Broadbill swordfish Xiphias gladius
Broadbill swordfish are largely solitary predators that have a broad distribution between 40°N and 40°S in all of the world's ocean basins. They grow to 4.5 metres and 600 kilograms, live for more than 30 years, and migrate daily from the surface at night more than 600 m deep during the day where they tolerate extreme cold. Swordfish move with prevailing currents, use their superior sight to stalk prey, and breed in waters above 24°C. They are prized for their pink flesh and commercial catches in New Zealand, Australia and the south-west Pacific high seas have expanded since the 1990s. Research suggests the Pacific Ocean has several, semi-independent stocks of swordfish (northern, south-western and eastern Pacific). Tagging studies show that in the Coral and Tasman Sea regions swordfish are largely resident around ocean floor features such as seamounts. This behaviour makes them vulnerable to localised depletion when commercial fishing is centred in these areas. Information on the movements of swordfish provides a better understanding of the degree of mixing between fishing areas and guides the management of populations across these regions.