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Where Have All the Winter Flounders Gone?

The winter flounder with its mild, slightly sweet white flesh, is frequently sought by recreational fishermen as a great food source. Easily prepared with its thin fillets and delicate flakes, it is recognized as a healthy source of dietary protein, B-vitamins and niacin. Recommended by the American Heart Association, eating flounder helps reduce cholesterol levels.

But for most anglers, winter flounders are becoming more difficult to locate. “Where have all the winter flounder gone, long time passing?” Partially taken from Pete Seger’s first verses, it seems an appropriate way to ask what has happened to the population of winter flounders, lobsters and some other bottom-living species traditionally found in our coastal waters. Can it be overfishing, pollution, climate change or a combination of these that is causing their decline? For Joseph Langan, marine biologist and PH.D. candidate at the University of Rhode Island School of Oceanography, the decrease in the numbers winter flounders from the waters of Narragansett Bay, Rhode Island, “is a murder mystery if there ever was one.”

To understand why the population of winter flounders is declining, we examine a bit of their life history. Under the cover of night, in waters whose temperature can drop to near freezing (January to late spring), mating pairs of winter flounders swim to the shallows to spawn. Flounders are equipped with antifreeze proteins, allowing them to survive water temperatures as low as 28.40F, the freezing point of ocean water. Depositing their eggs at low temperatures affords them protection for warmer water predators.

In the shallows, as they swim in tight circles, the females release their eggs. (A single female may spawn 500,000 to over a million eggs over repeated seasonal spawnings.) The eggs sink to the bottom where they form tight clusters. Over the next 15 to 18 days, the tiny embryos develop and finally hatch at less than a quarter inch in length. Like other species of fishes, the hatchlings have eyes on both sides of their head, but as they grow, the left eye begins to migrate over to the right side. By the time that the newborn flounders have grown to about one third inch, the left eye has migrated all the way to the right side, allowing the fishes to lie flat on the bottom, blind side down.

After spawning, adults remain close to shore until the water temperatures reach around 590F. They then migrate to deeper, cooler waters. They return to the shallows as the autumn waters begin to cool again to just below 590F. They often occupy the same general area, year after year. Adults spend their entire lives very close to the sea floor, on mud-shell, sand or gravel sediments. They seldom swim much more than two feet above the bottom. While seeking prey, they often bury themselves in soft sediments with their turret-like eyes peering just above the bottom. If a small shrimp swims within six inches of the flounder, the fish bolts out and snatches it up. It also feeds on other small crustaceans, worms and clams. But within a short time, if a prey is not spotted, the flounder changes location to increase its odds. When encountered by a scuba diver, a winter flounder often seems to simply stare back at its intruder. However, if lightly touched by a finger, the fish scurries off to a short distance away.

Winter flounders range from Labrador to Chesapeake Bay and out to the continental shelf. They can live up to 15+ years, growing to about 22 inches in length. The species IGFA world record was 24.8 inches long, caught off Fire Island, New York in 1986. In the northern part of its range, the fish grows at a much slower rate. Any winter flounder over 15 inches, is considered a great catch! However, throughout its range, the minimum length is12 inches and the season varies from state to state.
“Since the 1970s, Long Island Sound’s surface and bottom water temperatures have increased by nearly 30F.” During the winter, its average temperature hovers around 410F, but in July, it easily reaches 720F+. In Narragansett Bay, winter temperature ranges between 27 to 430F. The summer sees temperatures of 68 to 750F. Recreational and commercial overfishing have traditionally been blamed for the decline in the winter flounder’s population. However, studies carried out in Narragansett Bay suggest that the decrease numbers of winter flounders is “strongly tied to temperature.” But it certainly could be a combination of the two.

Around the late 1990s, Long Island Sound’s lobster population crashed. Increased water temperatures have also impacted winter flounder, but the numbers of summer flounder and other warm water fish species have increased. It does not however, take away the value of a catching a winter flounder.
They are still out there!

When fishing for winter flounder, it must be remembered that they have very small mouths. A light fishing rod, equipped with 6 to 10-pound test using a small single hook and sinker, is generally recommended. Pieces of bloodworms, sand worms, small shrimp or strip of clam work well as bait. Chum pots, filled with frozen chum logs purchased from a tackle shop or a combination of ground up shrimp, clams, whole kennel corn and squid are a great help in attracting the fish. And if you don’t get a hit within 15 to 30 minutes, raise the anchor and move on to another site.
Other names for winter flounder: include black back, flounder, flatfish, mud dab, sole, lemon sole and Georges Bank flounder. For information regarding state by state winter flounder regulations, go to,%20Winter.