Deciphering the movements of great white sharks

 

(GERMANY OUT) Great white shark, Carcharodon carcharias, United States, California, Pacific Ocean, Farallon … [+] Island, San Francisco Bay (Photo by Reinhard Dirscherl/ullstein bild via Getty Images)

ullstein image via Getty Images

Animal movements are not random at all: they are governed by a multitude of factors, both internal and external. But understanding the movements of animals in their natural habitat is like deciphering a complex puzzle. A puzzle whose pieces are missing or somewhere in the box, and whose instructions are written in a foreign language that Google Translate does not offer in its list.

How do monarch butterflies travel thousands of miles during migration, returning to the same overwintering sites each year?

How do salmon find their way back to the exact river where they were born after years of ocean travel, often spanning thousands of miles?

How do African elephants know the location of distant water sources as they migrate across vast savannas?

The questions are endless.

We know that predator movements are influenced by a multitude of factors, including energetic needs, reproductive status, environmental conditions, prey availability, competition, and predation risk. For great white sharks (Carcharodon carcharias), these factors play a crucial role in how they move across vast ocean environments, with particular attention paid to aggregations around pinniped colonies. These aggregations serve as hotspots for feeding opportunities, particularly for larger individuals capable of capturing such prey. Not all sharks are created equal in their culinary prey, with juveniles honing their skills on smaller prey before moving on to feasting on seals as adults. But it’s not clear why individuals choose specific aggregation areas or how movements vary by size, sex or environmental conditions. The answers… well, they’re coming. And a groundbreaking study led by Dr. Oliver Jewell of Murdoch University in Western Australia has recently found one of those missing pieces of the puzzle, with his study exploring how internal and external factors influence the movements of great white sharks off the coast of central California. “We tagged 22 sharks over the three years of my PhD fieldwork and found that their movements were shaped by the habitats they swam in, meaning sharks behaved differently in different areas, regardless of their size or sex,” Jewell said in a Facebook post.

TO GO WITH THE AFP ARTICLE, USA-MARINE ANIMALS-TOURISM (DOSSIERS) A great white shark jumps out of the water as … [+] At least two great white sharks were spotted near a beach on Cape Cod, Massachusetts, in July 2012, causing anxiety and excitement among tourists and locals. The sharks, one of which measured nearly five meters, were spotted on July 3, reports the website Capecodsharkhunters.com. Media reports conclude that the increase in the seal population in the area has attracted the sharks. AFP PHOTO/Carl de Souza/FILES (Photo credit should be CARL DE SOUZA/AFP/GettyImages)

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Sharks exhibited distinct movements, shaped primarily by their location and demographic characteristics. Juvenile sharks from Aptos followed erratic trajectories, while their counterparts from Año Nuevo and the Farallon Islands opted for deeper dives and more focused trajectories. Nocturnal movements differed significantly from diurnal activities, with sharks exhibiting lower activity levels and straighter swimming trajectories at night.

Understanding the intricacies of predator movements has profound implications for conservation and management efforts. “The findings are important because they suggest that the same shark will likely behave differently from one area to another,” Jewell said. By elucidating the factors that drive movement patterns, researchers can better predict and mitigate human-wildlife conflicts, preserve critical habitats, and inform the design of marine protected areas. As our understanding of white shark movements continues to evolve, so will our ability to protect these predators and the fragile marine ecosystems they inhabit.