Most recently they have been able to identify that 21% of scalloped hammerhead fins sampled from Hong Kong markets were actually sourced from western Atlantic populations, where the species is already listed as endangered by the IUCN. The samples from the western Atlantic also identified three subdivisions within the population due to particular sequences being geographically segregated, indicating that breeding females either remain close, or home back, to their natal region of origin for parturition.

Hammerhead shark at market. Photo by Dan Beecham.

‘The fact that scalloped hammerhead shark DNA shows strong population DNA signatures means that we can trace the geographic origin of most of their fins sold at markets,’ Mahmood said. ‘From a broader perspective, this type of DNA forensic testing of fins will be an incredibly useful tool to prioritize areas for conservation and ensure sharks aren’t wiped out in particular regions by excessive fishing.’

One of Mahmood’s co-authors, Dr Demian Chapman plans to attend the CITES meeting in Qatar this coming March to urge that scalloped hammerheads are listed under Appendix II to receive more comprehensive protection from the international market.

To learn more about Mahmood’s research be sure to check out his project page here.

‘The threat of extinction for European Dipturus together with mislabelling in fishery statistics highlight the need for a huge reassessment of population for the different Dipturus species in European waters. Without revision and recognition of its distinct status the world’s largest skate, D. intermedia, could soon be rendered extinct.’

Similarly, genetic analysis of ragged-tooth sharks (Carcharias taurus) has found that the critically endangered population of Australia, although still the same species, may in fact be divided between eastern and western populations, essentially requiring that they are now managed as two separate populations: one does not have the ability to replenish the other.

Genetic tools can prove incredibly powerful, providing insights that direct observations and fisheries records can easily miss. Be sure to read more on how the SOSF shark DNA forensics project aims to characterise the global population structure of shark species and implement techniques to identify featureless fins from their ‘DNA barcode’, thereby aiding enforcement efforts to prevent trade in protected species.

“Individuals persistently return to the same network of coastal hotspots following distant oceanic migrations and comprise a population genetically distinct from previously identified phylogenetic clades.” state the authors of the article published in Proceedings of the Royal Society B. They used a combination of acoustic and satellite tags, as well as tissue samples for DNA analyses, to demonstrate this strong homing behaviour that has presumably generated this genetic isolation from other populations, frequenting areas such as Hawai’i, the coast of California and a mid ocean spot termed ‘white shark café’.

The authors emphasise that this isolation highlights the need for North Pacific white sharks to be recognised as a “demographically independent management unit”. As such in management terms they may as well be a separate species, warranting their own protection measures independent of other white shark populations, even in the rest of the Pacific.

To read about the study in greater detail, along with some fantastic diagrams to help illustrate what the white sharks are up to, check out the original publication here.

Also be sure to check out ongoing research into the behaviour of South African white sharks over at the SOSF White Shark Project homepage.