they're that aggressive, the pit bull of the ocean. Every shark has its own personality, and landing one can take anything between 45 minutes and nearly three hours, regardless of size."

For the record, all sharks caught on Bowman-guided trips are released. "We use barbless hooks, but we prefer to get close enough to physically release them. My job is to grab the line and slide a special hook on to the fly. Light pressure then releases it from the shark's mouth."

The moment of release, he says, is the most dangerous part of the exercise. "One swipe of the tail could launch it directly into my face. The business end of a mako shark is really gnarly." In this context it seems a rather appropriate adjective.

Particularly in light of one trip Bowman made last August. On a recce out of San Diego with a US fishing journalist, Bowman decided to take along a small kayak for his guest to observe various bluewater species at close quarters. When a 60lb mako began circling the boat, the writer decided to stay put. "As it was relatively small fish I jumped in the kayak, paddled out and made a cast at it," Bowman explains. "Then I felt something bump the kayak. I looked behind me and saw this huge shark, 200lb according to the other guys on the boat." At nine-and-a half feet it was longer than his kayak, and makos flipping over such small vessels is not unheard of.

Rather than paddle to safety, Bowman's natural fisherman's instinct took over - he made a cast. "It took the hook and it was off to the races," Bowman says casually. "In six minutes it towed me three quarters of a mile. It was only then it occurred to me it might turn round."

Which is precisely what it did. "Before I could reel in the slack it came right under the boat and just sat there, about 10 feet down. It was jerking the kayak from side to side, which was very unusual. The guys in the boat were like, 'Dump the rod, let it go, get out of there'. Then it bit through the line."

For all the gung-ho adventuring, Bowman is a keen conservationist. "Unfortunately, game fishing tends to attract the bloodsport crowd," he says ruefully, "especially when it comes to sharks. Game anglers like to kill stuff, hoist it up on big cranes and be the macho guy. What they fail to understand is that these large sharks are the breeding population, and while mako sharks in the San Diego area are well stocked, around the world they're diminishing rapidly."

Bowman insists his take on game fishing is about creating a more equal contest between fisherman and quarry. "Every time I catch a mako shark," he says, "it just reinforces what amazing creatures they are."

A shark-fishing trip with Bowman Bluewater costs $525 (£300) a day for two anglers, all tackle provided. Details: 001 619 822 6256, bowmanbluewater.com

Fish'n'tips: a guide to Bowman's best

EAST CAPE OF BAJA, MEXICO

Roosterfish reign supreme here. The pez gallo, as the Mexicans call it, is tough, challenging and powerful. You can sight-cast from the beach or from a panga (a type of Mexican skiff). The size range is 10-60lb, and April to July is the prime time. If you can, stay at Rancho Leonaro, the coolest place on the east cape: cold beer; cool cabanas; and a nice pool to jump into after a hard day at sea. Details: 001 800 334 2252, wildernessways.com/rancholeonero.

BELIZE

Tarpon, snook and bonefish are the grand slam here; snook are particularly abundant in the vast mangrove areas. This is saltwater fly-rodding at its best, and the sight-casting is the best in the world. Tarpon over 100lb are common, and there are lots of baby tarpon (20-50lb) as well. Permit fish are also plentiful - but very challenging. The English-speaking guides are outstanding. April to July is the best time to go; try and stay at the Belize River Lodge, a classic plantation-style lodge on the banks of the Belize River with outstanding food and service. Details: 001 888 275 4843.

GASPE, CANADA

Salmon fishermen visiting for the first time often act as if they've found the Holy Grail. The Atlantic salmon can reach up to 50lb and the clear rivers, the York in particular, make for the best sight casting in the world. It is fly fishing only, and the guides are some of the best in the world. I recommend the Malbaie River Lodge: malbaieriveroutfitters.com, 001 603 472 4043.

SAN DIEGO

I've fished all over the world, but still rate my home patch as one of the best areas bar none. Mako sharks represent what I call "the ragged edge" of fly fishing, pushing it to its limits. They are abundant here, so there are plenty of opportunities for sight-casting with a fly rod for one of the ocean's top predators (between 20-300lb). The season is June to November. If you're keen, I suggest you come with me.