Winter flounder

Language English

Onglets

Description

Distinguishing features

The winter flounder is an oval, asymmetrical flatfish that lives on the seafloor. Both eyes are located on its right side. Its upper body is reddish-brown and heavily mottled, helping it blend in effectively with sandy or muddy bottoms.

Its underside is creamy beige. Its mouth curves slightly upward, and its long dorsal and anal fins form fringes along the edges of its body.

Reproduction

Winter flounder breed mainly in winter and early spring. Females can lay from 500,000 to more than 2 million eggs, which form a mass attached to the substrate.

When they hatch, the pelagic larvae feed on plankton. They drift in the water before undergoing metamorphosis. Initially symmetrical in shape, like a typical fish, the larvae gradually develop the asymmetry of flatfish as one eye migrates to the other side of the skull. At the end of this process, the young flounder settles on the seafloor, resting on its left side.

Diet

The winter flounder is an opportunistic benthic (bottom-dwelling) predator. It feeds on a variety of invertebrates, including crustaceans, marine worms, snails, soft-shell clams, and capelin eggs.

An ambush predator, it lies buried in the sediment and captures prey that pass nearby. It feeds during the day, and more actively in summer than in winter.

Predators

In winter, when the winter flounder moves into deeper waters, it becomes prey for a variety of bottom-dwelling predatory fish. Belugas and grey seals also prey on this species.

In summer, when young flounder move back into shallower waters, they are often caught by herons, cormorants, and ospreys.

The European green crab (Carcinus maenas), an introduced invasive species, may also prey on young flounder when they settle on the seafloor after metamorphosis.

Lastly, the winter flounder is a heavily fished species.

Habitat

The winter flounder is found on the soft bottoms of the northwest Atlantic, including sand, mud, and gravel, from the Bay of Fundy and the Gulf of St. Lawrence to Newfoundland, and farther north toward Greenland.

It is most often found at depths of 10 to 300 metres, as it prefers cold waters ranging from 0 to 10 degrees Celsius.

Ecology, behaviour

Thanks to chromatophores, pigment cells controlled by nerve and hormonal signals, the winter flounder can change the colour and patterning of its skin to blend in with the seafloor.

The winter flounder is an important part of seafloor food webs. Not very mobile, it makes mainly seasonal movements linked to temperature and reproduction. Its effective camouflage helps protect it from predators and also allows it to blend into the sediment to ambush prey.

Like other benthic species, it is sensitive to disturbances of the seafloor, most of which are caused by fishing gear.

French name

Plie rouge

Scientific name

Pseudopleuronectes americanus

Phylum

Chordata

Class

Osteichthyes (bony fish)

Order

Pleuronectiformes

Family

Pleuronectidae

Size

Maximum length: 45 cm

Weight

1.4 kg on average

Life span

About 20 years

Status

Vulnerable

At the Biodôme

The winter flounder at the Biodôme hides in the large basin of the Gulf of St. Lawrence ecosystem, usually on sand or among rocks. When still, it is hard to spot because it takes on the colour of the substrate it rests on.

Menu header en

Languages

Space for life

About Us

Menu header Billetterie en

Global menu

Espace pour la vie App

The Green Pages

Indoor plants

Espace pour la vie Foundation

Espace pour la vie Foundation

Subscribe to the Naturally curious newsletter

School newsletter

Our institutions’ expertise

Research and conservation at Espace pour la vie