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Distribution, Population, and Status
Great hammer heads are found in circumtropical costal waters, 68 degrees or higher. The great hammerhead population is critically fragmented, and decreasing. Information on their population sizes, distribution, migratory patterns, and catch data are extremely deficient. While the extinction rate is unknown, scientists estimate the decline to be more than 80% over three generations (about 70 years).
Reasons for Great Hammerheads Decline
By catch from longlines, bottom nets, gill nets, trawls, and bather fisheries.
Sensitive to capture and release. High mortality rate rate as a result of evident behavioral and physiological stress.
Threatened by commercial fishing for their large fins.
Subject to fishing stressors in a range of jurisdictions due to large scale migrations.
Issues with species identification.
Slow growth rates, biennial reproductive cycle, reducing their recovery potential.
High levels of inbreeding and low levels of genetic diversity.
Inadequate protection.
Conservation Groups
PADI Aware: Global shark and ray census, shark and ray species protection to monitor shark and ray populations.
World Wildlife Fund (WWF): Encouraging communities across the world to develop an interest in marine biodiversity. Providing protection for poorly understood, and over exploited species. Advocating for stronger legislative protections.
Humane Society International Australia: Moving to terminate the use of drum lines.
Center for Biological Diversity: Monitoring and scientific research initiatives.
IUCN Protections
Listed as critically endangered, it is recommended that all retention and landings be prohibited. Initiatives to prevent capture, minimize bycatch mortality, promote safe release, and improve catch reporting. Full implementation of additional commitments agreed through international treaties.
Conservation Proposal
Modifying fishing methods with high mortality rates.
Education on identification - photographs, records etc.
Critical habitat research.
Identify and conserve, nursery and residency sites with philopatric behavior.
Restricting gear, and compensating fishers for lost profit. To encourage compliance with regulations.
Why Should The Great Hammerhead Shark Be a Priority?
As an apex predator the great hammerhead shark plays a crucial role within the coastal marine system, a biodiversity hotspot. They prey on a wide range of species in the lower trophic levels. Great hammerheads support healthy levels of species density and diversity by consuming diseased and injured marine animals, supporting natural selection. If the great hammerhead is permitted to become extinct the impact on costal ecosystems, and inevitably the world would be catastrophic.
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