Seining for Long Pond Creatures

BY LUKE MACKAY, ENVIRONMENTAL EDUCATION INTERN

In recent months, we have begun seining in the North Head of Long Pond. Seining is a fishing method that involves two people spreading out a large net (seine) in water and slowly dragging it in to catch the fish. We are not seining for sport, but rather to learn more about the different types of fish, crabs, and other species we might find in the pond.

Seth & Hannah run the seine net through the Head of Long Pond to see who’s home!

In the first round of seining we made some exciting new discoveries about the biodiversity of Long Pond. We entered the pond from the eastern shore and waded into the pond with the seine net. After making a couple of sweeps in the shallow water, we collected a large amount of fish and some crabs. More specifically, we caught a ton of Atlantic Silversides, juvenile White Perch, Mummichogs, Atlantic Blue Crabs, Northern Pipefish and even some small American Eels. There was an ample amount of Atlantic Silversides and White Perch while we only found a few Mummichogs and Northern Pipefish. We will have to do much more seining to understand a comprehensive view of what is found in the pond, but this first sample of fish was very informative and fascinating. We can be somewhat certain there are a good amount of White Perch in the pond because the Osprey are always diving and catching these fish to eat. We look forward to seining more in the future and seeing what we can learn!

The field team sorts through the fish collected in the seine net to see what species are present.

Although seining is certainly the most effective way to collect fish samples in the pond, we had some luck with another kind of capture method. During our weekly water quality monitoring, we placed minnow traps in the pond, simply thinking we may be able to get something in the net. When we checked the net, a wild surprise awaited us. What do you think we caught? We have caught snapping turtles in the traps before and a crab could easily crawl in. I don’t think anyone was ready for the almost two-foot American Eel (Anguilla rostrata) in the trap! Libby, Seth, and Hannah did a great job handling the slimy and slithering eel without getting bitten or injuring it.

The find of the summer: a large American Eel!

American Eels (and eels in general) are intriguing creatures that can reach lengths of up to four feet and live for around five years (or in rare cases even up to 20!). In Long Pond, these eels most likely feed on some of the small fish I identified above (Atlantic Silversides, White Perch, etc.) and possibly Atlantic Blue Crabs. Although American Eels are predators in their own right, Osprey have been known to prey on them. With so many Ospreys around the property, keep your eyes peeled for one of these magnificent raptors clutching a long, narrow eel in its talons.

American Eels are catadromous (like all eels), which means they live in freshwater and spawn in the ocean. They swim out of freshwater in the fall and go to the Sargasso Sea, an area just east of the Bahamas, to spawn and die (Chesapeake Bay Program, ND). Once fertilized, the larvae drift around for 9 - 12 months until they turn into 3 - 4 inch “glass eels” where currents carry them to the U.S. coast and they swim into rivers and other freshwater access points. At some point in their laborious journey, some eels have managed to make it all the way to the North Head of Long Pond, which makes sense since the pond is constantly open to the Atlantic Ocean via the Madaket Ditch.

Eels have a complicated, but fascinating life history.

Although you will not likely see these eels from above the water, late summer on Nantucket is a beautiful time of year to hit our trails!

The Seine Team! From left, Hannah, Seth, Daria, Libby & Luke

Smile! You're On Camera

BY LUKE MACKAY, ENVIRONMENTAL EDUCATION INTERN

It is currently the peak of egg laying season for Common Snapping Turtles (Chelydra serpentina). These omnivorous turtles’ breeding season is from April to November; they lay eggs primarily in June and July. 

Females strive to find sandy soil and will dig a hole to deposit 25-80 eggs each year. She will then cover these holes with sand for protection and will make extra empty nest holes to confuse predators. At the Linda Loring Nature Foundation property, we have a plentiful population of snapping turtles and sandy nest pits can be frequently found on our trails, especially the eastern part of the property where there are numerous wetlands.

It is important to be wary of these incubation holes so as to not disturb the safety of these eggs. This is especially true because the literature says that and other predators will look to eat snapping turtle eggs. Nantucket is very limited with small mammalian predators so the primary predators tend to be birds, rats, feral cats, or possibly snakes. When setting a turtle trap on the eastern part of the LLNF property, we discovered some broken eggs and a deposit that had been destroyed by a predator. With various predators in the area, we couldn’t determine exactly what preyed upon the snapping turtle eggs. So we decided to investigate…

To unmask the perpetrator we set up a trail camera directly adjacent to an egg incubation deposit. While we waited and debated for a couple days before checking the trail cameras, a certain predator returned to the scene of his previous crime. We speculated that it could have been a deer, especially because there are so many deer trails around the property and it would have been easy for one to inspect it through digging. Another possible perpetrator was a feral cat. There are many of these cats around the island and on the property, and although we didn’t see any cat tracks in the sand, they were certainly a suspect. One of our volunteers, George, was dead set on the predator being a crow because of how intelligent and crafty they are. That said, an Osprey most likely would have also seen the snapping turtle mother laying her eggs and could easily have swooped down and eaten them. What do you think it was?

Well, George happened to be spot on. The trail camera footage revealed what had disrupted the nest and eaten the snapping turtle eggs to be a pair of American Crows. The included photo reveals how these clever birds not only are able to locate the egg incubation site, but stick their heads into the holes to uncover eggs.

The predators caught in the act!

Crows can identify people who have previously posed a harm to them and can use gestures for communication. Once crows successfully figure out how to get their food, they will keep trying over and over because they know it worked once. From there, these birds will teach their offspring and other crows how to obtain this food. In addition, crows have such a wide variety of food in their diet and eggs are often at the top of that list. These highly intelligent birds are major predators to snapping turtle eggs. That said, in and around Long Pond there are many snapping turtles and undisturbed egg deposits are very common. 

So, if you’re on the trail on our property or anywhere near a wetland or pond this time of year, keep your eyes peeled for a snapping turtle nest!