Shark Repellent Responses USA part I
United States of America
I’ve never seen or tested a shark repellent that I would bet my life on. I just don’t think that we know enough about shark behavior to develop repellents that would be successful under a wide enough range of conditions and across a wide range of species. In addition, I’ve seen people exhibit more risky behavior because they believe the devices are 100% foolproof – and that is, in my opinion, a disaster in the making. The ocean’s a dangerous place, if you want to play or work in it, accept the risks. However, you can reduce those risks by being smart about what you do and how you do it when out on or in the water.
Christopher G. Lowe, Ph.D.
Professor and Director of the CSULB Shark Lab
Dept. of Biological Sciences
California State University Long Beach
Response
Sharks are endangered already. We know the electromagnetic field exposure increases risk of leukemia and maybe other cancers in people that are excessively exposed, and brain cancer if they spend too much time on their cell phone. Will use of electromagnetic shark repellents increase risk of shark cancer? Perhaps we need to balance protecting the sharks verses protecting the surfers!
David O. Carpenter, M.D.
Director, Institute for Health and the Environment University at Albany
Response
Most of the ideas you propose look OK, with the exception of these:
"2) Would emitting orca sounds from surfboards, swimsuits, or the bottom of the ocean at surf breaks provide any additional benefit?"
First, because sharks lack a swim bladder, they do not appear to have a very good sense of long distance hearing. And they certainly are very unlikely to be able to hear the high frequency "orca sounds". More importantly, there is the very real possibility that these sounds would adversely impact the behavior of marine mammal species (e.g., California grey whales) that are regularly preyed upon by orca. So it's very likely that the adverse unintended impacts of playing "orca sounds" would have to be thoroughly researched and the technique would need to be approved by state and federal governmental agencies involved with marine mammal issues, both of which can be lengthy and costly procedures.
"We believe a safe method would be to tag all great whites with a sensor/transmitter capable of interacting with strategically placed shark safety beacons dialed into the same frequency of the great white tags. When the tagged shark gets too close to the beacon they get a shock and leave the area – similar to an underground electric dog fence."
I'm very skeptical that you would be able to "tag all great whites with a sensor/transmitter..." because of the expenses and difficulties associated with doing so. Plus I doubt that you'd be allowed to do so, given the very real possibility of seriously injuring or killing great white sharks, and other species.
Richard Brill
Fishery Biologist
NMFS, NOAA & Adjunct Faculty VIMS
Response
In short, the sea belongs to its denizens and we are ecotourists when we enter it. Our venturing there comes with associated risks – drowning, jellyfishes, stingrays, and – yes – occasionally sharks. Sharks kill on average six humans a year (only a fraction of those are surfers) but thousands die by drowning.
A central tenet of ecotourism is not to leave behind any footprints and we should endeavor to do the same. We need to be smarter than the animals that inhabit the alien environment we choose to visit and avoid times and places where a negative interaction might take place. It’s common sense.
This may necessitate us abandoning a great break because sea lions haul out there, drawing white sharks. Or we may choose to continue to go there at our own risk, but we can’t blame the critters if a bite occurs because our playground is their dining room. Most surfers are already of that mindset, i.e. “Surfing is a wilderness experience that comes with risks that I’m willing to accept.”
Can I have an “Amen,” brothers and sisters…
George H. Burgess
Director, Florida Program for Shark Research
Curator, International Shark Attack File
Response
I definitely don’t like the idea of electronic tags (dog collar style) for sharks but am glad to see that people are looking at methods other than culling, which is not the answer and was one of the main messages of the Ferretti paper.
Sue Silver PhD
Editor-in-Chief, Frontiers in Ecology and the Environment
Response
The thought that we can engineer nature to make it safer for humans sends a chill to my heart. People need to take responsibility for their actions, which includes being aware of and accepting the risks of entering the ocean. There is something unique in our fear of sharks that make many compelled to try to engineer ways of preventing them. Many more people die each year by drowning in rip-currents then by sharks, yet they do not spark the controversy and outrage that a shark attack does. If a surfer drowns politicians and communities do not close the beach or build a break-wall to stop the waves or currents. Yet, driven by our fear of sharks we invest millions into the design and implementation of shark culls, shark shields, and patterned wet suites and surf boards. I believe that the best way for us to protect sharks is to better understand Galeophobia (fear of sharks) and why humans respond to shark attacks in the way they do, and most importantly to change our cultural views of sharks. In my opinion engineering equipment, such as electric fences, to reduce shark attacks is unlikely to be met with any level of success. Our biggest investments should be in rewiring society’s views of sharks.
Trisha Atwood
Assistant Professor
Watershed Sciences and Ecology Center, Utah State University
(The views expressed above are those of Dr. Atwood’s and do not represent the position or views of Utah State University)
Response
I read through the responses, which are quite varied. I have no professional opinion about the efficacy of shark repellents, but I have an ethical view that sharks should not be killed as a precaution.
The little I can add, personally, is that some years ago while briefly living in Hawaii, I did daily swins across a wide bay mouth in Kauai. As the days went by I was increasing spooked about looking down, quite far, into the fading deep and imagining something come up from below. Finally I decided I was not comfortable swimming in deep water and gave it up.
Jim McWilliams
Dept of Atmospheric and Oceanic Sciences
University of California, Los Angeles (UCLA)
Response
First off I’d like to make it clear that I am a 4th year PhD student with research interests in physical oceanography. So I work mostly with fluid dynamical concepts and problems, and am not necessarily qualified to confidently give insight on behavioral patterns of sharks as they respond to temperature or fish stock changes. That being said, there is a rather obvious intuitive inference that marine life will have a response to environmental conditions (water temperature, nutrient levels). The only confident claim I would make is that this response will temporarily shift patterns away from what is statistically normal. Maybe that is obvious, but without doing an actual quantitative assessment (potentially a couple of years of work) I do not know what the nature of that response would be from a statistical standpoint (e.g. what is the probability that you run into a shark while surfing during an El Nino vs La Nina year at the same location).
The ENSO (El Nino Southern Oscillation) event this year has already brought much warmer water along the California coast via the collapse of upwelling in the eastern equatorial Pacific and maintained by the eastward propagation of oceanic Kelvin waves along the equator and up/down the west coasts of North/South America. The California Current System has been shown to respond to an El Nino event with reduced upwelling. This essentially means warmer waters and less nutrients brought up from depth, thus lower primary productivity (i.e. plankton blooms). Lower primary productivity means less food in the water for larger organisms, so it is probably a safe assumption that there would be some migrations of California Current marine life in search of food due to the lower local food supply. Again, without giving a quantitative assessment, I would think it is reasonable to assume that marine life (starting from plankton all the way up to sharks) will show a transient response to these increases in water temperature and decreases in nutrients/primary production; the normal geographical patterns of where sharks are found could be influenced (and thus changed) by the trophic system’s response to ENSO.
I think the most feasible shark deterrent system presently in place is Shark Shield (https://sharkshield.com/). Orca patterns on the bottom of a surfboard are easy and cheap, but a surfboard is nowhere near the size of an actual orca, so I have a hard time imagining why a 15ft Great White would back away from a ~6’1 x 19’ x 2.5’ orca. From what I read, the orca pattern is only meant to disrupt the shark’s vision in the final phase of an attack (when the prey is near), so my interpretation is that this will not necessarily prevent collisions/onset of attack (it may change a bite to a bump). Also, attempting to tag every shark out there just strikes me as way to laborious with no guarantee that every shark is accounted for; it seems like a very costly way to go about solving the problem, with the constant need to update the system (i.e. find and tag new sharks).
To my eye, Shark Shield has shown the most promise in testing with actual quantitative results indicating less probability of attack with the Shark Shield turned on (https://sharkshield.com/
I think there are two ways to think about the extrapolation of the single unit Shark Shield to cover a larger area. The first, I would guess would be heavily endorsed by the Shark Shield people: if most of the surfers in a crowded break have Shark Shields, you already have an array of units all sending signals out, thus protecting most of the surf-zone. The other, is some form of the idea mentioned in the article, in which the same technology used in Shark Shield is somehow retrofitted to a surf-break. I think I share the same thoughts with most of the other people responding, that testing would definitely need to be done to see what the fundamental effects on all marine life are before that is implemented.
Daniel Dauhajre, PhD Student
UCLA Department of Atmospheric and Oceanic Sciences
Response
Response
Patterns on the bottom of a board as a potential repellant does make some sort of sense. A surfer with appendages dangling over the edge of his board does look rather seal/sea lion like, and anything capable of changing that pattern might be a positive development. The electromagnetic idea might work, but sadly its effectiveness would probably be limited to very close quarters (unless vast amounts of power were used – inverse square law and all that). Tagging with beacons any significant percentage of Great Whites in this area would be a near-impossible task. Good idea, though.
Meanwhile, there is a sort of backward-positive bit of good news about this temporary inundation of sharks: Folks are beginning to think climate change is real, and about its effects on the ocean.
-Tom Garrison
Orange Coast College
Response
Shark Repellent Strategies:
In light of the success of mimicry strategies in deterring predators in the wild (Viceroy butterflies versus Monarch butterflies or scarlet king snakes versus coral snakes), Orca patterns on surfboards, or devices to emit Orca sounds from surfboards, swimsuits, or the ocean floor would seem to be the most promising.
Strategies to tag white sharks with a sensor/transmitter capable of interacting with safety beacons seems to be a good strategy, although the challenge is to make sure that all sharks that might appear in the area are tagged. The main concern in this respect is the huge range of great white sharks tagged and tracked in the wild.
The electromagnetic field strategy would have to be tested. Location strategies in electric fish work well in navigation and for locating prey, and involve very low voltage. The safety of higher voltages and the effectiveness of specific electromagnetic fields to repel sharks would need to be tested. I expect that insufficient information is available on the safety effects of the proposed voltage ranges on humans (and marine life).
Julian H. Lombard, Ph.D.
Professor—Department of Physiology
Medical College of Wisconsin
Response
As to mutagenesis or carcinogenesis from electromagnetic fields, while I'm not qualified to speak authoritatively, I harbor doubts about any significant effect. Every news note or study I ever heard reported on the subject came back negative or (in rare cases) a small trend effect "worthy of further study" (but perhaps not even statistically significant) was seen. Given the pervasiveness of such fields in modern society and their absence in remote environs, we're not seeing the difference in cancer rates among city and wilderness residents to suppose any strong effect. (Also, unlike "ionizing radiation" at the highest end of the EM spectrum, EM fields are not ionizing, and it's therefore a little harder to imagine how they would significantly prompt mutations or other chemical changes predisposing to cancer (or other major disease). An MRI is still safer than a CT...
Case Ketting, MD
Response
Human nature is designed to focus on the threats even when the statistical likelihood is low. For example. Most folks way overestimate the risk of dying from terrorist attack or plane crash. In fact the risk of dying from road accident is orders of magnitude greater. Ditto, sharks.
Paul D.
Response
It appears that my concern and opinion are pretty consistent with those more directly involved with the field of study...I think that products or ideas such as this feed the fear and seek to profit in some manner than to really help...the magnetic anklets are a good example...you have a higher risk of getting speared through the leg, gut or head with your or someone else's surfboard. Pura vida.
Robb Havassy
Artist
Response
I'm an avid surfer and spearfisher which puts me in the highest risk groups for shark bites, but I don't use shark repellents because I'm skeptical about their effectiveness in reducing the already very low risk of a shark bite.
Commercially-available shark repellents run the gamut from absurd to potentially-effective, but none are likely to be 100% reliable. Nonsensical repellents include wetsuits and surfboards with stripes and other disruptive patterns. The rationale behind these patterns is that they mimic the appearance of highly-venomous sea snakes and hence will be avoided by sharks. The genius who came up with this notion apparently overlooked the fact that sea snakes are a regular component of the tiger shark diet in many regions, plus when viewed from below against a brightly-illuminated sea surface, objects decorated with patterns still appear as dark silhouettes!
Electrical repellents, such as Shark Shield, have a more scientific foundation, and I've actually tested one in a very basic experiment with wild sharks. I attached the Shark Shield below a floating PVC frame at the site of a Galapagos shark aggregation off Hawaii. I first deployed the Shark Shield with the power off, and dropped chunks of fish next to it. Galapagos sharks approached to within 30 cm of the Shark Shield to consume the fish. I then switched on the Shark Shield and repeated the experiment. Guess what!? Galapagos sharks approached to within 30 cm of the active Shark Shield to consume the fish! I was actually very surprised by this result, because the manufacturer’s website has videos of huge sharks flinching and turning away when the Shark Shield is turned on. However, I was unable to produce this response in Galapagos sharks.
I still believe electrical repellents may deter sharks under certain circumstances but I certainly wouldn't bet my life on one. More experimental work is needed to understand the limitations of these devices.
Carl Meyer, Ph.D.,
The Hawai'i Institute of Marine Biology
Response
While the pursuit of shark repellents is a worthwhile one, I am afraid most of the products on the market or in development are not based on rigorous scientific testing and their effectiveness is inconclusive at best. At worst, they may provide surfers and other ocean enthusiasts with a false sense of security that could lead to them to engage in risky behavior, like being in the ocean alone, at night, near sea lion haul-outs etc.
Electromagnetic repellent devices may be the most promising, but these need more independent testing. The orca pattern on the bottom side of a surf board may or may not do anything. The same could be said for the striped pattern or even striped wetsuits. These may offer some camouflage effect, but animals are also attracted to novelty and if it is something the shark has not seen before, it may investigate (with its mouth). Orca sounds may or may not be a deterrent, if the sharks can even hear the sounds. Sharks hear very low frequencies and the machines needed to generate low frequency noise that travels far distances are large and expensive.
Lastly, tagging all the white sharks in the ocean is not feasible and very costly. It would also require a constant effort because newborn sharks would have to be constantly tagged as they grew as well as new sharks that enter from other areas. Even if you could tag most of the white sharks, how would the public respond when one was detected nearshore? Would they not enter the water? White sharks are all over, so there would be detections all the time. If there were no detections, would people assume there are no sharks in the water? That would also be incorrect because there would obviously be untagged sharks out there. Given how few people are injured by white sharks every year off California, I'm not sure that the investment in time and money could be justified.
I think what is most important is that we keep things in perspective. The chances of being injured or killed by a shark are vanishingly small. Perhaps that small risk is just something we have to accept when we enter the water for any purpose? This does not mean we shouldn't think about ways of further minimizing risk. After all, that's why we have seat belts in cars and why there is a growing push for self-driving vehicles. That is also why hikers carry bear spray in the woods. However, at this point, the best way to minimize risk of a shark bite is to always have a buddy nearby who can help in the event of a shark encounter (or other much more likely medical emergency), minimize water activities at dusk, night, and dawn, when sharks are most active, and to avoid places with lots of food like bait, marine mammals, and river outflows.
Andrew Nosal, Ph.D.
Postdoctoral Researcher, Scripps Institution of Oceanography
Response
My thought is this, if it's strong enough to drive away Great Whites how good can it be for humans, and "everybody knows" you can get cancer from cell phones, and living near power lines (cancer cluster debate). The practical issue is the liability issue for the device's risk real or imagined and public perception.
We all know irradiating food would save thousands of lives from food borne epidemics, and how about nuclear power to save hundreds of thousands of lives each year from air pollution deaths alone. Gosh no!!! We can't have nuclear, or electromagnetic or cosmic rays!!! Don't the astronauts and flight attendants get more cancer over a lifetime???? But wait, there's hope to market this device!!! The earth's magnetic field holds all that bad stuff at bay in the Van Allen Belt!! There you go, that's the ticket!!! I'm sold! Great piece dude!
Claude Zanetti, MD
Response
Better research and education on shark sensory biology and behavior to limit shark-human interactions is needed for many reasons, both for human safety and for protection of declining shark and ray populations. This is why I have chosen to study this particular field and contribute to development of more effective methods, specifically aimed at shark and ray bycatch (unintentional catch) reduction from fisheries. There is a lot of misinformation about shark sensory capabilities and in many cases much more research is needed. Sharks and rays are a very diverse group and with the exception of a few well studied species, we know relatively little about them as a whole. In general, we know sharks can use all of the types of sensory information that we can, with the addition of the electrosensory system to detect electric fields and the lateral line system to detect water flow. Some information can travel long distances underwater, like chemical odors and some sounds, while others like vision are useful at intermediate distances (depending on water clarity and light levels), and still others are useful only at very close range like electric signals. As far as researchers have been able to tell, sharks are just as sensitive to odors as other fish, hear low frequency sounds about as well as other fish that don't have advanced hearing apparatuses, have large visual fields with good low light vision, though are likely unable to distinguish colors (though at least some rays can), and are highly sensitive to minute electric fields.
Shark repellents have been of interest since WWII, yet there is still no 'one-size-fits-all' solution. This is in large part due to the diversity- what works in one situation with one species may not work in another situation with the same species or in other species. While there is a very small number of shark species that have been involved in human deaths, these species are often difficult to conduct robust experiments with. Furthermore, in the development of commercial shark repellents, very few have been independently tested. Unfortunately, it is possible for a device to be profitable if it makes people feel safer even if it has no actual effect on deterring a shark bite- this is because shark bites are so rare. The purchaser is unlikely to ever be approached by a shark while using the device, so whether it would make a difference or not becomes irrelevant.
Shark & Ray Sensory Biologist & Ocean Educator
World Below the Waves
Response
I believe that the ocean should not be a big safe bathtub.
We are seeing globally the consequences of human activity that is changing and threatening all life and future life in our planet. One aspect is the loss of the top predators in our ecosystems, on land and in the ocean. I refer you to this study. https://scripps.ucsd.edu/news/1925
"The decline of apex consumers has been most pronounced among the big predators, such as wolves and lions on land, whales and sharks in the oceans and large fish in freshwater ecosystems. But there have also been dramatic declines in populations of many large herbivores, such as elephants and bison. The loss of apex consumers from an ecosystem triggers an ecological phenomenon known as a "trophic cascade," a chain of effects moving down through lower levels of the food web."
We Humans need to temper our needs and desires for unbridled consumerism with consideration for these consequences. That is the challenge of our times, to preserve the world for future generations of life.
Carmen Ramírez
Mayor Pro Tem,
City of Oxnard, CA
Response
Surfing is an inherently dangerous sport. Anyone that decides to pursue this undertaking has to accept responsibility for personal injury and any potential environmental effects. The only action I would consider are measures that are paid for by the responsible human parties, and have zero impacts on shark populations, that are already threatened due to human related activities such as habitat encroachment, overfishing, and pollution.
Karen Crow-Sanchez
Associate Professor
Department of Biology
San Francisco State University
Response
My personal opinion is that we (humans) are entering the shark's home.
Ryan K Walter
Dept of Physics, Cal Poly