scholarly journals Capture of a Blue Shark Prionace glauca (Linnaeus, 1758) (Chondrichthyes: Charcharhinidae) by a Swordfish Longliner off Fethiye (Mediterranean Sea, Turkey)

2020 ◽  
pp. 62-65
Author(s):  
Okan AKYOL ◽  
Tevfik CEYHAN
Keyword(s):  
Mediterranean Sea ◽  
Blue Shark ◽  
Prionace Glauca

scholarly journals Genetic differentiation and phylogeography of Mediterranean-North Eastern Atlantic blue shark (Prionace glauca, L. 1758) using mitochondrial DNA: panmixia or complex stock structure?

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4112 ◽  
Author(s):  
Agostino Leone ◽  
Ilenia Urso ◽  
Dimitrios Damalas ◽  
Jann Martinsohn ◽  
Antonella Zanzi ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Atlantic Ocean ◽  
Mediterranean Sea ◽  
Spatial Genetic Structure ◽  
Population Expansion ◽  
Phylogeographic Structure ◽  
Blue Shark ◽  
Prionace Glauca ◽  
North Eastern ◽  
The Mediterranean

BackgroundThe blue shark (Prionace glauca, Linnaeus 1758) is one of the most abundant epipelagic shark inhabiting all the oceans except the poles, including the Mediterranean Sea, but its genetic structure has not been confirmed at basin and interoceanic distances. Past tagging programs in the Atlantic Ocean failed to find evidence of migration of blue sharks between the Mediterranean and the adjacent Atlantic, despite the extreme vagility of the species. Although the high rate of by-catch in the Mediterranean basin, to date no genetic study on Mediterranean blue shark was carried out, which constitutes a significant knowledge gap, considering that this population is classified as “Critically Endangered”, unlike its open-ocean counterpart.MethodsBlue shark phylogeography and demography in the Mediterranean Sea and North-Eastern Atlantic Ocean were inferred using two mitochondrial genes (Cytb and control region) amplified from 207 and 170 individuals respectively, collected from six localities across the Mediterranean and two from the North-Eastern Atlantic.ResultsAlthough no obvious pattern of geographical differentiation was apparent from the haplotype network, Φst analyses indicated significant genetic structure among four geographical groups. Demographic analyses suggest that these populations have experienced a constant population expansion in the last 0.4–0.1 million of years.DiscussionThe weak, but significant, differences in Mediterranean and adjacent North-eastern Atlantic blue sharks revealed a complex phylogeographic structure, which appears to reject the assumption of panmixia across the study area, but also supports a certain degree of population connectivity across the Strait of Gibraltar, despite the lack of evidence of migratory movements observed by tagging data. Analyses of spatial genetic structure in relation to sex-ratio and size could indicate some level of sex/stage biased migratory behaviour.

Biological characteristics of blue shark, Prionace glauca, in the Mediterranean Sea

2009 ◽  
Vol 89 (6) ◽  
pp. 1233-1242 ◽  
Author(s):  
Persefoni Megalofonou ◽  
Dimitris Damalas ◽  
Gregorio de Metrio
Keyword(s):  
Sex Ratio ◽  
Mediterranean Sea ◽  
Oocyte Diameter ◽  
Longline Fishery ◽  
Blue Shark ◽  
Prionace Glauca ◽  
Ovary Weight ◽  
Caudal Vertebrae ◽  
The Mediterranean ◽  
Age Estimates

A total of 870 blue sharks ranging from 70 to 349 cm in total length (LT) were sampled from the swordfish longline fishery in the Mediterranean Sea during the period 1998–2003. Males predominated and the sex-ratio (1:1.8) showed an increase in the proportion of males as size of fish increased. Gonad observation revealed that females smaller than 120 cm LT had immature ovaries with no mature oocytes, while mature ovaries with visible yolky oocytes were present in specimens larger than 203 cm LT. Ovary weight varied from 4–137 g and maximum oocyte diameter was 21.1 mm in mature females. All males smaller than 125 cm LT were immature while males larger than 187 cm LT were mature, as indicated by the presence of heavily calcified claspers, which extended beyond the posterior end of the pelvic fins. Length at 50% maturity (L50) was estimated to be 202.9 cm LT for males and 214.7 cm LT for females. Age estimates using caudal vertebrae ranged from 1 to 12 years, while age at 50% maturity was estimated at 4.9 years for males and 5.5 year for females.

When prey becomes killer: does a double lethal attack on a blue shark reveal a precise defensive strategy in young swordfish?

2020 ◽  
Vol 100 (5) ◽  
pp. 831-836 ◽  
Author(s):  
Teresa Romeo ◽  
Pietro Battaglia ◽  
Domenico Macaluso ◽  
Giuseppe Tagliavia ◽  
Teresa Manuela Vicchio ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Mediterranean Sea ◽  
Rare Case ◽  
Defensive Strategy ◽  
Blue Shark ◽  
Prionace Glauca ◽  
Strait Of Sicily ◽  
Computed Tomography Scanning ◽  
The Right ◽  
Tomography Scanning

AbstractIn this paper a rare case of a double swordfish mortal attack against an adult blue shark (Prionace glauca) is reported. A female blue shark, with a total length of 3 m, was found stranded along the southern Sicilian coast (Strait of Sicily, Mediterranean Sea) on 30 May 2018. The analysis of this carcass revealed the presence of two swordfish bill fragments, impaled in the shark head; the former on the snout, the latter near the eye. The results of anatomical and computed tomography scanning analysis on the head of the blue shark showed that the larger bill fragment (19.7 cm) probably determined the death of this animal, having been impaled in a vital point, just behind the right eye. The analysis of both these events and other similar swordfish-shark interactions reported in the literature makes possible the hypothesis that young swordfish specimens put in place a precise defensive strategy against their potential predators or competitors, aimed at hitting vulnerable and vital points and delivering a mortal blow.

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

Spatial distribution of the parasite Kroyeria carchariaeglauci Hesse, 1879 (Copepoda: Siphonostomatoida: Kroyeriidae) on gills of the blue shark (Prionace glauca (L., 1758))

1987 ◽  
Vol 65 (5) ◽  
pp. 1275-1281 ◽  
Author(s):  
George W. Benz ◽  
Kevin S. Dupre
Keyword(s):  
Spatial Distribution ◽  
Natural Selection ◽  
Distribution Pattern ◽  
Surface Area ◽  
Blue Shark ◽  
Prionace Glauca ◽  
Homogeneous Groups ◽  
Secondary Lamellae ◽  
Gill Filaments ◽  
Gill Surface Area

Five blue sharks (Prionace glauca) were examined for gill-infesting copepods. Three species of siphonostomatoid copepods were collected: Gangliopus pyriformis, Phyllothyreus cornutus, and Kroyeria carchariaeglauci. The spatial distribution of K. carchariaeglauci was analyzed. The number of K. carchariaeglauci per shark was positively related to gill surface area and host size. Copepods were unevenly distributed amongst hemibranchs; flanking hemibranchs could be arranged into three statistically homogeneous groups. Female K. carchariaeglauci typically attached themselves within the middle 40% of each hemibranch; males were more evenly dispersed. Eighty percent of all K. carchariaeglauci attached themselves to secondary lamellae, the remainder were in the underlying excurrent water channels. Most K. carchariaeglauci were located between 10 and 25 mm along the lengths of gill filaments. Overall, the spatial distribution of K. carchariaeglauci was quite specific in all study planes. Explanation of this distribution is set forth in terms of natural selection pressures; however, the equally plausible explanation that the distribution pattern exhibited by these copepods is phylogenetically determined and may have little to do with contemporary selective constraints should not be ignored.

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