New global strategy to protect sharks and rays released

Working together, several of the most influential conservation organisations have published a new global strategy to conserve sharks and rays. The report, published in January 2016, is a partnership of IUCN Species Survival Commission (SSC) Shark Specialist Group (SSG), Shark Advocates International, The Shark Trust, TRAFFIC, Wildlife Conservation Society (WCS) and World Wide Fund for Nature (WWF) and is the product of an intensive 18 month planning process.

The primary goal of the global strategy is to halt the decline of shark and ray populations globally and to improve the conservation status of the worlds shark and ray species. This main goal will be driven by three further goals which are to have been achieved by 2025:

"2025 Sustainable Fisheries Goal: Fisheries driven overexploitation and waste of sharks and rays are substantially reduced through increased adoption and implementation of sound, science-based fisheries management measures in at least 40 priority countries and in Areas Beyond National Jurisdiction (ABNJ)"

"2025 Responsible Trade Goal: Effective trade controls are in place to ensure international trade in sharks and rays, and the products derived from them, is legal, sustainable and traceable."

"2025 Responsible Consumption Goal: The demand for (largely unsustainable) shark and ray meat, fins, squalene, manta and devil ray gill plates, and freshwater stingrays is significantly reduced in the most important global markets, while markets increasingly demand that any shark and ray products are sustainably produced and traceable."

This global management strategy comes at a critical time for the worlds sharks and rays. Not only are populations being exponentially reduced by the practise of shark finning, but unsustainable fishing practices mean that shark populations are being depleted at a faster rate than they can restock. in addition to this a general paucity of data on global shark populations and fisheries means many species are hard to assess and thus protect. Whilst 181 of the 1,038 known shark and ray species are listed in one of the three threatened categories in the IUCN Red List, almost half of the total number are listed as Data Deficient, meaning that we do not yet have enough information on the particular species in order to make an assessment of its conservation status.

Urgent attention will be given to the most threatened species first which includes the sawfishes, angel sharks, guitarfishes and wedgefishes; these families all contain species which have been classified as Critically Endangered or Endangered by the IUCN Red List.

Implementation of this global strategy will require extensive engagement with the public and governments in the primary target countries as well as continued research to bridge the gaps in current data. However, ambitious as this strategy is it is entirely necessary if shark and ray populations are to be protected; more heartening perhaps is the commitment that these large conservation organisation have promised towards protecting the worlds sharks and rays by releasing this strategy.

Bräutigam, A., Callow, M., Campbell, I.R., Camhi, M.D., Cornish, A.S., Dulvy, N.K., Fordham, S.V., Fowler, S.L., Hood, A.R., McClennen, C., Reuter, E.L., Sant, G., Simpfendorfer, C.A. and Welch, D.J. (2015). Global Priorities for Conserving Sharks and Rays: A 2015–2025 Strategy.

Shark teeth could pave the way to new dental therapies for humans

Whilst humans might be able to make do with a set of false teeth once the two sets we have during our lives have worn out, tooth loss is more critical amongst the rest of the animal kingdom. Elephants, for example, have 6 sets of replacement molars and once they have all been worn down the animal will die from starvation - a major cause of death in mature elephants. Sharks however, have developed a strategy to deal with the problem of tooth loss and that is to have unlimited sets of new teeth during their lifetime - something which most other vertebrate lineages have lost.

The genetic basis for tooth regeneration in sharks has recently been investigated by scientists at University of Sheffield using the catshark (Scyliorhinus spp.) as a model. The research indicated that the ancestral condition of vertebrates was likely to be that of constant tooth regeneration and that tooth development in vertebrates is governed by a core set of genes. The team discovered several potential reasons why sharks are able to produce unlimited sets of replacement teeth: firstly having a jaw made of cartilage as oppose to harder, bony material allows new teeth to constantly move forward replacing older, worn out teeth. Secondly sharks have an expanded dental lamina which houses multiple sets of teeth ahead of being required and the team suggests that this is essential for continuous tooth regeneration.

What is significant about these findings is how similar this core set of genes governing dental development is between sharks and our own species; in fact many of the genes which govern tooth development in vertebrates have thought to have remained unchanged for around 450 million years. The research suggests that slight genetic changes to this gene set could be the key to unlimited tooth regeneration as oppose to a finite set of teeth. Understanding how this gene set functions across the vertebrate lineage could contribute to the development of novel therapies for tooth loss in humans.

Rasch,L.J.,et al., An ancient dental gene set governs development and continuous regeneration of teeth in
sharks. Dev.Biol.(2016) http://dx.doi.org/10.1016/j.ydbio.2016.01.038i

The 2015 Worldwide Shark Attack Summary is out!

According to the 2015 Worldwide Shark Attack Summary of the International Shark Attack File (ISAF), 2015 saw a record high number of unprovoked shark attacks. Out of a total of 164 recorded attacks, 98 were categorised as unprovoked; this figure surpasses the previous highest number of 88 unprovoked shark attacks in 2000.

However, before you go grabbing your speargun and practising the line "Smile you son of a bitch", it's important to point out that whilst the number of unprovoked attacks has risen in 2015, the overall rate of attacks could very well have remained unchanged or even fallen. The researchers who curate the ISAF attributed the increase in shark attacks to more humans in the water and better reporting of shark attacks rather than an increase in the rate of shark attacks. The researchers also caution against putting too much faith in short term trends owing to year to year variability of environmental conditions which can affect shark populations.

Of the 98 unprovoked shark attacks in 2015, there were only 6 fatalities worldwide and long term trends indicate that the rate of fatalities owing to shark attacks is decreasing. Whilst news of shark attacks will always draw media attention and excitement, the numbers pale into insignificance when compared to the 1.24 million people who were reported to have been killed in road traffic accidents in 2010.

Geographically the majority of the shark attacks occurred in North American waters, with Australia coming a close second with 18 unprovoked attacks - 1 of which was fatal. People participating in activities which caused a lot of surface turbulence such as surfers were the most vulnerable to attack whilst snorkellers constituted only 9% of the number of people attacked. There were no reports of unprovoked attacks on scuba divers in 2015.

The ISAF has been run from the Florida Museum of Natural History since 1988 and is the longest running database on shark attacks globally. As well as curating worldwide shark attack information, the ISAF also provides regular advice on shark attacks issues.

Shark research - evolution of the vertebrate jaw

A recent article published in Nature has found new evidence that the origins of the vertebrate jaw may lie with bony fish, as oppose to cartilaginous fish as previously thought.

By examining a 325 million year old, Palaeozoic shark-like fossil (Ozarcus mapesae), the researchers found many similarities to the visceral branchial arch arrangement of osteichthyans (bony fish). This has thrown into question the existing idea that cartilaginous fish are responsible for the origin of the vertebrate jaw.

All vertebrate embryos develop pharyngeal arches - in fish these develop into the gill (or branchial) arches and in humans they ultimately become part of the larynx and trachea.

Cartilaginous fish (sharks, skates, rays and chimeras) are often described as "primitive fish", and are thought not to have changed much since their original evolution. Bony fish (or Osteichthyes) are considered to be the derived state and to have a more "modern" physiology. However, this new shark-like skeleton suggests that far from being unchanged since their evolutionary origin - around 420 million years ago - sharks may have undergone several evolutionary adaptations along the way and that our own mammalian jaw may have a closer evolutionary history with that of bony fish rather than cartilaginous fish.

Pradel, A., Maisey, J. G., Tafforeau, P., Mapes, R. H. and Mallatt, J. (2014) A Palaeozoic shark with osteichthyan-like branchial arches. Nature (16th April 2014)