By Dr. E. K. Ritter
Mid-April in Florida: Within the space of one week seven people were
bitten by sharks - a report which was quickly picked up by the news
media in all of the U.S. as well as various European countries. None of
the bites were serious, they were simply scratches, still it was
considered reason enough to precisely reexamine domestic and foreign
accident statistics. In Australia two people were also bitten by sharks.
Florida's unique location and form.
© Shark Foundation
From an international point of view, Florida registers the most
accidents. Since 1916 the relevant Institute GSAF (Global Shark Attack
File) and the ISAF (International Shark Attack File) recorded 439 cases,
29 of which were fatal. California holds rank two in the number of
accidents, but has about four times less accidents than Florida and only
ten fatal accidents. The question thus arises as to why considerably
more accidents occur in Florida compared to other places.
Florida's geographical position and shape are unique. Stretching for a
distance of more than six degrees latitude, it separates two oceans and
its continental tip reaches into the Caribbean Sea, while the Gulf
Stream flows to the north off its eastern coast.
The Gulf Stream and the narrow Florida strait are one reason why many
shark species migrate seasonally along the coast of Florida. Still, it
is not the favorable current conditions which are the deciding factor
for shark migrations, but rather the availability of food, mating and
parturition grounds. During their migrations some shark individuals swim
very close to the coast.
One reason for the accidents which happened in mid-April off the coast
of New Smyrna near Daytona Beach is the fact that on their annual
migrations to the north blacktip sharks (Carcharhinus limbatus)
encountered surfers. Only very few shark species have been investigated
in detail concerning their migrational behavior. Based on current
knowledge blacktip sharks are a more heterogenous species when it comes
to migrations. Some populations appear to make yearly migrations, others
remain in the same region the entire year.
Blacktip sharks in Florida
are the species which bite the most, however, their average size of
approximately 1.5 meters hardly makes their bites fatal. The causes of
accidents with the surfers in New Smyrna were not examined any closer,
but as with other shark species - such as the white shark (Carcharodon carcharias)
- it is possible that blacktip sharks want to look closer at
any objects they see but do not recognize on the water's surface and
that in doing so they may bite. This theory appears to be plausible. For
example, the "Ponce de Leon" bay is located in the same region where the
accidents occurred and where various fish swarms gather to spawn
during this time of the year. This circumstance could excite blacktip
sharks to a point where their inhibition threshold is lowered, prompting
them to look at anything which resembles food.
Despite the frequent accidents, blacktip sharks are not really
dangerous. But then which species are responsible for the almost 30
fatal accidents over the past 85 years in Florida?
Shark accidents in Florida usually
involve blacktip sharks, but their
bites are not very dangerous.
© Shark Foundation
These accidents can
be attributed to large-sized sharks such as bull sharks (Carcharhinus
Ieucas) and tiger sharks (Galeocerdo cuvier). The latest fatal encounter
with a bull shark occurred in the year 2000 in St. Petersburg, whereby
in this case one cannot speak of it as being a real attack. The victim
had noticed a large swarm of excited fish and then sprang into the very
murky water to observe them more closely. What then happened is
currently being more closely investigated by the GSAF (Global Shark
Attack File). In most cases it is a string of unfortunate circumstances
which lead to an accident. Unfortunately this is always played down or
even ignored in reports on shark accidents. It should thus come as no
surprise that none of the reports over the past weeks delved into the
behavior of blacktip sharks or to last year's incident with the bull
sharks in St. Petersburg. On the contrary, reports emphasized the fact
that in the year 2000 the number of accidents reached the absolute
record of 79, 10 of which were fatal. Another subject presented in all
the newspapers was the increase of shark accidents over the past 10
years. Nonetheless, if one looks at the number of increasing people who
go swimming each year another tendency can be recognized: namely, a
reduction in accident frequency, a fact which does not sell newspapers.
* Dr. Erich K. Ritter is a shark biologist,
senior scientist of the Green Marine Institutes and assistant
professor at Hofstra University, New York.
May be published only by indicating the source: Shark Info / Dr. E. K. Ritter