Learning to live with sharks How to eradicate the dangers of sharks while preserving this vital link of ocean life. Bulldog and tiger shark attacks are a problem for tourism in many places in the world. Apprehension of danger during aquatic activities has become extremely acute. In Reunion, I met people who have lost a loved one due to a shark attack and I decided to put my expertise at the service of this problem. So I designed a totally new strategy that solves the problem by bypassing it. The techniques used in many parts of the world to secure the swimming areas from sharks are essentially static with no interaction with the animal. They are essentially large mesh nets, submerged lines of hooks, repellents or electric fields. The ideal system would be one that respects biodiversity, would be resistant to climatic conditions, would not cause risk for people and that sharks could not interpret as artificial.
St Philippe, 2015.
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 1
Which solutions to adopt in the face of uncertainties: Sharks: How many are there?
What events trigger the attacks?
What phenomenon contributes to the sudden increased danger that appeared in 2011?
Only the sharks have all the answers and most of our certainties are only plausible hypotheses.
Acting without knowing: Man mastered fire without understanding its chemistry. Would the people of the Reunion eliminate the shark risk without understanding the animal?
The method: 2 sentences suffice to describe this project: Pain exists for all living beings and this sensation causes a flight response linked to the survival instinct. Sharks can remember sounds from a painful experience and flee whenever they hear them, even very weakly.
Limit the impact. The ecosystem is only partially understood, to change it would be a risk.
Only 2 races attack near the coast when adults.
The system only targets bulldog and tiger sharks with a length less than 1.5 meters.
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 2
Methods at all scales. Existing strategies: Scare
Monitor, alert
Barricade
Eliminate the animal
Deter
Solutions and scope of protection: I protect myself:
My beach is secured:
Preserve my area of risk:
- aerial or underwater cameras, - lookouts, - repellent installed on my board,
- a surface drone,
- the belt device,
- a net,
- the color of my bathing suit,
- a sonar,
- there is a lot of people in the water, the victim will be someone else,
- an artificial algae curtain,
- the capture of sharks, - the sonic fence.
- the "dead shark" scent, - some electric poles, - the sonic fence.
As long as security is not complete, new solutions have to be tested. The sonic fence is the only strategy will deters and repels dangerous sharks. A prototype has to be made, tested and certified by an authority.
Detailed description of the sonic fence. Experimental measurements: The CHARC [1] program (knowledge of the ecology and Habitat of two species of coastal sharks on the West Coast of the Reunion) has conducted a fundamental study on bulldog and tiger sharks behaviors on the island. It shows the essential elements to consider for a device for an island: •
the bulldog shark explores the entire coastline,
•
It spends most of its time at a depth between 0 and 80 meters,
•
there would be about 1200 specimens. Thus, all bulldog sharks off the island can be found in only two or three zones of limited
depth. The tiger sharks geographical area is less well-known. The scientific study CHARC has brought new insights into the behavior of bulldog and tiger shark populations. This study has achieved its objectives, providing critical knowledge, and it is important to use this knowledge in order to develop a solution. http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 3
Aversive conditioning. Aversive conditioning produces a change in behavior as a result of the repetition of an unpleasant experience. If the experience is very painful, the conditioning can be very fast and only one time may be enough. This principle is used with electric fencing installed in the fields, where the cattle after a few shocks, carefully avoid the wire. Also, when we got a finger smashed by a slammed door, we never put our hands in that place after that. This process is essential to the survival of all species. There is no "artificial" problem in the sense that pain is real and naturally associated with danger.
Aversive machines: A series of automated machines operates all day and night. They are located on the coastline, 30 meters deep and automatically identify the dangerous sharks. An attractive signal such as a fragrance or vibrations mimicking those of a wounded fish is periodically emitted. When a dangerous shark is identified, •
a series of artificial notes is emitted,
•
the power of this noise increases when the animal gets closer,
•
when the pain threshold is reached, the animal leaves,
•
as soon as the animal leaves, the noise is greatly increased.
Any animal who would forget its conditioning and would come across this machine again would undergo the experience again.
Repellent devices: The repellent device consists of an underwater speaker that emits low-power noises identical to the conditioning device every 5 minutes. On the one hand emitted frequencies propagate without attenuation in water, on the other, sharks are particularly sensitive to them. This simple device can emit sounds at a very long range with low power. It can be static to cover a beach or be installed on a boat. Thus, only dangerous individuals are marked with a threatening "melody". These sound signals are weak and will be ignored by other animals. The repulsive buoy must emit an alert if it stops working. To this end, it is equipped with an independent device which receives the repulsive sound. In normal operation, it emits a green light at the top of the buoy. In case of malfunction, this system emits a warning sound in the air and red flashing lights.
This new method eliminates hazards and preserves the ecosystem.
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 4
The strengths of the sonic fence: a) A minimum impact on the marine ecosystem with •
the preservation of useful but dangerous species,
•
with no consequences for aquatic life.
b) A comprehensive solution for an island. c) Performance do not depend on sea state or turbidity. d) A reduced cost compared with other solutions.
Implementation Aversive conditioning buoys must be placed far away from swimming and diving areas — the painful experience could lead to aggressive behavior. The effect of conditioning will last for very long provided it is not in competition with the basic needs of the animal, for example sufficient space to live. To this end, deserted areas with no tourist or fishing activity nor aversive or repellent devices will be reserved for the unwanted sharks. In case of difficulty of geographical implementation, the same device could perform conditioning at night, for example from 9pm to 8am, and be repellent by day, provided that people respect the times of prohibition.
Development of Conditioning. Many issues can only be resolved experimentally. Experiment in enclosure: A shark is placed in a cage and undergoes aversive conditioning. a) the interaction between the machine and the animal is adjusted. The reproduction of a wounded fish movements — used for attraction — is tested. The necessary conditioning sound power is measured. b) The persistence of the conditioning: on a weekly basis, the behavior of the animal after a repulsive emission is evaluated. After several weeks, in the absence of reaction, aversive conditioning is performed again and the duration of its persistence is evaluated again. Measuring reaction time helps to determine the number of required aversive devices. c) The sound threshold required to get a reaction from the animal is measured. This quantity details the power and scope of the repellent device. It is linked with the number of buoys to be installed in order to achieve an exclusion zone. Caged experiments must be carried out on bulldog and tiger sharks in an area without artificial noises and if possible on several sharks. As there must be only one individual per cage, it would be preferable to have several cages. Full-scale experiment consists of: •
observing the reduction of catches by the drumlines of the existing sharks capture program — CAPREQUIN in the Réunion Island — located in the areas with repulsive buoys,
•
tracing the evolution of the number of large fish who fled during the repulsive emission with a special long-range sonar [2].
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 5
Socio-economic integration. The benefits of the project include: •
a drastic reduction in the risk associated with sharks which is very favorable to commercial and tourist activities.
•
If buoys contain elements of advanced technologies, the maintenance of these devices (algae on windows) can be done without special knowledge and with a light material. Maintenance contracts could be offered to local fishermen.
•
Serial manufacturing of equipment will be local, to the extent possible.
•
Enclosure experiments and follow-up in real situation may lead to the development of unique expertise worldwide.
•
A management company for the device will be created. This company would grow by exporting the required equipement. Indeed, on the one hand, the risk is global, on the other hand there is a gradual increase in risk (study of the University of Florida in 2016).
A supplementary device: Aversive conditioning of large bulldog and tiger sharks of the island will take several months and the effectiveness of the device will be progressive within six months or so. A tiger shark coming from distant coastline would temporarily -for lack of conditioningignore the repellent buoys. In this context, it may be particularly tempted by the baits of the CAPREQUINS program. This simplistic example clearly illustrates the multiplier effect of combining several risk-mitigation methods. The global increase of the attacks means that solutions have to be strengthened by a combination of different methods. If the notion of risk reduction is statistical, the attacks on people are very real. The sonic fence would considerably enhance the safety of aquatic activities on the island, but it is necessary to be patient and invest a little money.
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 6
Technical presentation Overview:
Overview of a sonic fence buoy.
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 7
The conditioning unit:
The aversive conditioning unit.
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 8
The solar energy buoy:
The solar energy buoy.
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 9
The intermediate float:
The intermediate float.
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 10
The repulsive buoy:
The repulsive buoy. http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 11
The automatic breed recognition. The characteristics of a shark's approach on a object that piques its interest are: •
it turns around and approaches gradually,
•
to be able to "breathe", it never keeps still,
•
it moves at the same height as the object it observes,
•
Its approach is rarely frontal and it will mostly remain horizontal. Thus the shark will be identified in profile.
The identification software will detect an animal by the variation in contrast with the background - the adjustable mirror and lighting completing the contrasting procedure. The size of the animal will be estimated angularly thanks to its accelerations divided by its dimensions. Bulldogs sharks differ from other species by •
A very slight change in contrast between body and fins
•
An eye right above the middle of its mouth unlike the hammerhead shark. The tiger sharks will be identified thanks to their vertical stripes. No other species has these features.
Other more sophisticated recognition techniques are perfectly operational and will be used if necessary.
Budget and delivery times. Prototype and development Manufacturing the prototype and completing the adjustment phase with caged sharks can be achieved •
within two years
•
with a budget of less than 400K Euros, margins included.
The protection of a whole island. Implementing and deploying the system will require •
Two years after the completion of the first phase.
•
a budget of roughly 5 million Euros (estimation).
The annual cost of maintenance will be around 1 million Euros.
The project's social context: The sonic fence project is technically exciting. As a state official, I do not wish (no longer wish cf. CV) to run a business and I have no particular financial interest in this project. I will be the project manager until the final deployment, at which point I will pass on all the information so that a company can take over. My function will be carried out on secondment, a sort of temporary transfer, with the participation of a team in fixed-term contracts. Members of the development team will be able join the company that will manage the buoys network.
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 12
In "2021", example of signs that could be seen all along the coast. Photo: Ste Rose, North of the Cove of the cascades.
Frequently asked questions: If there are a lot of bulldog and tiger sharks, what will be the conditioning buoys' capacity? With 4 aversive conditioning buoys, 50 meters apart and arranged on a line perpendicular to the coast, the technical limit of this part of the device will be a maximum of 20 conditioning an hour (more than 14,000 per month which is more than the number of sharks on an island like the Reunion). The CHARC study indicates that bulldog sharks stay for a long period of time in a same place, and then will revert to an exploratory phase cruising along the coast. Thus, with 2 or 3 lines of aversive conditioning buoys, conditioning all the sharks of a large island can be achieved over a few months. The aversive conditioning buoys' "industrial" treatment capacity is limited by photovoltaic energy which means that it is far from being used to its maximum capacity.
Will the sound intensity be sufficient to condition the sharks? The experimentation and development phase will determine the necessary sound intensity. If it turns out to be very high, other solutions to achieve the conditioning will be used, such as: - a non-lethal electric shock, - a strong variable electric field, without power, in order to target the ampullae of Lorenzini. The intensity level will be adjusted in order to mark the animal without hurting it.
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 13
The sonic fence repellent device allows to move the dangerous sharks. Will the municipalities that will not be equipped suffer an increase in accidents? The answer is twofold : -The cost of the repellent device will be very affordable. It is composed of simple and economical elements. Only the integrated software and the "soundtrack" are more sophisticated elements but they can be replicated for free. The municipalities which are responsible for beach safety can be equipped without substantial budget and maintenance will be light. - On an island like the Reunion, a lot of areas on the coast are not suitable for aquatic activities. These deserted places which are free from all interference will be largely enough to accommodate the dangerous animals.
Many reports indicate that underwater sounds disrupt the ecosystem, is your device likely to harm aquatic life? Aversive conditioning buoys emit a high power signal but it is much lower than that of a boat's outboard engine. In addition, emission is occasional. The sonic fence repellent device which is installed facing beaches emits low-power sounds and is not on all the time. Aquatic life will suffer no disturbance.
Will your device replace others shark risk reduction systems? There is no such thing as zero risk. The effectiveness of the repulsion in heavy traffic areas must be evaluated continuously to detect a possible evolution like for example a new predator. - CapRequin must be maintained in the exclusion zones to assess ongoing performance repulsion (lack of capture = good performance of repulsion). An alternative financing formula for the capture program, independent from samples, could be considered. - The shark nets offer a very reassuring extra level of security. In case of damages on a net between two inspections, the security level will remain high thanks to the repulsive buoys.
Large predators will be excluded from large areas, what will be the consequences? Consequences are difficult to predict and depending on the theories the following may happen: - Fishermen may catch a part of what big sharks used to ate. - Black or whitetip sharks which are harmless to humans and predators of small bulldog sharks might come back — if indeed big bulldog sharks were the cause of their disappearance. - ...
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 14
You announce a period of 4 years, is it possible to reduce it? Delivery times in a project are partially the result of a compromise between budget and financial risk. It is actually often possible to conduct all activities at the same time with more people, but this would mean betting on the results of phases which are prerequisite of others. The delivery time could be compressed to 3 years, but with a 150% higher budget, given losses induced by risk-taking.
What is the use of the Wifi antenna that is located at the top of the conditioning buoy? This antenna is intended to : - maintenance, to monitor the good status of the components, - allow transmission of photographs or videos of sharks during the conditioning phases, - measure the decrease in the number of conditioned sharks over a period of time after installation ( evidence of fence effectiveness).
What are you waiting for? A new solution always upsets people because it calls into question previous actions that are based on known solutions. In a context of demands for results, an innovation occurs when people stop believing that quick and simple solutions will produce the desired effect (no more risk). In the Reunion Island, after 4 years of dramas, bans and losses in economic activity, people are gradually becoming aware that only a new solution will really get them out of the deadlock. It is important to understand that the sonic fence - will be implemented in addition to existing mechanisms while mitigating some of their downsides. - will participate to the correction of the imbalance at the top of the food chain, without ecological impacts, - will secure nautical leisure activities, and therefore can defuse conflicting "debates" that impede decisions.
Your questions contribute to improving the project, do not hesitate to ask them. I will answer all questions concerning the technical aspects and management of the project. However those looking for causes and culprits will not be answered.
E-mail:
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 15
Additional documents: I will forward -on official request- the documents relative to the prototype phase such as - the chronogram, - the detailed budget - drawings of mechanical sets - the study on the recognition software, - the detailed proposal of social status, - the presentation of underwater cameras for testing in cages, - a detailed proposal for additional experiment explaining why sports boards are the favorite target of sharks.
Books and articles: [1] the CHARC (Connaissances de l’écologie et de l’HAbitat de deux espèces de Requins Côtiers sur la côte ouest de La Réunion) report: http://www.la-reunion.ird.fr/toute-lactualite/l-actualite/l-actualite-du-programme-charc/rapport-scientifique-final-du-programmecharc [2] a long-range special sonar: http://francoisrigaud.free.fr/sonar.html François Rigaud, July 2016.
http://francoisrigaud.free.fr
The anti-shark sonic fence project
Rev. on the 15th Sept. 2016, p. 16
