Sharks may be closer than you think. Photo: Rebecca Parsons
Sharks. As surfers, they are one of our biggest fears and greatest mysterious. Where do they live? How many of them frequent our local breaks? What is the probability that they will attack? These are the questions we often ask ourselves before paddling out.
According to a 2017 study by the United Nations, it is predicted that 66 percent of the world’s population will live in urban areas by 2050. As more and more people migrate to coastal cities, it is more important than ever that we understand how our lifestyle and behavior will impact coastal environments.
Typically, animals are either categorized as urban adapters or urban avoiders. As the name suggests, urban adapters take advantage of their new environment and human-provided resources. Urban avoiders, on the other hand, steer clear of developed areas and thrive in more natural environments.
Recently, scientists from the University of Miami Rosenstiel School of Marine and Atmospheric Science tracked three types of sharks off the Miami coast including 14 hammerheads, 13 bull sharks, and 25 nurse sharks. Their goal was to track the shark’s behavior and determine how frequently they visited developed coastal areas. They predicted that sharks would act as urban avoiders and would only venture into densely populated areas late at night or at times when there were fewer people. Much to their surprise, their findings were the opposite of their predictions.
The scientists found that the shark’s behavior was in line with urban adapters and they frequently visited areas with high urbanization. They found that sharks visited urban areas due to easy access to food waste, leftover fish from the Miami Seaquarium being dumped into the ocean, and runoff creating bottom-up food webs.
“Few studies have investigated the movements of ocean predators in relation to urbanization, but since other studies have shown that land predators are urban avoiders, we expected sharks to be too,” said Neil Hammerschlag, director of the UM Shark Research and Conservation Program and lead author of the study. “We were surprised to find that the sharks we tracked spent so much time near the lights and sounds of the busy city, often close to shore, no matter the time of day.”
Despite the sharks close proximity to shore, shark attacks are still extremely rare.
