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What is an Alewife?

Kecia Hambrick
Kecia Hambrick

The alewife, of the species Alosa, is a fish belonging to the herring species, and is also known as the sawbelly, gaspereau, and kiack. These fish are native to the Atlantic coast along the eastern United States and Canada. The fish became well known in the 1950s and 1960s for their rapid invasion of the Great Lakes, particularly Lake Michigan and Lake Huron. Their population has since been controlled due to predators such as salmon being released in the lakes.

The average adult alewife grows to 10-11 inches (25-28 cm) and generally weighs no more than 9 ounces (255 grams). The alewives found on the Atlantic coast tend to be larger than those found in the freshwater lakes. The typical life span of this fish is six years. These fish range in color from silver to a metallic blue-green, with their darkest color found on their backs. They also have a characteristic line down their belly that resembles a line of saw blades, hence one of their common names. Alewife scales were once a hot commodity due to their role in the production of fake pearls.

Veterinarian with a puppy
Veterinarian with a puppy

Though they are closely related, alewives differ from the sea herring in appearance — they have a broader body, a spot behind the gills and the dorsal fin is closer to the nose than to the tail. When filleted, their abdominal cavity lining is often much lighter than that of the herring. For human consumption, they are often chosen over the herring due to a better taste and more meat per fish.

The alewife tends to reach sexual maturity between three and four years of life. They are anadromous, meaning they migrate for spawning. They typically mature in saltwater oceans before venturing to freshwater to spawn. Once the female has laid approximately 60,000-100,000 eggs, the fish return to the ocean. This journey from varying waters is difficult for the fish, and they tend to lose weight and act sluggish during these trips. Repeated journeys often lead to death.

The alewife tend to feed on plankton, but some will also consume small fish such as herring, cunners, and eels. They usually do not eat while traveling to spawn, but typically devour shrimp on their return trip to the sea. Bait is often not necessary to catch alewives, as they can be scooped up using large dip nets as they are venturing down stream after spawning. They can be caught for human consumption, or to use as bait for other fish, particularly pollock, lobster, and cod.

Frequently Asked Questions

What is an alewife?

An alewife is a small fish, Alosa pseudoharengus, native to the North Atlantic region. It's part of the herring family and is known for its significant role in the ecosystems of freshwater and marine environments. Alewives are anadromous, meaning they migrate from the ocean into freshwater rivers and streams to spawn.

Why are alewives important to the ecosystem?

Alewives serve as a crucial food source for a variety of predators, including larger fish, birds, and mammals. Their presence in aquatic ecosystems helps maintain balance by providing sustenance for these species. Additionally, their migration patterns contribute nutrients to both marine and freshwater systems, supporting overall biodiversity.

How do alewives reproduce?

Alewives migrate upstream to freshwater habitats to spawn, typically in the spring. Females can lay between 60,000 to 100,000 eggs, which they deposit on sandy or gravelly riverbeds. After hatching, the young spend several months in freshwater before returning to the sea, continuing the cycle of migration and reproduction.

What threats do alewives face?

Alewives face several threats, including habitat loss due to dam construction, which impedes their migratory routes. Overfishing and pollution also pose significant risks. Efforts such as dam removal and the installation of fish ladders are underway to help conserve alewife populations and ensure their migratory pathways remain open.

Can alewives be consumed by humans?

Yes, alewives can be consumed by humans and have been historically important for food and fertilizer. They are often smoked, pickled, or used as bait for lobster fishing. However, due to their bony structure, they are not as popular as other fish for direct consumption.

What is being done to conserve alewife populations?

Conservation efforts for alewives include habitat restoration, such as the removal of dams that block their migratory paths, and the installation of fish ladders to help them bypass obstacles. Regulations on fishing quotas and seasonal restrictions also help manage and conserve alewife populations for future generations.

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      Veterinarian with a puppy