Common names for the alewife are gaspereau, river herring, sawbelly, or kiack.
The alewife is found in rivers and lakes along the eastern
coast of North America, from Newfoundland to North Carolina,
and the adults live in coastal marine waters 56 to 110 m
(180 to 350 ft) deep. Landlocked populations exist in several
Ontario and New York lakes. Since the Welland Canal was
built in 1824, the alewife has spread throughout the Great
The alewife is a member of the herring family. Here are some things to note:
Facts on Alewife
- a slender, laterally compressed fish coloured greyishgreen on the back, and silvery on the sides and belly;
- gaspereau entering freshwater often have a copper sheen colour;
- a single black spot is present on each side, just behind the head;
- each eye is relatively large and has an obvious eyelid;
- a row of scales, known as scutes, form a sharp edge along the mid-line of the belly which is how the alewife came to be called "sawbelly."
- The alewife in Nova Scotia is usually 25 to 30 cm (10 to 12 in) long and weighs up to 340 g (1 2 oz). There is no lateral line.
- Another species known as the blueback herring is very
difficult to distinguish from the alewife. They inhabit
the same watersheds and have similar natural histories.
Any reports of alewife probably include the blueback herring
Alewife eggs, or roe, are canned and sold as a delicacy.
Despite the many thousands of eggs laid by spawning alewife,
very few offspring actually survive. In some populations,
as few as three young-of-the-year fish migrate downstream
for each female that spawned.
- During the spawning runs, commercial fishermen set
large trap nets or enclosures called weirs in coastal
rivers and estuaries to catch migrating alewives.
Major Canadian fisheries are on the Shubenacadie,
Miramichi, and Saint John Rivers.
- The catch is used for fish meal lobster bait, petfood
or it is smoked, canned, salted or pickled. Although
tasty, alewives are not favoured locally for human
consumption because they are bony.
Alewife eggs are about 1 mm in diameter and are left to lie on the bottom or float with the current. Depending on the water temperature, the eggs hatch in about a week. After the yolk-sac is absorbed the tiny, larval fish stay near the spawning grounds preferring shallow, warm, and sandy areas. They feed on tiny zooplankton.
From August to October young-of-the-year (32 to 152 mm
(1.25 to 6 in) in length) migrate downstream in large schools
to live in estuaries and coastal areas. Adults overwinter
at sea in the George's Bank, Gulf of Maine or Nantucket
Shoals. Alewives can live at least 10 years. Alewives are
eaten by many species of fish and birds including striped
bass, salmonids, smallmouth bass, eels, perch, bluefish,
weakfish, terns, eagles, ospreys, great blue herons, and
In the Maritimes the alewife spends most of its life growing
in salt water, feeding mainly on zooplankton (tiny invertebrates
that live in the water column). Beginning each spring, from
April to July, large runs of adult alewives migrate up coastal
rivers to spawn in freshwater lakes, ponds and streams (this
movement from sea to freshwater makes the alewife an anadromous
Alewives also spawn in brackish water. Like trout and
salmon, alewives use their sense of smell to return to the
streams and lakes where they hatched. Female alewives usually
begin spawning at age 4. Male alewives often mature a year
earlier than females. About 75% of alewives entering Nova
Scotia rivers are repeat spawners. Alewives can move into
coastal areas in late winter but will not migrate into fresh
water until river temperatures begin to warm. Males enter
the river first. Alewives only migrate into freshwater during
daylight hours. However, spawning occurs at night and can
occur in lakes or in slow moving or fast mid-river water.
A single female can lay as many as 200,000 eggs. After spawning
many alewives die. However, those that survive return to
the sea within a few days.
For more information contact your local federal or provincial
Department of Fisheries, or write to:
For more information contact your local federal or provincial Department of Fisheries, or write to:
|Fisheries & Oceans Canada
PO Box 550
Halifax, Nova Scotia
Facsimile: (902) 426-1489
||Nova Scotia Fisheries and Aquaculture, Inland Fisheries Division|
PO Box 700
Pictou, Nova Scotia
Facsimile: (902) 485-4014
Email: Inland Fisheries
Published With Funding from the Canada-Nova Scotia Cooperation Agreement on Economic Diversification, Resource Competitiveness Program.