Month: January 2021

 

Sharks inhabit all five of the Earth’s oceans and can even be found in some freshwater rivers and lakes too. While this may be alarming to some people, it is important to remember that not all sharks pose a potential threat to people. There is an incredibly diverse range of shark species, from the smallest ninja lantern shark to the giant whale shark, and they all play an essential role in ecosystem function and resilience and help keep our oceans healthy.

Of the over 400 shark and ray species worldwide with around 200 of those in South Africa’s waters, only a small percentage are implicated in unprovoked bites on humans. Of these, only three species are responsible for most incidents, namely the tiger, bull and great white shark. These three species all inhabit coastal waters, which puts them in close proximity to us humans.

Many people have a disproportionate fear of sharks compared to the level of risk they face. However, no matter how small the risk, there is no doubt that shark bite incidents are traumatic events that have wide-ranging impacts on communities, local economies, and the environment.

For nearly 100 years, governments around the world have been looking for ways to manage shark-human conflict, to reduce shark bites and protect people. Historically, shark bite mitigation has involved lethal control of sharks. Lethal control includes sporadic shark hunts immediately after a shark bite, or long-term shark culls using methods such as shark nets and drumlines. Alongside this, some countries have chosen to ban all recreational water activities like swimming and surfing with permanent beach closures. These measures are often knee-jerk reactions that are not sustainable in the long run and often have significant environmental impacts.

Thankfully, following public pressure and improved knowledge of the importance of sharks in the oceans, there has been a shift in recent years to look towards sustainable, non-lethal shark mitigation measures, that protect both people and our marine environment. But what are these measures, and how effective are they?

Most sustainable solutions implemented by governments cover an entire beach, or portion thereof, and provide safety for multiple water users at once. These systems rely on preventing sharks and people from sharing the same space, what we call “reducing the spatial overlap”, and work by either detecting sharks close to shore, or deterring them from an area.

Several places around the world have shark detection programs in place to prevent human-shark interactions. These programs work as proactive early warning systems, alerting water users to the presence of sharks nearby and asking them to exit the water until the shark has left the area. In Australia, this is done using aerial patrols, whereas in Cape Town, South Africa, trained observers (shark spotters) are positioned at elevated vantage points scanning the ocean for sharks. Unfortunately, aerial patrols have been shown to have limited efficacy when it comes to beach safety, due to their low detection rates, and the short period of time they spend over a beach. The use of shark spotters has proven to be effective in Cape Town since 2004 however, they are also subject to some limitations, including the need for mountains or similar elevation close to the sea, the impact of weather conditions on spotting ability, and the potential for human error.

There are also several emerging technologies being investigated in the field of shark detection, including the use of drones for aerial surveys, as well as inshore sonar detections systems. Cleverbuoy is an Australian based company that has been developing a system with a string of sonar buoys across a beach that would detect any sharks that come past. The technology is still in the development and testing phase, and due to the dynamic nature of the surf environment, several challenges need to be overcome, however, the investment in novel technologies for shark bite mitigation is a promising step forwards for sustainable shark safety.

Perhaps the oldest forms of sustainable beach-wide safety measures in existence are those of exclusion barriers. These have been used since the early 20^th Century in different styles and work on the principle of creating an exclusion zone that prevents sharks from entering a “safe bathing area”. Shark exclusion barriers are primarily non-lethal and are therefore different from traditional shark nets. Fixed exclusion barriers can be found in Australia, Hong Kong and Seychelles. Unfortunately, they are only suitable for relatively calm and sheltered bays as strong winds and swells easily damage them, and their repair and maintenance costs tend to be high. In South Africa, a unique design of shark exclusion barrier that is deployed and retrieved daily is in use at a beach in Cape Town and has proved to be very successful and cost-effective. By removing the barrier every day, it reduces entanglement risk and negates the need for costly repairs as if the sea conditions are not suitable then the barrier is simply not deployed, and therefore not damaged.

Recently, several new concepts for deterring sharks from an area have been explored. The KZN Sharks Board in South Africa is developing an electronic repellent cable that uses a low frequency pulsed electronic signal to disrupt the electroreceptors of sharks and deter them from an area. It is hoped that this non-lethal exclusion system will eventually replace the shark nets and drumlines currently in place along the Kwa-Zulu Natal coastline. Another South African product, the SharkSafe barrier, uses fake kelp containing rare earth magnets to create a visual and magnetic deterrence for sharks entering an area. Both of these systems are still in the development and testing phase and are not yet market-ready.

For those wanting to reduce their individual risk of encountering a shark several personal protective devices have been developed over the years, but how effective are they? Using everything from cryptic wetsuits to chilli powder, clever marketing has got nervous ocean lovers reaching for their wallets and spending stacks of cash on products with very little evidence to back up their claims that they can improve shark safety.

A 2018 study from Flinders University in Australia compared the effectiveness of five of the most popular personal shark deterrents commercially available for surfers including the Freedom+ Surf, Rpela, SharkBanz bracelet, SharkBanz surf leash and Chillax wax. These repellents use a range of different methods to deter sharks including electrical currents, magnetic fields and olfactory stimulants and were subjected to rigorous scientific testing on great white sharks at the Neptune Islands, South Australia. The results were worrying, with only one device, the Freedom+ Surf, seen to have a significant effect on white shark behaviour, and even then, it was only effective 40% of the time. All other devices had limited to no measurable impact on the sharks, even though they are often marketed as “100% proven” to keep you safe. This study highlights the challenges consumers face when looking for personal shark repellent devices and how strong marketing campaigns and celebrity endorsements can be deceptive when assessing which product to use. Instead, water users must search for peer-reviewed scientific research that supports a company’s claims about its products.

There are a plethora of possible sustainable alternatives to the lethal shark control measures governments have been using around the world for decades. Some of these are tried and tested systems with proven effectiveness, while others are emerging technologies, showing promise for future applications. However, there is no silver bullet, each beach, and each situation needs a tailored solution, and no strategy, whether lethal or sustainable, can ever guarantee 100% effectiveness.

Ultimately, there is one thing that all of us can do to reduce our risk of shark bite when entering the ocean, whether you are in Durban or Cape Town, Reunion Island or the Neptune Islands, and that is #BeSharkSmart. Being “Shark Smart” means learning safety tips on how to avoid encountering a shark, asking about shark activity when going to the beach and looking out for warning signs of the increased likelihood of shark presence in the area. These factors empower us to take responsibility for our own safety and make informed decisions around shark risk when entering the water, changing our behaviour accordingly.

By Sarah Waries

CEO Shark Spotters

Did you know that the shark nets along the KwaZulu-Natal coast do not prevent sharks from reaching the surf zone on swimming beaches? Luckily, it is highly unlikely that you will ever be attacked by a shark. So unlikely, in fact, that the odds of dying from a shark attack in South Africa are one in 878 956. For decades, the human fear of sharks has transcended logic and statistics. You are more likely to have a coconut fall on your head than be attacked by a shark!

Shark nets are not actually barriers but are staggered 300m and 500m parallel from the shore with gaps between and below them. Each net is usually 214m long and 6m deep, with a stretched mesh of 51cm, and is secured at each end by two anchors. Sharks can therefore swim under, around and between them to reach the surf zone. The nets are really a form of fishing gear, called gill nets, which work by trapping fish and sharks by their gills once they have pushed their heads through the net.  Unfortunately, sharks are not the only marine life that gets caught in this unselective gear. For example, in 2017, 18 turtles, 26 dolphins, 4 whales and 30 rays died in the nets.

There are currently 37 beaches along the KwaZulu-Natal coastline that have “shark safety” gear installed, owned, and maintained by the KwaZulu-Natal Sharks Board (KZNSB), with the nets supplemented by 177 drumlines. Drumlines are a more targeted form of fishing (targeting large sharks) and consist of an anchored float from which a single baited hook is suspended. The species composition of the catch differs with fishing gear type – some sharks and other species do not take bait whereas gill nets are indiscriminate and can catch anything over a specific body size or shape. The logic behind drumlines is to reduce the number of large sharks in the vicinity of bathing beaches by catching them, thus lowering the probability of encounters between large sharks and people.

Herein lies the conundrum – many of the shark species killed in the nets along our beaches are highly endangered (as endangered as pangolins or wild dogs). In fact, sharks and rays are arguably now one of the most endangered taxa on the planet. South Africa is one of three global hotspots for sharks and rays (with over 200 species in our waters) and could play a significant role in preventing further extinctions, and aiding the recovery of these imperilled species.

According to catch statistics (between 2013 and 2017) on KZNSB’s website, dusky sharks are the most caught shark annually, with 92 caught (15% released alive). Most sharks caught are harmless juveniles, less than 100cm in length. The second most frequently caught shark is the Critically Endangered scalloped hammerhead, with an average of 69 caught per year (1% released alive), almost all juveniles. This is problematic since, according to the IUCN (International Union for the Conservation of Nature), this species is one step away from becoming extinct. They are followed by spinner sharks, assessed as Near Threatened in 2005, with an average of 62 caught (12% released alive) per year. Every year, we  lose about 416 sharks and rays to the safety gear, of this 62% are listed as threatened. The fact that this gear is mainly catching juvenile sharks is also a major concern, i.e., removing the stock which has the potential to procreate, especially since sharks generally mature late in life and have few offspring. When we consider that globally we are losing around 100 million sharks per year and that some are even more endangered than our beloved rhino, can we afford to keep another threat to their survival in the form of bather safety gear?

The KZNSB has taken strides over the years to reduce the environmental impact of their bather safety gear. Since the 1990s they have reduced the number of beaches “protected”, and the total number/length of nets along the coast. They are also slowly replacing nets with drumlines, which has reduced both shark mortalities and deaths of other marine animals. Although drumlines target a different group of sharks, they do not entirely solve the problem. For example, they catch an increased number of Endangered juvenile dusky sharks.

For many years, KZNSB and others have been trying to develop methods for bather safety which do not kill or harm sharks, such as a shark repellent electric cable. The KZNSB has also experimented with acoustic deterrents to reduce the number of dolphin and whale entanglements in the nets, but these have not proved very effective. The Shark Spotters programme in the Western Cape is a proudly South African example of a non-lethal solution that keeps both bathers and sharks safe. The recently launched SharkSafe Barrier system, a configuration of pipes with strong magnetic fields, has also proven to be a strong deterrent for shark species. Unfortunately, due to KZN’s open and high energy coastline, these alternatives are not currently viable here, but this certainly does not mean that additional options should not continue to be explored.

Furthermore, to reduce shark and dolphin catches associated with the sardine run and the entanglement of humpback whales during their annual migration from the Southern Ocean, the nets are removed from most beaches between May and July every year. To do this, KZNSB tracks the sardines and the whale migration by undertaking observation flights and remove net installations as the sardines and whales enter KZN. This has proven to be extremely effective in reducing deaths of endangered species and should pave the way for a new permanent protocol of removing the nets along the entire KZN coast for the full duration of the sardine run and whale migration (June to November).

The success of this strategic removal of nets could also be used to protect threatened sharks near areas where they gather in large numbers to breed or where specific habitats are important for their survival and recovery. For example, the Protea Banks Marine Protected Area (MPA) recently proclaimed on the KZN South Coast, is well-known for its diving and diverse shark sightings. Thousands of Critically Endangered scalloped hammerhead sharks aggregate every year between November and January, and other threatened shark and ray species such as sand sharks and ragged-toothed sharks frequent the area. One of the recognised objectives of this MPA is to provide protection for these species, and in turn, this has yielded an internationally renowned vibrant “dive with sharks” tourism attraction.  Ironically, the popular bathing beaches just inshore of the Protea Banks MPA have both nets and drumlines, aimed at catching and killing many of the same species of sharks and rays. There seems to be a strong case for KZNSB to remove gear from the proximity of this shark sanctuary permanently or, at the very least, seasonally.

Between 1984 and 2014, KZNSB staff tagged and released over 4250 sharks, and dead sharks were examined and measured for research. As a result, South Africa has one of the most comprehensive shark datasets in the world, contributing globally to better understanding sharks. The nets have also allowed assessment of their status over the years and provided useful data to inform conservation efforts.

South Africa, we can do better. It is time to shift the mindset of our beach-goers, tourists, and officials, have discussions over viable bather safety gear alternatives, and most importantly, we require political will. What is needed is a new long-term strategy for the KZNSB, investment and dedication into the implementation of non-lethal alternatives for KZN, the potential redeployment of staff and boats to fisheries enforcement instead of implementation of a harmful fishery, responsible tourism, and focused education on the environmental and tourism benefits of our sharks.

There is strong scientific evidence proving how important our sharks are in balancing our ocean ecosystem. Surely, we as humans entering the ocean should be modifying our behaviour to sensibly avoid contact with them and to protect them rather than trying to eradicate them. And, given that the shark safety gear essentially provides a false sense of security to bathers – are they worth the risk to the existence of iconic keystone species in our ocean?

Written by Dr Jennifer Olbers – WILDTRUST Scientist: WILDOCEANS Programme