Researchers launch pilot study to learn more about seal population now inhabiting local waters

When I first started fishing on Long Island in the early 1980s, observing a marine mammal in the wild was an extremely rare occurrence. 

Due to years of unregulated hunting, many populations declined to the point where they faced extinction. In 1972, the Marine Mammal Protection Act was signed into law and many species have since made remarkable comebacks. 

Members of one such group, the pinnipeds, are now commonly seen across Long Island from October to March. Pinnipeds are marine mammals that include three families: true seals, eared seals and walruses. Only true seals can be found in our region, with five species potentially being encountered. Harbor seals are the most common, followed by grey seals. On rare occasions, we can also see Arctic species such as harp, hooded and ringed seals.

Now that seals are once again inhabiting our waters, researchers have begun to focus on the status of the various populations. This past winter, the Atlantic Marine Conservation Society (AMSEAS) partnered with the Naval Undersea Warfare Center in Rhode Island, Marine Mammals of Maine, Northeast Fisheries Sciences Center and staff at the Marine Sciences Center of Stony Brook University to perform a pilot study that would explore the feasibility of conducting health assessments as well as a behavioral study of harbor and grey seals that inhabit the waters of southern New England and New York. As manager of the Marine Sciences Center, I was fortunate enough to join the team as a vessel captain on its third expedition.

To perform a health assessment, researchers need to first catch a seal. Seals will haul out of the water, typically at low tide, to rest. Although harbor seals are very slow on land, they never venture too far from the water’s edge so they can make a quick splash at the first sign of danger. This behavior makes it just about impossible to sneak up on a beached seal, so the research team needs to catch them while they are in the water. For this project, chief scientist Robert DiGiovanni Jr. from AMSEAS worked with staff from the Marine Sciences Center on modifying a research vessel to accommodate a 600-foot-long prototype net that would be deployed in an area of Shinnecock Bay that is a known haul-out site for harbor seals. 

On the day of the expedition, under scientific research permit No. 21719, two vessels — each with a team of researchers — approached a sandbar where approximately 50 harbor seals had hauled out. As we advanced, the seals slid quickly into the water, but they didn’t go very far. 

The seals’ initial signs of fear quickly turned to curiosity as they bobbed up and down in the water to watch what we were doing. At this point, the lead vessel dropped one end of the net into the water and started to deploy it parallel to the sandbar. The crew on the second vessel grabbed the floating end of the net and I put the bow of the boat on the sandbar. 

This allowed the researchers to disembark and pull the net ashore. After the lead vessel had deployed the entire net, it too beached its bow and that team landed on the sandbar and pulled in the other end of the net. Many of the seals gracefully swam under the net while others simply jumped over it. As we pulled in the last section of net, four harbor seals were caught and hauled onto the beach.

The research team worked quickly and efficiently to carefully remove each seal from the net, restraining them individually in large sock nets. Once secured, the seals were monitored for any signs of extreme stress. 

One by one, the seals were restrained in a wooden platform so both they and the researchers would be safe during the work-up. Each seal was photographed for potential future identification, weighed and measured. Then various biological samples — blood, tissue biopsy, whisker, and nasal, ocular and rectal swabs — were collected. 

True seals, the only type found in our region, lack an external ear flap. They also move in a different manner from other seals, propelling themselves with their rear flippers and steering with their front flippers. (Credit: Chris Paparo)  

This data will allow researchers to look at overall population health, genetics, diet and differences between populations. 

While the health assessment is taking place, other team members prepare the seal to be satellite and acoustically tagged. The satellite tag is epoxied directly to the fur on the back of the seal. Each time the tag comes out of the water (i.e., when the seal surfaces to breathe or hauls out), a signal marking the seal’s location is sent to a satellite and is then relayed to researchers. 

This tag is not permanent, and will fall off later this spring when the seal molts its fur. The acoustic tag is attached to the seal’s rear flipper like an earring. It emits a “ping” that can be heard by underwater receivers that have been placed throughout the world’s oceans by scientists who are studying a wide array of critters. For example, researchers at Stony Brook University are currently using acoustic tags to track fish such as winter flounder, summer flounder, Atlantic sturgeon and sharks. 

With a battery life of 10 years, an acoustic tag can give a long-term look at how seals move throughout the environment.

The entire procedure takes less than 15 minutes per seal. Upon completion, the seal is released and, hopefully, the data it reveals will give researchers a better understanding of the health of local seal populations and how they utilize our area.

Over four different outings, the research team completed health assessments and tagging for seven harbor seals and one grey seal. 

Fundamentally, the pilot study was a success. It showed that the resources needed to assess and monitor harbor and grey seals of the northwest Atlantic are available locally. 

Moving forward, AMSEAS hopes to start sampling earlier in the season, sampling more animals and combining the data received through this study with their ongoing aerial survey work. 

As seal populations continue to grow, studies such as this will be extremely important in understanding the role seals play in our marine environment. 

With a degree in marine biology from LIU/Southampton, Chris Paparo is the manager of Stony Brook University’s Marine Sciences Center. Additionally, he is an award-winning member of the Outdoor Writers Association of America and the NYS Outdoor Writers Association. You can follow Mr. Paparo on social media at @fishguyphotos.