The Species and Origin of Shark Fins in Taiwan’s Fishing Ports, Markets, and Customs Detention: A DNA Barcoding Analysis

<div><p>The increasing consumption of shark products, along with the shark’s fishing vulnerabilities, has led to the decrease in certain shark populations. In this study we used a DNA barcoding method to identify the species of shark landings at fishing ports, shark fin products in retail stores, and shark fins detained by Taiwan customs. In total we identified 23, 24, and 14 species from 231 fishing landings, 316 fin products, and 113 detained shark fins, respectively. All the three sample sources were dominated by <i>Prionace glauca</i>, which accounted for more than 30% of the collected samples. Over 60% of the species identified in the fin products also appeared in the port landings, suggesting the domestic-dominance of shark fin products in Taiwan. However, international trade also contributes a certain proportion of the fin product markets, as four species identified from the shark fin products are not found in Taiwan’s waters, and some domestic-available species were also found in the customs-detained sample. In addition to the species identification, we also found geographical differentiation in the <i>cox1</i> gene of the common thresher sharks (<i>Alopias vulpinus</i>), the pelagic thresher shark (<i>A</i>. <i>pelagicus</i>), the smooth hammerhead shark (<i>Sphyrna zygaena</i>), and the scalloped hammerhead shark (S. <i>lewini</i>). This result might allow fishing authorities to more effectively trace the origins as well as enforce the management and conservation of these sharks.</p></div

Maximum likelihood tree for the pelagic thresher shark, <i>Alopias pelagicus</i>.

<p>The tree was constructed with a 403 bp <i>cox1</i> gene fragment and ran for 1,000 bootstrap replications. DNA sequences of the sharks from the Indo-West Pacific Ocean can be distinguished from those of the East Pacific Ocean. The sequences from the database were expressed as accession numbers and our specimens as label abbreviations (PL, FP, and CD for port landings, fin products, and customs-detained samples, respectively). Different sequences with the same haplotype were placed in a single taxon (with dashes to connect consecutive sequences and commas to separate disjunctive ones). Only bootstrap values higher than 70% are shown on the branch.</p

Maximum likelihood tree for all 660 sequences obtained in this study.

<p>Each species formed a distinct group in the tree, indicating the robustness of the DNA barcoding method on shark species identification. The tree was constructed with 1,000 bootstrap replications and only bootstrap values higher than 70% are shown on the branch.</p

Maximum likelihood tree for the common thresher shark, <i>Alopias vulpinus</i>.

<p>The tree was constructed with a 651 bp <i>cox1</i> gene fragment and ran for 1,000 bootstrap replicateion. DNA sequences of the sharks from the Indian Ocean and those from other regions form two distinct groups. Only bootstrap values higher than 70% are shown on the branch.</p

Maximum likelihood tree for the smooth hammerhead shark, <i>Sphyrna zygaena</i>.

<p>The tree was constructed with a 403 bp <i>cox1</i> gene fragment and ran for 1,000 bootstrap replications. DNA sequences of the sharks from the Atlantic Ocean can be distinguished from those of other regions. Only bootstrap values higher than 70% are shown on the branch.</p

Trends in brain cortical thickness relative to IBS duration in the IBS patients (n = 29).

<p>Trends in brain cortical thickness relative to IBS duration in the IBS patients (n = 29).</p

Differences in the affected cortical regions between the IBS and control groups.

<p>Differences in the affected cortical regions between the IBS and control groups.</p

Comparison of thickness in six areas in the cortex between the IBS and control groups.

<p>Comparison of thickness in six areas in the cortex between the IBS and control groups.</p