Photo credit: Unsplash, Gerald Schombs
Seacoast Science Center’s (SSC) Marine Mammal Rescue (MMR) team works closely with the region’s leading shark researchers, to help advance our collective understanding of predator-prey dynamics in the rapidly changing Gulf of Maine. One recent example of this work came up when the team responded to a suspected shark predation on a sub-adult harbor seal at Wallis Sands Beach in Rye, NH. In its response territory (from the Maine border to Essex, MA) the MMR team responds to 2-4 shark predations on seals each year since the program first began in 2014. Shark predations on seals are not a new occurrence, but they do provide a unique opportunity to learn more about the Gulf of Maine ecosystem.
Advancing Science
When the MMR Team responds to a suspected shark predation on a seal, they work directly with researchers to confirm first, that the wound is in fact from a shark and not a boat strike or other cause, and second, what species of shark interacted with the seal based on the nature of the bite. One of these researchers is John Chisholm (social media: @MASharks), who is an Adjunct Scientist at New England Aquarium and works closely with Atlantic White Shark Conservancy (AWSC). John helps to manage the Sharktivity App, which is the region’s best resource to learn more about shark sightings.
Anytime a white shark predation is confirmed by John, he uploads this information into the Sharktivity App. The MMR Team is also working with John to opportunistically collect DNA samples from confirmed white shark bite marks on seals. The goal of this new study is to learn more about the age of white sharks that are predating seals in the region. Juvenile white sharks (less than 9 feet in length) have narrower teeth designed for feeding on fish and squid, but since these animals can be opportunistic predators, John is curious if younger animals are also seeking larger prey items.
The SSC MMR Team is obligated to confirm all information from a response before sharing it with the public. Once confirmed, the MMR Team notifies local first responders and public safety officials. The information helps public safety officials remain prepared, and can help the public to become educated on shark safety. Ultimately, instances of shark predation on seals in our local waters serve as a reminder to us that the ocean is home to a great diversity of wildlife, including sharks.
Addressing Misconceptions
Shark predations on seals can tell us a lot about the predator-prey dynamics that are occurring in the Gulf of Maine, but what they cannot do is serve as a warning system for beachgoers who want to know real-time information about shark presence in local waters. Unless observed directly, it is impossible to tell where or when a shark predation may have occurred thanks to currents, tides, winds, and the ability of wounded animals to move away from the scene of a predation event.
Currently, a few towns along the Seacoast have deployed acoustic buoys to detect tagged sharks by AWSC. However, depending on the buoy, shark “pings” are typically not relayed in real-time. The goal of these technologies is to continue advancing our understanding of white shark movements and behaviors in the region. They are not deployed with the intent of creating an early warning system.
Shark Safety
White sharks typically inhabit Gulf of Maine waters from early Summer through the Fall, and can be found anywhere from New Jersey to Nova Scotia. When you choose to enter the water during these months, you are entering the natural habitat of these animals.
The return of sharks and seals to the Gulf of Maine following intense exploitation in the 1900’s is a conservation success story. The goal today is to learn to co-exist with the results of 50+ years of conservation efforts.
A Deeper Dive Into the World of Sharks
Although white sharks garner the majority of our attention during the summer months, the Gulf of Maine is home to a great diversity of shark species, both large and small. Sharks are crucial to a healthy marine ecosystem, occupying many different roles in food webs from the coast to deep offshore waters.
