Age and length at maturity of the female spiny dogfish,Squalus acanthias, in the Strait of Georgia, British Columbia, Canada

1993 ◽  
Vol 38 (1-3) ◽  
pp. 49-57 ◽  
Author(s):  
Mark W. Saunders ◽  
Gordon A. McFarlane
Keyword(s):  
British Columbia ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Strait Of Georgia

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Life History ◽  
Pacific Coast ◽  
Puget Sound ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Dietary Analysis ◽  
Strait Of Georgia ◽  
Food Items ◽  
Abundance Estimates ◽  
Commercial Species

Abstract.—Spiny dogfish <em>Squalus acanthias </em>have been an important commercial species on Canada’s Pacific coast for more than 130 years. In this study we show that the spiny dogfish life history results in juveniles remaining in pelagic waters for 10–15 years after birth, with lengths up to about 60 cm. Abundance estimates show that the numbers of these young dogfish, as well as some older dogfish in the pelagic waters, appear to represent a relatively large percentage of the population in these two regions. Dietary analysis shows that while euphausiids and teleosts constitute the major food items, regardless of size/age, dogfish feed on a number of species within the ecosystem. After about 15 years, there is a movement into demersal habitats where individuals eventually mature. Because dogfish are long lived, and because they are found throughout the pelagic zone and demersal habitats, it is probable that they play a key role in the Strait of Georgia and Puget Sound ecosystems.

Age and Growth of Dogfish Squalus acanthias in British Columbia Waters

1975 ◽  
Vol 32 (1) ◽  
pp. 43-59 ◽  
Author(s):  
K. S. Ketchen
Keyword(s):  
British Columbia ◽  
Growth Curve ◽  
Squalus Acanthias ◽  
Age And Growth ◽  
Von Bertalanffy ◽  
Large Fish ◽  
Length Frequency ◽  
Strait Of Georgia ◽  
Frequency Distributions ◽  
Net Uptake

Ages of dogfish have been determined from markings on the second dorsal spine by a technique that enables use of badly worn spines from relatively large fish to correct for the tendency to underestimate age. While the technique may have led to slight overestimation of age, particularly of dogfish from Hecate Strait, there is some corroborating evidence for the Strait of Georgia drawn from length-frequency distributions, sizes of fish in relation to reproductive stages, and assumptions about the average annual net uptake of mercury. It is tentatively concluded that the growth curve for females, expressed in terms of the von Bertalanffy equation, has parameters of K = 0.048, [Formula: see text], and t0 = −4.88 yr. Parameters suggested for males are: K = 0.070, [Formula: see text], and t0 = −4.70 yr. The implication emerging from these results is that females and males on the average take 23 yr and 14 yr, respectively, to reach maturity.

Age Determination of an Elasmobranch (Squalus acanthias) by X-ray Spectrometry

1977 ◽  
Vol 34 (1) ◽  
pp. 44-48 ◽  
Author(s):  
Barry C. Jones ◽  
Glen H. Geen
Keyword(s):  
Age Determination ◽  
Element Composition ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Strait Of Georgia ◽  
X Ray ◽  
Spectrometric Technique

Ages of spiny dogfish (Squalus acanthias) in the Strait of Georgia, B.C., have been estimated by an X-ray spectrometric technique which involves measuring variations in the element composition within vertebrae.

Mercury Content of Spiny Dogfish (Squalus acanthias) in the Strait of Georgia, British Columbia

1972 ◽  
Vol 29 (10) ◽  
pp. 1487-1490 ◽  
Author(s):  
C. R. Forrester ◽  
K. S. Ketchen ◽  
C. C. Wong
Keyword(s):  
Total Mercury ◽  
River Estuary ◽  
Mercury Content ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Fraser River ◽  
Female Fish ◽  
Male And Female ◽  
Strait Of Georgia ◽  
Total Length

Total mercury content of Squalus acanthias sampled in the Strait of Georgia reached levels of 0.5 ppm at fish lengths of 72 and 77 cm for male and female fish, respectively. For any given length above 65 cm the mercury content was higher among males than females and higher in samples taken off the Fraser River Estuary than in other areas of the Strait. Levels of mercury reached 1.7 ppm in males (to 95 cm in total length) and almost 2.0 ppm in females (to 120 cm in total length).

Population Dynamics of Spiny Dogfish (Squalus acanthias) in British Columbia Waters

1979 ◽  
Vol 36 (6) ◽  
pp. 647-656 ◽  
Author(s):  
C. C. Wood ◽  
K. S. Ketchen ◽  
R. J. Beamish
Keyword(s):  
British Columbia ◽  
Population Dynamics ◽  
Age Structure ◽  
Squalus Acanthias ◽  
Minimum Size ◽  
Spiny Dogfish ◽  
Natural Mortality ◽  
Structure Model ◽  
Density Dependent ◽  
Sustained Effort

An age-structure model that incorporates recent information regarding growth and reproduction has been developed to investigate the dynamics of spiny dogfish (Squalus acanthias) populations in British Columbia waters. Mechanisms for density-dependent regulation of abundance were evaluated on the basis of theoretical effectiveness and ability to predict observed patterns in simulations of the historical fishery. Compensatory change in the rate of natural mortality appears to be the principal mechanism for density-dependent response. The instantaneous rate of natural mortality at natural equilibrium was estimated to be 0.094 MSY for British Columbia waters is ~ 9000–11 000 t/yr. The minimum size at entry to the fishery has little effect on MSY. Sustained-effort, sustained-yield, and periodic fisheries were modeled to determine optimum harvesting strategies. Periodic fisheries were found to vary widely in feasibility and appear to be impractical from a management perspective whereas a sustained-effort fishery would ensure maximum stability. Key words: spiny dogfish, population dynamics, age-structure model, density-dependence, simulation model, commercial fishing strategies

Food and Feeding of Spiny Dogfish (Squalus acanthias) in British Columbia Waters

1977 ◽  
Vol 34 (11) ◽  
pp. 2056-2066 ◽  
Author(s):  
Barry C. Jones ◽  
Glen H. Geen
Keyword(s):  
British Columbia ◽  
Stomach Content ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Commercial Catch ◽  
Food Items ◽  
Annual Consumption ◽  
Food And Feeding ◽  
Dietary Components ◽  
Winter Annual

Stomach content data on 14,796 spiny dogfish (Squalus acanthias) from British Columbia waters are presented. The major dietary components based on occurrence were 55% teleosts, 35% crustaceans, and 5% molluscs. The principal food items were herring (22%) and euphausiids (14%). Prey was largely pelagic (80%), with fishes predominating in winter and invertebrates in summer. Fishes became more important in the diet with increasing dogfish size. Dogfish consumed twice as much food in summer as in winter. Annual consumption varied from 5 times biomass for small dogfish to 2.5 times for larger animals. Preliminary analyses suggest that dogfish consume over 5 times the current annual commercial catch of herring, but insignificant quantities of salmon. Key words: dogfish, Squalus, feeding, food, biomass, predation, metabolism, seasonality, survivorship, digestion

Reproduction and Embryonic Development of Spiny Dogfish (Squalus acanthias) in the Strait of Georgia, British Columbia

1977 ◽  
Vol 34 (9) ◽  
pp. 1286-1292 ◽  
Author(s):  
Barry C. Jones ◽  
Glen H. Geen
Keyword(s):  
Embryonic Development ◽  
Length Distribution ◽  
Uterine Cavity ◽  
Mesh Size ◽  
Squalus Acanthias ◽  
Population Characteristics ◽  
Spiny Dogfish ◽  
Total Catch ◽  
Strait Of Georgia ◽  
Males And Females

Lengths at 50% maturity of spiny dogfish (Squalus acanthias) in the Strait of Georgia, B.C., are 78.5 and 93.5 cm, corresponding to ages 19 and 29 yr, for males and females, respectively. Modal lengths of mature males and females are 85 and 100 cm, respectively.Mating occurs from October to January, with a peak in December. Males are capable of mating every year, with smaller dogfish mating earlier in the year than larger ones. Females mate every 2nd yr. Ovulation of 4 cm diam eggs closely follows mating. The fertilized eggs are enclosed in gelatinous capsules for 4 mo after which the embryos are released into the uterine cavity. The external yolk supply of the embryos is totally absorbed by parturition, although the internal yolk is not fully utilized until 2 mo later. Parturition occurs from September to January, with a peak in November. Gestation is roughly 23 mo. Breeding females produce a mean of 7.14 progeny.These population characteristics indicate that regulation of a future fishery should be by total catch limit rather than net mesh size selection. Key words: spiny dogfish, reproduction, length distribution, survivorship, fecundity, fishery regulation

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