Thymallus arcticus

  • Scientific name
  • Thymallus arcticus (Pallas, 1776)

  • Common name
  • Arctic grayling

  • Family
  • Thymallidae

  • External links
  • Fishbase
Trait completeness 74%
Total data136
References14
Image of Thymallus arcticus

Author: Fabrice Téletchéa
License: All rights reserved

Traits detail



Egg (100%)


Trait id Trait Primary data Secondary Data References
4 Egg adhesiveness Apparently adhesive for only a short period of time Adhesive Scott and Crossman, 1973
4 Egg adhesiveness Slightly adhesive Adhesive Northcote, 1995
4 Egg adhesiveness Slightly adhesive Adhesive Northcote, 1993
4 Egg adhesiveness Salmonidae, whose eggs are not sticky Non-Adhesive Woynarovich, 1962
4 Egg adhesiveness The eggs were very adhesive when first stripped, but this stickinessgradually disappeared as the eggs became water-harened Adhesive Bishop, 1971
5 Incubation time 11-12 11.5 days Fishbase, 2006
5 Incubation time 13-18 days at 11-12°C 15.5 days Scott and Crossman, 1973
5 Incubation time 16-18 days at 9°C 17.0 days Northcote, 1995
5 Incubation time 16.0 [Mean time to egg hatch within the range of average post-spawning the range post-spawning water temperatures] 16.0 days Olden, 2006
5 Incubation time Most eggs hatched after 14-19 days after fertilization 16.5 days Kaya, 1989
5 Incubation time 13.7 at 8.8°C 13.7 days Bishop, 1971
7 Degree-days for incubation 120-140 130.0 °C * day Scott and Crossman, 1973
7 Degree-days for incubation 156-181 168.5 °C * day Northcote, 1995
7 Degree-days for incubation The eggs required 186.24 day-degrees to hatch. Also found that eggs reuqired 176.75 day-degrees to hatch at a mean daily temperature of 7.07°C 186.24 °C * day Kratt and Smith, 1977
7 Degree-days for incubation Range from 124 [At 15.5°C] to 209 [At 8.8°C], mainly 140-180 160.0 °C * day NO REFERENCE
7 Degree-days for incubation 216.5 [At 8.8°C], also described at 250 216.5 °C * day Bishop, 1971
6 Temperature for incubation 7-11 9.0 °C Scott and Crossman, 1973
6 Temperature for incubation 9 9.0 °C Northcote, 1995
6 Temperature for incubation Full range 5.8-15.5, but mainly 7-9 10.65 °C Northcote, 1993
6 Temperature for incubation Water temperatures ranged from 2.0 to 9.2°C during the incubation period in 1975. Temperature ranged from 1.0°C to 10.3°C on the west side and from 1.0°C to 11.5°C on the esat side in 1976. The mean daily temperature on the east side was 5.82°C 2.0 °C Kratt and Smith, 1977
6 Temperature for incubation The eggs initially were incubated in jars with springwater 8.0 ± .°C 8.0 °C Kaya, 1989
6 Temperature for incubation 8.8°C 8.8 °C Bishop, 1971
2 Egg size after water-hardening 3.5 [Swollen egg] 3.5 mm Fishbase, 2006
2 Egg size after water-hardening 2.7-4.3 [After water hardening] 3.5 mm Scott and Crossman, 1973
2 Egg size after water-hardening 4-4.8 [Seems to be fertilized eggs] 4.4 mm Bonislawska, 2001
2 Egg size after water-hardening The average diameter of 100 measurements of water hardened eggs was 2.7 mm 2.7 mm Bishop, 1971
2 Egg size after water-hardening 4.3 [Fully hardened eggs] 4.3 mm Penaz, 1981
3 Egg Buoyancy Demersal Demersal Scott and Crossman, 1973
3 Egg Buoyancy Heavy No category Northcote, 1995
1 Oocyte diameter 2.5 2.5 mm Fishbase, 2006
1 Oocyte diameter Egg size in ovary is about 2.5 2.5 mm Scott and Crossman, 1973
1 Oocyte diameter 2-3 [Prior to fertilization] 2.5 mm Northcote, 1995
1 Oocyte diameter 2-3 [Prior to fertilization] 2.5 mm Northcote, 1993
1 Oocyte diameter 3.0 [Mean diameter of mature, fully yolked, ovarian oocyte] 3.0 mm Olden, 2006
1 Oocyte diameter The diameter of fresh eggs measured 2.6 mm [Also found 2.5 mm before the eggs were water-hardened] 2.6 mm Bishop, 1971

Larvae (86%)


Trait id Trait Primary Data Secondary Data References
11 Temperature during larval development Rearing temperature, controlled by mixing cold and warm sprinwater, was increased to 10.0 ± 1.0°C after hatching was completed 10.0 °C Kaya, 1989
12 Sibling intracohort cannibalism Most of the grayling were eating fish eggs, but it was impossible to tell whether they were grayling of pike eggs Absent Bishop, 1971
13 Full yolk-sac resorption 60-70 [A post-hatching sub-gravel stage of 3 to 4 days'duration appears to be a normal feature of the life cycle of Arctic grayling in the Fond Lac River. The newly hatched fry possess large yolk sac wich are almost completely absorbed by the time they emerge. Also observed between 4-7 days at about 10°C] 65.0 °C * day Kratt and Smith, 1977
13 Full yolk-sac resorption About 100 [The young developed in the trays until most were free-swimming (24-29 days after fertilization) i.e. 10 days at 10°C] 26.5 °C * day Kaya, 1989
14 Onset of exogeneous feeding Young grayling begin taking food as late as 9 days after hatching 9.0 °C * day Bishop, 1971
8 Initial larval size About 8 8.0 mm Scott and Crossman, 1973
8 Initial larval size 7-11 up to 15 at emergence ! 9.0 mm Northcote, 1995
8 Initial larval size From 7-11 to 14-15 at emergence 9.0 mm Northcote, 1993
8 Initial larval size 8.1 8.1 mm Olden, 2006
9 Larvae behaviour First 3-4 day period of sub-gravel residence for hatched larvae Demersal Northcote, 1995
9 Larvae behaviour Remain in the gravel during 3-4 days Demersal Northcote, 1993
9 Larvae behaviour A post-hatching sub-gravel stage of 3 to 4 days'duration appears to be a normal feature of the life cycle of Arctic grayling in the Fond Lac River Demersal Kratt and Smith, 1977

Female (42%)


Trait id Trait Primary Data Secondary Data References
19 Relative fecundity Average 10, range 6.475-16.887 11.681 thousand eggs/kg Northcote, 1995
19 Relative fecundity Range from 6.475 to 16.887 or a mean of 10.915 in different regions 6.475 thousand eggs/kg Northcote, 1993
19 Relative fecundity 310.9 eggs per ounce of fish [Also desribed as 376 eggs per ounce] 310.9 thousand eggs/kg Bishop, 1971
27 Age at sexual maturity Some at 4 for bot sex but most at 6-9 7.5 years Scott and Crossman, 1973
27 Age at sexual maturity Most at 4-5, few at 3 and rarely at 2 [Both sex] 4.5 years Northcote, 1995
27 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 Northcote, 1993
27 Age at sexual maturity 4.0 [Both sex] 4.0 years Olden, 2006
27 Age at sexual maturity Fish in the 6- to 9- year group made up 93.5 percent of the run 6.0 years Bishop, 1971
20 Absolute fecundity Average number is probably 4-7 [6.12-15.9] 5.5 thousand eggs Scott and Crossman, 1973
20 Absolute fecundity 1.120 and 1.226 eggs for females of 197 and 219 mm respectively 1.12 thousand eggs Northcote, 1995
20 Absolute fecundity The 15 fish had an average of 9670 eggs [described in other studies as 4000 to 7000, but a few of the largest females yielded more than 10000 eggs each] 15.0 thousand eggs Bishop, 1971
17 Weight at sexual maturity 2.1-3.8 pounds !!! 2.95 kg Scott and Crossman, 1973
16 Length at sexual maturity Mostly 40.6-50.8 45.7 cm Scott and Crossman, 1973
16 Length at sexual maturity 26.8 [Both sex] 26.8 cm Olden, 2006
15 Age at sexual maturity Some at 4 for both sex but most at 6-9 7.5 year Scott and Crossman, 1973
15 Age at sexual maturity Most at 4-5, few at 3 and rarely at 2 [Both sex] 4.5 year Northcote, 1995
15 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 Northcote, 1993
15 Age at sexual maturity 4.0 [Both sex] 4.0 year Olden, 2006
15 Age at sexual maturity Fish in the 6- to 9- year group made up 93.5 percent of the run 6.0 year Bishop, 1971

Male (44%)


Trait id Trait Primary Data Secondary Data References
30 Male sexual dimorphism No nuptial tubercles and none of the body changes so characteristic of salmonids at spawning time, but colours darken and the males become more brilliant than the females Absent Scott and Crossman, 1973
30 Male sexual dimorphism Territory-holding dish in their study had a different color, the flanks and back becoming a brownish or dark grey, while the tip of the nose in many specimens became white Absent Bishop, 1971
30 Male sexual dimorphism Seasonnal occurrence of tubercles on breeding male and female. Male tubercles, knob-like structures located on the anterior portion of the scale. Female tubercles were less sharply defined, covering most of the surface of the affected scales Absent Kratt and Smith, 1978
28 Length at sexual maturity Mostly 40.6-50.8 45.7 cm Scott and Crossman, 1973
28 Length at sexual maturity 26.8 [Both sex] 26.8 cm Olden, 2006
29 Weight at sexual maturity 2.1-3.8 pounds !!! 2.95 kg Scott and Crossman, 1973
29 Weight at sexual maturity Spawning males may be larger than females at a given age No data Northcote, 1993

Spawning conditions (100%)


Trait id Trait Primary Data Secondary Data References
47 Mating system By pair, but male mate several times Monogamy Fishbase, 2006
47 Mating system The male and female were near the bottom. They were side by side, touching each other. The male had his fin erect and partly laid over the female, in much the same way it was laid on the boot or rock during the vibration. The female gaped widely, but the male did not gape until just before the act was over. The whole act took perhaps 7 seconds No category Bishop, 1971
46 Nycthemeral period of oviposition There is no spawning at night and it is most active during warmer water temperatures of midday Ambiguous Scott and Crossman, 1973
46 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 Northcote, 1995
46 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 Northcote, 1993
46 Nycthemeral period of oviposition Montana grayling slackened its spawning activities after 11 p.m. [Also noted that in the afternoon the intensity of the spawning rose, reached a maximum when the water was warmest, and then gradually decreased in the evening] Day Bishop, 1971
50 Parental care Nonguarders No care Fishbase, 2006
50 Parental care No parental care is given to eggs or young No category Scott and Crossman, 1973
50 Parental care Redds are not constructed or covered by the female No category Northcote, 1993
50 Parental care The male swam off as soon as the act was over, the female stayed around for a few seconds and then also sawm off. Male parental care Bishop, 1971
44 Spawning substrate Gravel or rock Lithophils Scott and Crossman, 1973
44 Spawning substrate Over stable coarse gravel (2-4 cm) Lithophils Northcote, 1995
44 Spawning substrate Lithophils Lithophils Balon, 1975
44 Spawning substrate Coarse gravel Lithophils Northcote, 1993
44 Spawning substrate Gravel: 5 mm to 76 mm in diameter Lithophils Kratt and Smith, 1977
44 Spawning substrate Studies showed that pure mud, sand, and clay were not chosen at all, only gravelled areas were used. Ambiguous Bishop, 1971
45 Spawning site preparation Brood hiders, no redd is constructed, but the vibrations of the tails during the spawning act stirs up the substrate and produce a slight depression Susbtrate chooser Fishbase, 2006
45 Spawning site preparation No actual nest or redd is prepared [Male are territorial on the spawning grounds] Susbtrate chooser Scott and Crossman, 1973
45 Spawning site preparation Altough redds are not constructed or covered by the female, in some cases shallow pits may appear in the stream as a result of prespawning activity [Males set up and hold spawning territories of 6-7 m²] Susbtrate chooser Northcote, 1995
45 Spawning site preparation Open substratum spawner Open water/substratum scatter Balon, 1975
45 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 Northcote, 1993
45 Spawning site preparation The eggs are buried to a depth of 2-3 cm despite the absence of nest digging behavior Susbtrate chooser Kratt and Smith, 1977
45 Spawning site preparation No redd was formed, but the eggs were covered by the loosened bottom material Susbtrate chooser Bishop, 1971
45 Spawning site preparation During the spawning period, male grayling defended rectangular-shaped territories approximatively 2.5 to 3 m wide and 3.5 to 4.5 m long [Female did not hold territories on the spawning ground] No category Kratt and Smith, 1980
41 Spawning temperature 7-10 8.5 °C Scott and Crossman, 1973
41 Spawning temperature 5-9 7.0 °C Northcote, 1995
41 Spawning temperature 5-9 7.0 °C Northcote, 1993
41 Spawning temperature 7 [Temperature at which spawning is typically initiated] 7.0 °C Olden, 2006
41 Spawning temperature Most of the spawning took place in a water at a temperature of about 10°C 10.0 °C Bishop, 1971
40 Spawning period duration 3-4 [Early to late May] 3.5 weeks Northcote, 1995
40 Spawning period duration 3 [Spawning activity was observed on the east side outlet between May 19 and June 10, 1975 and peaked from May 23 to May 25. In 1976, spawning began on the east and west sides of the outlet on May 15 and May 18 respectively. Adult grayling were seen on the east spawing grounds until June 2 and on the west spawning grounds until June 8, 1976. The peak of spawning occured from May 25 to May 29 on the east side.] 3.0 weeks Kratt and Smith, 1977
40 Spawning period duration Spawning activity was observed in the Fond du Lac River from 15 May to 18 June, with peak activity 25-29 May 27.0 weeks Kratt and Smith, 1978
40 Spawning period duration The spawing period lasted 22 days in 1975 and 24 days in 1976. Male held territories for up to 7 days during the breeding season and one male was observed attempting to spawn on 54 occassions. 22.0 weeks Kratt and Smith, 1980
42 Spawning water type Small tributaries, if not available spawning takes place in gravelly to rocky parts of the main river [Sometimes occurs in mud-bottomed vegetated poools below rapids] No category Scott and Crossman, 1973
42 Spawning water type Tributaries No category Fishbase, 2006
42 Spawning water type Use mainstream river tributaries and sidechannels, rarely in lakes [Flows of 0.5-1.0 m/s] Ambiguous Northcote, 1995
42 Spawning water type Mainstream river tributaries and side-channels, tributary streams, also in lakes Stagnant water Northcote, 1993
42 Spawning water type Spawning in lake Agnes occurs primarily in the largest inlet stream, with minor spawning activity in two smaller inlet streams an possibly along shawllow shoreline areas. Spawning in Deer Lake appears to occur only in the outlet stream Stagnant water Kaya, 1989
42 Spawning water type The spawning area of Providence Creek was a depper part of the stream just below a riffle used as a feeding area, the current about 25 feet per second Flowing or turbulent water Bishop, 1971
43 Spawning depth 10-40 cm 25.0 m Northcote, 1995
43 Spawning depth 10-40 cm 25.0 m Northcote, 1993
43 Spawning depth The depth was about 3 feet 3.0 m Bishop, 1971
36 Spawning migration distance Grayling made a post-spawning migration extending a 65 km stretch of the mainstream river 65.0 km Northcote, 1993
36 Spawning migration distance Apparently grayling migrate from the lakes and larger streams to the smaller tributaries, which are the first to become free of ice No data Bishop, 1971
37 Spawning migration period As the ice is breaking-up in the small streams, adults migrate from ice-covered lakes and from larger rivers to small gravel- or rock-bottomed tribitaries No data Scott and Crossman, 1973
37 Spawning migration period Move onto spawning areas shortly after ice-out at temperatures near 4°C, usually in May ['May'] Northcote, 1995
37 Spawning migration period Often moving onto spawning areas shortly after ice-out at temperatures near 4°C, usually occur in mid-May ['May'] Northcote, 1993
39 Spawning season May-June ['May', 'June'] Fishbase, 2006
39 Spawning season April to June ['April', 'June'] Scott and Crossman, 1973
39 Spawning season Spring spawners: May, but vary from April to as late as July ['April', 'May', 'July'] Northcote, 1995
39 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'] Northcote, 1993
39 Spawning season Spawning activity was observed on the east side outlet between May 19 and June 10, 1975 and peaked from May 23 to May 25. In 1976, spawning began on the east and west sides of the outlet on May 15 and May 18 respectively. Adult grayling were seen on the east spawing grounds until June 2 and on the west spawning grounds until June 8, 1976. The peak of spawning occured from May 25 to May 29 on the east side. ['May', 'June'] Kratt and Smith, 1977
39 Spawning season May and June ['May', 'June'] Kaya, 1989
39 Spawning season The spawning of the grayling in Gret Slave Lake and surrounding areas takes place during spring - from April to May. This spawning period corresponds to the breakup of the ice on the rivers ['April', 'May', 'June'] Bishop, 1971
39 Spawning season Spawning activity was observed in the Fond du Lac River from 15 May to 18 June, with peak activity 25-29 May ['May', 'June'] Kratt and Smith, 1978
39 Spawning season Between 19 May and 10 June 1975, and between 15 May and 8 June 1976 ['May', 'June'] Kratt and Smith, 1980
38 Homing Reproductive homing may be involved Present Northcote, 1993
48 Spawning release A female may spawn only once, or several times in different areas Mutliple Fishbase, 2006
48 Spawning release The female may spawn once only, or several times in different areas Mutliple Scott and Crossman, 1973
48 Spawning release Grayling females in Providence Creek release most, or all, of their eggs in one act, because, as nearly as could be ascertained, no female was caught with only part of her ripe eggs remaining in the ovary No category Bishop, 1971
49 Parity Adults spawn several times but possibly not all of them every year No category Scott and Crossman, 1973
49 Parity Grayling may spawn every year No category Northcote, 1995
49 Parity Once reaching sexual maturity, grayling may spawn every year, although they do not necessarily do so No category Northcote, 1993