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The International Shark Attack File (ISAF) 2011 Worldwide Shark Attack Summary

The International Shark Attack File (ISAF) investigated 125 alleged incidents of shark-human interaction occurring worldwide in 2011. Upon review, 75 of these incidents represented confirmed cases of unprovoked shark attack on humans. "Unprovoked attacks" are defined as incidents where an attack on a live human by a shark occurs in its natural habitat without human provocation of the shark. Incidents involving sharks and divers in public aquaria or research holding-pens, shark-inflicted scavenge damage to already dead humans (most often drowning victims), attacks on boats, and provoked incidents occurring in or out of the water are not considered unprovoked attacks. "Provoked attacks" usually occur when... a ....human initiates physical contact with a shark, e.g. a diver bit after grabbing a shark, a fisher bit while removing a shark from a net, attacks on spearfishers and those feeding sharks, etc.. The 50 incidents not accorded unprovoked status in 2011 included 29 provoked attacks, 13 cases of sharks biting marine vessels, one incident dismissed as not involving a shark, one air-sea disaster, three "scavenge" incidents involving post-mortem bites, and three cases in which available evidence was insufficient to determine if an unprovoked shark attack had occurred.

The 2011 yearly total of 75 unprovoked attacks was lower than the 81 unprovoked attacks recorded in 2010. However, the number of worldwide unprovoked shark attacks has grown at a steady pace since 1900 with each decade having more attacks than the previous. The numerical growth in shark interactions does not necessarily mean that there is an increase in the rate of shark attack; rather it most likely reflects the ever-increasing amount of time spent in the sea by humans, which increases the opportunities for interaction between the two affected parties.

The number of shark-human interactions occurring in a given year is directly correlates with the amount of time humans spent in the sea. As world population continues its upsurge and interest in aquatic recreation concurrently rises, we realistically should expect increases in the number of shark attacks and other aquatic recreation-related injuries. If shark populations remain the same or increase in size, one might predict that there should be more attacks each year than in the previous year because more people are in the water. Shark populations, by contrast, actually are declining or are holding at greatly reduced levels in many areas of the world as a result of over-fishing and habitat loss, theoretically reducing the opportunity for these shark-human interactions. However, year-to-year variability in local economic, social, meteorological and oceanographic conditions also significantly influences the local abundance of sharks and humans in the water and, therefore, the odds of encountering one another. As a result, short-term trends in the number of shark bites - up or down - must be viewed with caution. Thus, the ISAF prefers to view trends over longer periods of time (e.g., by decade) rather than trying to assign too much significance to often high year-to-year variability.

In addition to increases in the number of hours spent in the water by humans, the ISAF's efficiency in discovering and investigating attacks has increased greatly over the past two and a half decades, leading to further increases in the number of recorded interactions. Transfer of the ISAF to the Florida Museum of Natural History in 1988 resulted in greatly expanding international coverage of attack incidents and a consequent jump in the number of documented attacks. In the early 1990's the ISAF developed important cooperative relationships with many Floridian beach safety organizations and medical facilities, leading to increased documentation of attacks from a region that is a world leader in aquatic recreation. Fundamental advances in electronic communication (the Internet, email, mobile phones, texting), a greatly expanded network of global ISAF scientific observers, and a rise in interest in sharks throughout the world, spawned in part by increased media attention given to sharks, have promoted more complete documentation of shark-human incidents in recent years. The ISAF web pages which include electronic copies of the Attack Questionnaire in four languages as well as a plethora of statistics and educational material about sharks, comprises the most highly accessed shark site on the Internet. Our strong web presence regularly results in the receipt of unsolicited documentation of shark attacks. Many of these attacks likely would have been missed in the past because they occurred in communication-poor locales or areas lacking ISAF representatives.

Following recent trends, North American waters had the most (35%: 26 attacks) unprovoked bites in 2011. The total of 29 attacks in the United States (including three in Hawaii) was lower than the 2001-2010 decadal average of 39.1. Elsewhere, attacks occurred in Australia (11), South Africa (5), Reunion (4), Indonesia (3), Mexico (3), Russia (3), the Seychelles (2), Brazil (2), and open sea (2), with single incidents reported from Antigua, Colombia, Costa Rica, Ecuador, Kenya, New Caledonia, New Zealand, Papua New Guinea, Puerto Rico, Tahiti, and the Turks & Caicos. Surfers and others participating in board sports (60% of cases) were most often involved in these incidents in 2011. Less affected recreational groups included swimmers/waders (35%) and divers (5%).

As in recent years, Florida again had most of the unprovoked attacks in the United States. The total of 11 Florida bites fell well below the 2001-2010 average of 23.4. Additional U.S. attacks were recorded in Alabama (2), North Carolina (4), California (3), Texas (2), South Carolina (2), Hawaii (3), and Oregon (2). Within Florida, Volusia County had the most incidents (6). This area normally has higher numbers of shark-human interactions as a result of very high aquatic recreational utilization of its attractive waters by both Florida residents and tourists, especially surfers. Other Florida areas having attacks in 2011 were St. Johns (2), Brevard (2), and Palm Beach (1) counties.

Despite continued human population growth and increased interest in aquatic recreation, the number of shark-human interactions has exhibited a slow but steady decline in the U.S., Florida, and Volusia County over the last decade. The 29 U.S. incidents in 2011 was the lowest total since 1998 (26), the 11 in Florida the lowest since 1993 (10), and the six in Volusia County it’s lowest since 2004 (3). Possible reasons include:

1. Less people in the water in traditional high shark-human contact areas. Post-9/11 slow-downs in local economies and the recession have reduced the number of tourists and vacationing residents entering the sea. Meteorological conditions also have played a role - the large number of tropical storms that battered Florida and other U.S. east coast states in 2004, 2005 and 2006 significantly reduced the amount of time spent in the water by humans in these areas. Since Florida annually has more attacks than any other region in the world, the large drops in number of attacks in this region are reflected in the U.S. totals over this period.

2. Less sharks in the water. Worldwide over-fishing of elasmobranchs (sharks and their relatives, the skates and rays) has left many populations at critically low levels. Nearshore sharks are the most affected because they are easily captured and are highly sought for their flesh and especially for their fins, which fetch a high sale price and are exported to eastern Asia, where they are used in shark fin soup, an expensive delicacy. Coastal areas are where humans most often enter the sea. This probably is of less consequence in the U.S./Florida as strict fishery regulations have had a positive impact in reducing the decline.

3. Humans may be getting smarter about reducing their interactions with sharks. Media coverage of sharks has been high over the past decade with a plethora of television and print stories detailing the "do's and don't's" involved in reducing shark-human interactions. It is possible that those engaged in marine aquatic recreation (and beach safety personnel charged with their oversight in many areas of the world) are doing a better job of avoiding high risk areas and times, thereby reducing chance meetings between sharks and humans.

Twelve fatalities resulted from unprovoked attacks in 2011, considerably higher than totals from recent years (the 2001-2010 yearly average was 4.3) and the highest yearly total since 1993 (also 12). These unprovoked fatalities were recorded from Australia (3), Costa Rica (1), Kenya (1), New Caledonia (1), Reunion (2), the Seychelles (2), and South Africa (2). The annual fatality rate was 16%, similar to the 1990’s average of 13%, but higher than the 6.7% average of the first decade of this century. The trend in fatality rate has been one of constant reduction over the past 11 decades, reflective of advances in beach safety practices and medical treatment, and increased public awareness of avoiding potentially dangerous situations. This year’s higher rate no doubt is a statistical anomaly based in part on where the serious attacks occurred geographically. The unusually low proportion of attacks occurring in the United States, particularly in Florida, and a jump in attacks in non-U.S. locales not blessed with as highly-developed safety and medical personnel and facilities lead to an unusually high number of deaths. The fatality rate in the U.S. was zero, elsewhere it was nearly 25%. This contrast highlights the need for increasing efforts to improve beach safety, including education of the public about the risk of sharks, providing well-trained lifeguards, and advancing emergency care and medical capabilities.

If one is actually under attack by a shark, we advise a proactive response. Hitting a shark on the nose, ideally with an inanimate object, usually results in the shark temporarily curtailing its attack. One should try to get out of the water at this time. If this is not possible, repeat bangs to the snout may offer temporary restraint, but the result likely become increasingly less effective. If a shark actually bites, we suggest clawing at its eyes and gills, two sensitive areas. One should not act passively if under attack - sharks respect size and power. For additional safety tips, see:

The International Shark Attack File, internationally recognized as the definitive source of scientifically accurate information on shark attacks, is a compilation of investigations of all known shark attacks. In existence since 1958, it is administered by the Florida Museum of Natural History at the University of Florida under the auspices of the American Elasmobranch Society, the world's foremost international organization of scientists studying sharks, skates and rays. More than 5,000 individual investigations are currently housed in the ISAF, covering the period from the mid-1500's to present. Many of the data in the ISAF originate from the voluntary submissions of numerous cooperating scientists who serve worldwide as regional observers. Data submitted to the ISAF is screened, coded, and computerized. Hard copy documentation, including original interviews and notes, press clippings, photographs, audio/video tapes, and medical/autopsy reports, is permanently archived. Biological researchers and research physicians study investigations housed in the ISAF. Access to ISAF data is granted only after careful screening on a case-by-case basis. Direct access by the press and general public is prohibited since much data, including medical records, is sensitive in nature and is given in confidence. Requests for summary information and non-privileged data are made to the ISAF curator, George H. Burgess.

For additional information on sharks and shark attack, visit the Florida Museum of Natural History's shark research web site at:

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