Great Hammerhead

The great hammerhead (or Sphyrna mokarran) is a large species of shark that inhabits warm temperate and tropical waters worldwide. It most commonly dwells along continental shelves, lagoons and near coral reefs, though it may also be found in deeper offshore areas. Great hammerhead sharks have a distinctive, nearly straight-edged hammer-shaped head with a notch in the centre. They have a tall, sickle-shaped first dorsal fin, and their colouration is grey-brown with a pale underside. Females are larger and heavier than males, usually measuring over 4m and up to 6m, while males are usually smaller, averaging around 3m. Weight may average at 150kg for males and 230kg for females, though pregnant and very large females can reportedly weigh over 500kg.

Critically Endangered, the great hammerhead is threatened across its range. Over the past 70 years, upwards of 80% of great hammerheads have been lost. Overfishing is a significant driver of population declines due to the demand for shark fins. The slow growth, late maturity and biennial reproductive cycles mean the great hammerhead has limited capacity to recover population losses. As its broad migratory behaviours span multiple national jurisdictions with inconsistent regulations and enforcement thereof, conservation management is very difficult. Protection for great hammerheads takes place on national and international levels. Internationally, trade is regulated, while some countries have implemented catch limits and monitoring systems in addition to restrictions on the shark-fin trade. Local community projects often focus on minimising bycatch, and research is done to better understand population dynamics. Several marine protected areas provide at least some safe habitats across the shark’s range. While these combined efforts aim to stabilise populations, their effectiveness ultimately depends on consistent enforcement and international collaboration.