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.
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 Since skin divers frequently hold onto false or outdated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.
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
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.
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!
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.
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.
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.
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
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 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
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
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.
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.
* 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