Maitland and Hatton-Ellis, 2000



Citation


Maitland, P.S. and Hatton-Ellis, T.W. (2000) Ecology of the Allis and Twaite shad., pp.

Associated characteristics


Species Development state Trait Primary Data Secondary Data
Alosa alosa Spawning conditions Nycthemeral period of oviposition Takes place at night Night
Alosa fallax Spawning conditions Nycthemeral period of oviposition Twaite shad accumulate in pools during the, moving out onto the shallow, sandy-gravel riffle areas of 30 cm or so in depth to spawn during the night. Night
Alosa alosa Spawning conditions Spawning substrate They deposit their eggs over a substrate that can vary from sand (0.02-2 mm) to pebbles (2-20 cm) Ambiguous
Alosa fallax Spawning conditions Spawning substrate Above appropriate areas of clean gravel Lithophils
Alosa alosa Spawning conditions Spawning temperature Mostly around 15°C 15.0 °C
Alosa alosa Spawning conditions Spawning water type In flowing water Flowing or turbulent water
Alosa fallax Spawning conditions Spawning water type Flowing water Flowing or turbulent water
Alosa alosa Spawning conditions Spawning depth In water depths of 0.5-1.5 m [Spawning involves much noisy splashing at the surface] 1.0 m
Alosa fallax Spawning conditions Spawning depth Spawniing is a noisy affair, with much splashing and chasing near the surface No data
Alosa alosa Female Female sexual dimorphism Female grow faster than males Absent
Alosa alosa Egg Egg adhesiveness Non-adhesive Non-Adhesive
Alosa alosa Egg Incubation time 4-8 6.0 days
Alosa fallax Egg Incubation time 4-6 5.0 days
Alosa alosa Female Relative fecundity From 60 to 236 [There is an indication of an increase in relative fecundity with increasing latitude, from approximatively 60,000 in Morrocco to 200,000 in the River loire] 60.0 thousand eggs/kg
Alosa fallax Female Relative fecundity 42,540-302,358, also 139,479, 147,378, 103,270, 421.0 thousand eggs/kg
Alosa alosa Female Age at sexual maturity 3-4 [Both sex] 3.5 years
Alosa fallax Female Age at sexual maturity The males start to mature after three years No data
Alosa alosa Egg Temperature for incubation The eggs are sensitive to water temperatures below 16-18°C, so temperatures above 18°C in June and July should be most favourable for incubation 17.0 °C
Alosa alosa Spawning conditions Spawning migration distance In some of the larger European rivers, allis shad habe been known to ascend upstream for several hundred kilometres-for exemple, more than 500 km in the river Loire 500.0 km
Alosa fallax Spawning conditions Spawning migration distance May spawn in, or just above, the tidal reaches of rivers, but many stocks spawn in freshwater upstrezam of this. Some fish travel over 190 km to reach their spawning grounds 190.0 km
Alosa alosa Egg Egg size after water-hardening 2.5-4.5 3.5 mm
Alosa fallax Egg Egg size after water-hardening 1.5-3.5 2.5 mm
Alosa alosa Egg Egg Buoyancy Semi-buoyant [Tend to drift dowstream, most falling to the bottom and remaining there in crevices, until they hatch, some eggs drift for long distances below the spawning areas, sometimes several tens of kilometres] Ambiguous
Alosa alosa Spawning conditions Spawning migration period Move into estuaries of large rivers, migrating into fresh water during late spring (April to June) Males migrate upstream first, followed by females on or two weeks later] ['April', 'May', 'June']
Alosa fallax Spawning conditions Spawning migration period Mature adults enter the estuaries of many European rivers from April and migrate some distance upstream, at 10-14°C, ['April']
Alosa fallax Female Absolute fecundity 25,942-675,000 808.5 thousand eggs
Alosa alosa Spawning conditions Spawning season Throughout the range of the allis shad, reproduction occurs from April to July, but in Britain, May to July seems to have been the main period ['April', 'May', 'July']
Alosa fallax Larvae Temperature during larval development Preference for a temperatures in the range 17-21°C for larvae 7.7-15.2 mm, and from 17-21.5°C for larvae 18.4-23.8 in length 19.0 °C
Alosa alosa Spawning conditions Homing Although there is some evidence of homing in shads, it it not known if adults return to their natal rivers or the same gravels over which they have previously spawned Present
Alosa fallax Spawning conditions Homing Although there is some evidence of homing in shads, it it not known if adults return to their natal rivers or the same gravels over which they have previously spawned Present
Alosa alosa Female Length at sexual maturity 30-40 [Both sex] 35.0 cm
Alosa alosa Male Length at sexual maturity 30-40 [Both sex] 35.0 cm
Alosa alosa Larvae Initial larval size About 10 on hatching 10.0 mm
Alosa alosa Larvae Larvae behaviour After hatching, the young remain in the slow-flowing reaches of the lower parts of rivers, then move into the estuary and eventually into coastal waters and the open sea Demersal
Alosa fallax Larvae Larvae behaviour The young fish then drop quickly dowstream in the current to the quieter waters of the upper estuary where they start to feed and grow [Both eggs and larvae are transparent] Demersal
Alosa alosa Female Age at sexual maturity 3-4 [Both sex] 3.5 year
Alosa fallax Female Age at sexual maturity The females do not start to mature until they are about five years old No data
Alosa alosa Spawning conditions Parity Almost all allis shad die after spawning Semelparous
Alosa fallax Spawning conditions Parity May spawn several times in their lives No category