Shark Research – Brazil looks for a better way to keep beaches shark safe

Whilst shark attacks are relatively rare, when there is a sharp increase in the number of attacks it will often provoke public outcry. Between 1992 and 2011 there was an abnormally high number of shark attacks in Recife, Brazil – around 55; the increase in attacks was owing to the development of a new port area in the region.

Whilst the Government was eager to take preventative measures against future attacks, they valued the aquatic ecosystems and understood that gill nets and longlines are non-discriminatory measures which kill species other than sharks. The Shark Monitoring Program of Recife (SMP) was set up to find a technique which could reduce shark attacks whilst causing minimal disturbance to the surrounding ecosystem.

Two researchers from Universidade Federal Rural de Pernambuco (UFRPE) looked at ways this could be achieved. They first used baiting techniques to attract sharks and then relocated problem sharks away from the hazardous area. These techniques showed a 97% reduction in the amount of attacks around the site, and reduction in the mortality rates of sharks and bycatch when compared with gillnets.

During the survey the researchers aimed to reduce the mortality rate of the sharks, as well as to reduce the mortality rate of people using the water in this region. The SMP techniques involved catching sharks using circle hooks – as oppose to the traditional J style hooks – as this lowered mortality rates in the sharks. During the relocation process steps were taken to reduce the stress caused to the sharks – such as covering their eyes with a cloth. Finally the capture and relocation of the sharks afforded the researchers the opportunity to tag the sharks. The tags proved that relocation was a suitable technique in this area, as the sharks did not return to the region after being transported.

The reduction in shark mortality rates was most prevalent in tiger sharks – in South Africa 40% of tiger sharks (Galeocerdo cuvier) are released alive, whereas using the techniques employed by SMP, 82% of tiger sharks were released alive. For the remaining shark species (including bull sharks, blacktip sharks, silky sharks etc) mortality averaged about 30% - which is still a fairly high number when we consider that many of these species are considered Near Threatened in the IUCN Red List of Threatened Species.

The notion of relocating sharks as oppose to culling them is something which this study proved can work – at least in this location. However, whilst it is refreshing to see a government attempting to protect their wildlife whilst keeping sharks away from the public, the fact remains that this study still uses hook based fishing gear to attract the sharks. If steps could be taken to reduce the mortality rate of captured sharks even further, then relocation could be a real, ecologically sound solution to removing sharks from certain areas – after all relocation techniques have been used to remove venomous snakes from properties for years and are a very successful strategy in this regard. 

Hazin, F. H. V. and Afonso, A. S. (2013), A green strategy for shark attack mitigation off Recife, Brazil. Animal Conservation. doi: 10.1111/acv.12096

Shark research: attitudes of divers towards encounters with grey nurse sharks

A recent paper published in Aquatic Conservation: Marine & Freshwater Ecosystems has examined the attitude of scuba divers towards the practice of diving with grey nurse sharks (Carcharias taurus). The research, led by Kirin Apps, interviewed divers who had dived with grey nurse sharks at Julian Rocks and Fish Rock in NSW. Using interview techniques, the researchers sought to learn more about the behaviour of scuba divers at these sites.

The main motivations for wanting to approach grey nurse sharks were to get a better view of the shark and to interact with the shark. However, divers were also concerned that their behaviours might scare the sharks or disrupt the natural behaviour of the sharks. A large proportion of the respondents were concerned that environmentalists would disapprove if they were to approach the sharks and most interestingly there was a great deal of concern regarding the opinion of other divers with some respondents thinking the dive community would approve of their approaching a grey nurse shark and others believing this behaviour would draw disapproval from their fellow divers.

Diver interaction with delicate marine structures such as corals, and marine species such as sharks can unintentionally have a negative effect on the conservation of the marine ecosystem. Furthermore, for many people diving with sharks is a unique experience and the desire to “make the most” of the experience can sometimes lead to behaviours which may not be wholly beneficial to the animal such as touching or disturbing the animal.

However, scuba divers do tend to show respect for the underwater environment and to be in favour of conserving the oceans and recent research has suggested that shark dive tourism overall can contribute to the conservation of many shark species as it is a very effective way of making a shark worth more alive than dead. In a world where the price of shark fin has increased the rate of poaching, making live sharks valuable to governments via shark dive tourism could be a realistic way to ensure that many shark species receive government protection. In an ideal world, all forms of shark tourism would be conducted in a responsible manner which attracted divers to the activity whilst ensuring minimum disturbance to the species involved.  

Grey nurse sharks are listed as Vulnerable in the IUCN Red List of threatened species.  A better understanding of the behaviour of divers towards C. taurus will help researchers and policy makers be more aware of the potential threat towards this species from tourism and implement this knowledge accordingly in their efforts to conserve this species.   

Shark research: Older than we first thought: it takes more than “counting the rings” to age a great white.

Despite the overwhelming fame and notoriety of the great white shark (Carcharodon carcharias) in the media, the reality is that there exists relatively little scientific data on this species. A group of researchers, led by Li Ling Hamady at Woods Hole Oceanographic Institution, used radiocarbon analysis to confirm the age of 8 white sharks and found that white sharks in the northwest Atlantic Ocean (NWA) were likely to live up to 70 years.  

The previous method of aging great white sharks – as with most fishes - was to count the number of mineralised layers laid down in specific tissue such as vertebrae; with this method it is assumed that the layers are laid down on an annual basis. However this method can be vulnerable to misinterpretation and collaboration of results gained in this manner by using radiocarbon dating has gained popularity.

The study, which was published in the journal PLOS ONE, increase exponentially the estimated longevity of C. carcharias in NWA. These results not only have implications for a need to reassess the methods by which sharks are aged, but an increased expected longevity in white sharks raises grave conservation issues. Like most sharks, white sharks are slow to reach maturity and have small litters. If NWA white sharks exhibit even greater longevity than we first thought, this could mean that their expected age to reach sexual maturity could also be longer than originally estimated and this would make white sharks even more vulnerable to fishing pressure and population decline. The white shark is listed as Vulnerable in the IUCN Red List of Threatened Species; many countries protect white sharks but a poor media image has left white sharks vulnerable to persecution – such as the recent decision of the Western Australian Government to bait for large sharks.

Obtaining a greater knowledge of the growth rates and longevity of white sharks will be beneficial for ensuring the protection of this species.  

Hamady LL, Natanson LJ, Skomal GB, Thorrold SR (2014) Vertebral Bomb Radiocarbon Suggests Extreme Longevity in White Sharks. PLoS ONE 9(1):

e84006. doi:10.1371/journal.pone.0084006

Shark Research: Magnets could be used to successfully repel bull sharks

A group of researchers led by Craig O'Connell at the University of Massachusetts Dartmouth, have discovered that C8 barium-ferrite (BaFe12O19) permanent magnets might be the key to repelling bull sharks (Carcharhinus leucas) from shark nets.

The research - to be published in the journal Ocean & Coastal Management - measured the responses of C. leucas to bait and barriers where permanent magnets were present. They discovered that bull sharks were less likely to approach bait or to enter areas when magnets were present. These results suggest that if magnets were used along shark nets they might deter C. leucas from approaching the nets.  

Shark nets are used extensively in three regions of the world: Queensland and New South Wales in Australia, and Kwa-Zulu Natal in South Africa. The use of these shark nets is somewhat controversial; whilst they have been put in place to protect beach-goers from large sharks who may stray close to shore and pose a risk to anyone in the water, the shark nets also result in the mortality of thousands of sharks per year. Furthermore, as the nets are non-discriminatory, other marine life such as dolphins and juvenile whales can also fall victim to shark netting. Finding a guaranteed way to repel sharks away from the nets would not only ensure that sharks are protected from the nets but could even lead to the removal of the nets altogether if the sharks could be kept away from the shore.   

The finding that permanent magnets can be used to deter select elasmobranchs is consistent with what we know about the biology of certain sharks; sharks have specialist sensory organs called Ampullae of Lorenzini which they use to detect bioelectric fields and are hypothesised to be capable of detecting the magnetic field of the Earth.

The researchers plan to publish similar papers focusing on the great white (Carcharodon carcharias), giant hammerhead (Sphyrna mokkaran) and the tiger shark (Galeocerdo cuvier). The inclusion of multiple shark species in this long-term study is important as there is a possibility that highly visual sharks such as C. carcharias may not be as sensitive to magnetic fields as C. leucas. 

With the recent decision of the Western Australian Government to implement a cull of all large sharks in response to a spate of fatal attacks in WA, further research into methods to repel sharks and the potential practical applications could not come at a better time.

Shark travel - bull sharks at Beqa Lagoon

A few months ago I finally made it over to Fiji to dive with bull sharks at Beqa Lagoon. I had been wanting to visit Fiji my whole life and since moving to Australia a year previously I had decided that it was time to make a trip to my new neighbour in the South Pacific.

As a scuba diver, any small island in the South Pacific is a huge draw for me. I have always had an image in my head of perfect turquoise seas, white beaches and water so warm you could bathe in it! When I turned to researching what type of diving Fiji has to offer, something exciting was revealed to me - Fiji has sharks and lots of them! It didn't take me long to realise that Beqa Lagoon was the place to go for the shark enthusiast.

I booked in for bull shark diving and a couple of reef dives with Beqa Adventure Divers. I had researched them quite thoroughly online before I committed and I wasn't about to be disappointed! The staff were fantastic and demonstrated really good customer service throughout.

The day long bull shark dive started with a 7am pick up from my hotel. With Beqa Adventure Divers situated only a 5 minute drive from the main road it was a quick trip to the dive centre where we kitted up. On board the boat we were given some tips on safety in the water. I was advised to switch out my high vis neon yellow ProForce fins for a pair of black stock fins as they would be less attractive to inquisitive sharks (...yes, I took a little persuading to surrender my Force fins!) We were also all issued with thick gloves - again to protect vulnerable fingers from the possibility of getting a small nip! I had brought a shortie wetsuit but was surprised to be given a 6mm full length instead and did find myself shivering a little on the dive - for the majority of the shark dive you are a static observer as oppose to constantly swimming so you can be a little more prone to the cold on this dive.

The first dive started with a descent to 30m and at around 20m I looked down and had my first glimpse of the bull sharks. The black tips (Carcharhinus limbatus) and ragged tooth sharks (Carcharias taurus) I dive with in South Africa get pretty big, but I had not anticipated the sheer bulk of the behemoths below me. Struggling against my ears - which were taking their sweet time to equalise against the depth - I descended painstakingly slowly towards the big sharks.

The bull sharks certainly didn't have personal space issues!

What an awesome sight! The setup of the dive meant that we human spectators were sat by a rocky dropoff, whilst the sharks were encouraged (as much as you can encourage a 2m+ predator!) to swim in the open water in front of us. We spent about 10-15 minutes at this level watching the bulls glide around in front of us. They clearly didn't have any qualms about our presence there and obligingly swam right in front of my camera lens. After this we ascended to about 10m where tawny nurse sharks (Nebrius ferrugineus) and reef sharks were being fed. Huge groups of scissor tail sergeants (Abudefduf sexfaciatus) had decided that the option of a scrap of food was well worth risking the mouths of the sharks for and were present of each dive. I also spotted some lined snapper, butterflyfish and a giant trevally (Caranx ignobilis) darting in and out amongst the sharks. The sheer volume and variety of fish in front of us was overwhelming - at one point I felt a whisper of current between my arms and looked down to catch a tawny nurse shark darting through my arms - the shark had such good spacial awareness that it hadn't even touched me as it sped past.

Bombarded by sharks and fish!

After a surface interval, we descended for a second dive - again with the bull sharks but this time we spend the whole dive with these large predators allowing plenty of time for filming and getting that perfect shot! The sharks were offered bony fish heads from a large bin, which they very politely and patiently almost queued up to get! For the second half of the dive the bin was shut and the behaviour of the sharks changed very quickly. With their attention no longer focused on receiving a meal from the bin, they were suddenly swimming very quickly all around us. Being bombarded by small sharks and fish was one thing, but a huge group of bull sharks certainly tested the nerves! Luckily the bulls were good as gold and showed not even a mild interest in any of the divers. It wasn't long before we were making out ascent and were safely back on the boat.

This is a baited shark dive and as such it draws in larger number of sharks than would be expected in a "natural" setting. I have always had a bit of internal conflict regarding baited shark dives - I generally don't approve of practises which alter the "normal" behaviour of the animals - but in light of the huge pressure on shark populations nowadays from finning, shark tourism may be the key to the long term survival of sharks. Making sharks worth more alive than dead with the tourist dollar is a great way to encourage governments to work to protect their wildlife. Plenty of people travel to Beqa Lagoon to dive with their bull sharks and this brings a lot of money in to the area; the simple equation is no sharks = fewer tourists.

Happy faces after surfacing say it all! 

Details

I went: October 2013. November - April is generally the time of year to avoid as the region can be prone to cyclones.
I flew: From Melbourne to Nadi with Virgin Australia (approx AUD$800)
I stayed: Dormitory style accommodation at Uprising Beach Resort. There are plenty of high end options to choose from in the area though!
I dove with: Beqa Adventure Divers

Shark News: Shark finning banned in New Zealand waters!

Yesterday the New Zealand Government announced plans to ban shark finning, ensure the long-term sustainability of their shark populations and promote shark research and community engagement.

The National Plan of Action for Sharks (NPOA-Sharks) was announced by Primary Industries Minister Nathan Guy and Conservation Minister Dr Nick Smith. With this, the New Zealand Government has pledged to eliminate shark finning (where the fins are removed and the carcass is disposed of at sea) in it's fisheries by 1st October 2015 with the exception of the highly migratory blue shark (Prionace glauca) which will come under the act by 1st October 2016. The elimination of finning for all other species will occur in 2 waves, with an initial group of sharks being protected by 1st October 2014, and the remainder gaining protection in 2015.

Seven species of shark are currently protected in New Zealand waters, including the great white (Carcharodon carcharias) and the whale shark (Rhincodon typus). Of the remaining 70+ species which have been reported to have been caught by fisheries in New Zealand, 11 species account for 90% of the total catch. These include the spiny dogfish (Squalus acanthias), mako shark (Isurus oxyrinchus) and the blue shark (P. glauca). Whilst it is currently an offence to remove the fins from a shark and return the live shark to the sea, the new policy will ban the practice of killing the shark, removing the fins and disposing of the carcass at sea - for any shark killed the entire carcass must be landed.

As well as including cultural involvement with the Maori and recognising the importance of sharks in marine ecosystems, the NPOA-Sharks also emphasises the importance of New Zealand being perceived as having sustainably managed shark fisheries among the international community. This indicates that the recent increase in public awareness of the plight of sharks and high profile media attention which sharks have been receiving of late could be having a positive effect on government policy making. In a media release, Dr. Smith commented "“The 45,300 submissions in favour of the proposal to ban finning show New Zealanders’ attitudes to sharks have come a long way since the ‘Jaws’ days. It is now widely recognised that sharks are an important part of the marine ecosystem and that we need to ensure the 113 species of shark in our waters survive."

Whilst some groups have criticized the NPOA-Sharks, stating that October 2015 is a very long deadline, the implementation of this 5 year plan is a positive step from the New Zealand Government towards ensuring the sustainability of their shark populations and sending a message to the international community that finning is not a practice to be tolerated.

Shark News: Sharks on Twitter

The Surf Life Saving WA Twitter feed (@SLSWA) is doing a fantastic job keeping water users up to date with shark sightings along the WA coast. Previously SLSWA used visual aids - such as shark surveillance by helicopters - to inform water goers that large sharks were in the area. Thanks to efforts by the Shark Monitoring Network to tag large sharks along the WA coast, tagged sharks can now be automatically detected when they stray too close to shore and an alert is sent to the SLSWA Twitter feed. The Tweets transmit data regarding the sharks species (if known), time and location of detection.

As of October, the WA Government reported that they had tagged 136 white sharks (Carcharodon carcharias), 171 whaler sharks (Carcharhinus brachyurus) and 19 tiger sharks (Galeocerdo cuvier).　Troy Buswell - the WA Fisheries Minister - stated that alerts could be sent out within 2 minutes of the shark straying too close to a monitor. The speed of these updates will ensure the SLSWA are able to respond faster to large sharks in the area and take action if necessary.

Whilst there has been some criticism that these Tweets may make large sharks vulnerable to hunting - especially in light of the recent decision of the WA Government to destroy large sharks close to beaches - giving water users advanced warning of sharks will hopefully not only reduce encounters between beach goers and sharks but will make people feel safer about entering the water.