Possessing no teeth or scales, but armed with a sharp rostrum up to four feet long, Xiphias gladius is arguably the most aggressive fish in the sea. The huge ones are always female, can weigh more than a thousand pounds and produce some thirty million eggs. A solitary pelagic speedster, the queen of the ocean – pez espada – is the Lamborghini of the deeps. Old-time harpooners warned against looking into her vast, mesmerising eye (it is fed with its own supply of warm blood to combat the chill of the abyss). When Keith Douglas wrote his lovely poem in 1941 about a sailor using a gouged swordfish eye to burn his floozy’s name onto the timbers of a ship, he entitled it simply ‘The Marvel’.

Notable American marine artist Richard Ellis certainly knows his fish. He once sailed out of Montauk with Peter ‘Jaws’ Benchley and shark-shooter Frank Mundus, the model for Captain Quint. The ‘swordie’ is, he explains, a sport fisher’s ultimate trophy. It is hard to find, tough to hook and fights by dancing on its tail. One angler lost his battle after more than 32 hours in the chair. Zane Grey – dentist turned bestseller – developed an obsession for them, landing just two in nine years. Ellis includes a natty picture of him in tweed breeks, toting a reel the size of his head – which was large.

Hemingway was more of a marlin man. These roundbill cousins of the swordie include blue, black and white varieties (which are, respectively, not blue, black or white). They can be equally dangerous. One went for me aboard a cruiser off the Kenyan coast in 1980, driving its bill into the hull just a whisker from my bare leg. Papa has Santiago’s heart broken by a giant blue marlin, but in his Islands in the Stream (of which The Old Man and the Sea was originally a part) he describes young Thomas Hudson losing a ‘grander’ swordfish, which sinks from sight ‘like a huge dark purple bird’. Both Ernesto and Zane insisted on calling all big billfish ‘he’, rather predictably.

This is an intriguing book about a fascinating creature. Ellis first traces the palaeoichthyology and biology of Xiphias, clearing away centuries of accreted myths that go back to Strabo and Pliny the Unreliable. The placid sawfish is unrelated (it is in fact a type of ray). The swordie does not skewer prey on its bill, kebab-style, nor use it to dig out crustacea (‘ridiculous nonsense’). But Ellis does give credence to numerous assaults on whales, squid and ships. Maybe the best-authenticated incident was in 1967, when the submersible Alvin was charged at a depth of two thousand feet by a swordfish that impaled itself in the coaming, and was later cooked for the crew.

They also attack humans. In 2003, a marine photographer named Mark Ferrari, swimming off Hawaii, was struck in the chest by a 15-foot swordie (female, naturally) that missed his carotid artery by half an inch – a nasty collision between Ferrari and Lambo, fortunately not fatal. Hooked fish often round on boats, too, but one could counterclaim that the boats attacked them first. Nevertheless, an element of real danger adds a piscine frisson to most encounters with this mysterious teleost. Much about its feeding behaviour and migratory patterns remains unknown, though Ellis has conducted an assiduous survey of the literature and appends an invaluable bibliography.

Because its firm white flesh is so delectable, for thousands of years the swordfish has been hunted for food. The history of commercial fishing is nowadays depressingly familiar, but so formidable an adversary is the swordie that only modern methods have been able to imperil stocks. Harpooning (or ‘darting’) was the traditional technique, still practised around Sicily and by some die-hards in the North Atlantic: this is the nearest thing to the gladiatorial duel suggested in the subtitle to Swordfish – requiring genuine skill and bravado, and concentrating on the largest specimens. But with the proliferation of long-lining (as featured in The Perfect Storm) came a drastic depletion of broodstock; baited hooks work indiscriminately (as do drifting, ‘wall of death’ nets), and many immature swordies, below the marketable size, are discarded (‘shacked’) to perish anyway, along with masses of other by-catch. In the Mediterranean, where regulations and quotas are routinely ignored, juvenile swordfish are openly sold by the side of the road.

Now, I’m no tunny-hugger – my ‘Kill ’em N Grill ’em’ T-shirt sees a lot of wear during the angling season – but with the world’s fleets baiting 1.5 billion hooks a year, pretty soon some draconian conservation measures are going to have to be enforced on a global scale if these and other vulnerable fish populations are not going to collapse – when a biography such as this one will have to double up as an obituary. That would be a disaster, because the swordfish truly is a marvel.