black marlin, heaviest billfish of all

Size
Length: 3–4.5 m, Weight: 200–600 kg
Lifespan
15–25 years
Diet
Carnivorous – feeds on large fish, tuna, mackerel, squid and smaller billfish. Hunts using its distinctive dorsal fin to herd prey. Slashes its bill through schools to stun or injure victims before eating. One of the fastest fish in the ocean.
Habitat
Open ocean waters near the surface, typically above the thermocline. Prefers warm and clear waters with temperatures above 20°C. Often found near current lines, drop-offs and offshore islands where prey concentrates.
Range
Found in tropical and subtropical waters of the Pacific and Indian Oceans. In New Zealand it is a summer visitor to northern waters from Northland to the Bay of Plenty. Most common from December to April when sea temperatures rise above 20°C.
Endemism
Native
Main Threats
Commercial and recreational overfishing is the primary threat. Targeted by longline and game fisheries across its range. Bycatch in tuna fisheries. Climate change shifting prey distributions. High vulnerability due to slow reproduction rates.
Population
Global populations have declined due to overfishing. The species is listed as Vulnerable by the IUCN. In New Zealand waters it is a rare seasonal visitor. Catch and release practices are encouraged for recreational fishers. International management is required for recovery.
Conservation Status
Not Threatened
Ocean's fastest hunter. It is a fish that is a sword and a missile. The black marlin can swim at speeds exceeding 80 kilometres per hour. This power comes from its crescent-shaped tail and sleek, muscular body. The Māori name Taketonga honours its strength and rarity. In summer it visits New Zealand's warm northern waters. It thrills game fishers with spectacular leaps and powerful runs. A fish that is a summer visitor. The body is streamlined and powerful. It is built for speed. The upper jaw extends into a long, pointed bill. This is used for slashing through schools of prey. The dorsal fin is high and distinctive. It is used to herd fish. The colour is a deep blue-black above. This fades to silver on the belly. It is a fish of the open ocean. It is built to hunt in the vast blue desert. It is a top predator. It feeds on tuna, mackerel, squid, and smaller billfish. It uses its bill to slash through schools. This stuns or injures its prey. It then turns and eats the wounded fish. It is one of the fastest fish in the ocean. Capable of bursts of speed that leave its prey no chance. It is a summer visitor to New Zealand waters. From December to April, sea temperatures rise above 20°C. It follows the warm currents north. It is most common off Northland and the Bay of Plenty. Game fishers travel from around the world to test themselves against this powerful fish. Overfishing has reduced global populations. It is listed as Vulnerable by the IUCN. In New Zealand, catch and release is encouraged. The warm northern sea is blue. The black marlin leaps. It tail-walks across the surface. Its bill slashes. It is silver and black. The angler holds on. The fish is released. It swims away. It does not know it is vulnerable. It does not know it is a prize. It just wants to eat a tuna. To see a black marlin is to see the ocean at its most powerful. The fight is the prize, not the meat. The black marlin is proof.