scholarly journals Mercury in blue shark (Prionace glauca) and shortfin mako (Isurus oxyrinchus) from north-eastern Atlantic: Implication for fishery management

2018 ◽  
Vol 127 ◽  
pp. 131-138 ◽  
Author(s):  
Sebastián Biton-Porsmoguer ◽  
Daniela Bǎnaru ◽  
Charles F. Boudouresque ◽  
Ivan Dekeyser ◽  
Marc Bouchoucha ◽  
...  
2016 ◽  
Vol 5 (4) ◽  
pp. 242-248
Author(s):  
Sheila Puspa Arrum ◽  
Abdul Ghofar ◽  
Sri Redjeki

ABSTRAK Ikan hiu merupakan predator tertinggi serta merupakan penjaga dan pembersih pada rantai makanan.Indonesia merupakan salah satu negara yang melakukan penangkapan hiu terbesar di dunia.Penangkapan hiu di Indonesia selama kurun waktu tahun 2000-2010 rata-rata sebesar 106.288 ton/tahun. Sebagai tindak lanjut dan menjaga keseimbangan ekosistem, maka diperlukan monitoring. Penelitian bertujuan untuk mengetahui komposisi jenis, produksi hasil tangkapan ikan hiu, serta titik koordinat penangkapan.Penelitian dilaksanakan pada bulan April-Mei 2016 di Pelabuhan Perikanan Samudera Cilacap, Jawa Tengah. Metode penelitian yang digunakan yaitu metode deskriptif dan pengambilan sampel dilakukan dengan cara purposive sampling. Dari hasil penelitian terdapat 9 jenis ikan hiu yang didaratkan yaitu Tikusan (Alopias pelagicus), Paitan (Alopias superciliosus), Lanjaman (Carcharinus falciformis), Selendang (Prionace glauca), Cakilan Air (Isurus paucus), Cakilan (Isurus oxyrinchus), Buas (Galeocerdo cuvier), Pasiran (Carcharhius plumbeus), dan Caping (Sphyrna lewini). Produksi terbanyak didominasi oleh jenis Paitan dengan jumlah produksi sebesar 11.257 kg. Selendang dan Tikusan total berat mencapai 6.625 kg dan 7.055 kg sedangkan Caping memiliki total berat 392 kg. Tren produksi tangkap temporal cenderung mengalami kenaikan dari tahun 2012-2015. Sebaran titik koordinat penangkapan berada pada kisaran lintang 7048’58,0” sampai 8005’42,9” dan bujur 109005’07,1” sampai 109045’03,5” untuk alat tangkap longline. Untuk alat tangkap gillnet berada pada kisaran koordinat lintang 7044’51,8” sampai 7049’09,0” dan bujur 109005’12,1” sampai 109011’20,4”. Daerah sebaran keseluruhan dari kedua jenis alat tangkap berada antara lintang 7049’27,0” sampai 8002’43,1” dan bujur 109007’06,4” sampai 109045’03,5” yang merupakan bagian dari perairan di bagian selatan Cilacap. Kata kunci: jenis hiu; distribusi titik penangkapan; perairan Cilacap. ABSTRACT Shark is the top predator that is guards and cleaners in the food chain. Indonesia is one of country that does highest shark fishing in the world. Shark fishing in Indonesia for the period 2000-2010 produced an average of 106.288 tonnes / year. As a follow up of this and maintain the balance of the ecosystem, it is necessary monitoring. The study was aimed to determine the species composition, production of shark catches, and the coordinates of the fish catching. The study was conducted in April-May 2016 at the Cilacap Oceans Fishing Port, Central Java. This research used descriptive method and sampling was done by a purposive sampling. There were 9 species of shark were landed, there are pelagic thresher (Alopias pelagicus), big-eyed thresher (Alopias superciliosus), silky shark (Carcharinus falciformis), blue shark (Prionace glauca), longfin mako (Isurus paucus), shortfin mako (Isurus oxyrinchus), tiger shark (Galeocerdo cuvier), sandbar shark (Carcharhius plumbeus), and scalloped hammerhead shark (Sphyrna lewini). The highest production was big-eyed thresher with total production of 11.257 kg. Blue shark and pelagic thresher total weight reached 6.625 kg and 7.055 kg, while the scalloped hammerhead shark has a total weight of 392 kg. Temporally capture production trends tended to increase from year 2012 to 2015. Distribution of fishing coordinate point was in the range of latitude 7048'58,0"until 8005'42,9" and the longitude 109005'07,1"until 109045'03,5" for longline fishing gear. For gillnet fishing gear was in the range of latitude 7044'51,8"until 7049'09,0" and longitude 109005'12,1"until 109011'20,4". Overall distribution of both types of fishing gear were between latitude 7049'27,0"until 8002'43,1" and longitude 109007'06,4"until 109045'03,5" which is part of the southern part of Cilacap  waters.  Keywords :Shark species; catch distribution; Cilacap waters. 


PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4112 ◽  
Author(s):  
Agostino Leone ◽  
Ilenia Urso ◽  
Dimitrios Damalas ◽  
Jann Martinsohn ◽  
Antonella Zanzi ◽  
...  

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.


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