Seatuck Environmental Association in Islip has discovered that the population of the North American river otter—a mammal once near extinction on Long Island—could be on the uptick.
Well over a century ago, Long Island’s river otters’ population had depleted due to trapping, water pollution and habitat loss. Luckily, conservation laws enabled remnant otters to expand and recolonize their former habitat. Reintroduction programs for the creatures helped to accelerate that process. By the 1990s, a breeding population of otters became established on Long Island.
These critters have been present along the Island’s North Shore in creeks, bays and ponds. Seatuck’s wildlife biologist Mike Bottini, who has studied river otters in the area since 2008, said it's believed that the otters came to Long Island’s North Shore from Connecticut and Westchester County. As they bred and had young, their territory expanded across the North Shore over the last decade, he said.
Further, a 2018 Seatuck survey found that “they basically have colonized all the available habitat between roughly Glen Cove east to Orient Point,” Bottini said.
However, these critters only showed up on the South Shore two years ago, Bottini said. They’ve also established homes in the Peconic River and some of the South Fork of Long Island.
Seatuck now has evidence that otters have shown up in three watersheds: the Connetquot River in Islip Town, the Carmans River in Brookhaven Town, and Little Seatuck Creek in Eastport.
Bottini said Long Island is a “very fragmented landscape with many major roads running east to west,” which serve as barriers to the otters’ movement. Somehow, they made a connection between the Nissequogue River in Smithtown and the headwaters of the Connetquot.
A culvert, or man-made steel or concrete pipe that works as a drainage funnel, also exists under the Long Island Expressway and the eastbound and westbound service roads. The river otters may have made their way to the South Shore through the culvert, Bottini said.
Seatuck executive director Enrico Nardone said that while river otters are often hard to spot, biologists are able to track their whereabouts from other non-visual indicators, such as their excretions.
“The resurgence of our native river otter population is great news for our environment, and speaks to the power of effective conservation strategies,” Nardone said.
The Islip-based environmental group has also documented a number of river otter deaths on roadways. While the roads may slow them down, “it's not preventing them from recolonizing other areas of Long Island,” he said.
After an otter was killed by a motor vehicle in Eastport last March, Seatuck staff and a Brookhaven Town staffer constructed a simple concrete-block “stairway” at Little Seatuck Creek for river otters. The roughly 4.5-foot-high structure allows the otters to travel over the dam at the creek and under East Moriches Boulevard in Eastport.
“It’s just one small solution in one area but as their population increases, we will need to find better and longer-lasting strategies to mitigate these occurrences,” Bottini said.
The next phase of Seatuck’s work could improve the dam and work on mitigation measures, Bottini said, to reduce the number of otter injuries caused by motor vehicles.
Seatuck is also partnering with Long Island Sound Study, New York Sea Grant, South Shore Estuary Reserve, and Peconic Estuary Partnership to train “community science volunteers” to locate and monitor river otter populations. Long Island residents that spot river otters are welcome to report their findings using Seatuck’s Otter Watch Survey online at: https://survey123.arcgis.com/share/c0e9b8d645cd406ba00a7af57d2744cb?open=menu.