Cape great white detections surpass 150,000 last year
They hit all-time high for the sixth straight year
More than 150,000 great white shark detections were recorded off of Cape Cod and along the coast of Massachusetts last year, according to the Atlantic White Shark Conservancy tagging tracker.
The total count of 159,598 shark detections in 2021 was a record high for the sixth straight year in the Conservancy’s White Shark Logbook, which has detection data from as far back as 2010. The previous all-time high from 2020 was 136,135 detections.
The Conservancy has continued to tag more sharks in the region every year, resulting in more detections each shark season.
“The greater number of detections logged in 2021 largely reflects the number of tagged sharks at liberty,” said research scientist Megan Winton, noting that “at liberty” means the “total number of tagged sharks swimming around.”
“These tags have a battery life of almost a decade, and last year, 46 additional white sharks were tagged with acoustic transmitters,” she added.
Last year, 132 total sharks were detected, an average of 1,209 detections per shark.
That compares to 117 total sharks detected in 2020, an average of 1,164 detections per apex predator. Dozens of receivers are deployed each year to track the shark activity.
Overall, 268 individual white sharks have been tagged with acoustic transmitters — “think of it like an E-ZPass for sharks,” Winton said — by the Massachusetts Division of Marine Fisheries since 2010.
“It’s important to remember that the receivers can only detect sharks tagged with acoustic transmitters, and there are still a lot of white sharks out there that haven’t been tagged,” Winton said. “As scientists, we use the data collected from tagged sharks to give us an idea of what the population is doing as a whole.
“People should think of the data provided by the Logbook the same way — as a proxy for shark activity off the coast,” she added.
The detection data shows that white shark activity is highest along Cape Cod, and the Outer Cape in particular, where seal densities are highest. The top hotspot for shark detections last year was Chatham Harbor Inlet South, which had 22,480 total detections — or 14% of all detections in 2021.
August was the busiest month for shark activity with 57,458 detections. The second-most active month was September with 32,935 detections, followed by October with 30,833 detections. Sharks were detected from May to December.
“White sharks have been detected all along the coast of Massachusetts,” Winton said. “They don’t occur exclusively off of Cape Cod. Similar to what has been documented at other white shark aggregation sites around the world, there is also a lot of individual variation in the visitation patterns of white sharks, which we are currently investigating in greater detail.”
To check out the Conservancy’s logbook, visit shiny.atlanticwhiteshark.org/logbook.