(DRAFT) - Taxonomy
Species shad, American
Species Id M010040
Date 26 AUG 96
TAXONOMY
NAME - shad, American
OTHER COMMON NAMES - shad, common shad, alose, Susquehanna shad, Delaware shad, Connecticut river shad, Potomac river shad, white shad, Buck shad, Poplarback shad and Atlantic shad
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - Chordata, Vertebrata
CLASS AND SUBCLASS - Osteichthyes, Actinopterygii
ORDER AND SUBORDER - Clupeiformes, Clupeoidei
FAMILY AND SUBFAMILY - Clupeidae, Alosinae
GENUS AND SUBGENUS - Alosa,
SPECIES AND SSP - sapidissima,
SCIENTIFIC NAME - Alosa sapidissima
AUTHORITY - Wilson
TAXONOMY REFERENCES - 23
COMMENTS ON TAXONOMY -
Other common names include shad, Alose, common shad, Atlantic shad, North
River shad, Potomac shad, Connecticut River shad, Delaware shad, Susquehanna
shad, white shad, buck shad, poplarback shad *23*.
Taxonomy - 1 (DRAFT) - Status
Species shad, American
Species Id M010040
Date 26 AUG 96
STATUS
Coded Status
Sport Fish
Commercial
Possibly in peril need more information
Commercial/consumption
REFERENCES FOR STATUS - 23
COMMENTS ON STATUS -
Historically an important commercial Fishery but fishery has collapsed and
is important only in a few rivers (Connecticut R., Neuse R., Hudson R., York
R.) in the mid-Atlantic region. In the rivers that support strong runs,
sport fishing for shad is more important than commercial fishing *23*.
Status - 1 (DRAFT) - Distribution
Species shad, American
Species Id M010040
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
HABITAT - ACQUATIC
LAND USE -
Water
Bays and Estuaries
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine OW0
Estuarine OW0
Estuarine OW0
Estuarine, subtidal OW0
Marine RB.
Estuarine RB.
Estuarine RB.
Estuarine RB.
Marine RB1
Estuarine RB1
Estuarine RB1
Estuarine RB1
Marine RB2
Estuarine RB2
Estuarine RB2
Estuarine RB2
Marine OW0 V
Estuarine OW0 V
Estuarine RB. V
Estuarine RB. V
Marine RB1 1
Marine RB1 2
Marine RB2 3
Marine RB2 4
Marine SS7 5
Marine SS7 6
Marine UB. 7
Marine UB. 8
Marine UB1 9
Estuarine UB1 0
Estuarine UB2 0
Estuarine UB2 0
Marine UB3
Estuarine UB3
Marine UB4
Estuarine UB4
Marine
Estuarine
Marine
Estuarine
Marine V
Estuarine V
Marine
Estuarine
Marine
Estuarine
Marine
Estuarine
Habitat Associations - 1
NWI NWICLS NWIMOD NWISPEC
Marine
Estuarine
Marine
Estuarine
Marine
Estuarine
Marine 1
Estuarine 1
Marine 2
Estuarine 2
Marine 3
Estuarine 3
Marine 4
Estuarine 4
Marine 5
Estuarine 5
Marine 6
Estuarine 6
Marine 7
Estuarine 7
Marine 8
Estuarine 8
Marine 9
Estuarine 9
Habitat Associations - 2 (DRAFT) - Food Habits
Species shad, American
Species Id M010040
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
REFERENCES FOR TROPHIC LEVEL - 23 and 136
LIFESTAGE FOOD FOOD PART
General Crustaceans Adult stage
General Crustaceans See Comments
General Copepods Adult stage
General Copepods See Comments
General Insects Adult stage
General Insects See Comments
General Osteichthyes Egg/Fetus stage
General Osteichthyes Adult stage
General Osteichthyes See Comments
Important Copepods Not Specified
Important Malacostraca Not Specified
Important Osteichthyes Juvenile stage
Important Osteichthyes Adult stage
Juvenile Crustaceans Not Specified
Juvenile Copepods Not Specified
Juvenile Insects Not Specified
Juvenile Osteichthyes Juvenile stage
Juvenile Osteichthyes Adult stage
Adult Crustaceans Not Specified
Adult Copepods Not Specified
Adult Malacostraca Not Specified
Adult Insects Not Specified
Adult Osteichthyes Juvenile stage
Adult Osteichthyes Adult stage
Important Crustaceans Not Specified
Important Ostracods Not Specified
Important Insects Not Specified
Larva Ostracods Not Specified
Larva Copepods Adult stage
Larva Insects Adult stage
Juvenile Insects Adult stage
Juvenile Insects Larva stage
Juvenile Trichoptera Larva stage
Juvenile Trichoptera Adult stage
Juvenile Diptera Larva stage
Juvenile Diptera Adult stage
Adult Ostracods Not Specified
Larva Copepods Not Specified
Larva Branchiopods Not Specified
Larva Diptera Larva stage
Larva Diptera Pupa stage
REFERENCES FOR GENERAL FOOD - 23
Food Habits - 1 (DRAFT) - Food Habits
Species shad, American
Species Id M010040
Date 26 AUG 96
REFERENCES FOR IMPORTANT FOOD - 23
REFERENCES FOR JUVENILE FOOD - 23
REFERENCES FOR LARVAE FOOD - 136
COMMENTS ON FOOD -
Young American shad in rivers feed mostly in the water column. After going
to sea, juveniles and adults feed on a variety of small crustaceans, many of
which are benthic organisms. Food was scarce in the stomachs of shad
migrating upstream to spawn *23*.
COMMENTS ON LARVAE FOOD -
Shad larvae consume cyclopoid copepods, midge larvae, midge pupae, and
Daphnia pulex *136*.
Food Habits - 2 (DRAFT) - Environment Associations
Species shad, American
Species Id M010040
Date 26 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Water Temperature: Specified in Comments
G Dissolved Oxygen: Specified in Comments
G Substrate: Mud or silt
G Substrate: Sand
G Substrate: Rocks
G Substrate: Wood
G Substrate: Animals
G Substrate: Plants
G Relation to Substrate: Unattached - normally free living
G Water pH: Between 6.5-8.5
LIM Water Temperature: Specified in Comments
BA Aquatic Features: Specified in Comments
BA Estuarine habitat zone: specified in comments
BA
E
E
E
E Water Temperature: Between 15-21 degrees C
E Water Temperature: Below 15 degrees C
E Water Temperature: Specified in Comments
BA Water Depth Preference: Specified in Comments
BA Substrate: Rocks
BA Substrate: Sand
BA Substrate: Specified in Comments
BA Water Velocity [Instream Flow Group Increments]: Specified in Comments
E Water Velocity [Instream Flow Group Increments]: Specified in Comments
E Water Temperature: Between 21-27 degrees C
L Water Temperature: Between 21-27 degrees C
L Water Temperature: Between 15-21 degrees C
L Water Temperature: Specified in Comments
E Water pH: Between 5.0-6.5
E Water pH: Between 8.5-10.0
E Water pH: Specified in Comments
L Water pH: Between 5.0-6.5
L Water pH: Between 8.5-10.0
L Water pH: Specified in Comments
L Dissolved Oxygen: Low [less than 5 mg/l] oxygen concentrations
L Dissolved Oxygen: Specified in Comments
L Dissolved Oxygen: Moderate [5-7 mg/l] oxygen concentrations
J Water Temperature: Between 15-21 degrees C
Environment Associations - 1 (DRAFT) - Environment Associations
Species shad, American
Species Id M010040
Date 26 AUG 96
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
J Water Temperature: Below 15 degrees C
J Water Temperature: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 23
REFERENCES FOR FEEDING ADULT ENVIRONMENTAL ASSOC_ - 23
REFERENCES FOR RESTING ADULT ENVIRONMENTAL ASSOC_ - 23
REFERENCES FOR BREEDING ADULT ENVIRONMENTAL ASSOC_ - 23 and 136
REFERENCES FOR JUVENILE ENVIRONMENTAL ASSOC_ - 136
REFERENCES FOR LARVAE ENVIRONMENTAL ASSOC_ - 136
REFERENCES FOR EGG ENVIRONMENTAL ASSOC_ - 23 and 136
COMMENTS ON RESTING ADULT ENVIRONMENTAL ASSOC_ -
The American shad adapts readily to either freshwater or seawater during
migration. The species is intolerant of cold water temperatures and
requires well-oxygenated waters either in rivers or in the sea. Little
depth preference is shown. Water velocity is crucial because shad must
negotiate river currents and occasional fishways when migrating upstream,
and pass safely over spillways when going dowmstream. For any fishway to
work, proper current at the entrance is essential *23*.
COMMENTS ON BREEDING ADULT ENVIRONMENTAL ASSOC_ -
Eggs are always deposited in freshwater and are believed to be intolerant
of full-strength seawater. Spawning runs into rivers at various latitudes
on the Pacific and Atlantic coasts of North America peak at water
temperatures of 15.5 to 20.0 deg C. American shad have been observed to
spawn successfully over silt, mud, sand, gravel, and boulders. Spawning
has been observed in rivers at depths ranging from 0.45 to 7 m. Spawning
normally takes place at water velocities of 30 to 90 cm/sec *23*.
Characteristic spawning and nursery grounds for shad are tidal freshwaters
in estuaries and rivers; however, some shad can tolerate moderate
salinities. Shad spawning areas vary in depth and substrate. Shad seem to
prefer areas dominated by shallow water or broad flats with sand or gravel
bottoms. Preferred velocities in spawning waters range from 30.5 to 91.4
cm/sec *136*.
COMMENTS ON JUVENILE ENVIRONMENTAL ASSOC_ -
Young remain in the nursery area until water temperatures begin to decrease
in the fall. The downstream migration begins at a water temperture of
approximately 21.1 degrees C. All young have left the nursery grounds by
the time the temperature reaches 8.3 degrees C *136*.
COMMENTS ON LARVAE ENVIRONMENTAL ASSOC_ -
Larval mortality was high at suspended sediment concentrations greater than
100 mg/l for 96 hours. Maximum survival of larvae occurs at 15.5-26.6
Environment Associations - 2 (DRAFT) - Environment Associations
Species shad, American
Species Id M010040
Date 26 AUG 96
degrees C. Temperatures of 7-9 degrees C were reported to be lethal to
larvae and temperatures of 20.0-23.4 degrees C caused extensive larval
abnormalities. The LD50 for acid pH was 5.5 and it was 9.5 for basic pH.
Larval shad LD50 for low dissolved oxygen (DO) ranges from 2.0-3.5 ppm,
depending on the population. Larvae exhibit significant signs of stress
when exposed to a DO level of 3.0 mg/l, and many died at 2.0 mg/l. A DO
level of >5.0 ppm is considered optimum. Larvae remain near the spawning
grounds, usually a short distance downstream *136*.
COMMENTS ON EGG ENVIRONMENTAL ASSOC_ -
Characteristic nursery grounds for shad are tidal freshwaters in estuaries
and rivers; however, some shad can tolerate moderate salinities. Successful
hatches have been reported at salinities ranging from 7.5 ppt at 12.0 oC to
15 ppt at 17 oC. No eggs hatched at a salinity of 22.5 ppt. Sufficient
water current velocitites are required to keep the shad eggs suspended in
the water column. Exposure of the eggs to suspended sediment concentrations
as high as 1,000 mg/l did not affect hatching success. Eggs hatch in 12 to
45 days at 12 degrees C and in 6 to 8 days at 17 degrees C. Maximum
survival of eggs occurs at 15.5-26.6 degrees C. Temperatures of 7-9 degrees
C were reported to be lethal to eggs. The LD50 for acid pH was 5.5 and it
was 9.5 for basic pH. Mortality of eggs was 100% at DO levels below 1.0
mg/l *136*.
Environment Associations - 3 (DRAFT) - Life History
Species shad, American
Species Id M010040
Date 26 AUG 96
LIFE HISTORY
PHYSICAL DESCRIPTION:
The American Shad is greenish, bluish, or brownish above, silvery below;
have dark shoulder spot sometimes followed by one or more small spots. Body
elongate, strongly compressed laterally and rather deep its depth 17 to 19%
of total length; bony scutes rather prominent with sharp points; a sharp
edge on median line of chest and abdomen. Mouth large, head broadly
triangular; teeth small and weak and few in number on premaxillary and
mandible and absent on the roof of the mouth. Number of dorsal rays 14 to
21 (usually 18 - 19); anal rays 18 - 25 (usually 21 - 22); pelvic (ventral)
rays 8-10; lateral line scales 52-64; 15-16 scale rows between base of
pelvics and anterior dorsal. American shad lives to be 5-7 years old; most
weigh between 1 to 3 kg; average total length is about 380mm.
REPRODUCTION:
Minimum age at sexual maturity is 2 years for both males and females.
Males become sexually mature when they are 3 to 5 years old and the females
mature at 4 to 6 years old. Water temperature is the primary factor
that triggers spawning. Most spawning is from 13 deg to 20 deg C and time
period ranges from mid Nov in Florida to July in Canadian rivers. Shad will
spawn in tidal or non tidal freshwater over broad flats with sand, silt,
muck, gravel substrates. They spawn in water depths about 1 - 10 meters but
often less than 3 meters. Current in spawning areas ranges from about 0.5 -
3 ft/sc. Shad lives several years in the ocean and them returns to its river
of origin to spawn. Males arrive before females. Spawning takes place at
all hours of the day and night but is more intense from noon to midnight.
BEHAVIOR:
Larvae remain near the spawning grounds, usually a short distance
downstream. Juveniles spend their first summer in the river; in fall they
migrate down the river to brackish water and then to the sea. A decrease
in river water temperature seems to trigger the migration. Shad migrate
seaward first in the Northern rivers and progressively later in southern
rivers. Once in the ocean, the shad remain there until they mature. The
American Shad in the Mid-Atlantic region form large schools and undertake
extensive ocean migration. It migrates as much as 21 km /day in Chesapeake
bay and Bay of Fundy. Some migrate up to 3000 km during Spring and Fall
migration. They return to natal river to spawn.
LIMITING FACTORS:
American Shad is intolerant of cold water temperatures.
It requires well oxygenated waters either in river or in sea. Larvae
intolerant of full strength ocean water.
POPULATION ATTRIBUTES:
The A.S. has a high fecundity (116000 to 659,000 eggs per female). Many
eggs fail to fertilize and only a small percentage hatch. High egg
mortality has been attributed to failure to fertilize, suffocation, fungus
infection and predation.
SPECIES INTERACTIONS:
Predators include American eel (Anguilla rostrata), catfishes, seals,
Life History - 1 (DRAFT) - Life History
Species shad, American
Species Id M010040
Date 26 AUG 96
sharks, bluefish tuna, Kingfish and porpoises. Adults have few enemies
except for humans.
SPAWNING: Spawning runs may begin as early as February, but are most
frequent in April. Characteristic spawning and nursery grounds for shad
are tidal freshwaters in estuaries and rivers; however, some shad can
tolerate moderate salinities. Successful hatches have been reported at
salinities ranging from 7.5 ppt at 12.0 oC to 15 ppt at 17 oC. No eggs
hatched at a salinity of 22.5 ppt. Shad spawning areas vary in depth and
substrate. Shad seem to prefer areas dominated by shallow water or broad
flats with sand or gravel bottoms. Sufficient water current veloitites are
required to keep the shad eggs suspended in the water column. Preferred
velocities in spawning waters range from 30.5 to 91.4 cm/sec. Exposure of
the eggs to suspended sediment concentrations as high as 1,000 mg/l did not
affect hatching success, but larval mortality was high at suspended sediment
concentrations greater than 100 mg/l for 96 hours *136*.
ENVIRONMENTAL CONDITIONS: Eggs hatch in 12 to 45 days at 12 degrees C and
in 6 to 8 days at 17 degrees C. Maximum survival of eggs and larvae occurs
at 15.5-26.6 degrees C. Temperatures of 7-9 degrees C were reported to be
lethal to eggs and larvae and temperatures of 20.0-23.4 degrees C caused
extensive larval abnormalities. The LD50 for acid pH was 5.5 and it was 9.5
for basic pH. Larval shad LD50 for low dissolved oxygen (DO) ranges from
2.0-3.5 ppm, depending on the population. Mortality of eggs was 100% at DO
levels below 1.0 mg/l. Larvae exhibit significant signs of stress when
exposed to a DO level of 3.0 mg/l, and many died at 2.0 mg/l. A DO level of
>5.0 ppm is considered optimum. Larvae remain near the spawning grounds,
usually a short distance downstream. Young remain in the nursery area until
water temperatures begin to decrease in the fall. The downstream migration
begins at a water temperture of approximately 21.1 degrees C. All young
have left the nursery grounds by the time the temperature reaches 8.3
degrees C *136*.
LIFE HISTORY CODES -
Hybrid
Reintroduced Native
Stocked
Breeding/Spawning Season: February
Breeding/Spawning Season: March
Breeding Spawning Season: April
Gestation/Incubation Period: 1-2 weeks
Gestation/Incubation Period: 3-4 weeks
Gestation/Incubation Period: 1-2 months
REFERENCES FOR LIFE HISTORY- 23 and 136
Life History - 2 (DRAFT) - Management Practices
Species shad, American
Species Id M010040
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Regulating harvest - setting seasons
Beneficial Regulating harvest - setting bag/creel limits
Beneficial Regulating commercial harvest levels
Beneficial Regulating commercial harvest gear types
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 23
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 23
REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 23
COMMENTS ON MANAGEMENT PRACTICES -
Connecticut- The season is open to commercial fishing from April 1 to June
15. During the season, fishing is prohibited from Friday sunset to Sunday
sunset. Monofilament gill nets are prohibited and the gill nets used must
have a minimum stretch measure of five inches. There are no size or sex
restrictions. License holders must report their catch at the end of each
fishing season. Sport fishing for shad is permitted from April 1 to a
closing date determined each year. Angling and scoop nets are permitted in
streams. The daily bag limit is six fish *23*.
New Jersey- Attempts at restoration were unsuccessful *23*.
Delaware- The legal commercial gear is 5- to 6-inch (stretch measure) gill
nets. Fishing is allowed from March until early May *23*.
Maryland- A sharp decline in the commercial catch of American shad led to
the closure of waters to shad fishing with the exception of the Potamac
River and coastal waters *23*.
Abundance in some rivers is limited by pollution or restricted by dams.*23*
Pool-and-weir fishways, vertical-baffle fishways, and elevators are better
carriers of American shad than traditional fishways *23*.
Management Practices - 1 (DRAFT) - References
Species shad, American
Species Id M010040
Date 26 AUG 96
References
23 * MacKenzie, C., L. Weiss-Glanz, J. Moring. 1985. Species
Profiles: Life Histories and Environmental Requirements of
Coastal Fishes and Invertebrates (Mid-Atlantic)--American Shad.
U.S. Fish and Wildlife Service Biol. Rep. 82(11.37) pp 18.
136 * Chesapeake Bay Program. 1988. Habitat Requirements for
Chesapeake Bay Living Resources. Chesapeake Executive
Council pp 86.
References - 1