The great hammerhead shark (Sphyrna mokarran) is the largest and longest lived species in the Sphyrnidae family. The species’ conservation status is listed by the IUCN’s Red List as endangered worldwide with a “Decreasing” population trend and a “Very High Risk of Extinction”. The principal conservation problem facing this species is its population decline. This problem, driven by the high economic value of its large dorsal fins has led to the species being overfished during all stages of its lifecycle.

Sphyrna mokarran is a costal-pelagic and semi-oceanic shark species native to coastal warm temperate and tropical seas. Its migratory nature in and through multiple Range States’ EEZs, slow growth, and lengthy gestation period place this common bycatch species at risk to fishing practices along continental shelves and throughout coastal birth zones. Because of its longevity, the species is at a higher risk to the bioaccumulation of physiologically altering levels of mercury and arsenic.

Given these current anthropogenic threats, in addition to a lack of management strategies by RFMOs, high rates of Sphyrna mokarran captures pose a serious threat to the specie’s survival. Because of difficulties in differentiating between the genus’ species, estimates of trends in abundance are often grouped together as a complex. Abundance trend analyses of catch-rate data for the hammerhead complex of Sphyrna mokarran, including Sphyrna lewini and Sphyrna zygaena, have reported large declines, ranging from 60-99% over recent years.

Given S. mokarran’s present situation, one that includes its overutilization, inadequacy of existing regulatory mechanisms, and other natural or manmade threats, inclusion of the species in CMS Appendix II is necessary in order to begin to restore its populations.