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Shark Info 2 / 98   (11-15-1998)

Author

  Intro:

Shark Accidents or Shark Attacks? 1/2

Shark Info

  Main article:

Shark attacks - an ever intriguing puzzle

Dr. E. K. Ritter

  Article 1:

Shark attacks in the Mediterranean

Ian K. Fergusson

  Article 2:

How much do you know about sharks and shark accidents?

Shark Info


Shark Info Survey: How much do skin divers know about sharks and shark accidents?

Report by Shark Info

(with explanations by the shark scientist Dr. E. K. Ritter)

In order to register the status of knowledge on sharks and understanding of shark accidents, Shark Info launched a survey with skin divers in September 1998 in Switzerland and Germany. The survey addressed skin divers and diving teachers involved in training skin divers. Divers who deal with sharks professionally were deliberately left off the list of recipients. A total of 19 questions addressing various complex themes were asked.

Evaluation, interpretation and additional comments by Dr. Erich Ritter

What follows is a presentation of the replies to the various themes, including remarks on conspicuous data and interpretations. Since skin divers frequently hold onto false or outdated views, Dr. Erich Ritter, a shark scientist, presents some explanations based on his long experience in field research work with sharks in the water.

Knowledge and personal experience with sharks

An interesting discrepancy is shown between actual experience with sharks and personal estimation of available knowledge on the animals. Twenty-eight percent (28%) of those questioned never encountered a shark in the water, and still 42% claimed to have "a fraction" of knowledge and 50% some "average" knowledge on sharks. This shows that the knowledge of many of those questioned must stem from magazines and television, for at least 58% consider the information contained in the popular press as "implausible" and only 14% as "average". This leads to the conclusion that knowledge and opinion on sharks are on the one hand influenced by the media, but that those questioned must also have obtained their information from other sources (e.g. from "hearsay") and based on own ideas or interpretations.

"Dangerous" situations with sharks in the water

Almost all of the persons participating in the survey consider "blood in the water" – either from open wounds or from injured fish – as being dangerous. Fifty-eight percent (58%) feel it is dangerous for the diver to thrash about in the water. Only 14% consider women’s menstruation as critical, 50% consider "swimming on the surface of the water" as potentially dangerous, while a "bright-colored diving suit" is deemed safe by 3%. "Nervousness" is regarded by 19% to be more clearly dangerous than a "high pulse" (6%).

Dr. Erich Ritter: The theme of "menstrual blood" has already been discussed several times in both diving magazines and doctors – the latter of which have practically no practical experience with sharks. For lack of the necessary test persons to carry out field research with sharks in the water, I have not been able to personally investigate the effects of menstrual blood on sharks. Since sharks are capable of perceiving even the most minute concentrations of blood in the water (1:10 billion particles), they undoubtedly can locate and react to menstrual blood. In my opinion, however, an intact, 7 mm thick diving suit provides an excellent barrier against any possible escaping blood particles. If the woman has no diving suit or is only dressed with a tropical suit, I recommend that she stays in the current below the shark and at an adequate distance. I do not assume that the shark will consider the woman as interesting prey should he locate blood particles, but I cannot exclude that the shark will not develop heightened curiosity. Although women’s menstrual blood is not a big problem if one behaves in the right manner, at the same time one should not minimize any potential danger. Often, women who have their period and go diving are nervous – probably because they feel uncertain as to how the shark will react to them – and this can also stimulate the shark.

Colors (e.g. loud-colored diving suits) and especially contrasts play a big role with sharks and can awaken their curiosity. They are also attracted by the contrast of a diver swimming against the bright surface of the water.

Both nervousness and a fast pulse change the electrical field and the low frequency sound waves emitted by the diver and perceived by sharks. A fast pulse – if one disregards some of the rare strains experienced in diving – is mostly connected with nervousness. Sharks register the low frequency sound waves considerably faster than bioelectrical fields.

How should one react to the sudden appearance of a shark?

Divers who find themselves IN OPEN WATER give quite different answers to this question. Most react at least partially correct in that they remain "calm" and swim "slowly". None of those questioned would swim towards the shark.

Dr. Erich Ritter: The safest way to react here is to swim towards the shark, for "swimming away" from the shark can provoke his instinct to chase. Swimming towards the shark will not trigger him into attacking, instead he will swim away or at least seek a greater distance (the so-called outer circle). It is important to always keep an eye on the shark. Many times divers – perhaps out of fear, simply look away, hoping somewhat naively that the shark did not see them. But he has! Sharks orient themselves to our bodies and recognize our head-oriented coordination, even when they actually do not "know" what a human is. The diver MUST signal to the shark that he has seen him, and the best way to do this is to swim towards him! Admittedly, this requires strong nerves. If necessary, you can swim to the ocean floor – but never to the surface!

A 64% majority of divers "seek cover in the reef" when they encounter a shark NEAR A REEF.

Dr. Erich Ritter: This is just about the worst possible reaction. The reef offers only deceptive shelter, for a reef shark may consider this his "temporary territory" and want to defend it. Seeking cover in the reef is only recommended in cases where the shark has not seen the diver. The better reaction when encountering reef sharks is to swim away from the reef into open water. Of course, the situation changes somewhat when the encounter is with a high sea shark, e.g. a white shark, in the vicinity of the reef. In this case the proper reaction could be to seek cover in the reef in case the diver’s courage is insufficient to allow him to swim towards the shark.

Potentially "dangerous" sharks

As expected, the answers here correspond to common opinions expressed in the media and popular literature. Eighty-three percent (83%) of those questioned consider the white shark to be the "most dangerous" shark. Fifty-three percent (53%) consider the tiger shark the most dangerous, followed by the maco shark (47%) and the hammerhead shark (31%).

Dr. Erich Ritter: Accidents with makos and hammerhead sharks have been registered but are so rare that you can almost count them on one hand. Astonishingly enough, only 8% of those questioned consider lemon sharks (Negaprion brevirostris) and 19% bull sharks (Carcharhinus leucas) as "dangerous". In effect, bull sharks are probably more frequently responsible for accidents with people than the feared white shark. When reconstructing accidents, investigators frequently look mainly at teeth impressions. The marks left by the teeth in the upper jaw of bull sharks closely resemble those of the white shark. When white sharks (Carcharodon carcharias) are seen in the vicinity of the accident, it often suffices to make them suspect. This does injustice to many white sharks and at the same time may lead to a strong underestimation of the danger stemming from bull sharks.

Behavioral patterns of sharks which signalize danger

The "circling" of sharks is considered menacing by 58%, while 56% categorize the "stiff tail fin" and 33% the "swimming of the shark towards the diver" as potentially dangerous.

Dr. Erich Ritter: Here again it is obvious that the behavioral patterns discussed in the media and in the local pub often dominate. Let’s take, for example, the "circling" behavior – although presented by the media as being dangerous, this should actually not be the cause for any special alarm. Due to its biology, the shark is destined to swim and this circling motion reflects normal behavior on its part when observing an unknown object such as a. diver. A more indicative sign that the shark may bite is the rhythmic opening and closing of his mouth (so-called "gaping"). When a shark, say a white shark, does this, one must be extremely careful. Note, however, that sharks justify their jaws while eating, which also takes place by opening and closing the jaws. When a shark swims up and down, it shows that he is not comfortable in a situation, and this, too, means being appropriately cautious.

Credibility of the popular press and diving magazines

Most divers judge the reports made by the popular press on shark attacks to be complete failures. Sixty-percent (60%) of those queried estimate their credibility to be a mere 10%, and an additional 20% of the divers consider the popular press as being only 25% credible. Diving magazines, as expected, are rated better. At least 20% of the divers say the shark articles found in diving magazines are "good" and 64% consider them "okay", but even here, 11% consider them "inferior" in quality. Although most diving magazines have been reporting a great deal on the subject of sharks in the past few months, 14% of those asked would like to read even more about them and not one reader (!) feels that he or she has read too much about them.

General interest in sharks

The skin divers asked to participate in this survey have a continually increasing interest in sharks and their environment. A substantial number of them (53%) have booked diving vacations – especially to see sharks in the water.

The importance of sharks for the "oceanic ecological system" and the existential threat of sharks

The divers' insight has been growing. Seventy-five percent (75%) are of the opinion that sharks are "absolutely necessary" (53%) for the ecological system of the ocean, and 22% consider them "very important". Here it becomes obvious that the more a diver knows, the higher he or she rates the animal's importance. Thirty-nine percent (39%) view the white shark, followed by "many" other shark species and diverse high-sea species, as being "threatened by extinction". Remarkably, 8% consider either "all" and another 8% "none" as being threatened in their existence.

Dr. Erich Ritter: From a scientific point of view, it is currently very hard to determine if any shark species is threatened by extinction and if yes, which species this may be. But already there are indications that the white shark most likely cannot be saved. One thing is sure, the populations of approximately 100 species is diminishing. Furthermore, it is also clear that the oceanic ecological system would finally collapse without sharks because of the resulting significant deregulation of the ocean environment. Sharks with their average body weight of about 50 kg and considered to be the most frequent top predators in the oceans – and indirectly in the entire world – are considered indispensable for the oceanic ecological system.

Organized dive-feedings of sharks and perceptions of face-to-face encounters

About 68% of the questioned participants consider the specially organized dive-feedings of sharks bad. Seventeen percent (17%) have no opinion and only 8% think the effort is "good". This emphatic viewpoint is further enforced by personal feelings about sharks: Seventy percent (70%) believe sharks to be marvelous animals, about 20% find them quite beautiful and none are repulsed by them.

Dr. Erich Ritter: I can well understand why feeding dives – in the sense of them being expensive, quite adventurous and for the sharks often degrading spectacles – are not well received by divers. Personally, I have observed enough misuse of such excursions and thus argue intensely against them. On the other hand, it must be said that very often such dives also save the lives of many sharks! Since paying diving tourists invest significant amounts of money for these excursions, the value of the sharks involved actually rises. Estimates made in the Bahamas yielded the information that on the average an individual shark may be worth between 10 and 20,000 dollars per year. Killing such an animal does not even bring 10 dollars! The recognition of the shark’s increased value prompted the Bahamas to generally ban long-line shark fishing, establish marine parks and enact further protective measures for sharks.

The greatest harm to sharks

In accordance with expectations, fishing is deemed to be the worst encroachment on shark populations (42%). "Cutting off fins", "Asian miracle drugs", "tourists" and "pollution" all hover around 20%. Surprisingly enough, about 33% of the queried people also consider the media and the press as harmful to sharks. This clearly indicates that the media promotes publicity on sharks, while at the same time also considerably damaging their reputation. Obviously, the readers of media reports – at least the divers – desire more adequate reporting on sharks, especially rejecting embellished articles which emphasize negative or sensational news, as often reported by the popular press.

Consumption of shark products

The answers to this question of conscious consumption of shark meat and shark products ("medication") are quite astonishing: 64% of all people replied that they never knowingly consumed shark products. Of the other 36% replying "rarely", more than 50% excused themselves willingly with comments like "a long time ago", when I was a "kid", or "only once"! This clearly indicates that the average consumer is well aware that the consumption of shark products is potentially harmful, and that they have a "bad conscience" when doing so.

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* Dr. Erich K. Ritter is a shark biologist and adjunct assistant professor at Hofstra University, New York (USA)

May be published only by indicating the source: Shark Info



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