When examining the various reasons for shark attacks, Brazil might serve as the best case study of how human coastal interaction can lead to a spike in attacks.
A 20-kilometre stretch of coastline encompassing the north-eastern coastal city of Recife is statistically the most dangerous place in the world for swimmers and surfers. Since 1992, there have been a record total of 53 shark attacks, 20 of which have been fatal. Previous to that year, shark attacks were more or less unheard of.
The problem first arose in the 90s following the construction of a huge harbour just 40km south of Recife in Boca del Suape. To facilitate the construction process, two freshwater estuaries were interrupted where a population of bull sharks were known to spawn.
It’s thought north-bound currents and fewer available fish displaced the sharks towards Recife, while a combination of over-fishing, increased maritime traffic and river waste (in particular slaughter houses discharging blood into the Jaboatão River) also attracted a further population of sharks closer to the coast in search of food.
As with our next shark zone, Reunion Island, the outbreak lead to a ban on surfing, authorities concerned at the negative knock-on effect attacks were having on local tourism.
In more recent years, authorities have taken to capturing and relocating the bull shark population further afield which is reported to have slowed the number of attacks but that’s not to say the waters are safe.