Alosa pseudoharengus was formerly classified as Alosa pseudoharengus. Common names for A. pseudoharengus include alewife, gaspereau, sawbelly, kyak, kiack, river herring, and glut herring.
Alewives have some interesting cultural and historical connections. Alewives are the fish the Native Americans in New England buried with crops as fertilizer (Grosvenor, 1965). The silvery coating on the scales is sometimes used in making costume jewelry and is called pearl essence by the jewelry industry (Grosvenor, 1965).
We don't know much about how alewives might communicate. Their large eyes probably help them find other alewives, their prey, and stay alert for predators.
Communication Channels: tactile ; chemical
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical ; electric
Alewives not listed as an endangered species, but in many places in their natural range, their habitat is threatened by dams along spawning rivers. On the other hand, their introduction into the Great Lakes and other areas resulted in declines in native fish in those areas.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Fertilized eggs are about 0.9 mm in diameter. Three to five days after hatching, the larvae begin to feed. They slowly transform into juvenile fish and remain in fresh water until the fall. While in freshwater, young-of-the-year grow 1.5 to 5 inches (3.8 to 12.5 cm). Little is known about sub-adult life-history traits.
Alewives have been considered a nuisance in the Great Lakes since their population explosion in 1873. Live fish tend to clog industrial intake pipelines and are “particularly obnoxious during periods of mass die-offs” because they can cause health hazards from the large numbers of dead fish in the spring (Scott and Crossman, 1998). Control measures, such as the introduction of coho salmon, Oncorhynchus kisutch, however, provide important sport fisheries for Lake Michigan (Scott and Crossman, 1998).
Since they feed mainly on planktonic and benthic organisms, alewives are particularly good at accumulating DDT (dichloro-diphenyl-trichloroethane) in their fatty tissues (Scott and Crossman, 1998). This bioaccumulation can make it dangerous for humans and other high-level predators to eat piscivorous fish, such as salmon, that feed primarily on alewives.
Alewives represent an important commercial fishery in the Atlantic Ocean. They are packaged fresh, smoked, salted, or pickled for human consumption and are often sold as “river herring.” Fishermen use weirs, traps, gill nets, and dip nets for alewives, which they consider one of the easiest fish to catch (Scott and Scott, 1988). Alewives have other uses, including pet food, lobster and snow crab bait, and processing into fishmeal and fish oil (Scott and Scott, 1988). The North American Fisheries Organization statistical bulletin includes alewives in the "other fish" category so no catch data are available (Scott and Scott, 1988). Alewives have not seriously been exploited as a fishery in the Great Lakes since these are small and too bony to eat. However, recently there has been a trend to use them for pet food and fish meal (Scott and Crossman, 1998).
Positive Impacts: food ; body parts are source of valuable material
Alosa pseudoharengus is now the most abundant planktivore in Lake Ontario and it is the main prey of salmonoids stocked into the great lakes (Klumb, Rudstam, and Mills, 2003). Its presence in the Great Lakes has caused the decline of many fish species due to competition.
There have been few studies published on alewife parasites (Scott and Scott, 1988). Anadromous populations host more species of parasites than land-locked populations. Alewives caught off the Atlantic coast were found to host the following parasites: acanthocephalans, cestodes, trematodes, copepods, and nematodes (Scott and Crossman, 1998). Parasites are rare in land-locked populations (Scott and Scott, 1988), but one important freshwater alewife parasite, the alewife floater, Anodona implicata, has been used to research the historical range of the alewife. Anodonta implicata is a mussel which is native to the tidal Hudson river and Delaware Rivers in New York (Daniels, 2001).
Commensal/Parasitic Species:
Little is known about the feeding habits of anadromous alewives (Scott and Scott, 1988). Adult land-locked fish eat mostly zooplankton, especially larger varieties such as copepods, cladocerans, mysids, and ostracods (Scott and Crossman, 1998). When they grow larger than 11.9 cm, they feed mostly on the benthic amphipod Pontoporeia (Scott and Scott, 1988). Some spawning adults eat small fish or fish eggs when in shallow waters (Scott and Crossman, 1998). Larval alewives eat mainly cladocerans and copepods.
Animal Foods: fish; eggs; aquatic crustaceans; zooplankton
Primary Diet: planktivore
Alosa pseudoharengus (Wilson, 1811) is an anadromous species, native to the Atlantic Ocean and the lakes and streams that drain to it from Newfoundland to North Carolina (Scott and Crossman, 1998). This includes the Gulf of St. Lawrence, the outer coast of Nova Scotia, the Bay of Fundy, and the Gulf of Maine (Scott and Scott, 1988). It is also present, although non-native, in all of the Great Lakes (USA), and many lakes in northern New York. In the Great Lakes, A. pseudoharengus was first caught in Lake Erie in 1931 off the coast of Nanticoke, Ontario, Canada. Populations then moved slowly upstream to the upper great lakes (Scott and Crossman, 1998). It was discovered in Lake Huron in 1933, Lake Erie in 1940, Lake Michigan in 1949, and Lake Superior in 1954 (Scott and Crossman, 1998). It is now abundant in Lake Huron and dominant in Lake Michigan. Alewives cannot dominate Lake Superior due to cold water and predation by lake trout (Salvelinus namaycush), nor can they dominate Lake Erie because the lake is too shallow to provide suitable overwintering grounds for large numbers of fish (Scott and Crossman, 1998). Several theories exist on how alewives could have become established in the Great Lakes. Scott and Crossman suggest that alewives may have been accidentally included in a batch of American shad (Alosa sapidissima) that were used to stock Lake Ontario. The alewives also could have migrated from Lakes Seneca and Cayuga in New York to the Great Lakes through the St. Lawrence River. A third argument for the current distribution is that alewives were native to Lake Ontario in small numbers but went unnoticed until the population explosion in 1873 (Daniels, 2001). Daniels (2001) argues against both the theory of introduction with stocked American shad and dispersal through canals. He argues against the canal introduction because the alewife floater, Anodonta implicata, is not found in the upper portions of canals or in Lake Ontario. Anodonta implicata is a mussel and a parasite of alewives (Daniels, 2001).
Biogeographic Regions: nearctic (Introduced , Native )
For anadromous populations, much is known about their freshwater spawning habits, but little is known about movements within the ocean. Alewives spend most of their time in coastal waters and most are caught in water 56-100 m deep at about 4°C (Scott and Scott, 1988). Light sensitive, they tend to be in deeper waters during daylight hours. They also follow diel movements of zooplankton in the water column (Scott and Scott, 1988). Adults can withstand temperatures up to 25°C and young of the year can live in waters up to 30°C (Scott and Scott, 1988).
Freshwater populations spend most of their time in the deep waters of the lakes but come to the shallows and tributary streams in the spring to spawn (Trautman, 1957). The fish go to the deepest parts of the lakes to overwinter.
Range depth: 56 to 100 m.
Habitat Regions: temperate ; saltwater or marine ; freshwater
Aquatic Biomes: lakes and ponds; rivers and streams; coastal
Other Habitat Features: estuarine ; intertidal or littoral
Young alewives have a very high mortality rate. Less than 1% survive to migrate into the sea (U.S. Department of Agriculture, 2004). Annual mortality for adult alewives is on the order of 70% per year. Most die during or shortly after the spawning season (U.S. Department of Agriculture, 2004). Few land-locked alewives live longer than 5 years (Smith, 1970).
Range lifespan
Status: wild: 10 (high) years.
Typical lifespan
Status: wild: 5 (high) hours.
Alosa pseudoharengus has an overall silvery color with a grayish green back. A black spot at the eye level is directly behind the head. Adults have longitudinal lines that run along the scale lines above the midline of the body. Small specimens have a violet sheen on the sides while anadromous adults have a golden cast on their heads and upper parts. The scales are deciduous and the lateral line is not well-developed (Scott and Crossman, 1998). Coloration is generally similar to that of the skipjack herring, Alosa chrysochloris. Scales on the midline of the belly form scutes, creating a serrated surface (Trautman, 1957). Females are bigger than males and generally live longer. The body is strongly laterally compressed and relatively deep. The head is broadly triangular. Eyes are large and have well-developed adipose eyelids. The front of the jaw is thick and extends past the lower jaw when the mouth is closed. The maxillary extends to below the middle of the eye. A few small teeth are present on the premaxillary and mandible (Scott and Crossman, 1998). There are more than 30 gill rakers on the lower angle of the first gill arch (Trautman, 1957). The singular dorsal fin usually has 13-14 rays but may have 12-16. The caudal fin is forked. The anal fin is short and wide with 15-19 rays (usually 17-18). The pelvic fins are rather small and contain 10 rays. The pectoral fins are low on the sides and usually have 16 rays but may have as few as 14 (Scott and Crossman, 1998). There are a few physiological differences between anadromous and land-locked individuals. Anadromous specimens tend to be longer, ranging from 255 to 355 mm while land-locked species average 150 mm in length. Land-locked fish mature faster than anadromous ones (Daniels, 2001).
Range length: 100 to 355 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Average mass: 110 g.
Alewives are considered a forage fish and have many predators. In freshwater, their main predators are burbot (Lota lota), lake trout (Salvelinus namaycush), eels (Anguillidae), bass (Micropterus), walleye (Sander vitreus), and whitefish (Scott and Crossman, 1998). Introduced predators include chinook and coho salmon. Little is known about the predators of anadromous alewives but their hatchlings have a high mortality rate. As few as one out of 80,000 will reach the sea (Scott and Scott, 1988).
Known Predators:
All alewives spawn in the spring. The young swim to sea in anadromous populations or to deeper water in lake populations in the fall (Grosvenor, 1965). For anadromous populations, the temperature of the river water determines the timing of spawning migrations upstream, so spawning happens first in lower latitudes. Spawning generally starts in April in the south and lasts until the end of May in upper latitudes (Scott and Crossman, 1998).
In all populations, females reach the spawning grounds first (Scott and Crossman, 1998) and older fish are the first to spawn (Grosvenor, 1965). The oldest fish recorded at spawning sites were 9-10 years old (Grosvenor, 1965). Spawning occurs in groups of 3 or in pairs (Scott and Crossman, 1998).
Mating System: polygynandrous (promiscuous)
Females broadcast their eggs simultaneously with males broadcasting sperm (U.S. Department of Agriculture, 2004). Although the eggs are adhesive at first and may stick to plants or rocks, they loose their adhesive qualities after a few hours and settle to the substrate (Scott and Scott, 1988). Alewives deposit their eggs over any type of substrate (U.S. Department of Agriculture, 2004). The number of eggs per female may be 10,000 to 12,000 (Scott and Crossman, 1998) or 48,000-360,000 (Scott and Scott, 1988).
In anadromous populations, adult alewives spend most of their lives at sea but spawn in streams above the influence of the tide. Although they cannot jump obstacles such as dams, they surmount rapids and fish runs migrating farther upstream than the closely related American shad (Scott and Crossman, 1998). Anadromous fish reach maturity at 3 years for males and 4 years for females (Scott and Crossman, 1998).
Land-locked populations mature at 2 years for males and 3 years for females. These fish move close to shallow beaches or up streams to spawn. They move on-shore at night and off-shore during the day. Adults leave the shallows immediately after spawning and have moved to deep water by late August (Scott and Crossman, 1998). Eggs hatch in 6 days at a mean water temperature of 60°F (15.6°C) and in 3 days at 72°F (22.2°C) (Scott and Crossman, 1998). Their maximum hatching success occurs at 20.8°C (Grosvenor, 1965).
Breeding interval: Alewives breed yearly.
Breeding season: Spawning occurs during the spring.
Range number of offspring: 10,000 to 360,000.
Range gestation period: 3 to 6 days.
Range age at sexual or reproductive maturity (female): 3 to 4 years.
Range age at sexual or reproductive maturity (male): 2 to 3 years.
Key Reproductive Features: seasonal breeding ; sexual ; fertilization (External ); broadcast (group) spawning; oviparous
Alewives do not have any parental investment in their young beyond spawning. The adults leave immediately after spawning in the spring and the young move to the open water in the fall.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female)
The alewife (Alosa pseudoharengus) is an anadromous species of herring found in North America. It is one of the "typical" North American shads, attributed to the subgenus Pomolobus of the genus Alosa.[4] As an adult it is a marine species found in the northern West Atlantic Ocean, moving into estuaries before swimming upstream to breed in freshwater habitats, but some populations live entirely in fresh water. It is best known for its invasion of the Great Lakes by using the Welland Canal to bypass Niagara Falls. Here, its population surged, peaking between the 1950s and 1980s to the detriment of many native species of fish. In an effort to control them biologically, Pacific salmon were introduced, only partially successfully. As a marine fish, the alewife is a US National Marine Fisheries Service "Species of Concern".
Alewife reach a maximum standard length (SL) of about 40 centimetres (16 in), but have a typical SL of about 30 centimetres (12 in).[2] The front of the body is deep and larger than other fish found in the same waters.
Alewife have bronze-colored heads and a grey-blue[5] to greyish green[6] dorsum. A humeral spot is often present.[6] The tongue does not bear teeth.[7] The peritoneum is light-colored with spots[5] to dusky-appearing,[6] an internal feature that distinguishes alewife from blueback herring (Alosa aestivalis), which have a dark peritoneum.[5] The otolith is shaped like a letter "L", unlike its hooked shape in A. aestivalis.[8] Additionally, the eye is larger than that of A. aestivalis;[7] the width of the eye often exceeds the length of the snout in A. pseudoharengus.[6]
Its common name is said to come from comparison with a corpulent female tavernkeeper ("ale-wife"),[9] or, alternatively, from the word aloofe,[10][11] possibly of Native American origin,[12] that was used to describe this fish in the seventeenth and eighteenth centuries.
In southwestern Nova Scotia, alewife are referred to as kiacks (or kyacks).[13] In Atlantic Canada it is known as the gaspereau, from the Acadian French word gasparot, first mentioned by Nicolas Denys. William Francis Ganong, New Brunswick biologist and historian, wrote:
Gaspereau, or Gasparot. Name of a common salt-water fish of Acadia (also called alewife), first used, so far as I can find, by Denys in 1672. Nowhere can I find any clue to its origin. It seems not to be Indian.[14]
Acadians named two rivers after the fish, the Gaspereau River in Nova Scotia and the Gaspereau River in New Brunswick.
Both anadromous and landlocked forms occur. The landlocked form is also called a sawbelly or mooneye (although this latter name is more commonly applied to Hiodon spp.) Adult alewife are caught during their spring spawning migration upstream by being scooped out of shallow, constricted areas using large dip nets. They are the preferred bait for the spring lobster fishery in Maine,[15] and are eaten by humans, usually smoked.
Alewife are known for their invasion of the Great Lakes by using the Welland Canal to bypass Niagara Falls. Alewife colonized the Great Lakes and became abundant mostly in Lake Huron and Lake Michigan. They reached their peak abundance from the 1950s through the 1980s. Alewife grew in number unchecked because the lakes lacked a top predator (lake trout were essentially wiped out around the same time by overfishing and the invasion of the sea lamprey).
For a time, alewife, which often exhibit seasonal die-offs, washed up in windrows on the shorelines of the Great Lakes. Various species of Pacific salmon (first coho, and later the Chinook salmon) were introduced as predators. Though marginally successful, this led to the development of a salmon/alewife fishery popular with many sport anglers.
In spite of such biological control methods, alewife remain implicated in the decline of many native Great Lakes species. It is also a common predator of numerous native and non-native zooplankton taxa (e.g. Bythotrephes longimanus,[16] Leptodiaptomus ashlandi, Limnocalanus spp.,[17] Leptodiaptomus minutus, Leptodiaptomus sicilis, and Leptodora kindtii[18]). Wells (1970) found that increases in population of alewife in the Great Lakes between 1954 and 1966 were associated with population declines in certain larger species of zooplankton, while an alewife die-off in 1967 was temporally related to population rebound in most of those species.[18]
Alewife populations have seen big declines throughout much of their range. Several threats have most likely contributed to their decline, including loss of habitat due to decreased access to spawning areas from the construction of dams and other impediments to migration, habitat degradation, fishing, and increased predation due to recovering striped bass populations.
In response to the declining population trend for alewives, the states of Massachusetts, Rhode Island, Connecticut, Virginia, and North Carolina have instituted moratoria on taking and possession.
In eastern Massachusetts, Alewife Brook flows through Arlington, Cambridge, and Somerville to the Mystic River. The brook gives its name to the Alewife Brook Parkway and the Alewife Brook Reservation. The Red Line (MBTA) of Boston's T ends at the Alewife station, so the name of this fish adorns the front of every northbound Red Line train. An extensive habitat restoration and education project, combined with a fish ladder with monitoring cameras, is yielding increasing numbers of alewife back in the improving Mystic River watershed.[19]
The alewife is a US National Marine Fisheries Service Species of Concern,[20] about which the National Oceanic and Atmospheric Administration, National Marine Fisheries Service, has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the US Endangered Species Act.
The alewife (Alosa pseudoharengus) is an anadromous species of herring found in North America. It is one of the "typical" North American shads, attributed to the subgenus Pomolobus of the genus Alosa. As an adult it is a marine species found in the northern West Atlantic Ocean, moving into estuaries before swimming upstream to breed in freshwater habitats, but some populations live entirely in fresh water. It is best known for its invasion of the Great Lakes by using the Welland Canal to bypass Niagara Falls. Here, its population surged, peaking between the 1950s and 1980s to the detriment of many native species of fish. In an effort to control them biologically, Pacific salmon were introduced, only partially successfully. As a marine fish, the alewife is a US National Marine Fisheries Service "Species of Concern".
