.png)
The Study: Tracking the Movements of Marine Megafauna
The study, conducted by scientists from Arizona State University, Oregon State University, and the Atlantic Shark Institute, involved the use of PSATs to monitor the movements and behavior of marine megafauna. These tags have become increasingly popular for studying species like sharks, providing detailed data on their movement patterns, behavior, and environmental preferences. In this case, the tag was deployed on a pregnant porbeagle shark, Lamna nasus, in the Northwest Atlantic.
The porbeagle, a large-bodied and highly mobile shark, is known for inhabiting cold-temperate waters. The shark was captured, tagged, and released southeast of Cape Cod, Massachusetts, in late October 2020. The research team recorded crucial details such as the shark's size, sex, and pregnancy status before attaching both a fin-mounted satellite transmitter and a PSAT to track its movements over the following year.
Evidence of Predation: A First in Shark Research
The tagged porbeagle was tracked for approximately five months as it migrated from the continental shelf waters of New England to the Sargasso Sea, near Bermuda. The data collected by the PSAT indicated that the shark was diving between the sea surface and depths of around 100 meters initially. However, a significant shift in behavior was observed from late December to late March, with the shark diving to depths of 600-800 meters during the day, suggesting a movement off the continental shelf.
On March 24, 2021, the PSAT data revealed a sudden and unusual increase in ambient water temperatures at depths of 150-600 meters. This temperature rise, approximately 5°C above ambient levels, indicated that the tag had likely been ingested by a predator. The elevated temperatures persisted until the PSAT popped off and transmitted data to satellites, confirming the predation event.
Potential Predators: Who Could Be the Culprit?
Given the location and the elevated temperatures recorded by the PSAT, the research team suggests that the predator responsible for the porbeagle's demise could be an endothermic shark species, such as the white shark (Carcharodon carcharias) or the shortfin mako (Isurus oxyrinchus). Both of these species are known for their ability to maintain a body temperature higher than the surrounding water, which aligns with the temperature data recorded during the tag's ingestion period.
This finding marks the first documented case of predation on a porbeagle shark and provides a unique glimpse into the interspecific interactions among large marine predators. The data also underscore the value of PSATs in capturing rare ecological events, contributing to our understanding of the complex dynamics within marine ecosystems.
Conclusion: The Impact of This Discovery on Marine Research
This study's findings highlight the critical role of advanced tracking technologies in marine research. The use of PSATs allowed researchers to document a previously unobserved predation event, offering new insights into the behavior and ecological interactions of large marine predators. As the first evidence of predation on a tagged porbeagle shark, this research opens the door for further studies on the interactions between different shark species and their prey in the deep sea.
Moving forward, the research team plans to continue their work with PSATs to explore additional aspects of shark behavior and predation. This discovery not only advances our scientific knowledge but also underscores the importance of continued investment in marine research and conservation efforts.
Keywords: predation on porbeagle shark, satellite archival tag, Northwest Atlantic marine life, shark predation, marine tracking technology, porbeagle shark behavior.
.png)
.png)
.png)
