Sharks Frequenting Coastlines Revealed in Miami Study

The coastlines around the world are rapidly urbanizing, but it is unclear how this increased human presence will affect various marine species.

In a new study led by scientists from the Rosenstiel School of Marine and Atmospheric Science at the University of Miami, researchers followed the movements of three shark species in Miami, namely the nurse, bull, and great hammerhead.

Wildlife and Urban Areas

The team expected the sharks to avoid areas near the city because of the light, chemical, and noise pollution that emanates from the coastal metropolis.

However, they have observed that that was not the case at all.

Raccoons and pigeons, for example, thrive in cities. These "urban exploiter" species have become increasingly reliant on human garbage for food.

Other animals, known as "urban adapters," may use urbanized areas only to some extent but still rely on natural habitats.

Some species, such as land predators like wolves, are extremely sensitive to human disturbance. Big cities are avoided by these "urban avoiders."

Neil Hammerschlag, the lead author of the study and director of the UM Shark Research and Conservation Program said that his team was surprised to discover that the sharks they tracked spent so much time near the sounds and lights of the city.

They found that the sharks are often close to shore, at any time of day.

The researchers concluded that the behaviors of the tracked sharks were similar to those of "urban adapters," and that sharks may be drawn to shore by land-based activities, such as the discarding of fish carcasses, which is a commercial activity.

The tracked sharks' frequent visits to urbanized areas may have consequences for both humans and sharks.

Hammerschlag pointed out that sharks are at risk of fishing and toxic pollutants because they spend so much time close to shore, which could have an impact on their health and survival.

While shark bites on humans are uncommon, the study identified areas near the shore that human water users should avoid to reduce the risk of a negative shark encounter and promote human-shark coexistence, Science Daily reports.

Sharks Explained

According to the National Geographic, sharks can be found in both deep and shallow waters throughout the world's oceans with some migrating great distances to breed and feed.

Some species live alone, while others congregate in varying degrees. Lemon sharks, for example, have been observed to socialize in groups.

Scientists are still trying to figure out how long sharks live, and only a small number of shark species have been studied.

The Greenland shark, with a lifespan of 272 years, is the world's longest-living vertebrate.

The majority of sharks eat small fish and invertebrates, but some of the larger species hunt seals, sea lions, and other marine mammals.

Shark populations are shrinking due to rising water temperatures and coastal development, which are destroying the mangroves and coral reefs that sharks use for breeding, hunting, and protecting young shark pups.

A drop in numbers is bad news not only for sharks, but also for ocean health in general: as top predators of the ocean, sharks are critical for maintaining a balanced food web.