DNA identification reveals threatened species being overfished in Brazil

New research has revealed an alarmingly high level of trade of endangered shark species in northern Brazil.

As one of the top seven global consumers of shark meat in the world the shark fishing industry in Brazil is of commercial significance yet data on shark fisheries remains scarce. Official statistics on shark fishing are derived from data provided by commercial fishing vessels, however globally a significant artisanal fishing industry is thriving which, if added to official records, would contribute up to an additional 50% of total landings.

In addition to hosting the largest continuous mangrove forest in the world, Brazil's north coast is a shark conservation hotspot and supports nineteen shark species. This region is also an important fishing ground.

Whilst some sharks are protected under Brazilian law, specimens are commonly landed finned and headless at Brazilian ports. The lack of morphological features makes species identification and subsequent law enforcement problematic. A recent study published in Nature's Scientific Reports utilised DNA-based techniques to identify sharks collected from some of the most important fishing ports in northern Brazil to determine which species were being caught.

Of the 427 shark specimens analysed 82 (19.14%) were listed as either Critically Endangered, Endangered or Vulnerable in the IUCN Red List. A further 125 (29.18%) were in the Near Threatened category. Seventeen species in total were identified with the Caribbean sharpnose shark (Rhizoprionodon porosus) making up the majority of the sample size. The species in the most threatened categories were the great hammerhead (Sphyrna mokarran) (Endangered), the scalloped hammerhead (Sphyrna lewini) (Endangered), the smalleye hammerhead (Sphyrna tudes) (Vulnerable) and the daggernose shark (Isogomphodon oxyrhynchus) (Critically endangered). Of these species the daggernose shark is of critical concern owing to its conservation status and the fact that this shark occupies a restricted range around northern Brazil making it particularly vulnerable to exploitation and the risk of extinction.

The results produced here should rightly be cause for alarm; for shark fishing to have been occurring in a location of significant shark biodiversity and without sufficient protection measures in place will have had an impact on shark populations. Despite efforts from the Brazilian government to pass legislation that protects the local fauna the reality is that lack of resources and inadequate monitoring have rendered official protection obsolete. With such a large proportion of specimens captured being classified in a category of threat the authors recommend urgent implementation of more effective monitoring and measures to reduce shark bycatch.

Where is the largest shark biomass in the world?

Cocos Island National Park and the Chagos Marine Reserve might be considered to be contenders for the largest fish biomass on the planet, but a new location has been found to have an even larger biomass and it consists almost entirely of sharks!

The islands of Darwin and Wolf in the Galapagos have recently received full protection from fishing from the Ecuadorian Government (see The Shark Post: New marine sanctuary in the Galapagos will protect a variety of fish species). This change was partly driven by the conclusion that these islands support a large amount of shark species; now publishing in the journal Peerj a team of researchers have presented their evidence that Darwin and Wolf support the largest biomass of sharks reported to date. 

Using underwater cameras to conduct stereo-video surveys the researchers recorded and measured the fish around Darwin and Wolf islands. This data was then used to convert length measurements to biomass and the fish were classified as apex predators, lower level carnivores, planktivores and herbivores.

Primarily consisting of the scalloped hammerhead (Sphyrna lewini) (48.0%), the Galapagos shark (Carcharhinus galapagensis) (19.4%) and the blacktip shark (Carcharhinus limbatus) (5.1%), the shark biomass made up almost 73% of the total fish biomass at these 2 sites. Interestingly the majority of the fish observed were found in the south-east section of both islands; the researchers hypothesised that this might be owing to the unique currents which flow through these islands or possibly the south eastern part of these islands are used as a cleaning station or a location for nightly foraging excursions. 

Sharks are incredibly important to the Galapagos and to Ecuador; not only do sharks help regulate the ecosystem as apex predators but an individual shark in the Galapagos has been estimated to be worth USD$360,000 per year through tourism, whilst a fisherman may receive a one off payment of USD$158 for the same dead shark.  

Whilst veteran divers have reported larger abundances of sharks at Darwin and Wolf 30 years ago, there exists a real lack of long term studies in the area to quantify these observations. Owing to the fact that these islands are home to the last true coral reef in the Galapagos Marine Reserve, are important waypoints for whale shark migrations in the region and have now been proven to support the largest shark biomass ever recorded it is important that studies such as this continue in order to ensure ongoing protection of this biologically significant region.   

Salinas de León P, Acuña-Marrero D, Rastoin E, Friedlander AM, Donovan MK, Sala E. (2016) Largest global shark biomass found in the northern Galápagos Islands of Darwin and Wolf. PeerJ Preprints 4:e1872v1 https://doi.org/10.7287/peerj.preprints.1872v1

Huge quantities of sharks and rays being caught by fisheries in Tunisia

The Gulf of Gabes lies on the east coast of Tunisia and supports many small scale fisheries. Here artisanal fisheries commonly set trammel nets to catch shrimp (Melicertus kerathurus) from May to August each year. Now a team of researchers has been researching the impact of these fisheries on the local shark and ray populations.

The scientists, based at Institut National des Sciences et Technologies de la Mer in Tunisia, spent 3 months recording the number of elasmobranchs caught in fishing nets of the artisanal shrimp fisheries in the Gulf of Gabes. They took note of species, sex and total length (or disc width in rays).

In total 926 elasmobranchs were caught during this 3 month period; the overwhelming majority of the sharks and rays caught was made up by the common smooth-hound (Mustelus mustelus) but six other species (blackspotted smooth-hound (Mustelus punctuatus), common stingray (Dasyatis pastinaca), marbled stingray (D. marmorata), common torpedo ray (Torpedo torpedo), sandbar shark (Carcharhinus plumbeus) and spinner shark (C. brevipinna)) were also retrieved. Despite the fact that the sheer numbers of elasmobranchs caught in 3 months is fairly jaw dropping, what's really shocking about the results is that all of the captured sharks were either neonates or juveniles.

Removing immature specimens from a population can have huge implications for conservation owing to the fact that the organisms in question have not had the opportunity to reproduce. This is especially true for sharks who tend to have slow growth, low fecundity and long reproductive cycles making it difficult for most species to recover their stocks once depleted. The results here led the researchers to believe that the Gulf of Gabes might be an important nursery area for several species of elasmobranch.

Whilst large commercial fisheries are barred from many marine protected areas, small scale artisan fisheries are often permitted to operate. Recently there has been more attention paid to the impact of these smaller fisheries with the result that some marine protected areas are prohibiting all fishing activity within their waters (see The Shark Post: New marine sanctuary in the Galapagos will protect a variety of shark species).

Studies such as this are critically important as they provide scientists with the evidence to convince policy makers that key areas need protecting either by closing fisheries or creating a marine protected area. Considering that one of the above species is listed as Near Threatened in the IUCN Red List and two as Vulnerable (including the most commonly caught common smooth-hound), protecting elasmobranchs in this region should be of high importance.

Saidi, B., Enajjar, S. and Bradai, M. N. (2016), Elasmobranch captures in shrimps trammel net fishery off the Gulf of Gabès (Southern Tunisia, Mediterranean Sea). Journal of Applied Ichthyology. DOI: http://dx.doi.org/10.1111/jai.13061

Tiger shark distribution is larger than we thought

Despite having a circumglobular distribution, the tiger shark (Galeocerdo cuvier) has heretofore been considered a coastal species, sticking close to the continental shelf. However, a recent assessment of populations of G. cuvier in the Atlantic Ocean has revealed that this species is more widespread than first thought.

Publishing their work in the Journal of Fish Biology, a team of researchers have been utilising at-sea observers on board pelagic longline fishing vessels to document tiger shark sightings. From 1992 to 2013, 2,764 tiger sharks were reported and whilst a great deal of these observations were from coastal regions, 86.4% of the data occurred outside the existing geographic range of this species as proposed by the IUCN Red List. The observations change the current view of the distribution of G. cuvier, showing that this species is present in the open ocean, as well as along the continental shelf and the researchers propose that the distribution of G. cuvier should be amended to show that this shark is present throughout the Atlantic.

Interestingly the data also showed consistent sightings of G. cuvier along the equator which were not matched further North, suggesting that tiger sharks in the Atlantic could be utilising the North and South Equatorial Currents and the North Equatorial Counter Current to move across the Atlantic.  

This data could have implications for the conservation and management of this species as it could indicate that there is a larger biomass of tiger sharks than previously thought, or that tiger sharks in the open ocean are more vulnerable to fishing pressure owing to the fact that it was not previously confirmed that this species was present in the open ocean. Either way this data fills yet another gap in our existing knowledge of this Near Threatened species.

Domingo, A., Coelho, R., Cortes, E., Garcia-Cortes, B., Mas, F., Mejuto, J., Miller, P., Ramos-Cartelle, A., Santos, M. N. and Yokawa, K. (2016), Is the tiger shark Galeocerdo cuvier a coastal species? Expanding its distribution range in the Atlantic Ocean using at-sea observer data. J Fish Biol, 88: 1223–1228. doi:10.1111/jfb.12887

The worlds first ever shark sanctuary: has it been effective?

Palau attracted international attention in 2009 when the island nation created the first ever shark sanctuary. Created in response to the rapid depletion of sharks in the region, all commercial shark fishing has been banned within the sanctuary, which covers an area of approximately 600,000 sq km.

However, despite all the best intentions, enforcement of these restrictions is incredibly tough - especially for a small island nation such as Palau. Not only is the area in question a very large area to patrol, many of the reefs which attract sharks are located far away from the main populace, making constant visibility of shark fishing activity around these reefs troublesome. These factors mean that any type of enforcement requires a great deal of time and money.

In order to ascertain if the shark sanctuary has been having any benefit to the local shark populations, a team of researchers have conducted surveys on a selection of reefs within the shark sanctuary. During the course of the surveys estimates of shark density based on sightings were calculated and observations of derelict fishing gear were recorded to try and ascertain any potential level of illegal fishing activity.  

The researchers found that areas with higher densities of derelict fishing gear (longlines and nets) had lower densities of sharks. They also discovered that grey reef sharks (Carcharhinus amblyrhyncos) observed close to reefs from the main island group were larger and occurred in higher densities than those from the southwest islands - a group of isolated islands occurring in the south of the country. A smaller total body length measurement and a lower density of sharks could be indicative of fishing pressure on the shark population; the fact that these attributes were observed on the most remote reefs could allude to the fact that illegal fishing is more commonly being practised away from the principal islands. In addition to the above, local rangers had reported seeing unauthorised fishing of sharks and the researchers did observe a shark caught in derelict fishing gear.    

These observations suggest that illegal fishing activity has not been entirely eradicated from the shark sanctuary and could potentially be having an impact on the shark populations in the more remote areas of the sanctuary. However it should be noted that the surveys took place only 4 years after the shark sanctuary was created and owing to the slow recovery rate of sharks the results reported here may reflect the historic state before fishing pressure was relieved from the shark populations within the sanctuary.

The Shark Post has been writing a lot about the effectiveness of marine protected areas (MPAs) recently (see The Shark Post: How well do marine protected areas truly protect highly migratory sharks? and The Shark Post: Can a Marine Protected Area truly ever be protected?) and more research is coming to light to show that the creation of a marine protected area is just one half of the battle; the real uphill struggle is enforcing the laws which have been laid down.

Vianna, G. M. S., Meekan, M. G., Ruppert, J. L. W., Bornovski, T. H. and Meeuwig, J. J. (2016) Indicators of fishing mortality on reef-shark populations in the world’s first shark sanctuary: the need for surveillance and enforcement.

The Ecological Role of Sharks On Coral Reefs Is Not As Straightforward As First Thought

The term "apex predator" is frequently applied when talking about sharks regardless of the species being discussed. However, a team of researchers based in Australia have been reviewing the trophic positioning of reef sharks and it seems as though not all shark species can be considered to be apex predators in their habitat.

It may seem rather obvious when you stop to consider it; after all the vast spectrum of shark species stretches from definite apex predators such as the great white (Carcharodon carcharias) to species which surely must occupy a lower level in the food web such as the epaulette shark (Hemiscyllium ocellatum). However, the authors suggest that owing to the deficiency of data on shark dietary habits, early researchers lumped all sharks together into a single "apex predator" class.   

The definition of an apex predator is an animal which occupies the top of a food chain, has no natural predators of its own and maintains the health of the habitat it resides in by exerting an influence over the species below. The researchers looked specifically at reef associated shark species and found that most of the species they focused on functioned more as mesopredators than apex predators. For example, the grey reef shark (Carcharhinus amblyrhincos), whilst occupying the highest trophic level in it's habitat, is vulnerable to being preyed upon by opportunistic apex predators such as the tiger shark (Galeocerdo cuvier). In addition to this, mesopredators such as the grey reef shark may be jointly occupying the top trophic level with large predatory teleost fish, further evidencing their removal from "apex predator" status. In contrast, a large pelagic apex shark such as the tiger shark will migrate between open ocean and reef and their trophic role may vary across habitats. However on the reef these sharks exert a high degree of influence over the associated community, have no natural predators and take a wide variety of prey items thus fulfilling all the requirements of being apex predators.     

So what is the value of sharks on a reef if they are not all fulfilling apex roles which would exert influence over the community? The researchers suggested a broad range of functions for sharks on reefs. For example the small home ranges of some of the mesopredatory sharks contribute to nutrient cycling between pelagic and reef habitats. Both apex and mesopelagic sharks will remove sick and weak individuals from coral reef habitats and potentially suppress the spread of disease by keeping population numbers in check. It has also been suggested that certain mesopredatory reef associated sharks may be able to keep invasive species such as lionfish in check. In addition to this, the presence of sharks has significant economic value: the researchers cite the shark sanctuary in Micronesia which was created to protect the local shark species owing to the socio-economic benefits of shark diving in the region. Despite being a "shark sanctuary", many fish and coral species will also enjoy the benefits of this marine protected area. 

This review is really rather interesting as it gives us all pause for thought regarding the diversity of shark species in our oceans and the fact that despite often being viewed as fearsome predators, some sharks will end up as prey for larger predators. The authors also raise a variety of questions on how sharks interact with coral reef communities and their influence on the reef system, laying the foundation for future research.

The original paper is published in trends in Ecology and Evolution. DOI: http://dx.doi.org/10.1016/j.tree.2016.02.014 

New marine sanctuary in the Galapagos will protect a variety of shark species

The Galapagos Islands are known globally as a rich area of biodiversity and the islands themselves have enjoyed 97% percent protection since they were declared a national park in 1959. However, despite the creation of a marine reserve in 1998 to protect the waters around the islands, some fishing has been permitted and less than 1% of these waters has complete protection.

Despite the fact that the marine park is closed to trawls and other high impact, commercial fishing activities, the artisanal fishing is still having an impact on populations of large predators. Owing to high demand, populations of key species are being depleted to unsustainable levels. In addition to this not all landings made within the marine reserve are declared, making the true numbers of species caught difficult to ascertain.

This is about to change however as on Monday the Ecuadorian President Rafael Correa Delgado announced a new marine sanctuary for The Galapagos. This new sanctuary will lie between Wolf and Darwin Islands and will cover a region of more than 15,000 square miles; unlike the current marine reserve, the new sanctuary will be completely off limits to any fishing activity.

The new marine sanctuary will mean that 33% of the waters around the Galapagos now enjoy complete protection from fishing. Happily it is predominantly sharks which have driven this change; the Galapagos Islands have been cited as having the greatest abundance of sharks in the world and the official announcement from the Ministry of Environment stated that the sanctuary had been created with the idea of protecting endangered species such as hammerhead sharks. Of course it is not just sharks that will benefit, the coral reef and fish in the marine protected area will also thrive under the new no-take policy.

Whilst declaring a marine sanctuary is only one part of the battle (see The Shark Post: Can a Marine Protected Area truly ever be protected?), this protection could not have come soon enough as many of the shark species which inhabit these waters are under threat; the scalloped hammerhead (Sphyrna lewinin) is listed as Endangered in the IUCN Red List, whilst the Whitetip Reef Shark (Triaenodon obesus) and the Galapagos Shark (Carcharhinus galapagensis) are listed listed as Near Threatened. These species will all benefit from this new no-take area.

On his Twitter account, the Environmental Minister Daniel Ortega Pachero (@dvortega) said that the new marine sanctuary is a moral obligation to the Galapagos, Ecuador and the world. Very true words as the benefits of protecting areas of rich biodiversity like The Galapagos will indeed be felt throughout the world.

Sources: Ministerio de Ambiente
National Geographic
Elucidating fishing effects in a large-predator dominated system: The case of Darwin and Wolf Islands (Galápagos)

How well do marine protected areas truly protect highly migratory sharks?

The designation of an area of ocean as a marine protected area will be a cause of celebration for most conservationists; restricting fishing activity within a certain area takes pressure off fish stocks and benefits the ecosystem. However, many marine protected areas (MPAs) are created with a certain goal - often to protect coral reefs or specific resident species. Highly migratory species such as sharks would only benefit from the protection an MPA offers when they are residing within the MPA zone. A team of researchers at University of Miami have been investigating how much time 3 key shark species spend within the MPA designated zones around Florida and the Bahamas in order to ascertain the true level of protection these species enjoy.

Over the course of 4 years the researchers satellite tagged tiger (Galeocerdo cuvier), bull (Carcharhinus leucas) and great hammerhead (Sphyrna mokarran) sharks within the study area. The study area contained a mixture of national parks, economic exclusion zones (EEZ) and a national marine sanctuary which included a no-take zone. In addition to this, shark harvesting has been entirely prohibited in the Bahamas since 2011, when a shark sanctuary was created. Within Florida state waters it is not permitted to take tiger, great hammerhead, scalloped hammerhead (Sphyrna lewini) or smooth hammerhead (Sphyrna zygaena) sharks and the maximum catch for all other shark species is one shark per person per day. This study also included parts of the US EEZ which has more relaxed laws than Florida state waters and allows up to 36 large sharks per boat per day to be removed.    

The researchers discovered that none of the core habitat use by the bull sharks tagged in this study overlapped with any of the areas which would have afforded them complete protection. For the great hammerhead, 27% of their core habitat range fell within protected, no-take regions and for tiger sharks it was 34.74%. These figures show that, despite there being several regions where shark fishing is completely prohibited around Florida and the Bahamas, the sharks are not staying within those regions. However, the researchers did discover that these shark species spent quite a bit of time within the U.S. EEZ and if the same protection which is afforded sharks in the waters around Florida state were extended to include U.S. federal waters then the practical level of shark protection would increase.

Owing to the fact that bull sharks are classified as Near Threatened in the IUCN Red List, tiger sharks as Threatened and great hammerheads as Endangered these species require immediate and urgent implementation of regulations which will afford them complete protection from fishing. Studies such as this can be used to inform policy makers and prove that extended protection zones are mandatory if the future of these species is to be assured.  

Graham, F., Rynne, P., Estevanez, M., Luo, J., Ault, J. and Hammerschlag, N. (2016) Use of marine protected areas and exclusive economic zones in the subtropical western North Atlantic Ocean by large highly mobile sharks http://onlinelibrary.wiley.com/doi/10.1111/ddi.12425/full

Can a Marine Protected Area truly ever be protected?

Whilst it is estimated that over 3% of the worlds oceans have been designated as Marine Protected Areas (MPAs), enforcement of the regulations within these areas is often difficult. This is owing primarily to the expense and logistics of patrolling large areas of ocean as well as the low probability of arrest leading to prosecution.

One area which has a rich abundance of marine wildlife is Cocos Island National Park (CINP). CINP is an offshore, no-take marine protected area of nearly 2,000 square kilometres located off the coast of Costa Rica. Despite having been afforded National Park status and being a world heritage site, CINP suffers from illegal fishing being carried out in its waters.

The resources currently offered by the Costa Rican Government to patrol the park and deter fishing infringements are not proving adequate to prevent illegal fishing in the region. Hoping to be able to suggest ways to improve the efficiency of the patrols, a group of researchers analysed the last 5 years worth of patrol data to try and ascertain where efforts could be best applied.

During the last 5 years the patrol boats recorded a total of 300 fishing infringements with 34,500 hooks set and 2,000 fish caught. The overwhelming majority of the catch (66%) was made up of yellowfin tuna (Thunnus albacares), but sharks comprised 25% of the total recorded catch - predominantly the silky shark (Carcharhinus falciformis). Shark finning has been reported from CINP and declines in the abundance of sharks within the park have been reported.

The researchers reported that policing the park is confounded even further by the conflict of interest within the fisheries authority: most of the board members are representatives of the fishing industry. In addition to this the poachers do not seem to feel the threat of prosecution: the probability of arrest is very low, the probability of conviction practically non-existent and fleeing poaching vessels have commonly been observed flinging insults back at the patrol boats via the radio.

It may seem as though all of this paints a rather bleak picture for our wildlife (and our sharks!) However the researchers aims were to increase efficiencies amongst the patrol boats to help the wardens make the best use of the limited resources available to them. The analysis conducted by the team revealed that poaching was highest during the first quarter of the lunar phase and the third quarter of the year; the likelihood is that the reduced light conditions during the new moon brought predators closer to the surface and were also favourable conditions to carry out illegal fishing owing to the reduced risk of detection. Time of year also appeared to be a significant factor influencing fishing activity. The researchers therefore suggested aligning the majority of the patrol times to coincide with these peak periods of poaching.

The team also discovered that illegal fishing is focused around a seamount within the park and by zoning this region the park boundary could be more obvious and manageable. Along with this the rangers should be looking to invest in better technology to detect poachers and should also be trained in environmental and marine law - all of which would require a not insignificant monetary investment.

This research goes to show that shark finning - and illegal poaching in general - is not limited to the open ocean, away from the eyes of the law. Preventing these activities from happening requires a greater set of efforts than simply designating an area to be a national park. Protection of the park needs to be enforced and the attitudes of governments changed to encourage them to provide resource to support this protection.

Arias, A., Pressey, R., Jones, R., Alvarez-Romero, J. and Cinner, J (2016) Optimizing enforcement and compliance in offshore marine protected areas: a case study from Cocos Island, Costa Rica http://dx.doi.org/10.1017/S0030605314000337

What happens when conserving an Endangered species impacts a fishery worth A$1 million?

Conservation efforts in many parts of the world are often impacted by money. This is not a reference to the usual lack of funding for the average not-for-profit - although that is an important side note - but the often lucrative reasons for why a species has fallen into decline in the first place. With rhino horn worth more than gold and a bowl of shark fin soup selling for up to HK$2000 there is a price on the heads of wildlife so high that it can offer some convincing reasons to some parties against supporting conservation efforts.

Financial implications of lost business are also of concern to the fisheries industry. Whilst sustainable fishing is, of course, important to the fishing industry as it translates to continued employment, closing a fishery to protect a non-target species can lead to socio-economic conflict between conservationists and fishers if the fishery in question also contains a valuable target species.

This is what happened in 2012 with the release of a management strategy for the upper slope dogfish in Australia. One species of upper slope dogfish - Harrissons Dogfish (Centrophorus harrissoni) - is classified as Endangered in the IUCN Red List and uses Taupo seamount off New South Wales as a refuge. The management strategy released in 2012 proposed a higher level of protection for Taupo seamount which would officially close it to all fishing activity, therefore protecting this vulnerable species.

The road to this proposed closure had been a long winded process; Harrisson's Dogfish was first nominated for listing under the Environment Protection and Biodiversity Conservation Act in 2005. Taupo seamount was then sampled and subsequently identified as a refuge for Harrissons Dogfish in 2009 and subsequently the seamount was closed to commercial fishing activity under the advice of the Australian Fisheries Management Authority (AFMA) in 2010.  

The closure of the fishery in this instance caused controversy as the seamount chain in question contributes 25% of the annual total allowable catch of Blue-Eye Travally (Hyperoglyphe antarctica). This is a fishery which has a total value of A$1million and so the closure would have had a significant impact on the lives of the fishers and the Australian economy. 

In 2015 the original closure and planned upgrading of the seamount to Marine National Park status was revised (AFMA Ecological Risk management 2015) to allow commercial line fishing around Taupo seamount. Whilst this may initially seem like a step backwards, the revision was undertaken with a view that the fishery could be compartmentalised to allow fishers to maintain their catch of Blue-Eye Trevally whilst not impacting the Endangered Harrissons Dogfish.

Harrissons Dogfish is a diel vertical migrator - the shark spends daylight hours at depths of >550m and ascends at night-time to feed on micronekton. Researchers at CSIRO and Australian Museum hypothesised that the seamount could potentially be open to line fishing above 550m; this would allow fishers to catch Blue-Eye Travally during the day but should not have any impact on the Harrissons Dogfish stocks.

The researchers carried out their own fishing effort around the seamounts, deploying fishing lines both during the day and at night as well as into the Mid (280-550m) Zone and Deep (550-830m) Zone. The results showed that catches of Harrissons Dogfish were avoided when fishing for Blue-Eye Travally at depths of 280-550m during the daytime, using standard commercial power handline. Whilst surveying the area, the researchers also discovered that the range inhabited by Harrissons Dogfish was much wider than previously thought.

These results were used to inform policy makers when finalising the management plan for Harrissons Dogfish. Whilst the zoning category of the Taupo seamount was relaxed to allow commercial handline fishing activities, the zoning category of the Derwent Hunter Seamount was increased and the Queensland and Britannia seamounts were included in the Commonwealth Marine Reserves network owing to the new evidence of Harrisons Dogfish in these regions.

The declassification of Taupo seamount from Marine National Park to Habitat Protection Zone is never a step in the right direction as far as any conservationist is concerned. However strict regulations are in place: the fishery is subject to 100% monitoring and if any vessels interact with more than 3 Harrissons Dogfish they will lose their rights to fish in the region for 12 months. In addition to this the removal of Harrissons Dogfish has been entirely prohibited.

So when conservation conflicts with huge financial profit can there be a happy medium? This solution may be a way to keep everyone happy; however the truth of the matter is that the only way we will known is by ongoing monitoring and sampling in the region to see if the populations of Harrissons Dogfish truly are unaffected by the Blue-Eye Travally industry.

New species of shark discovered in Argentina!

Researchers from Buenos Aires have discovered an exciting array of fossilised selachian teeth, including a new species.

The fossilised teeth were collected from the Calafate Formation in Argentina and were discovered during the preparation of another fossil of a very large elasmosaurid plesiosaur. After conducting a thorough analysis of squaliform phylogeny and evolution, the authors were able to ascertain that some of the teeth discovered had never been described before and comprised a new species of the genus Protosqualus: Protosqualus argentinensis.  

Images of fossilised P. argentinensis teeth. Image courtesy of Sergio Bogan at Fundación de Historia Natural Félix de Azara Departamento de Ciencias Naturales y Antropología CEBBAD - Universidad Maimónides

The exciting news doesn't end there, however. Not only did the authors describe a new species, but this is also the first time any member of the genus Protosqualus has been discovered in South America. Previous examples of this genus have been noted from Russia, Australia and India and it has been suggested that this species would have had an anti-tropical distribution which is supported by the findings here.

The authors also discovered teeth belonging to the previously described Hexanchiform Notidanodon dentatus. Whilst today most Hexanchiform species are extinct, were it alive today Notidanodon dentatus would have a handful of living relatives in the cowsharks and frilled sharks. Interestingly previous examples of this extinct species have also been found in association with an elasmosaurid plesiosaur suggesting that this species may have been a scavenger opportunistically taking advantage of these marine reptiles.

Fossilised N. dentatus teeth. Image courtesy of Sergio Bogan at Fundación de Historia Natural Félix de Azara Departamento de Ciencias Naturales y Antropología CEBBAD - Universidad Maimónides

What's even more exciting (yes - there's more!) is the placement of these species. As noted in the paper, the Northern Patagonian fossil record is dominated by Lamniform (living species of which would include mackerel sharks like the Great White) and ray teeth, whilst the Southern Patagonia fossil record is comprised of cold water species suggesting that there was little species overlap in the late Cretaceous oceans around South America.

Whilst these species may be long extinct, piecing together their life history from the fossil record will help us to understand modern day sharks better and provides insight into how the prehistoric oceans may have looked.

Sergio Bogan, Federico L. Agnolin & Fernando E. Novas (2016) New selachian records from the Upper Cretaceous of southern Patagonia: paleobiogeographical implications and the description of a new taxon, Journal of Vertebrate Paleontology http://www.tandfonline.com/doi/full/10.1080/02724634.2016.1105235

All female Tiger Shark hangout found in the Bahamas

You might not expect to hear that ultrasounds are being given to pregnant tiger sharks (Galeocerdo cuvier), but that is exactly what happened in a recent research study carried out at Tiger Beach in the Bahamas. Tiger Beach is a popular shark diving destination owing to the large numbers of tiger sharks there. The area has warm, calm water and is relatively shallow leading the researchers to hypothesize that the sharks present in the region could be pregnant females taking advantage of the clement conditions. 

In order to test this assumption the team captured 65 tiger sharks; in order to assess whether these sharks were pregnant they carried out ultrasounds and tested levels of circulating sex steroid hormones in the sharks. Typically in a study of this nature, the most effective sampling techniques would result in killing the animal in question in order to assess pregnancy - not so beneficial when your end goal is to protect the species you are studying! Happily, the researchers in this study were able to successfully gather the required information using the non-lethal sampling techniques described above. 

Of the 65 tiger sharks captured, only 6 were male. Of the 59 females 19 had not yet reached maturity, 17 were mature, non-pregnant females and 23 were mature, pregnant females. These results suggest that Tiger Beach is a high-use site for female tiger sharks and may function not only as a secure site in which to give birth but also as a place for young female tiger sharks to reach maturity free of harassment from males.  

Knowing that Tiger Beach is an area favoured by pregnant female tiger sharks could have significant implications for the conservation of this species; the removal of pregnant females from a population can have dramatic effects on population size and thus this population should be afforded protection from fisheries. Whilst Tiger Beach is situated within the Bahamas Exclusive Economic Zone (EEZ) which is a shark sanctuary where all harvest of sharks is forbidden, tiger sharks can freely move out of the boundaries of the EEZ and may then be at risk from fisheries.   

The full article is Open Access and can be read at http://www.int-res.com/abstracts/ab/v24/n3/p175-184/.

Sulikowski JA, Wheeler CR, Gallagher AJ, Prohaska BK, Langan JA, Hammerschlag N (2016) Seasonal and life-stage variation in the reproductive ecology of a marine apex predator, the tiger shark Galeocerdo cuvier, at a protected female-dominated site. Aquat Biol 24:175-184

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.

Crackdown on illegal shark fishing in Dubai

Posting on their Facebook Page on Wednesday, Dubai Municipality have reported that the Environment Department have confiscated a large number of sharks from Deira fish market. The sharks had been landed at a time of the year when shark fishing is not permitted in the UAE and the photos showed the fins had been removed from the carcasses - something which is also illegal in the UAE.

Sharks which had been illegally landed at Deira fish market. Photo credit: Dubai Municipality

According to Ministerial Decree No. 500 - which came into effect on the 1st September 2014 - registered fishermen may only fish for sharks between the 1st of July to the end of January the following year; in addition to this the Government has put in place further restrictions on shark fishing  in the waters around the UAE. Fishermen may only use circle hooks to catch sharks; circle hooks have been proven to be more humane than J hooks (See The Shark Post: Researchers in Brazil find new techniques to improve the survival rate of tiger sharks caught in longline fisheries). The decree also forbids the taking of shark and manta species listed in CITES appendix I and II and enforces a 5 mile exclusion zone around the mainland. More importantly, the UAE Government has addressed the issue of shark finning by making it illegal to catch sharks solely for their fins. In addition to this sharks must be brought to land whole, preventing the removal of fins at sea.

Evidence that the Dubai Government is enforcing these laws and issuing heavy penalties to the violators is good news as it shows their commitment to protecting the fish species in their waters.

Lemon sharks benefit from Marine Protected Area in Turks & Caicos

You may be forgiven for thinking that the creation of a marine protected area (MPA) would obviously lead to a greater abundance and diversity of marine life within the MPA as oppose to outside it's boundaries. However whilst creating marine reserves does typically lead to a greater density and size of organisms within the reserve boundaries, it is not to be assumed that this will be the case and until the particular reserve has been assessed it's success may largely be unknown.

In 1992, Bell Sound Nature Reserve (BSNR) in the Turks and Caicos Islands was established with a view to protect juvenile bonefish which are targeted in the Turks and Caicos Islands. A team of shark researchers led by Aaron Henderson from the Center for Marine Resource Studies in South Caicos have investigated whether this MPA is also having an effect on populations of the lemon shark (Negaprion brevirostris).

Lemon sharks are classified as Near Threatened in the IUCN Red List as they are caught in both commercial and recreational fisheries; as yet no management plans have been put in place to protect these sharks.

The researchers observed higher numbers of lemon sharks within BSNR than in the waters outside the reserve. Lemon sharks do exhibit a preference for shallower water and so the increased quantity of sharks within BSNR could be owing to habitat selection rather than protection from fishing, however he researchers surmised that the protection from predation offered by the MPA was attractive to the sharks and could cause them to want to remain in the reserve as oppose to moving outside.

Whilst the reasons for the higher number of sharks inside the MPA as oppose to outside is not yet entirely clear, the conclusions drawn were that BSNR is important to the local juvenile lemon shark population.

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

Predator and prey - even a whale shark isn't too much for a great white!

It seems as though great white sharks (Carcharodon carcharias) are not adverse to taking on prey much bigger than themselves as two whale shark (Rhincodon typus) centra have been found amongst the stomach contents of a great white.

The centra - the central part of a vertebra - were removed from the stomach of a 4.5m long white shark which was caught in the 1960s at Cheynes Beach Whaling Station, Western Australia. The vertebrae remained at the Western Australian Museum until they were re-examined after a chance visit by Dr. Michael Newbrey from the Royal Tyrrell Museum of Palaeontology in Alberta, Canada. Dr. Newbrey immediately identified the vertebrae - which had been mis-labelled all those years ago as belonging to a Basking Shark (Cetorhinus maximus) - as those of a whale shark. Based on the size of the centra, the individual they belonged to would have been at least 8.5m long.

The find raises a series of interesting questions. First of all, the ranges of the white shark and the whale shark do not commonly overlap; white sharks - whilst having a circumglobal distribution - prefer temperate waters whilst whale sharks are found in tropical and warm temperate seas. Secondly, did the white shark attack a live adult, whale shark or did it ingest the centra whilst scavenging from an already dead whale shark? White sharks are known to eat other elasmobranchs and have been observed feeding on dead baleen whales in certain areas so it is not out of the question that the whale shark was deceased by the time the great white came to feed on it.

Whilst we may never know the fate of the two sharks in this story, this new discovery is the first confirmed proof that white sharks will eat adult whale sharks, and that even the largest fish in the ocean is not safely off the menu for the worlds greatest predator (in this writers opinion :)

Read the article here
Glenn Moore's Blog @Western Australian Museum

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.

Sustainability of shark fisheries on the Great Barrier Reef

The Great Barrier Reef Marine Park (GBRMP) is known worldwide as a natural wonder: a protected underwater haven for tropical fish, sharks and other marine fauna. However, only 33% of this marine protected area is closed to commercial fishing activities - within the rest of the park commercial fishing boats are allowed to operate and to carry out large scale fishing activities such as trawling and gill netting.

This is not to say that these activities are allowed to happen unchecked, however. Commercial fishing within the park operates under strict zoning rules and, as with most commercial fisheries there are maximum fishing quotas and possession limits in place.

The difficulty with any type of commercial fishing activity is assessing whether the existing marine populations truly can bear the brunt of the fishing activity. The ocean is a huge area and species are typically wide ranging, making accurate assessment of animal numbers difficult.    

In recent study published in Fisheries Research a team of researchers have discovered that some commercial fishing activities within the GBRMP may not be sustainable.

The study focused on tagging and assessing the three most commonly harvested sharks in the GBRMP: the Australian blacktip shark (Carcharhinus tilstoni), the Spot-tail shark (Carcharhinus sorrah), and the Spinner shark (Carcharhinus brevipinna). The Pigeye shark (Carcharhinus amboinensis) and the Australian Sharpnose shark (Rhizoprionodon taylori) were also included as two example of non-target species. In total, 3,413 sharks were tagged during the course of the study.

Whilst the team discovered that harvest rates were highest for the Pigeye shark it was summarised that the numbers were still around the acceptable optimal equilibrium harvest rate for this species. Only a small amount of the population of this stock were vulnerable to commercial fishing activity and therefore the species may be able to withstand greater fishing pressure. However such high harvest rates for this species are surprising as it is not a target species and is instead being caught as bycatch by fishing boats.

The more worrying outcome of the study was that whilst the annual harvest rate was lower for Australian Blacktip sharks than for Pigeye sharks, the current level of exploitation of this species could be too high. This is owing to 2 main factors: the population of Blacktip sharks in the GBRMP is thought to have a lower reproductive rate than populations from northern Australia making it more difficult for stocks to replenish themselves, and this species is available to commercial fisheries from age 0 meaning that all of the population can be fished at any stage of their life cycle.

Whilst these findings can only make assumptions about localised depletion of the study species within the GBRMP, the results are important and further research and monitoring is essential to ensure that fish stocks remain healthy in this marine protected area.      

Harry et al. (2016) Assessment of a data-limited, multi-species shark fishery in the GreatBarrier Reef Marine Park and south-east Queensland

The Sharksafe barrier - an ecological way to keep sharks away from beaches!

The Sharksafe barrier has been causing quite a bit of fuss amongst shark enthusiasts as it has been promised to provide an environmentally friendly way to exclude sharks from swimming beaches. Now it's success has been proven as a team of researchers has successfully tested the barrier with live sharks. 

Currently, shark netting (where nets are strung close to swimming areas to try and protect the public from sharks) is in effect in New South Wales and Queensland in Australia and Kwa-Zulu Natal in South Africa. Existing shark nets do not simply exclude sharks from swimming beaches; instead the intention is that the sharks will become entangled in the nets and die. The impact of shark nets is not limited to sharks either as dolphins, dugongs, turtles, whales and other marine fauna are often found dead in these nets (if you are interested in reading an in depth analysis hop along to The Shark Post - The Truth About Shark Nets). As well as shark netting, governments sometimes employ other techniques to try and reduce shark attacks near public beaches such as drumlines or shark culls. 

None of the activities above are successful in completely excluding sharks from the waters around public beaches, and they have all have a detrimental impact on other marine fauna. 

In their work the researchers deployed the Sharksafe barrier around Gansbaai, South Africa - a region commonly populated with Great White Sharks (Carcharodon carcharias). The barrier was equipped with artificial kelp and electro-sensory magnets to see if these additional stimuli would elicit further changes in the swimming behaviour of the great whites. Great whites have been observed to show reluctance to enter kelp forest and the researchers had success with repelling bull sharks with magnets in previous studies (The Shark Post - Magnets could be used to successfully repel bull sharks).

The Great Whites showed a strong aversion to swimming between the regions with additional stimuli and a general avoidance of the Sharksafe barrier. In addition to this the barrier is ecologically friendly as no changes to the behaviour of the Cape Fur Seals which inhabit the area was noted, and unlike shark nets marine animals will not get entangled in the more rigid structure of the Sharksafe barrier. 

Whilst further studies will be needed to see the best way to utilise the barrier to ensure total exclusion of Great Whites from swimming beaches, these results are positive and lend hope to a more ecological friendly way to ensure swimmer safety in the future.      

Connell, C., Andreotti, S., Rutzen, M., Meyer, M., Matthee, C. and He, P. (2014) Effects of the Sharksafe barrier on white shark (Carcharodon carcharias) behavior and its implications for future conservation technologies. Journal of Experimental Marine Biology & Ecology. 460.