| Alewife | |
|---|---|
 | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Clupeiformes |
| Family: | Alosidae |
| Genus: | Alosa |
| Subgenus: | Pomolobus |
| Species: | A. pseudoharengus |
| Binomial name | |
| Alosa pseudoharengus | |
| Synonyms[3] | |
| |
Thealewife (Alosa pseudoharengus;pl.:alewives[4]) is ananadromous species ofherring found inNorth America. It is one of the "typical" North Americanshads, attributed to thesubgenusPomolobus of the genusAlosa.[5] As an adult it is a marine species found in the northern West Atlantic Ocean, moving into estuaries before swimming upstream to breed infreshwater habitats, but some populations live entirely in fresh water. It is best known for its invasion of theGreat Lakes by using theWelland Canal to bypassNiagara 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 it biologically,Pacific salmon were introduced, only partially successfully. As a marine fish, the alewife is a USNational Marine Fisheries Service "Species of Concern".
Alewife reach a maximumstandard 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[6] to greyish green[7] dorsum. Ahumeral spot is often present.[7] The tongue does not bear teeth.[8] Theperitoneum is light-colored with spots[6] to dusky-appearing,[7] an internal feature that distinguishes alewife fromblueback herring (Alosa aestivalis), which have a dark peritoneum.[6] Theotolith is shaped like a letter "L", unlike its hooked shape inA. aestivalis.[9] Additionally, the eye is larger than that ofA. aestivalis;[8] the width of the eye often exceeds the length of the snout inA. pseudoharengus.[7]
Its common name is said to come from comparison with a corpulent female tavernkeeper ("ale-wife"),[10] or, alternatively, from the wordaloofe,[11][12] possibly ofNative American origin,[13] that was used to describe this fish in the seventeenth and eighteenth centuries.
In southwesternNova Scotia, alewife are referred to as kiacks (or kyacks).[14] InAtlantic Canada it is known as the gaspereau, from theAcadian French wordgasparot, first mentioned byNicolas 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 in1672. Nowhere can I find any clue to its origin. It seems not to beIndian.[15]
Acadians named three rivers after the fish, theGaspereau River in Nova Scotia, as well as theGaspereau River nearGrand Lake andGaspereau River nearNorthumberland Strait that are both inNew Brunswick.
Bothanadromous and landlocked forms occur. The landlocked form is also called a sawbelly or mooneye (although this latter name is more commonly applied toHiodon spp.) Adult alewife are caught during their spring spawning migration upstream by being scooped out of shallow, constricted areas using largedip nets. They are the preferred bait for the spring lobster fishery in Maine,[16] and are eaten by humans, usually smoked.
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Alewife are known for their invasion of theGreat Lakes by using theWelland Canal to bypassNiagara Falls. Although theUnited States Department of Agriculture suggests they may be native toLake Ontario,[17] alewife colonized the other Great Lakes and became abundant mostly inLake Huron andLake Michigan. It appears that they had spread fromLake Erie to other Great Lakes by theDetroit River andLake St. Clair.[17] 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 byoverfishing and the invasion of thesea lamprey)[18]
For a time, alewife, which often exhibit seasonal die-offs, washed up inwindrows on the shorelines of the Great Lakes. Various species ofPacific salmon (firstcoho, and later theChinook salmon) were introduced aspredators. Though marginally successful, this led to the development of a salmon/alewife fishery popular with manysport anglers.[citation needed]
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,[19]Leptodiaptomus ashlandi,[citation needed]Limnocalanus spp.,[20]Leptodiaptomus minutus,[citation needed]Leptodiaptomus sicilis,[citation needed] andLeptodora kindtii[21]). 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.[21]
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Alewife populations have seen big declines throughout much of theirrange. Several threats have most likely contributed to their decline, including loss ofhabitat 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 institutedmoratoria on taking and possession.
In eastern Massachusetts, Alewife Brook flows through Arlington, Cambridge, and Somerville to theMystic River. The brook gives its name to theAlewife Brook Parkway and theAlewife Brook Reservation. TheRed Line (MBTA) of Boston's T ends at theAlewife 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.[22]
The alewife is a US National Marine Fisheries Service Species of Concern,[23] 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 USEndangered Species Act.
