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.

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.

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

scholarly journals Life-history traits of the spiny dogfish Squalus acanthias in the Adriatic Sea

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Giada Bargione ◽  
Fortunata Donato ◽  
Mario La Mesa ◽  
Carlotta Mazzoldi ◽  
Emilio Riginella ◽  
...  
Keyword(s):  
Life History ◽  
Life History Traits ◽  
Adriatic Sea ◽  
Growth Parameters ◽  
Sampling Period ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
The North ◽  
Size At Sexual Maturity ◽  
The Individual

Abstract Pivotal life history traits concerning age structure and reproduction of the spiny dogfish (Squalus acanthias, Linnaeus 1758) were investigated in the Adriatic Sea from mid February 2012 to mid July 2013 and in 2016. The whole sample consisted of 176 females and 150 males, ranging between 217–1025 mm and 219–875 mm, respectively. The individual age, which was estimated using a cross-sectioning technique of the second dorsal-fin spine, ranged from 0 to 13+ years for females and from 0 to 9+ years for males. Based on the length-at-age estimates, the Gompertz growth parameters were L∞ = 1130 mm, k = 0.18 and L∞ = 920 mm, k = 0.24 for females and males, respectively. The size at sexual maturity (L50) was 659 mm for females and 575 mm for males, corresponding to 7.5 and 5.5 years of age (A50), respectively. Mean biennial fecundity was approximately 11 embryos/female and 12 ripe oocytes/female. Mature males occurred during much of the sampling period, while mature females with nearly full-term embryos were exclusively recorded in May 2013 and July 2016. Monitoring of catches conducted in a sample port of the north Adriatic (Chioggia) over the past 20 years has shown fluctuating trends in landings, with peaks during the summer reproductive season.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Age Estimation ◽  
Squalus Acanthias ◽  
Dorsal Spine ◽  
Spiny Dogfish ◽  
Band Formation ◽  
Inaccurate Measurement ◽  
Sources Of Error ◽  
Potential Sources

Abstract.—Counts of annuli that form on the mantle of the second dorsal spine of 59 spiny dogfish <em>Squalus acanthias </em>that had been at liberty for up to 20 years after marking with oxytetracycline in most cases corresponded to the years at liberty (87% within 1 year). These results confirm the pattern of annual band formation on the second dorsal spine and validate its use in age estimation. We identified two potential sources of error when estimating the number of annuli on the spine: 1) inaccurate annuli counts near the base of the spine due to irregular enamel deposition and 2) inaccurate location of the no-wear point and subsequent inaccurate measurement of the spine diameter at the no-wear point, which affects estimation of missing annuli using the no-wear point algorithm. In addition, we confirm the validity of Ketchen’s (1975) no-wear point algorithm for the estimation of missing annuli on the worn portion of the distal tip of the spine.

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.

Life history aspects of two species of the Squalus genus in the Eastern Ionian Sea

2017 ◽  
Vol 98 (4) ◽  
pp. 937-948 ◽  
Author(s):  
Aikaterini Anastasopoulou ◽  
Chryssi Mytilineou ◽  
Panayiota Makantasi ◽  
Christopher J. Smith ◽  
Stefanos Kavadas ◽  
...  
Keyword(s):  
Life History ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Ionian Sea ◽  
Single Specimen ◽  
Spawning Activity ◽  
Positive Allometry ◽  
The Mean ◽  
Continuous Reproduction ◽  
First Maturity

Data on life history aspects of two species of Squalus genus were collated from five different studies carried out in the Eastern Ionian Sea from 1995 to 2014. Data were collected from 948 longnose spurdogs Squalus blainville (Risso, 1827) and 65 spiny dogfish Squalus acanthias Linnaeus, 1758 caught by trawl and longlines. The mean length of both species increased with depth. Sexual segregation was observed for S. blainville, whereas a segregation of immature and mature individuals was detected for S. acanthias. The length–weight relationship for S. blainville indicated positive allometry (b > 3) for both sexes, whereas a negative allometry (b < 3) was found for S. acanthias for the combined sexes. The sex ratio of both species was in favour of males. For S. blainville, the gonadosomatic and hepatosomatic indices differed significantly between sexes but not between seasons with the maturity data supporting the hypothesis of continuous reproduction throughout the year. Length at first maturity (L50) for female and male S. blainville was 603 and 413 mm respectively. For S. acanthias, males collected in autumn had finished their spawning activity; the single specimen caught in summer was reproductively active. Females, caught only in summer, were all gravid. Prey identified in the stomachs of S. blainville belonged to three major groups: fish, cephalopods and shrimps. Other groups such as echinoderms and ascidians were also found. Identified prey in the stomachs of S. acanthias belonged to two main groups, fish and cephalopods, although other groups (including echinoderms and polychaetes) were also present.

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