Northcote, 1993



Citation


Northcote, T.G. (1993) A review of management and enhancement options for the Arctic grayling (Thymallus arcticus) with special reference to Williston Reservoir watershed in British Columbia.
British Columbia Ministry of Environment, Lands and Parks

Associated characteristics


Species Development state Trait Primary Data Secondary Data
Thymallus thymallus Spawning conditions Nycthemeral period of oviposition Latter part of the day near the diel temperature maximum Day
Thymallus arcticus Spawning conditions Nycthemeral period of oviposition Most spawning is said to take place in mid to late afternoon, but some said that most spawning occured in evening or night Ambiguous
Thymallus arcticus Spawning conditions Parental care Redds are not constructed or covered by the female No category
Thymallus thymallus Spawning conditions Spawning substrate Fine gravel shallows with moderate current Lithophils
Thymallus arcticus Spawning conditions Spawning substrate Coarse gravel Lithophils
Thymallus thymallus Spawning conditions Spawning site preparation Spawning territories set up by the males No category
Thymallus arcticus Spawning conditions Spawning site preparation Males set up and hold spawning territories of 6 to 7 m² rather than defending access to female [Redds are not constructed by females] Susbtrate chooser
Thymallus thymallus Spawning conditions Spawning temperature 4 to 7, but sometimes up to 15 4.0 °C
Thymallus arcticus Spawning conditions Spawning temperature 5-9 7.0 °C
Thymallus thymallus Spawning conditions Spawning water type European grayling are mainly a river fish, but those in slow flowing parts of rivers migrate to faster flowing tributaries near spawning time, and lae populations all depend on streams for spawning Flowing or turbulent water
Thymallus arcticus Spawning conditions Spawning water type Mainstream river tributaries and side-channels, tributary streams, also in lakes Stagnant water
Thymallus arcticus Spawning conditions Spawning depth 10-40 cm 25.0 m
Thymallus arcticus Egg Egg adhesiveness Slightly adhesive Adhesive
Thymallus arcticus Female Relative fecundity Range from 6.475 to 16.887 or a mean of 10.915 in different regions 6.475 thousand eggs/kg
Thymallus arcticus Female Age at sexual maturity A few reach sexual maturiy at age 3, about a quarter at age 4 and all by age 5 [Sex not specified] 3.0 years
Thymallus thymallus Egg Degree-days for incubation 180-200 190.0 °C * day
Thymallus arcticus Egg Temperature for incubation Full range 5.8-15.5, but mainly 7-9 10.65 °C
Thymallus arcticus Spawning conditions Spawning migration distance Grayling made a post-spawning migration extending a 65 km stretch of the mainstream river 65.0 km
Thymallus arcticus Spawning conditions Spawning migration period Often moving onto spawning areas shortly after ice-out at temperatures near 4°C, usually occur in mid-May ['May']
Thymallus thymallus Egg Oocyte diameter As low as 2.0 up to 3.5 even 4.0 in Europe [Not specified] 2.0 mm
Thymallus arcticus Egg Oocyte diameter 2-3 [Prior to fertilization] 2.5 mm
Thymallus thymallus Female Absolute fecundity From a low of 1.5 to a high over 36 1.5 thousand eggs
Thymallus thymallus Spawning conditions Spawning season Late March-April to June ['April', 'March', 'June']
Thymallus arcticus Spawning conditions Spawning season Spring spawners: mid-to late May and mid July [Some as early as April and others as late as July] ['April', 'May', 'July']
Thymallus thymallus Larvae Temperature during larval development 12-18 [Between 12-18 the larvae spend 5 to 10 days in the gravel] 15.0 °C
Thymallus arcticus Spawning conditions Homing Reproductive homing may be involved Present
Thymallus thymallus Larvae Initial larval size 10-12 [size at hatching] 11.0 mm
Thymallus arcticus Larvae Initial larval size From 7-11 to 14-15 at emergence 9.0 mm
Thymallus arcticus Larvae Larvae behaviour Remain in the gravel during 3-4 days Demersal
Thymallus arcticus Male Weight at sexual maturity Spawning males may be larger than females at a given age No data
Thymallus arcticus Female Age at sexual maturity A few reach sexual maturiy at age 3, about a quarter at age 4 and all by age 5 [Sex not specified] 3.0 year
Thymallus arcticus Spawning conditions Parity Once reaching sexual maturity, grayling may spawn every year, although they do not necessarily do so No category