Black marlin can be found in tropical and sub-tropical waters of the Indian and Pacific oceans, generally ranging northwards from 36 degrees south off Western Australia. They are mostly found in the surface layer of the ocean, in water deeper than 100 meters. Generally this fish is found not too far from land masses. The best known black marlin hot spots lie along shallow reefs off Australia, Mozambique, Panama and the Pacific coasts of several other Central American countries. This fish is frequently confused with blue marlin, especially when the fish are less than 100 kilos in weight. Many anglers think that black marlin gets bigger than blues, but they are wrong.
Black marlin tends to sport larger heads and massive, club-like bills. On the other hand, blue marlin wields a more slender. Both species bottom and upper jaws are covered with rough tooth-like denticles. However, the most easily observed and distinguishing features use to separate blues from blacks are the rigid pectoral fins found on all adult black marlin.
Black Marlin is a very fast swimmer and is known for its long runs and tail walking. This is one of the fastest fish on earth reaching speeds up to 80 mph or 128km/h. They are similar in quickness to the cheetah. Black Marlin speed secret is the unique characteristic of being a warm-blooded fish. The fastest of the marlin species, they are renowned for their speed, leaping ability, their elegant beauty and the difficulty that anglers often encounter in baiting and hooking them.
Some people use an analogy with horses to compare blue and black marlin. Black marlin represents the thoroughbreds of the sea; they are extremely fast and could break the line due to the friction their sheer speed imparts to the line trailing behind them. They are also known as powerful aggressive fighters, for their impressive athletic abilities on the surface, clearing the water time and time again.
It has been estimated that most of the anglers retaining less black marlin each year. The largest threat posed to black marlin stocks right around the Indian Ocean is from the large foreign long line fleets. This fish is already recognized by Australian researchers as having stock levels well below what is desirable. Some hold the view that this fish stock may be down to as little as 10 per cent of what they were before they were fished in the Indian and Pacific Ocean. The future for black marlin in the Indian Ocean does not look good.
Handling/hooking marlin is potentially a dangerous business for the anglers because of their speed and fighting ability and all care should be taken to protect the crew.