The Charlevoix Coast and the St-Lawrence Estuary

Marine mammals

Seals

Two species of seals frequent the Saint Lawrence Estuary near Saint-Irénée: the harbor seal and the gray seal. These marine mammals regularly haul out on rocks exposed at low tide, where they can be observed from the shore. Their presence reflects the richness of the ecosystem and the health of the marine environment.

Harbor seal

The harbor seal is the most common species near the coast and resides year-round in the estuary. Easily recognizable by its “dog-like” head and V-shaped nostrils, it spends much of its time resting on rocks at low tide. Its characteristic “banana pose,” with its body arched and flippers raised, signals relaxation and safety. A strong swimmer, it also explores coastal waters to feed on fish and crustaceans. Its regular movements and visibility from the shore make it an excellent indicator of marine ecosystem health.

• Length: 1.5 to 1.8 meters
• Weight: 80 to 100 kg
• Lifespan: ~36 years
• Birthing season: mid-May to mid-June
• Dive duration: 3–7 minutes (max 20 minutes)
• Dive depth: up to 100 meters

Gray seal

Larger and more massive than the harbor seal, the gray seal frequents the estuary from spring to autumn, generally staying offshore, though some individuals venture closer to the coast. Its long snout and large head make it easily identifiable. Unlike the harbor seal, it is less often seen, preferring isolated sandbanks or open waters. Gray seals are excellent divers and can travel long distances in search of fish and crustaceans, playing a key role in the marine ecosystem.

• Length: 2 to 2.5 meters
• Weight: 200 to 350 kg
• Lifespan: ~40 years
• Birthing season: December to February
• Dive duration: 5–10 minutes (max 30 minutes)
• Dive depth: up to 200 meters

Cetaceans

Two cetacean species regularly inhabit the Saint Lawrence Estuary: the beluga, present year-round, and the harbor porpoise, most active during the summer. Observing them from the shore or by kayak adds a fascinating dimension to wildlife watching.

Beluga

The beluga, an iconic resident of the Saint Lawrence, is highly social and extremely vocal, earning it the nickname “canary of the sea.” Often seen in groups at the surface, belugas are easily observed from the shore. Their rounded back, lack of dorsal fin, and distinctive white coloration make them unmistakable. Belugas feed on fish, crustaceans, and mollusks, playing a crucial role in maintaining ecosystem balance.

• Length: 3–5 meters
• Weight: 500–1,500 kg
• Lifespan: 50–70 years
• Birthing season: June to September (one calf every three years)
• Dive duration: 10–15 minutes
• Dive depth: typically 20–50 meters (max 300–400 meters)

Harbor porpoise

The harbor porpoise is a small, discreet, and shy cetacean that lives in small groups. Its triangular dorsal fin appears briefly at the surface, and it rarely approaches boats. It primarily feeds on fish and crustaceans, performing short, rapid dives that highlight its agility in estuarine waters. Despite its smaller size compared to the beluga, it plays an important role in maintaining local biodiversity.

• Length: 1.5–2 meters
• Weight: 45–65 kg
• Lifespan: 15–20 years
• Birthing season: June to July (one calf per year)
• Dive duration: 2–6 minutes
• Dive depth: typically 50–100 meters (max 200 meters)

Birds of the estuary

The shores of the Saint Lawrence host a wide variety of seabirds and waterbirds, many easily observed from the shore or by kayak. Notable species include the common loon, great cormorant, great blue heron, and two small alcid birds: the thick-billed murre and the razorbill. These species highlight the biological richness of the river and its coastal zones.

Common loon

A symbol of lakes and rivers, the common loon is recognizable by its haunting summer call. An excellent diver, it primarily feeds on fish and crustaceans. Loons are monogamous during the breeding season and may remain with the same partner for several years. Their behavior and spectacular dives make them fascinating to observe.

• Length: 66–91 cm
• Wingspan: 127–147 cm
• Weight: 3–7 kg
• Lifespan: 20–30 years
• Presence: May to September
• Dive duration: 1–3 minutes (max 5)
• Dive depth: 5–20 meters

Great cormorant

Recognizable by its wings often spread to dry, the great cormorant is an efficient diver, able to stay underwater to catch fish and crustaceans. Monogamous for the season, it frequents coasts throughout summer. Wing-drying is necessary because their feathers are not completely waterproof, giving them a unique appearance when perched on rocks.

• Length: 80–90 cm
• Wingspan: 120–160 cm
• Weight: 2–2.5 kg
• Lifespan: 15–20 years
• Presence: April to October
• Dive duration: 30 sec–1 min (max 2)
• Dive depth: 5–20 meters (sometimes up to 30)

Great blue heron

This tall wader hunts by standing still along the water’s edge, waiting patiently for fish, frogs, or small mammals. In flight, its neck folds into an “S” and long legs trail behind, making it easily identifiable. Nesting in trees near water, it plays a vital role in coastal ecosystem balance.

• Length: 97–137 cm
• Wingspan: 167–201 cm
• Weight: 2–2.5 kg
• Lifespan: ~15 years
• Presence: April to October
• Diet: fish, frogs, insects, small mammals

Similarity and distinction : Thick-billed murre and razorbill
Offshore, two small alcid birds draw attention: the thick-billed murre and the razorbill. They are similar and not always easy to distinguish.

Thick-billed Murre

A compact seabird, the thick-billed murre is known for rapid wingbeats and agile dives to catch fish and crustaceans. Although mostly offshore, it can be seen from rocky shores.

• Length: 39–43 cm
• Wingspan: 60–69 cm
• Weight: 500–800 g
• Special trait: rapid wingbeats
• Dive depth: up to 60 meters

Razorbill

Sleeker than the murre, the razorbill is recognizable by small white wing markings. It is the only flying “penguin” and moves quickly in air and underwater. Its deep, powerful dives make it an efficient hunter in the estuary.

• Length: 38–46 cm
• Wingspan: 64–73 cm
• Weight: 900–1,100 g
• Special trait: fast flight

Coastal algae and plants

The shores and beaches of Saint-Irénée host a variety of marine and coastal vegetation, essential to ecosystem balance. They provide food and shelter for many animals, protect the coastline from erosion, and contribute to local biodiversity.

Algae

Fucus bifidus (bladderwrack)

A brown algae forming flat ribbons, attached to rocks. Highly visible at low tide, it shelters small marine animals and helps protect the coastline from erosion.

• Role: Provides shelter for small marine animals and protects the coastline
• Appearance: Brown algae in flat ribbons
• Where? Attached to rocks, highly visible at low tide
• Edible? Yes, rich in iodine and minerals, though quite strong in taste

Palmaria palmata (dulse)

This red algae appears as flexible, wine-red to purple strips. Found on rocks or larger algae in the lower intertidal zone, it serves as food and shelter for small marine invertebrates.

• Role: Source of food and shelter for small marine invertebrates
• Appearance: Red algae in flexible strips
• Where? Attached to rocks or larger algae in the lower intertidal zone
• Edible? Yes, very nutritious with an umami flavor, can be eaten raw, dried, or cooked

Sea lettuce (Ulva lactuca)

A green algae with thin, bright green leaves, it contributes to coastal ecosystem balance and feeds small marine animals. Found on rocks, visible at low tide.

• Role: Contributes to the balance of the coastal ecosystem and feeds small marine animals
• Appearance: Green algae with thin, bright green leaves
• Where? Attached to rocks, highly visible at low tide
• Edible? Yes, delicate and consumable raw, dried, or in salads

Coastal plants

In addition to algae, the beaches and dunes of the Saint Lawrence host vegetation adapted to extreme coastal conditions. These plants play a crucial role in stabilizing sand, providing shelter and food for wildlife, and sometimes even ending up on our plates.

Sea Rocket (Cakile maritima)

A low-growing plant with fleshy, bluish-green leaves, found on sandy beaches just above the high-tide line. It stabilizes dunes and provides food and shelter for insects and birds.

• Role: Stabilizes dunes and provides food and shelter for certain insects and birds
• Appearance: Low-growing plant with fleshy bluish-green leaves, small mauve flowers, and plump clustered fruits
• Where? In beach sand, just above the high-tide line
• **Edible? Yes, with a spicy taste reminiscent of mustard or radish, can be eaten raw in salads or as garnish

Estuary and tides

High tide, Low tide

As soon as you start visiting the banks of the river in Charlevoix, you are struck by its constantly changing nature—its colors, its smells, and especially its tides! Yes, you can observe up to four tides per day (24h). But what exactly is a tide, and how does it work?

It all starts with astronomy! The Sun and the Moon play a crucial role in creating tidal waves. First, the Sun exerts a gravitational pull on all bodies in the Solar System; the mass and distance of objects directly affect the gravitational force between them.

Par sa grande proximité avec notre planète, la Lune exerce une force similaire. La Terre elle-même possède sa propre force gravitationnelle, ce qui lui permet de rester entière; car toute matière est soumise à la gravité, qu’elle soit à l’état solide, liquide ou gazeux. Mais! Concentrons-nous sur l’eau. Tout dépendant de la position relative entre le Soleil, la Terre et la Lune, les marées connaîtront une hauteur variable, ce qu’on appelle le marnage. Les plus grands marnages sont aussi appelés marées de « hautes-eaux » (spring tides) et ont lieu durant les phases de nouvelle et pleine Lune. Les plus petits marnages sont les marées de mortes-eaux (neap tides), et ont lieu durant les phases lunaires du premier et dernier quartier. Par conséquent, on observe les deux types de marées dans un même mois¹. Voici une illustration qui permet de mieux comprendre cette influence.

Due to its proximity to our planet, the Moon exerts a similar force. The Earth itself has its own gravitational force, which keeps it together, as all matter—solid, liquid, or gas—is affected by gravity. Now, let’s focus on water. Depending on the relative positions of the Sun, Earth, and Moon, tides will vary in height—a phenomenon called the tidal range:

• The highest tidal ranges are called spring tides, occurring during new and full moons.
• The smallest tidal ranges are called neap tides, occurring during the first and last lunar quarters.

Thus, both types of tides are observed within the same month¹. Here is an illustration that helps to better understand this influence.

Next, think of a tidal wave like a cycle: a rising period (flood tide), a very short period of balance (high tide), followed by a falling period (ebb tide), and another brief period of balance (low tide). This cycle repeats, particularly frequently in the Saint Lawrence Estuary: 3 to 4 times in 24 hours.

Where fresh and salt water meet

Caution! Tides do not behave the same way along the entire Saint Lawrence River. They also help define four distinct sections:

1. Fluvial Section: Between Cornwall and Lac Saint-Pierre, where the water is fresh and tides are absent.
2. River Estuary: From the Lac Saint-Pierre outlet to the eastern tip of Île d’Orléans, where water is mostly fresh but tidal effects can be measured.
3. Middle Estuary: From the eastern tip of Île d’Orléans to Tadoussac, where the river widens and freshwater from the Great Lakes mixes with salty water from the Gulf; this is called brackish water. Want to test it? Taste the water in Baie-Saint-Paul, then in Saint-Siméon—you’ll likely be surprised! The Charlevoix coasts are entirely within this middle estuary. This section is also where the habitat of several marine mammals, including belugas, begins. Tides here are significant (up to 6 meters tidal range) and navigating this section is challenging due to rapidly changing bathymetry.
4. Maritime Estuary and Gulf: From Tadoussac to Pointe-des-Monts, where water is definitely saltier and colder. The riverbed widens and deepens, allowing observation of a wide variety of marine mammals, from harbor porpoises to blue whales, Greenland seals, and white-sided dolphins.

A river for experienced navigators

Did you know that all vessels longer than 35 meters operating in the Saint Lawrence must be piloted by an expert? This is the role of the Corporation of Pilots of the Saint Lawrence, which trains specialists for each river section to ensure safe and efficient navigation. In the middle estuary, vessels must follow the Laurentian Channel, located between Isle-aux-Coudres and Saint-Joseph-de-la-Rive. Navigating south of the island is nearly impossible due to shallow waters and numerous shoals.