Alosa sapidissima

  • Scientific name

    • Alosa sapidissima (Wilson, 1811)

  • Common name

    • American shad

  • Family

    • Clupeidae

  • External links

    • Fishbase
Trait completeness 80%
Total data224
References25
Image of Alosa sapidissima

Author: Fabrice Téletchéa
License: All rights reserved

Traits detail

Egg (100.0%)

Trait id Trait Primary data Secondary Data References
1 Oocyte diameter >1.6 [Hydrated yolked oocytes] 1.6 mm Olney et al, 2001
1 Oocyte diameter 1.8 [Unfertilized egg] 1.8 mm Mills, 2004
1 Oocyte diameter Two modes for hydrated oocytes: 1.8 and 2.0 [Range from 1.6 to 2.4] 1.8 mm Olney and McBride, 2003
1 Oocyte diameter 0.8-1.27 1.04 mm Anonymous, 2006 Chapter 3
2 Egg size after water-hardening 2.5-3.5 [Fertilized eggs] 3.0 mm Scott and Crossman, 1973
2 Egg size after water-hardening 2.5-3.5 3.0 mm Mellinger, 2002
2 Egg size after water-hardening 2.5-3.8 3.15 mm Internet, 2005
2 Egg size after water-hardening 2.5-3.8 [Min-max] 3.15 mm Fishbase, 2006
2 Egg size after water-hardening 2.5-3.8 [Not specifed] 3.15 mm Mills, 2004
2 Egg size after water-hardening 2.5-3.8 3.15 mm Burdick and Hightower, 2005
2 Egg size after water-hardening Average egg diameter was 3.4 mm 3.4 mm Zydlewski and McCormick, 1997
3 Egg Buoyancy Demersal, semi-demersal or slightly heavier than fresh water, suspended by water-current [a moderate current (about 1 meter per second or less) will keep eggs floating] Demersal Internet, 2005
3 Egg Buoyancy Only slightly heavier than water, they settle singly and are carried along by the current No category Scott and Crossman, 1973
3 Egg Buoyancy Demersal, semi-demersal or slightly heavier than fresh water, suspended by water-current [a moderate current (about 1 meter per second or less) will keep eggs floating] Demersal Everly and Boreman, 1999
3 Egg Buoyancy Slightly heavier than water and are carried by the currents and gradually sink Demersal Mills, 2004
3 Egg Buoyancy On the bottom (demersal) Demersal Fishbase, 2006
3 Egg Buoyancy Semi-demersal to pelagic Pelagic Rue, 2001
3 Egg Buoyancy In coastal habitats, females lay demersal eggs Demersal Anonymous, 2006 Chapter 3
3 Egg Buoyancy Eggs are released into open water where they are carried along by currents, and being slightly heavier than water, gradually sink to the bottom Demersal Bradbury et al, 1999
3 Egg Buoyancy Shortly after being spawned, the water-hardened eggs start to sink. [described as either demersal or semidemersal depending on whether the researcher assume that eggs stayed on the bottom or were lifted off the bottom by turbulent current. Some eggs remained suspended in the water column for several kilometers] Demersal Burdick and Hightower, 2005
3 Egg Buoyancy Calculations based on eggs ages when collected indicate most eggs traveled only 1 to 4 miles from where spawned. Pelagic Marcy, 1972
4 Egg adhesiveness Initially adhesive or slightly adhesive and then non-adhesive Non-Adhesive Internet, 2005
4 Egg adhesiveness Non-adhesive Non-Adhesive Scott and Crossman, 1973
4 Egg adhesiveness Not sticky Non-Adhesive Fishbase, 2006
4 Egg adhesiveness Non-adhesive Non-Adhesive Everly and Boreman, 1999
4 Egg adhesiveness Initially adhesive and later become non-adhesive Non-Adhesive Mills, 2004
4 Egg adhesiveness Nonadhesive Non-Adhesive Bradbury et al, 1999
4 Egg adhesiveness Initially adhesive but quickly become non-adhesive Non-Adhesive Burdick and Hightower, 2005
5 Incubation time 8-12 [11-15°C] or 17 [12°C] 10.0 days Internet, 2005
5 Incubation time 8-12 days at 11-15°C 10.0 days Scott and Crossman, 1973
5 Incubation time 7 [15.50°C], 13.50 [12.00°C] 7.0 days Fishbase, 2006
5 Incubation time 2-17 [But 12-15 at 12°C] 9.5 days Everly and Boreman, 1999
5 Incubation time 4-6 [15-18°C], 6-8 [17°C], 8-12 [11-15°C] 5.0 days Mills, 2004
5 Incubation time 2 [24°C], 3 [23.3°C], 7 [15°C], 11 |13.30], 13.5 [12.00] 2.0 days Fishbase, 2006
5 Incubation time 2-17 depeding on temperature 9.5 days Rue, 2001
5 Incubation time 8-12 at 11-15°C 10.0 days Bradbury et al, 1999
5 Incubation time Development of eggs starts between 13°C and 17°C and increases rapidly between 17°C and 20°C 13.0 days Burdick and Hightower, 2005
5 Incubation time Hatching occurred on June 13, i.e. 6-7 days at 16.6-19°C 6.5 days Zydlewski and McCormick, 1997
5 Incubation time Eggs were fertilized and reared in the laboratory at temperatures similar to those in the river (13.8-23.0°C). Hatching occurred 71 to 86 hours after fertilization 18.4 days Marcy, 1972
5 Incubation time Hatched from eggs 6 days after fertilization. […] The temperature of water during the egg incubation and larval development was 17-18°C 17.5 days Laiz-Carrion et al, 2003
6 Temperature for incubation 11-15 13.0 °C Internet, 2005
6 Temperature for incubation 11-15 13.0 °C Scott and Crossman, 1973
6 Temperature for incubation 15.5-26.5 [Optimum temperature] 21.0 °C Carscadden and Leggett, 1975
6 Temperature for incubation 17 17.0 °C Fishbase, 2006
6 Temperature for incubation 12-15.50, up to 27 13.75 °C Fishbase, 2006
6 Temperature for incubation 12 12.0 °C Everly and Boreman, 1999
6 Temperature for incubation 17 is considered optimal [The survival rate decreases at 24°C] 17.0 °C Mills, 2004
6 Temperature for incubation 13-26 are required for the development and survival of eggs 19.5 °C Rue, 2001
6 Temperature for incubation 11-15°C 13.0 °C Bradbury et al, 1999
6 Temperature for incubation Filtered Connecticut river water (16.6-19°C during incubation) was supplied to an upwelling jar 17.8 °C Zydlewski and McCormick, 1997
6 Temperature for incubation Eggs required temperatures > 13°C. Incubation temperatures was 17°C 13.0 °C Leach and Houde, 1999
6 Temperature for incubation Glass aquaria contaning fresh water held at room temperature 20.6°C 20.6 °C Limburg and Ross, 1995
6 Temperature for incubation The temperature of water during the egg incubation and larval development was 17-18°C 17.5 °C Laiz-Carrion et al, 2003
7 Degree-days for incubation About 120-150 135.0 °C * day Internet, 2005
7 Degree-days for incubation 120-140 [8-12 days at 11-15°C] 130.0 °C * day Scott and Crossman, 1973
7 Degree-days for incubation 108.5-162 135.25 °C * day Fishbase, 2006
7 Degree-days for incubation 130-150 [12-15 days at 12°C] 140.0 °C * day Everly and Boreman, 1999

Larvae (86.0%)

Trait id Trait Primary Data Secondary Data References
8 Initial larval size 6.5-10 8.25 mm Internet, 2005
8 Initial larval size 9-10 9.5 mm Scott and Crossman, 1973
8 Initial larval size 8.7 8.7 mm Wiggins et al, 1985
8 Initial larval size Either 9-10; 6-10 9.5 mm Mills, 2004
8 Initial larval size Larvae hatch at a size of approximatively 2.5-5.0 mm 3.75 mm Anonymous, 2006 Chapter 3
9 Larvae behaviour Newly larvae are pelagic, and most abundant at the surface Pelagic Internet, 2005
9 Larvae behaviour Both feeding and yolksac larvae are planktonic [Dispersal therefore occurs by passive transport] Demersal Everly and Boreman, 1999
9 Larvae behaviour Larvae are planktonic for about 4 weeks Demersal Mills, 2004
9 Larvae behaviour Larvae are planktonic and do not metamorphose into juveniles for 4-5 weeks Demersal Bradbury et al, 1999
9 Larvae behaviour Larvae drift downstream until they are capable of swimming freely Demersal Burdick and Hightower, 2005
10 Reaction to light The incidence of feeding was higher for larvae reared in continuous light Photopositive Wiggins et al, 1985
11 Temperature during larval development 15.5-26.5 [Optimum temperature] 21.0 °C Carscadden and Leggett, 1975
11 Temperature during larval development 15.6 15.6 °C Wiggins et al, 1985
11 Temperature during larval development 17-25 for juveniles 21.0 °C Mills, 2004
11 Temperature during larval development Reared at about 20°C 20.0 °C Johnson and Dropkin, 1995
11 Temperature during larval development Rearead at 17°C 17.0 °C Everly and Boreman, 1999
11 Temperature during larval development The temperature was maintained at 20.0 ±1°C 20.0 °C Zydlewski and McCormick, 1997
11 Temperature during larval development Required temperatures are in the range 15.5-26.1°C. Reared at 20°C 20.8 °C Leach and Houde, 1999
11 Temperature during larval development The temperature of water during the egg incubation and larval development was 17-18°C 17.5 °C Laiz-Carrion et al, 2003
13 Full yolk-sac resorption 94 [6 days at 15.6] 94.0 °C * day Wiggins et al, 1985
13 Full yolk-sac resorption 70-85 [Yolksac larvae absorb their yolk in 4-5 days at 17°C] 77.5 °C * day Everly and Boreman, 1999
13 Full yolk-sac resorption [About 4 to 7 days after hatching; 9-12 mm or 12.2 when yolk is absorbed] 10.5 °C * day Mills, 2004
13 Full yolk-sac resorption 4-7 days 5.5 °C * day Rue, 2001
14 Onset of exogeneous feeding 94 [5 days at 15.6] 94.0 °C * day Wiggins et al, 1985
14 Onset of exogeneous feeding The transition from endogenous to exogenous feeding occurred between days 3 and 6, at 20 ± 1.0°C 20.0 °C * day Zydlewski and McCormick, 1997
14 Onset of exogeneous feeding Feeding stage larvae was 6-8 days post-hatch at 19-20°C 7.0 °C * day Leach and Houde, 1999

Female (58.0%)

Trait id Trait Primary Data Secondary Data References
15 Age at sexual maturity 4-5 [Not specified] 4.5 year Scott and Crossman, 1973
15 Age at sexual maturity 2-5 [Female] 3.5 year Fishbase, 2006
15 Age at sexual maturity 4-5 [Female] 4.5 year Mills, 2004
15 Age at sexual maturity 4-5 [Female] 4.5 year Olney and McBride, 2003
15 Age at sexual maturity 4-5 [Female] 4.5 year Anonymous, 2006 Chapter 3
15 Age at sexual maturity Most american shad mature and return to spawn at betwenn 3 and 5 years of age [Not specified] 3.0 year Burdick and Hightower, 2005
15 Age at sexual maturity 4.2-4.5 [Female] 4.35 year Carscaden and Legget, 1975
15 Age at sexual maturity The annual spawning run of American shad Alosa sapidissima in the York River, Virginia consists of virgin (ages 3-7 years) and fish that spawned in previous years (repeat spawners, ages 4-10) 5.0 year Olney et al, 2006
16 Length at sexual maturity 45-48 [Not specified] 46.5 cm Scott and Crossman, 1973
16 Length at sexual maturity 38-48 [Female] 43.0 cm Fishbase, 2006
16 Length at sexual maturity Mean of fork length of 42.5-47.3 [For females of 4-8 years] 44.9 cm Olney and McBride, 2003
16 Length at sexual maturity 28.4-30.8 [Female] 29.6 cm Anonymous, 2006 Chapter 3
16 Length at sexual maturity 46.8-49.5 [Mean length of repeat spawners] 48.15 cm Carscaden and Legget, 1975
17 Weight at sexual maturity Mean of 1.241-1.483, range from 0.848 to 1.900 [Female specified] 1.36 kg Olney and McBride, 2003
17 Weight at sexual maturity 1.622-2.095 [Mean weight of repeat spawners] 1.86 kg Carscaden and Legget, 1975
19 Relative fecundity Average batch fecundity (the mean number of oocytes > 1.6 mm per kg of somatic weight) was estimated for six hydrated/running ripe females and ranged from about 20 000 to 70 000 eggs 1.6 thousand eggs/kg Olney et al, 2001
19 Relative fecundity Means varies between 188.3 to 236.3, all variations range from 159.9 to 360. Means of batch sizes vary from 39,658 to 48,113 eggs 188.3 thousand eggs/kg Olney and McBride, 2003
20 Absolute fecundity 155-410 or 2.150 or 30-300 282.5 thousand eggs Internet, 2005
20 Absolute fecundity Average of 125.166 [Range 58-390] 224.0 thousand eggs Scott and Crossman, 1973
20 Absolute fecundity From various sources, American shad produce 2-300 eggs [Also 116-468 and 98.6-225.6] 151.0 thousand eggs Mills, 2004
20 Absolute fecundity 37-44 40.5 thousand eggs Olney and McBride, 2003
20 Absolute fecundity 60-300 180.0 thousand eggs Anonymous, 2006 Chapter 3
20 Absolute fecundity 58,534-659,000 596.5 thousand eggs Burdick and Hightower, 2005
20 Absolute fecundity 118.929-165.776 [Mean population fecundity] 142.35 thousand eggs Carscaden and Legget, 1975
21 Oocyte development Group-synchronous ovarian development Group-synchronous Olney et al, 2001
21 Oocyte development Oocyte sizes are bimodal, the hydrated oocytes representing a cohort distinct from the smaller oocytes No category Olney and McBride, 2003
21 Oocyte development Groups-synchronous oocyte development No category Burdick and Hightower, 2005
24 Maximum GSI value Mean 20.5, up to 35.4 20.5 percent Olney et al, 2001
24 Maximum GSI value 14-19 [Calculated from values given by the authors] 16.5 percent Olney and McBride, 2003

Male (56.0%)

Trait id Trait Primary Data Secondary Data References
27 Age at sexual maturity 3-5 4.0 years Internet, 2005
27 Age at sexual maturity 4-5 [Not specified] 4.5 years Scott and Crossman, 1973
27 Age at sexual maturity 2-4, male 3.0 years Fishbase, 2006
27 Age at sexual maturity 3-4 [Males] 3.5 years Mills, 2004
27 Age at sexual maturity 3-4 [Males] 3.5 years Anonymous, 2006 Chapter 3
27 Age at sexual maturity Most american shad mature and return to spawn at betwenn 3 and 5 years of age [Not specified] 3.0 years Burdick and Hightower, 2005
27 Age at sexual maturity 3.8-4.1 [Female] 3.95 years Carscaden and Legget, 1975
28 Length at sexual maturity 45-48 [Not specified] 46.5 cm Scott and Crossman, 1973
28 Length at sexual maturity 30-44, male 37.0 cm Fishbase, 2006
28 Length at sexual maturity 26.5-27.8 27.15 cm Anonymous, 2006 Chapter 3
28 Length at sexual maturity 42.9-46.9 [Mean length of repeat spawners] 44.9 cm Carscaden and Legget, 1975
29 Weight at sexual maturity 1.210-1.803 [Mean weight of repeat spawners] 1.51 kg Carscaden and Legget, 1975
30 Male sexual dimorphism In all populations and years, males matured at a significantly younger age than females Absent Carscaden and Legget, 1975

Spawning conditions (100.0%)

Trait id Trait Primary Data Secondary Data References
36 Spawning migration distance As maturing fish migrate 100 km up the estuary to the freswater spawnig grounds 100.0 km Olney et al, 2001
36 Spawning migration distance Some shad spawn immediately on entering fresh water while others may undertake fairly long journeys, as musch as 630 km upstream, to their favored spawning grounds 630.0 km Fishbase, 2006
36 Spawning migration distance During spawning season, they move to shallower inshore waters to spawn No data Anonymous, 2006 Chapter 3
36 Spawning migration distance York River fish segregate from mixed-stock assemblages and migrate at least 130 river kilometers (rKm) up the estuary to freshwater 130.0 km Olney et al, 2006
36 Spawning migration distance In the Hudson River in New York state, spawning of American shad takes place more than 160 kmfrom the river mouth, and most of the eggs are found above 200 km 160.0 km Limburg and Ross, 1995
37 Spawning migration period Shad begin to enter the estuary as early as fall, the spawning runs occur in March ['March', 'October', 'November', 'December'] Internet, 2005
37 Spawning migration period Peak of spawning run occurs at temperature of about 18.3°C No data Scott and Crossman, 1973
37 Spawning migration period The peak of spawning migrations in all Atlantic coast populations of closely related with a narrow range of water temperatures (13-18°C) No data Carscadden and Leggett, 1975
37 Spawning migration period Adults move into the Hudson River from Atlantic waters in early spring, usually begin in March and April, and temperature must be 12°C or above before the shad begin their run ['March', 'April', 'May', 'June'] Everly and Boreman, 1999
37 Spawning migration period Up stream migrations in southern streams reportdly occur early in the spring and progressively later northward [the upstream migration of Amrican shad in the Sacramento river estuary reportdly takes about 3 months occuring in March, April and May). Migrate upstream in the spring [Take place when water is about 16.0-19.5°C ['March', 'April', 'May', 'June'] Mills, 2004
37 Spawning migration period In eastern Canada, spawing runs of shad enter rivers between late April and late June, with few, if any, entering rivers before water temperatures reach at least 4°C ['April', 'June'] Bradbury et al, 1999
37 Spawning migration period 90% of the run occurred at temperatures between 15/5-19.5°C, and the peak run occurred at about 18°C No data Burdick and Hightower, 2005
37 Spawning migration period Reproductive adults migrate into coastal rivers in the spring when river temperatures are between 14 and 20°C ['April', 'May', 'June'] Zydlewski and McCormick, 1997
37 Spawning migration period The spawing run begins when maturing (prespawning) fish enter the mouth of the river in late January through late February and continues for approximatively4 months through mid-May ['January', 'February', 'May'] Olney et al, 2006
38 Homing The american shad is reported to home to its natal river to spawn Present Carscadden and Leggett, 1975
38 Homing Most sexually mature fish return to natal streams to spawn Present Olney et al, 2001
38 Homing To their natal streams to spawn Present Mills, 2004
38 Homing Return to its natal river to spawn Present Bradbury et al, 1999
38 Homing Return to their natal stram to spawn Present Dodson and Legget, 1973
38 Homing Our life history and meristic data suggest that homing to a tributary within a river system was also occuring [Adlys shad do not feed during the freswater migration and this lack of food would accentuate the effects of temperature and distance of migrating fish) Present Carscadden and Legget, 1975
39 Spawning season April-June ['April', 'June'] Internet, 2005
39 Spawning season May-June, but even as late as July ['May', 'June', 'July'] Scott and Crossman, 1973
39 Spawning season May-June, but also from February until July ['February', 'March', 'April', 'May', 'June', 'July'] Fishbase, 2006
39 Spawning season In most years, spawning begins in late February and ends in early June ['February', 'June'] Olney et al, 2001
39 Spawning season May or early June ['May', 'June'] Mills, 2004
39 Spawning season May-June but as early as February and late as July ['February', 'May', 'June', 'July'] Fishbase, 2006
39 Spawning season May take place anytime between mid-March and early June ['March', 'May', 'June'] Rue, 2001
39 Spawning season Spring ['April', 'May', 'June'] Anonymous, 2006 Chapter 3
39 Spawning season Spawning normally occurs in May and June, but may occur as late as July ['May', 'June', 'July'] Bradbury et al, 1999
39 Spawning season Spawning was detected between February 21 and May 28 in 2003 and between March 16 and May 17 in 2004 ['February', 'March', 'May'] Burdick and Hightower, 2005
39 Spawning season Spawning occurred between 13 May and 27 June, the peak being June in 1967 and May in 1968. ['May', 'June'] Marcy, 1972
40 Spawning period duration The males arrive on the spawning grounds first, soon followed by the females No data Scott and Crossman, 1973
40 Spawning period duration 10-12 [In most years, spawning begins in late February and ends in early June, But spawning duration are unknown] 11.0 weeks Olney et al, 2001
40 Spawning period duration Sevreal weeks of duration No data Rue, 2001
40 Spawning period duration [Spawning was detected between February 21 and May 28 in 2003 and between March 16 and May 17 in 2004] 21.0 weeks Burdick and Hightower, 2005
41 Spawning temperature 8-26 [Max 15-20] 17.0 °C Internet, 2005
41 Spawning temperature Above 12 and will continue until temperaure do not drop below this point 12.0 °C Scott and Crossman, 1973
41 Spawning temperature Diffrente temperatures according to authors: 8-26; 12-17; 14-21; 17-24; 18.5, prefer 16.7-20.0 17.0 °C Mills, 2004
41 Spawning temperature Generally 12-21 [Range from 8-26°C] 16.5 °C Fishbase, 2006
41 Spawning temperature 12-21 16.5 °C Rue, 2001
41 Spawning temperature Beginning when water temperatures reach 13 to 15°C, and ending when they exceed 27°C 13.0 °C Anonymous, 2006 Chapter 3
41 Spawning temperature 13-20 16.5 °C Bradbury et al, 1999
41 Spawning temperature Mean water temperature was 11°C in May 1967 and 15°C in May 1968 11.0 °C Marcy, 1972
42 Spawning water type Concentrated near the shore, main channel [Freshwater, possibly brackish water] Stagnant water Internet, 2005
42 Spawning water type Rarely if ever in lakes Stagnant water Scott and Crossman, 1973
42 Spawning water type Freshwater of moderate current Flowing or turbulent water Everly and Boreman, 1999
42 Spawning water type In the main channels of rivers, preferred moderate current for spawning, about 0.3-0.93 or 0.15-0.61 m/s Flowing or turbulent water Mills, 2004
42 Spawning water type Primarily in tidal or sometimes in non-tidal freshwater No category Rue, 2001
42 Spawning water type in their native coastal habitats, alewifes spawn in the upper reaches of coastal rivers, in slow-flowing sections of slightly brackish or freshwater. Flowing or turbulent water Anonymous, 2006 Chapter 3
42 Spawning water type Spawn in rivers or brackish estuarine rivers, seldom if ever in lakes [River spawning usually takes place in moderate to strong flowing water, generally where there is sufficient velocity to eliminate silt deposits, and at the same time, far enough upstream for eggs to drift and hatch before reaching saltwater] Stagnant water Bradbury et al, 1999
42 Spawning water type Spawning occurs in open water beyond tidal influence No category Zydlewski and McCormick, 1997
42 Spawning water type Current velocities ranged from 0.5 to 2 ft/sec. Flowing or turbulent water Marcy, 1972
42 Spawning water type American shad choose either tributary and spawn in upsream segments characterized by shallow depths, high dissoled oxygen,and relatively high currents Flowing or turbulent water Olney et al, 2006
43 Spawning depth Near the surface No data Internet, 2005
43 Spawning depth Shallow No data Everly and Boreman, 1999
43 Spawning depth Near the surface: 0.9-12.2; or less than 3 meters 6.55 m Mills, 2004
43 Spawning depth Shallow No data Rue, 2001
43 Spawning depth Shallow, water less than 2 m 2.0 m Anonymous, 2006 Chapter 3
43 Spawning depth Range from 0.2-12 m 6.1 m Bradbury et al, 1999
43 Spawning depth A range of appropriate depths have been described between 0.45 m and 10.0 m. However in Neuse River, Amrican shad spawn almost entirely at depths of less than 2 m 0.45 m Burdick and Hightower, 2005
43 Spawning depth Eggs were found at depths of 0.6 to 7.3 m. An almost equal number of eggs/hr were collected above 3 m as below 7.3 m Marcy, 1972
44 Spawning substrate None, but survival is apparently higher when deposited over sandy and gravel areas Lithophils Internet, 2005
44 Spawning substrate Various substrate No category Everly and Boreman, 1999
44 Spawning substrate Usually spawn over sand and gravel Lithophils Mills, 2004
44 Spawning substrate Sandy or rocky bottoms Lithophils Rue, 2001
44 Spawning substrate Pelagophilous Pelagophils Balon, 1975
44 Spawning substrate It is generally thought that subsrate is unimportant to shad since spawning occurs in the water column and eggs are carried dowstream by the current. Spawning was observed over sand, silt, muck, gravel and boulder substrates, also over sand or gravel. Lithophils Bradbury et al, 1999
44 Spawning substrate Substrates dominated by cobble to be a positive attribute for american shad spawning sites. However, also reported over sandy bottoms free of mud and silt. Psammophils Burdick and Hightower, 2005
45 Spawning site preparation No, eggs are released in the open water Open water/substratum scatter Scott and Crossman, 1973
45 Spawning site preparation Broadcast their eggs in the water Open water/substratum scatter Mills, 2004
45 Spawning site preparation Open substratum spawner Open water/substratum scatter Balon, 1975
45 Spawning site preparation Eggs are released into open water Open water/substratum scatter Bradbury et al, 1999
45 Spawning site preparation Eggs are broadcast Open water/substratum scatter Burdick and Hightower, 2005
46 Nycthemeral period of oviposition Midnight to early morning Day Internet, 2005
46 Nycthemeral period of oviposition Spawning took place in the evening after sundown and continued until midnight or even later Night Scott and Crossman, 1973
46 Nycthemeral period of oviposition Mainly at night Night Everly and Boreman, 1999
46 Nycthemeral period of oviposition Most spawning occurs after dark, taking place between 2100 and 0700 hours, peaking at 2300-2400 Night Mills, 2004
46 Nycthemeral period of oviposition Spawning occurs from sunset to approximatively midnight Night Burdick and Hightower, 2005
46 Nycthemeral period of oviposition Spawning was seen only on dark afternoons and during the evening Day Marcy, 1972
47 Mating system During the spawning act, the female is accompanied by several males No category Scott and Crossman, 1973
47 Mating system The fish pair and swim close together, releasing egg and milt No category Fishbase, 2006
47 Mating system Spawning as several males coming up next to a female No category Burdick and Hightower, 2005
47 Mating system Spawning involves pairs of fish, or presumably several males and a single female. In group spawning, fish swam with their backs exposed. They splashed about forming a closely-packed circle Promiscuity Marcy, 1972
48 Spawning release Broadcast singly No category Internet, 2005
48 Spawning release Batch spawner: an individual female spawns repeatedly during each spawning season [Spawning frequency (every four fays) is preliminary] American shad probably exhibit indeterminate fecundity, contradicting previous studies Multiple Olney et al, 2001
48 Spawning release Batch spawner Multiple Fishbase, 2006
48 Spawning release American shad in the St. Johns river are batch spawners Multiple Olney and McBride, 2003
48 Spawning release Histological evidence that an individual spawn in batches over a period of days or weeks Multiple Burdick and Hightower, 2005
49 Parity After spawning, the spent fish begin to drop back to salt water and vanish until the next spawning season [Some might die] Semelparous Scott and Crossman, 1973
49 Parity Populations may be either semelparous in southern rivers from Florida to North Carolina or predominately iteroparous in more northerly rivers Iteroparous Olney et al, 2001
49 Parity Iteroparous, spawn annualy Iteroparous Mills, 2004
49 Parity Adults descend shortly after spawning No category Fishbase, 2006
49 Parity Iteroparous or semelparous Iteroparous Olney and McBride, 2003
49 Parity Although alewifes generally do not die after spawning, the fluctuating temperatures that the adults are exposed to when they move to inshore waters often results in mortality due to osmotic stress. In some years, temperature changes caused by upwelling may result in a massive die-off of spawning alewifes Semelparous Anonymous, 2006 Chapter 3
49 Parity May spawn up to 7 times and live to be 13 years No category Bradbury et al, 1999
49 Parity Some adults die after spawning with the percentage generally decreasing with increasing latitude Semelparous Burdick and Hightower, 2005
49 Parity The proportions of repeat spawning fish in the sample decreased to 85% for males in 1972 and 78 and 64% for males and females respectively in 1973 Iteroparous Carscaden and Legget, 1975
49 Parity American shad stocks in Virginia may be partially iteroparous (i.e., some proportion of the population dies after spawning), however there is no direct evidence of the phenomenon (e.g., spent carcasses on the shore) in the York River Iteroparous Olney et al, 2006
50 Parental care Non guarders No care Fishbase, 2006