Vertebral rings as a means of age determination in the blue shark (Prionace glauca L.)

1975 ◽  
Vol 55 (3) ◽  
pp. 657-665 ◽  
Author(s):  
J. D. Stevens
Keyword(s):  
Age Determination ◽  
Alternative Methods ◽  
Tooth Replacement ◽  
Blue Shark ◽  
Prionace Glauca ◽  
Vertebral Centra ◽  
Rate Of Growth ◽  
Elasmobranch Fishes

Elasmobranch fishes cannot at present be aged by scale or otolith readings as can certain teleosts. Consequently comparatively little is known about their age or rate of growth, particularly in the case of larger sharks. Alternative methods of age determination within this group have utilized tagging data (Bonham et al., 1949; Holden, 1972); size frequencies (Olsen, 1954; Aasen, 1966); the spine of Squalus sp. (Kaganovskaia, 1933; Holden & Meadows, 1962); tooth-replacement rates (Moss, 1967, 1972) and vertebral rings. These rings on the vertebral centra, resulting from variations in calcification, have also been used in the age determination of teleosts. In the scombroids there is often considerable variation in results even between authors working on the same species, mainly due to difficulty in interpreting the rings and deciding whether they are true year marks (Aikawa & Katô, 1938; Partlo, 1955; Otsu & Uchida, 1959; Hui-chong, Nose & Hiyama, 1965).

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.

scholarly journals Dentition and age determination of the Warthog Phacochoerus aethiopicus in Zululand, South Africa

Koedoe ◽  
1984 ◽  
Vol 27 (1) ◽  
Author(s):  
D.R Mason
Keyword(s):  
Population Control ◽  
Age Determination ◽  
Dry Mass ◽  
Eye Lens ◽  
Tooth Replacement ◽  
Older Individuals ◽  
Age Classes ◽  
Relative Growth ◽  
Reliable Differentiation

Age-specific stages of tooth replacement, eruption and attrition are described for warthogs shot during population control in Zululand. Patterns of tooth replacement and eruption allowed reasonably accurate age determination up to 24 months, whereafter 2-3 year old warthogs could generally be distinguished from older individuals by the relative growth of their third molars. Although stages of wear and loss of the teeth, especially the three molars, were associated with broad age classes, age of adult warthogs may be determined more precisely by counting cementum annuli in sectioned incisor teeth. However, cementum annuli were insufficiently distinctive to permit age estimation in approximately 33 of sections, reflecting particularly variation in intensity and clarity of staining and splitting and merging of rest lines. The use of eye lens dry mass and tusk length: snout width ratios as indices of age was also evaluated. Eye lens dry mass became increasingly unreliable for predicting age beyond 24 months. Considering males and females separately, tusk length: snout width ratios for yearling, 2-3 year old and 3-4 year old warthogs were reasonably distinctive, but subsequent overlap was apparently unfavourable for reliable differentiation of year classes among older warthogs. Body size and tusk * development criteria for distinguishing between three age classes ofwarthogs in the field are presented.

scholarly journals Determination of functional compounds in blue shark (Prionace glauca) liver oil obtained by green technology

2020 ◽  
Vol 71 (2) ◽  
pp. 354
Author(s):  
D. N. Santos ◽  
F. S. Silva ◽  
A. B. Verde ◽  
G. M. Bittencourt ◽  
A. L. De Oliveira
Keyword(s):  
Vitamin A ◽  
Unsaturated Fatty Acids ◽  
Acid Value ◽  
Green Technology ◽  
Blue Shark ◽  
Prionace Glauca ◽  
Shark Liver Oil ◽  
Saponification Value

The objectives of this research were to obtain blue shark liver oil using supercritical CO2 and to characterize the physicochemical parameters of the oil, and the contents of squalene and vitamin A. Supercritical extractions were performed at 50 and 60 °C and pressures from 100 to 300 bar. The oil yield obtained was up to 60% and presented a profile equivalent to that of refined oils for density (0.920 – 0.922 g/mL); viscosity (52.55 – 56.47 Pas.s); refractive index (1.4760 – 1.4785); acid value (1.13 – 2.22% oleic acid); peroxides (10.47 – 24.04 meq of active O2 /kg of oil); saponification value (171.37 – 556.03 mg KOH/g oil), and iodine value (120.05 – 149.21g I2 /100g oil). The fatty acid profile indicated a majority of unsaturated fatty acids. High levels of squalene and vitamin A corroborate the high nutritional quality of this oil from an underexploited by-product with great processing potential.

scholarly journals Bomb dating and age determination of skates (family Rajidae) off the eastern coast of Canada

2009 ◽  
Vol 66 (3) ◽  
pp. 546-560 ◽  
Author(s):  
Romney P. McPhie ◽  
Steven E. Campana
Keyword(s):  
Growth Models ◽  
Age Determination ◽  
Age And Growth ◽  
Eastern Coast ◽  
Vertebral Centra ◽  
A Value ◽  
Bomb Radiocarbon ◽  
Absolute Age ◽  
Two Parameter

Abstract McPhie, R. P., and Campana, S. E. 2009. Bomb dating and age determination of skates (family Rajidae) off the eastern coast of Canada. – ICES Journal of Marine Science, 66: 546–560. Recent declines in abundance of skates off the eastern coast of Canada have heightened the need for validated age and growth estimates in the region. In all, 502 winter (Leucoraja ocellata), little (Leucoraja erinacea), thorny (Amblyraja radiata), and smooth (Malacoraja senta) skate vertebral centra collected seasonally between 1999 and 2004 were sectioned using a mass processing method, then used to reconstruct growth in each species. Bomb radiocarbon (Δ14C) analysis was used to provide evidence of annual band-pair deposition in thorny skates. Estimates of L∞ from traditional von Bertalanffy growth models (VBGM) ranged from 60.6 cm (little skate) to 89.7 cm (thorny skate), and K estimates from 0.07 (thorny skate) to 0.19 (little skate). A modified two-parameter VBGM (Lmax = 94.1 cm) fitted to winter skate length-at-age data yielded a value of K of 0.15. Maximum observed ages ranged from 12 (little skate) to 19 years in both winter and thorny skates. The year-specific incorporation of Δ14C milled from thorny and winter skate vertebral sections closely resembled shark-derived reference chronology values from the Northwest Atlantic. Pre-bomb Δ14C in a thorny skate collected in 1988 and aged at 23 years appeared to validate age interpretations and suggested that thorny skate reach an absolute age of at least 28 years, the oldest validated age reported for any species of batoid.

Isotopic niches of the blue shark Prionace glauca and the silky shark Carcharhinus falciformis in the southwestern Indian Ocean

2012 ◽  
Vol 17 (1) ◽  
pp. 83-92 ◽  
Author(s):  
N Rabehagasoa ◽  
A Lorrain ◽  
P Bach ◽  
M Potier ◽  
S Jaquemet ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Blue Shark ◽  
Prionace Glauca ◽  
Silky Shark ◽  
Carcharhinus Falciformis ◽  
Southwestern Indian Ocean

Seasonal migrations of pregnant blue shark Prionace glauca in the northwestern Pacific

2020 ◽  
Author(s):  
Y Fujinami ◽  
K Shiozaki ◽  
Y Hiraoka ◽  
Y Semba ◽  
S Ohshimo ◽  
...  
Keyword(s):  
Northwestern Pacific ◽  
Blue Shark ◽  
Prionace Glauca ◽  
Seasonal Migrations
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