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

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