The continuous urbanization of the world's coastlines is also increasing human presence which may impact species living in the ocean, such as sharks. Animals have been forced to adapt to their new urban environment, which is not yet fully understood.
Scientists believed that sharks and other marine organisms would avoid going close to the cities because of human presence. However, the new study suggests otherwise. It seems that sharks have great success and are doing well living near coastal cities instead of going away from them.
This picture taken on April 20, 2021 shows an aerial view of sharks swimming near an inflatable kayak in the shallow Mediterranean Sea water off the Israeli coastal town of Hadera north of Tel Aviv.
Sharks Starts to Venture Closer to Cities
In the new study titled "Urban Sharks: Residency Patterns of Marine Top Predators in Relation to a Coastal Metropolis," published in the journal Marine Ecology Progress Series, researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science discussed how movements of ocean predators are affected by the increasing urbanization in coastal cities.
Previous studies show that other animals, like pigeons and raccoons, have learned to thrive in cities. According to Phys.org, those are called "urban exploiters" who depend on human garbage or food. Meanwhile, some animals are also called "urban adapters" after being observed using urbanized areas, even if they still rely on natural areas.
But there are also some animals, like wolves, who are called "urban avoiders" because they try to avoid going to big cities. These animals are so sensitive to human disturbance. Their number would decrease with high human activity nearby, and increases only when there was lower human activity, like the weekdays.
UM Shark Research and Conservation Program director Neil Hammerschlag, the lead author of the study, noted that there are only a few studies that investigated the effects of urbanization on the residency patterns of marine apex predators. So, they were surprised to find out that many sharks swim near the lights and sounds of the busy city, no matter the time of the day.
They tracked the movements of three shark species, including bull, nurse, and great hammerhead, in relation to the city of Miami. Their findings show that those sharks resembled urban adapters, who are attracted to shore because off land-based activities, like discarding fish carcasses.
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Highly Urbanized Coastal Areas May Have Negative Impact on Sharks and Humans
Sharks being urban adapters and not avoiders, like their land predator counterparts, could have consequences for both humans and sharks. Hammerschlag said that it could naturally lead to possible encounters with sharks.
A report suggests that the possibility of shore-based "food provisioning" activities may have attracted these marine apex predators to coastal cities. Researchers wrote that their data pinpoint areas within Miami that have driven human-wildlife conflict to promote human safety and shark conservation. They noted that these areas should be avoided to reduce shark encounters.
While shark bites on humans are relatively rare, bordering on "extremely low" per the 2021 data from the University of Florida, the findings of the new research are still relevant to both sharks and humans. The former could be putting themselves at risk of exposure to toxic pollutants and fishing by coming closer to the cities
Researchers of the study recommend further research on "urban ecology," especially as the world's coastal areas become highly urbanized.
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