By Emma Abbott
You might have heard about the basking shark that got stranded on the coast of South Blue Hill, Maine. Many of you were surprised to hear that we even have basking sharks swimming around the Gulf of Maine. More often than in years past, we are getting reports of marine species like this getting closer to land than ever before. Is it a sign of something?
When the basking shark was discovered on August 7, Allied Whale and the Shaw Institute were able to respond, thanks to the local community providing information about its location and allowing us access through their properties. This event, though a unique opportunity to learn more about this species, was still sad to witness, especially since this species is endangered according to the IUCN Red List. Time was of the essence to be able to access the shark, so the following morning staff from Allied Whale and our team began performing an autopsy. The procedure, called a necropsy, was done under the jurisdiction of the National Oceanic and Atmospheric Administration (NOAA) due to permitting access since this is a protected species in the United States. In doing so, multiple samples were taken and sent to NOAA where they will be analyzed to gather more information about the biology and health of this species.
“It’s such a very unfortunate situation, which is all the more reason why we need to make the most of it as a learning opportunity,” said Dr. Charlie Rolsky, our Executive Director at the Shaw Institute. “It presented an invaluable experience for our entire team, especially our summer interns, so we wanted to be sure to react and collaborate with our partners as quickly as possible. The tissue samples and data collected by will not only allow us to determine the basking shark’s cause of death, but also to better understand other indicators of the health of the species and that of the ocean.”
Basking sharks are one of about 23 different species of sharks that can be found in the Gulf of Maine, both year round and seasonally. They (left picture) are not your typical heavily toothed predatory shark (right picture).
They may look like it, but in fact basking sharks pose no general threat to humans. Instead, they are filter feeders, similar to humpback whales. They are the second largest fish in the world, behind whale sharks, and can be up to 40 ft long while weighing close to 10,000 lbs, yet they eat some of the smallest organisms, such as plankton and shrimp. This species will spend most of its time swimming near the surface of the water with its mouth gaping open to collect its prey in both shallow bays and the deep ocean. Basking sharks are migratory and will travel across ocean basins and into bays and estuaries around the world following food. They migrate between seasons and typically arrive in the Gulf of Maine in May and will stay until October, or until their food supply runs out.
Basking sharks have also been known to travel in groups that vary from 2 to 100 individuals. Despite this, local scientists believe, this basking shark was traveling alone and might have followed its prey into shallow waters during high tide in South Blue Hill, but then got stuck between some rocks as the tide receded. However, it is difficult to tell the exact cause of death until we get information about the samples that were passed onto NOAA.
For the longest time, I thought that humpback whales and other large marine animals did not come into coves or bays because the water in the Atlantic Ocean is too shallow closer to shore. However, this summer there have been multiple sightings of humpbacks along the Maine coast, practically right in people’s backyards. Is it possible that these humpbacks are getting closer to shore for the same reason as our basking shark? Should we be expecting to see more in this area in the future?
While talking with Dr. Rolsky, he was able to answer some questions I had related to both the basking shark and other marine mammals found in this area, and the potential future trends that we may start seeing in the coming summers. I asked him whether he felt this was a one summer experience for us all or if increased numbers of prey in the area might cause more of these sightings and he stated that “I’ve spoken with some fishermen as well as other collaborators and they all seem to think these animals are following the food inland. That could explain humpbacks in Castine or basking sharks coming close to land in Blue Hill.”
Though the Shaw Institute typically works with marine mammals in the Blue Hill area, we recognize the importance of sharks in our community and understand their essential role in the health of our marine ecosystems. In fact, if you want to learn more about what sharks can be found in the Gulf of Maine and how they may be affected by climate change, please join Dr. Rolsky for his webinar “Friends in the Field: All About Sharks!” in partnership with Blue Hill Heritage Trust and the Island Heritage Trust on September 19, 2024 from 4:00pm to 5:00pm. Registration can be done through this link, HERE!
If you also want to learn how to track sharks from your computer, come to the Shaw Institute during business hours and check out our Ocearch shark tracker monitor to see what sharks we may have in the area.
CLICK HERE TO DONATE IN SUPPORT OF SCIENCE AND OUR NONPROFIT MISSION
