Predictions & Data for this entry

Model: std climate: MB, MC migrate: Mo phylum:
COMPLETE = 2.7 ecozone: MAN, MAm, MAS food: biCi, biCvf class:
MRE = 0.135 habitat: 0iMcd gender: D order:
SMSE = 0.035 embryo: Mv reprod: O family:

Zero-variate data

Data Observed Predicted (RE) Unit Description Reference
ab 690 625.1 (0.09404) d age at birth JoneGeen1977
ap 2190 2718 (0.2411) d age at puberty Avsa2001
am 2.92e+04 2.92e+04 (3.169e-05) d life span Steh2007
Lb 24 20.02 (0.1657) cm total length at birth JoneGeen1977
Lp 72 60.75 (0.1563) cm total length at puberty Avsa2001
Li 136 151.4 (0.1135) cm ultimate total length (fem.) Avsa2001
Li_m 121 122.7 (0.01416) cm ultimate total length (males) Avsa2001
Ww0 35 37.94 (0.084) g wet weight at start (egg) YigiIsme2013
Wwp 950 911.9 (0.04015) g wet weight at puberty Avsa2001

Uni- and bivariate data

Data Figure Independent variable Dependent variable (RE) Reference
LW_f Data for females, males (South-eastern Black Sea) total length wet weight (0.2132) Avsa2001
LW_m Data for females, males (South-eastern Black Sea) total length wet weight (0.1809) Avsa2001
LW_f2 total length wet weight (0.1289) YigiIsme2013
LW_m2 total length wet weight (0.1996) YigiIsme2013
LN total length mean numer of embryos (0.09723) Avsa2001
LW_e Data for embryos, North Aegean sea total length wet weight (0.2275) YigiIsme2013
tLe Data for embryo age embryo length (0.1512) JoneGeen1977
tYe Data for embryo age yolk volume (0.1848) JoneGeen1977

Pseudo-data at Tref = 20°C

Data Generalised animal Squalus acanthias Unit Description
v 0.02 0.02774 cm/d energy conductance
kap 0.8 0.8485 - allocation fraction to soma
kap_R 0.95 0.95 - reproduction efficiency
p_M 18 34.36 J/d.cm^3 vol-spec som maint
k_J 0.002 0.002 1/d maturity maint rate coefficient
kap_G 0.8 0.8027 - growth efficiency

Discussion

  • males are assumed to differ from females by {p_Am} only - we use the max. observed values of males and females from Avsa2001, not the von Bert paramter that they estimate.
  • predictions assume a mean temperature of 9 deg C
  • t-L data from YigiIsme2013 and Avsa2001 not included because after a lot of testing the age-length relationship is incoherent point to errors in the ageing, possible different type of error of the young ones with respect to the older ones. Possible different type of error between the studies. YigiIsme2016 age free swimming individuals of 17 cm to be ca 300 d old while length at birth is reported at 24-26 cm. These age estimates suggest a very high p_M while the rest of the data do not support this.
  • We use the actual length/ weight of smallest mature female in Avsa2001 and not the length where 50% were observed to be mature. We use the age estimate of sexual maturiaty from that study.
  • Notice that egg weight is around 30 - 40 g (JoneGeen1977, YigiIsme2013) but that embryo weight around birth is > 50 g or more (YigiImse2013, fig. 6 of this AmP entry). This point to some external source of food from before birth. For this reason the slight discrepancy in predicted embryo length as function of time is acceptable.

Facts

  • main food species: demersal fishes like: whiting (Merlangius merlangus euxinus), red mullet (Mullus barbatus) and black goby (Gobius niger) were the commonest. Also some common shrip Cragnon cragnon) (Ref: Avsa2001)
  • Ovoviviparous. Depth around 50-149m, but have been found deeper than 700m. (Ref: Wiki)
  • spurdogs favor a temp of 7 - 15 C (Ref: Steh2007)

Acknowledgment

  • The creation of this entry was supported by the Norwegian Science Council (NFR 255295)

Bibliography

Citation