A Shark Attack Outbreak Off Recife, Pernambuco, Brazil: 1992Œ2006
Total Page：16
File Type：pdf, Size：1020Kb
BULLETIN OF MARINE SCIENCE, 82(2): 199–212, 2008 A SHarK AttacK OutbreaK off Recife, Pernambuco, BraZil: 1992–2006 Fábio H. V. Hazin, George H. Burgess, and Felipe C. Carvalho Abstract An unprecedented series of shark attacks on humans off Recife, Pernambuco, Brazil within a 14-yr period from September 1992 to September 2006 resulted in 47 incidents, including 17 fatalities. A suite of biotic and abiotic factors was examined to determine commonality in the attacks. Surfers and body boarders were the group most affected with a majority of victims being young (< 20 yrs old) males. Attacks occurred predominantly in shallow water, close to shore at beaches lying on a nar- row channel bordered by an adjacent reef. Attacks transpired year-round with peaks in July and were distributed daily from Thursday to Tuesday, with peak on Sundays and no attacks recorded on Wednesdays. The construction and growth of the Suape Port, located just to the south of Recife, has resulted in major environmental degra- dation and is likely to have played a role in the recent onset of shark attacks. Individ- uals of the species most often implicated in the attacks, the bull shark, Carcharhinus leucas (Müller and Henle, 1839), may have been displaced from preferred estuarine/ inshore habitats to the nearby Jaboatão River and the adjacent lagoon resulting in increased interaction with humans. Shark attack on humans is not a recent phenomenon. The first writings on shark attacks date back to ancient Greece, about 500 yrs BC (Coppleson, 1958). In more recent years, despite the impact of fishing pressure on shark populations, the world- wide trend towards more intense recreational use of marine waters has increased the chances of shark-human interactions, resulting in an increase in the total number of attacks (Burgess, 1990). The gradual post-World War II increase in shark attacks, plus the military relevance of shark attacks as related to air and sea disasters during war- time, prompted the U.S. Office of Naval Research to establish the International Shark Attack File (ISAF), in 1958 (Baldridge, 1974). Presently, the ISAF is maintained at the Florida Museum of Natural History at the University of Florida, under the auspices of the American Elasmobranch Society. Recife is a rather large city located in northeastern Brazil. The capital of Pernam- buco State, it has a population of about 1.5 million and the tourism industry is one of its major economic activities. In 2005, Recife accounted for 5.15% of the total number of national and international tourists in Brazil (EMBRATUR, 2006). Recife has a coastline of about 20 km, with beautiful beaches and warm waters, which are several of its main attractions. Recife seawater temperatures range from about 24 °C during winter to 30 °C during summer (Hazin et al., 2000), fostering year-round bathing, surfing, and other aquatic recreational activities. Despite intense recreational use of Recife beaches since the early 1950s, except for a few unconfirmed anecdotal reports of shark attacks, there were virtually no records of such incidents in the area until 1992. However, within a period from June 1992 to September 2006, 47 attacks were recorded, including 17 fatalities. All attacks occurred along a 20 km stretch of shoreline, which included the beaches of Paiva, Candeias, Piedade, Boa Viagem, and Pina, all of which are under the influence of the Jaboatão River estuary (Fig. 1). This sudden outbreak of shark attacks was highly Bulletin of Marine Science 199 © 2008 Rosenstiel School of Marine and Atmospheric Science of the University of Miami 200 BULLETIN OF MARINE SCIENCE, VOL. 82, NO. 2, 2008 Figure 1. Recife, Pernambuco, Brazil. The gray area represents the metropolitan region of Recife. publicized by local and national media, resulting in a negative economic impact on tourism, which, unfortunately, is difficult to fully assess (Gaiser, 1976). Shark attacks are relatively uncommon worldwide, annually averaging 50–75 un- provoked incidents and resulting in about 5–10 deaths (Burgess, 1990). Most attacks are recorded in waters of the United States (primarily in Florida and California), South Africa, and Australia (ISAF, 2006). Thus, this sudden outbreak of attacks in Brazil with more than one-third of the incidents resulting in fatalities, occurring within almost 14 yrs and along a narrow band of 20 km of shoreline, is quite unusual. In this study, we examine the characteristics of the recorded shark attacks in Recife, and consider several possible causes. HAZIN ET AL.: BRAZILIAN SHARK ATTACKS 201 Materials and Methods Information on the shark attacks was obtained from numerous sources, including pub- lished accounts in the local media, direct interview with witnesses, victims, and doctors that treated the wounds, and, in the case of fatalities, direct inspection of the remains of victims at the local Institute of Legal Medicine, in Recife. After the initial cases, the Universidade Feder- al Rural de Pernambuco (UFRPE) became a central clearinghouse for regional shark attacks. Whenever an attack occurred, members of the UFRPE staff were immediately contacted by local media, fire/rescue officials and/or physicians, the latter from emergency hospitals as well as from the Institute of Legal Medicine, facilitating the investigation of the incidents. Bodies bearing shark bites were considered the result of an attack incident only when the coroner’s report indicated that blood loss had been the causa mortis. All victims that died by drown- ing were thus excluded from the attack statistics. The total number of fatal drowning victims (those who disappeared at sea with the body subsequently recovered), including those bear- ing post-drowning shark-inflicted scavenge bites, occurring during the January 1990–April 1995 period were obtained from the archives of the Institute of Legal Medicine. Data from the 32-mo period prior the shark attack outbreak (January 1990–August 1992) were then compared to the 32-mo period after it began (September 1992–April 1995). As in Baldridge (1974) and McCosker and Lea (2006), the present study analyzed the at- tacks in relation to attack location, day of the week, time of the day, moon phase, and distance from shore. Information on distance from shore, however, must be interpreted with caution since it is based on the testimony of victims and eyewitnesses. Similarly, testimonies on the estimated depth of the attack site were, in many instances, very inaccurate and inconsistent with known bathymetry of the region and thus not considered in the present analysis. The possible influence of local bathymetry on shark behavior and attack occurrence was investigated by making a detailed bathymetric survey of Recife beaches to a distance of 8.0 km from shore (Fig. 2), with 500 m spacing between contours. The survey was conducted from a small boat equipped with a Furuno digital echosounder, with all depth data being reduced to level 0 for the Port of Recife using Brazilian Navy tidal tables (DHN, 2001). The activities of the victims were divided into two categories: (a) board riders (surfers or body boarders), and (b) bathers (swimmers and bodysurfers). Due to the increase in shark at- tacks, all board-riding activities in the attack area were banned by a Government decree on 1 January 1995. The prohibition was later reinforced by a new, stricter decree in May 1999. Therefore the activities of victims were analyzed for two periods bounded by the initial de- cree. The first period is prior to surfing prohibition, from September 1992 to December 1994, and the second period ranges from January 1995 to September 2006, during the surfing ban period. The severity of injuries was defined as either fatal or non-fatal, and the injured body part was classified as legs (calf, knee, and thigh), arms (hand, forearm, elbow, and upper arm), torso, and multiple body regions, noting that in some instances more than one body part was injured (e.g., torso and leg). Based on bite patterns, tooth fragments and description of the shark by victims and eyewitnesses, it was possible to identify the responsible species in only seven of the 47 attacks. In the early 1980s, construction began on a new port facility, the Suape Port, located just to the south of the attack area (Fig. 1). During this construction, major changes to the local marine ecosystem were noted; therefore, we investigated the possible contributing role of the port construction in the increased frequency of shark attacks. Since sharks are known to fol- low ships (Baldridge, 1974; Schultz, 1975) and port areas are recognized as having a higher risk of shark attacks (Coppleson, 1958), data on the monthly frequency of incoming ships were obtained and compared to the monthly frequency of shark attacks. The number of drowning victims bearing shark scavenge bites was also examined to determine whether they exhibited a similar increase as the confirmed attacks, which could mean a higher number of scavenging sharks in the area or perhaps an increase in unreported attacks. 202 BULLETIN OF MARINE SCIENCE, VOL. 82, NO. 2, 2008 Figure 2. Bathymetry of Recife, Pernambuco, Brazil. The arrow indicates nearshore channel ly- ing adjacent to popular beaches and surfing locations. We also evaluated a possible relationship between the rise in shark attacks and an increase in the number of people living in Recife. As data on the actual number of people living in coastal areas, as well as the census of people frequenting Recife beaches by year or days of week were not available, the analysis was done by using Recife population data from 1980 to 2005 (IBGE, 2006) as a proxy for human utilization of nearshore waters. Fluctuating environmental variables could also be important in understanding the dynam- ics of the ecosystem and its influence in shark attacks.