Nature Notes: What’s a Flounder to Do?
It seems that there are more seals around this year than ever before. Just the other day Peter Van Scoyoc saw three basking on the shore of Hicks Island. There’s been at least one seal in Three Mile Harbor all winter and another spent most of the winter in Accabonac Harbor. As many as 100 seals use Warner’s Island in Shinnecock Bay every winter and stay later and later into the spring each year. From year to year 300 to 400 seals can be found along the shores of Great Gull Island.
It’s not that seals on Long Island are a new phenomenon. Early Long Islanders like Roy Latham and Roy Wilcox reported seals now and then along Long Island Sound’s shore, along the Atlantic Ocean, and very occasionally in the waters of the Peconic Estuary. But sightings were rare — a seal or two a year, and that was that.
When we think of global warming we think of southern animals — birds, mammals, and sea turtles — ranging farther and farther north each year, but, now in some cases, we see that the opposite is true as well. Our seals — harbor, harp, gray, and ringed — are northern species used to colder water. But marine mammals in general can tolerate a wide variety of water temperatures. It’s not water barriers that hold them back from increasing their ranges, it’s the presence or absence of food.
Why hang around the edges of Shinnecock Bay, Great South Bay, Napeague Bay, Lake Montauk, Three Mile Harbor, and Accabonac Harbor? There’s a very good reason, and it’s the same one that caused sea lions from the San Francisco area to bolt north to Oregon. It’s the pursuit of food! And for most seals in the Long Island area it’s one fish in particular, the winter, or black-backed, flounder.
This is one of the very few species of fish occupying waters at our latitude that breeds in winter and early spring, when the seals are most likely to be around. It’s also one of the few species of commercially important food fishes that comes into all of the above-named water bodies to spawn. It spawns in shallow water bodies with very little competition from other fish or crabs at a time when most fish are out to sea or torpid. As Howard Reisman, the fish biologist who taught at Southampton College, has shown, winter flounders are especially adapted — they have “antifreezes” in their body fluids that enable them to live and remain active in waters that approach 32 degrees Fahrenheit.
Thus, when they come into spawn they usually have a given water body all to themselves. But nature abhors a vacuum. When the seals discovered that these flatfish are about during the winter and early spring months when they are in need of food to get through the cold period when other stocks are low, they took advantage of it.
Flounders are not swift swimmers in the sense of, say, mackerel, herring, salmon, and weakfish. Their primary strategy when it comes to eluding predators is their cryptic coloration: Their white sides are pressed against the bottom so as to be undetectable, their mottled, variegated brownish upper sides blend in to a sandy bottom. They can lighten or darken their upper sides according to the lightness or darkness of the sand upon which they are resting.
This works well for other predatory fish, but not so well for getting by hungry seals. Seals are no dummies. They are mammals with comparatively large brains and like dogs can be trained to do a lot of circus tricks. When it comes to eating — their primary occupation in addition to reproduction — they learn quickly. Flounders are no match for them; they cannot outswim them, the way a bluefish could, for example. And they are not like us; they don’t go out of their way to vary their diet. What is conveniently proximate and easy to catch is what is eaten.
Evolution works very slowly. Given 1,000 years or so, the winter flounder might develop a quirk, say, a very unpalatable or toxic taste that would deter seals. But time is of the essence. The flounders don’t have enough time to experiment with this or that new protective strategy. As long as the seals remain in the bree ding territory during the breeding season, they are doomed.
And the seals keep finding flounder territories like the Shinnecock Canal in which to ply their trade. It used to be that during the heyday of the winter flounder, hundreds of fishermen would line up along each side of the canal when the flounders were passing through from bay to bay. Now it’s the seals that line up.
These days the few flounders that make it through the seal gauntlet and breed successfully as they still do each year in Napeague Harbor, have to face a gauntlet of a different sort — a double-crested cormorant one. The double-crested cormorant just may be the most redoubtable of all Atlantic coast fishing birds. They are speedy underwater swimmers, they have eyes especially adapted for seeing underwater, and a long, sharp beak with a hook at the end for grabbing fish and holding on to them while returning to the surface where they swallow them whole. Their jaws are narrow when not being used to feed, say, when preening, but are very expandable, as a snake’s is, when swallowing a fish as wide as a flat fish whole.
Just as the seals are leaving, the cormorants arrive in droves. It’s a rare baby flounder that is fortunate enough to escape that beak and live to leave the nursery waters, maybe even grow up to maturity and breed on its own. The number of cormorants that hang around Napeague Harbor from midspring through the summer gets larger and larger each year as they breed in rookeries as close by as on Gardiner’s Island.
What is the winter flounder to do? Don’t blame the poor fisherman who is barely getting by. Point the finger at the seal and the cormorant.
There is a human way to reduce the seal population — use modern contraceptive techniques. It works for people, it can work for seals. One doesn’t have to shoot the seal or harpoon it, one can dart it with a contraceptive that makes the female’s eggs reject the sperm. It is done in black bears, wild horses, deer, even elephants.
What about the cormorants? The seals are protected by the Marine Mammals Protection Act, the cormorants by the Migratory Bird Act, which is almost 100 years old. Unfortunately, humans by law have been put in the awkward position of having to manage the other macrofauna one way or another. They are doing a fairly good job of saving species such as the California condor and whooping crane from extinction, but at a great cost. For example, our national bird, the bald eagle, is no longer considered endangered, merely threatened. But humans have a very long way to go when it comes to reducing species that have multiplied beyond their carrying capacity and are threatening the very existence of other species, in this case, the winter flounder.
Something has to be done to level out the playing field. On the West Coast sea lions are controlled around the mouths of rivers. A case in point: the mighty Columbia River, which runs to the Pacific between the states of Washington and Oregon. Sea lions are removed from the mouths of such rivers because they have been depredating the salmon trying to get upstream to breed. They are as damning as dams.
We should follow that example, but in a humane way, or the winter flounder may go the way of the Labrador duck, the heath hen, the passenger pigeon, and the Carolina parakeet. Now, wouldn’t that be a tragedy?