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.

scholarly journals Validation of the use of vertebrae and dorsal-fin spines for age determination of spiny dogfish (Squalus acanthias) in the western North Atlantic Ocean

2021 ◽  
Vol 119 (1) ◽  
pp. 41-49
Author(s):  
Kelsey C. James ◽  
Lisa J. Natanson ◽  
Christopher Flight ◽  
Cindy Tribuzio ◽  
John Hoey ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Age Determination ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Dorsal Fin ◽  
Fin Spines

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.

Are Pacific spiny dogfish lying about their age? A comparison of ageing structures for Squalus suckleyi

2018 ◽  
Vol 69 (1) ◽  
pp. 37 ◽  
Author(s):  
Cindy A. Tribuzio ◽  
Mary Elizabeth Matta ◽  
Christopher Gburski ◽  
Calvin Blood ◽  
Walter Bubley ◽  
...  
Keyword(s):  
Age Determination ◽  
Spiny Dogfish ◽  
Suitable Alternative ◽  
Thin Sections ◽  
Full Sample ◽  
Vertebral Centra ◽  
Dorsal Fin ◽  
Sample Set ◽  
Fin Spines

Historically, Pacific spiny dogfish (Squalus suckleyi) have been aged using dorsal fin spines, a method that was validated through bomb radiocarbon analysis and oxytetracycline tagging. However, ages generated using this method generally have poor precision and require estimation of missing growth bands in eroded spines, prompting a search for improved age determination methods. In the present study, spiny dogfish were aged using the historical spine method and a new method involving stained thin sections of vertebral centra. Results of an inter-laboratory exchange demonstrated the need for readers to calibrate ageing criteria with a reference collection before reading structures, a practice that yielded significant improvements in between-reader precision of spine band pair counts. After calibration, the primary readers examined the full sample set. The two structures yielded similar age estimates for younger animals, but centrum estimates were consistently younger than spine estimates after age-10. Although further work is necessary to fully explore potential reasons for the observed bias, such as centrum size and location within the vertebral column, at the present time centra are not a suitable alternative to dorsal fin spines for age determination of Pacific spiny dogfish >10 years of age.

Annulus Development on the Second Dorsal Spine of the Spiny Dogfish (Squalus acanthias) and Its Validity for Age Determination

1985 ◽  
Vol 42 (11) ◽  
pp. 1799-1805 ◽  
Author(s):  
Richard J. Beamish ◽  
Gordon A. McFarlane
Keyword(s):  
Life History ◽  
Age Determination ◽  
Squalus Acanthias ◽  
Dorsal Spine ◽  
Spiny Dogfish ◽  
Stem Base ◽  
Life History Parameters ◽  
Upward Growth

Annual marks were visible in three different areas of the dogfish (Squalus acanthias) spine. The annuli in the mantle, the stem base, and the inner dentine develop independently of each other. Annuli that formed on the mantle were readily identifiable externally, making them the most useful for age determination. The mantle annulus is an accumulation of pigment that appears to form because enamel deposition is not synchronous with the upward growth of the spine, resulting in the production of darkened bands that often form ridges. We validated our interpretation of annuli from fish aged 20–70 yr by tagging and recovering dogfish that were injected with oxytetracycline. Through validation we were able to demonstrate that some previous studies have underestimated age, resulting in a misunderstanding of important life history parameters.

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).

scholarly journals XRF ANALYSIS OF ARSENIC AND SELECTED METALS IN CONTAMINATED SAND FROM THE DISMANTLING OF INDUSTRIAL DISTILLATION PLANTS

2020 ◽  
Vol 20 (4) ◽  
pp. 1011-1018
Author(s):  
ANTOANETA ENE ◽  
FLORIN SLOATA
Keyword(s):  
Simultaneous Determination ◽  
Chemical Compounds ◽  
Energy Dispersive ◽  
Toxic Substances ◽  
Portable Xrf ◽  
X Ray ◽  
Spectrometric Technique ◽  
Accredited Laboratory ◽  
Very High

This paper refers to the application of XRF method for the simultaneous determination of arsenic and selected metals from waste samples resulted from the dismanlting of distilleries in the perimeter of Azomures S.A., Mures County, Romania. The dismantling operation was carried out by a specialized Romanian company, and from this operation resulted several refractory construction wastes, such as sands with a very high content of arsenic and its chemical compounds. In order to determine the arsenic and other metals concentration, the energy-dispersive X-ray fluorescence (ED-XRF) spectrometric technique was employed. Application of the ED-XRF method was performed in an accredited laboratory for the determination of toxic substances from various samples, using a Genius portable XRF (p-XRF) spectrometer manufactured by Skyray Instruments Inc.

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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