Description
The rainbow smelt, a small fish eagerly pursued by anglers because
of its fine flavor, is found along the coastal inshore areas of
northeastern North America from Newfoundland to New Jersey, but
is most abundant from the southern Canadian Maritime Provinces
south to Massachusetts. Once exclusively an anadromous species
(residing in saltwater, but entering freshwater to reproduce),
the smelt has been successfully introduced into freshwater systems
throughout the northeastern and central United States.
The rainbow smelt is slender, with a pointed head and a large
mouth. This species can be distinguished from other small-bodied
species along the Massachusetts coast by the presence of relatively
large teeth, a deeply forked tail, and a small adipose fin. The
smelt is mostly silver in color with various shiny hues along
lateral line and a pale green dorsal surface.
Smelt length at age
| Age |
Length (inches)
|
| |
males
|
females
|
|
|
1
|
5.6
|
5.6
|
|
2
|
7.4
|
7.8
|
|
3
|
8.2
|
8.6
|
|
4
|
9.3
|
9.6
|
|
5
|
9.5
|
9.8
|
|
|
Large smelt may reach 13 to 14 inches in length, but most adults
do not exceed 7 to 9 inches, and 1 to 6 ounces in weight. Females
are larger than males of identical age after their first year
of life. The table to the left lists average lengths of adult
fish in a population studied within the Parker River estuary of
Massachusetts. Few smelt live beyond 5 years of age.
Both sexes become sexually mature at about 2 years of age, although
some 1-year-olds may participate in spawning. Fecundity (number
of eggs produced by a female per spawning season) ranges from
33,400 eggs for a 6 ½ inch fish to 75,600 for a 9 inch
fish.
Habits
Smelt are a pelagic, schooling species that spends most of
its time in nearshore waters. Their movement patterns are associated
with seasonal changes in water temperatures. In summer, schools
move to deeper, cooler, waters; in the fall they enter bays and
estuaries where they actively feed until the onset of winter.
During winter months, both adults and juveniles are found between
estuary mouths and the brackish water areas of coastal streams.
The spawning season in Massachusetts begins in late February south
of Cape Cod and early March along Massachusetts Bay. The onset
of spawning is influenced by an increase in water temperatures
to about 40 to 42 degrees F, increasing day length, and the break-up
of ice covering the water's surface at the spawning grounds.
To spawn, rainbow smelt move from estuaries into fresh or slightly
brackish stream stretches where they release eggs and milt. Upstream
movement to the spawning ground typically occurs during floor
tides, and spawning occurs only at night. Adults move back downstream
into resting areas in estuaries before sunrise. Most spawning
occurs in fast flowing, turbulent water in stream sections dominated
by rocks, boulders and aquatic vegetation. Fertilized eggs sink
and adhere to each other and to any stationary material on the
stream bottom. Eggs display the highest rates of survival when
deposited in high velocity water, and on aquatic vegetation rather
than bare rock substrates or sediment. Smelt eggs laid in low
velocity areas suffer extremely high death rates due to siltation
and possibly to inadequate amounts of dissolved oxygen.
Larvae are about ¼ inch long when they hatch and carry
about a week supply of nutrition in a yolk sac. They move passively
downstream in freshwater currents until reaching estuarine waters.
By mid-summer, the juveniles reside in the deeper waters of estuaries,
particularly during daylight hours.
Larvae and juveniles feed upon zooplankton, particularly microscopic
crustaceans. Adult smelt feed primarily on small crustaceans and
fish. In shoreline areas of Massachusetts Bay, smelt often key
on sand and mysid shrimps. Smelt in turn are an important prey
for a variety of predatory fish, including, striped bass, bluefish;
and several bird and marine mammal species. Mortality due to predation
is quite high for this species: up to 72% of adult fish die annually.
Management
Coastal smelt stocks throughout New England declined markedly
by the 20th century, due to the construction of dams and to reduction
in water quality. In some areas, after dams cut off traditional
spawning grounds, eggs were deposited so densely in downstream
sites that fungal infections caused massive egg mortality. High
egg mortality also occurred due to siltation in watersheds experiencing
extensive development. In 1874, the Massachusetts legislature
initiated legislation to protect smelt in the Commonwealth. Starting
about 1910, a widespread stocking program was established to restore
smelt runs. Two methods were attempted. Specially constructed
trays were placed in stream sites where extensive spawning was
still occurring. After its surface was covered with developing
eggs, each tray was transferred to streams that have been identified
for smelt restoration. Transplanting was also attempted by stocking
adult fish that were ready to spawn. These restoration efforts
appeared to provide little or limited benefits to local stocks.
Coastal smelt populations have not shown much improvement in recent
decades, although specific watersheds produced occasional pulses
of recruitment. Impediments to passage and the degradation of
spawning habitat are thought to contribute to the ongoing poor
status of local smelt populations.
Coastal stocks in Massachusetts are managed by the Division of
Marine Fisheries, and inland ones by the Division of Fisheries
and Wildlife. Management of coastal stocks in the 1980s included
evaluation of environmental problems within watershed and regulation
of the fisheries. Harvest was limited to hook-and-line fishing
in most rivers, with dip-netting allowed in only one or two designated
watersheds. Also, fishing was closed annually during the spawning
season (closed March 15th through June 15th).
