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Shark Info 2 / 02   (07-20-2002)

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  Intro:

Modern technology aids shark protection

Shark Info

  Main article:

Modern technology aids white shark protection

Shark Info

  Article 1:

The role of CITES in protecting and managing sharks

Shark Info

  Article 2:

Shark Exhibit in Zurich

Shark Info

  Article 3:

Sharks in Research and Industry

Shark Info

  Article 4:

Dr. Erich Ritter's accident with a bull shark

Shark Info

  Fact Sheet:

Salmon Shark

Shark Info


Modern technology aids white shark protection

Report by Shark Info

White Shark

White sharks (Carcharodon carcharias) belong to the most endangered shark species, still they are hunted for their meat which lands on the world's fish markets.

© Klaus Jost / Shark foundation

The white shark (Carcharodon carcharias) is one of the best protected shark species worldwide. Its name appears on the Red List of the IUCN (International Union for Conservation of Nature) under the "most vulnerable" species (Category A1bcd + 2cd). With CITES it is still on Appendix III which calls for close observation of any trade with white sharks, although efforts are being made by Australia and the U.S. to have it put on Appendix I, a list of animals and plants which are directly endangered by extinction. Trade with species found on Appendix I is prohibited worldwide, except for scientific reasons.

Nevertheless, despite all efforts to protect white sharks, the effective implementation of protective measures on the level of international trade has proven to be extremely problematic. Primarily this is because it is still almost impossible to prove that trade with white sharks even takes place. This is especially true in regions where, in addition to white sharks, other near relative species which do not enjoy protection are traded, making it insuperably difficult to identify shark meat, fins or already processed trunks. Shark protectors and customs observers obviously do not only encounter this problem with sharks but instead with all protected species whose sister species can be traded.

Meanwhile, in his laboratory at Nova University, Daniela Beach, Florida, Professor Mahmood Shivji developed a simple method of determining whether or not tissue samples stem from white sharks. The method can also be successfully used to check if parts of white sharks have been processed in a mixture of different shark species, e.g. in cartilagenous mixtures.

For several years Dr. Shivji has been working in the area of molecular biological analysis and shark identification. The Shark Foundation recognizes the importance of his research work for shark protection and has been supporting him since 2000.

Up until now, Dr. Shivji has worked on identifying various, commercially used shark species using minute tissue samples. Thanks to his molecular biological methods – which we reported on in our article "Molecular biology helps protect sharks" ( Shark Info 1/2000) – 16 different shark species can now be identified.

Although these methods are sufficiently reliable for statistical analyses on catches and scientific research, a bitter fight is being waged in international trade. This means that any test methods must be doubly and triply reliable if they are to be recognized by international courts. The new method developed by Dr. Shivji's laboratory functions with five probes in one single step (Pentaplexer PCR Test) and will more likely meet these requirements.

While the "simple" method only looks at one especially appropriate gene, the new method of identifying white sharks includes the same analysis of a base sequence of the cell nucleus plus a mitochondrial gene in one step. Since it makes use of DNA variations in two cell organelles, it is also called the Bi-organelle Test. Its reliability is further increased by an additional reaction which makes it possible to determine if a provable reaction even took place.

Gel

The so-called agarose gel-elektrophoresis technique makes reaction products of the B-organelle PCR tests visible. This method allows clear identification of white shark tissue based on its band pattern.

© Mahmood Shivji / Shark Foundation

Furthermore, Dr. Shivji extensively scrutinized the Bi-organelle Test. First, he had to prove that the proper recognition sequences were selected from the white shark's genetic material. The sequences would have to be specifically for white sharks, but not so specific as to only recognize certain white shark populations. Dr. Shivji thus took tissue samples from 53 white sharks stemming from all ocean regions, all of which were positively recognized by the test.

In a second step he had to determine if the test was specific enough to differentiate white sharks from its close relatives. In actual practice this has proven to be the crux of the problem where the greatest possibility exists of mistaken identification. So Dr. Shivji tested four additional species from the Lamnidae family: mackerel sharks (Lamna nasus), shortfin macos (Isurus oxyrinchus), longfin macos (Isurus paucus) and salmon sharks (Lamna ditropis). Once again the results were positive, being specific enough to differentiate between the white shark's close relatives.

For implementation in the fishing industry, the test had to be extended to other shark species, especially those from the orders of the mackerel sharks (Lamnifores) and the ground or whaler sharks (Carcharhiniformes) which represent the most common commercially fished shark species, as well as – to be on the safe side – diverse species from other orders.
For this purpose DNA from various shark species was mixed and the mixture tested using the new method of establishing proof. Results were again successful, showing a highly specific positive result only in cases where the DNA mixture contained remnants of white sharks.
All in all 68 different shark species were tested. In all cases the Bi-organelle Tests fulfilled each reliability requirement.

Finally, even financial aspects play a substantial role when it comes to species protection. Dr. Shivji's test requires no special reagents or laboratory installations apart from the average standard equipment found in the normal biochemical laboratory. Through its high specificity 10 samples can be analyzed simultaneously in only one test tube and with only one set of the relatively expensive reagents.

These results are expected to be published shortly in a scientific journal. When this happens, CITES, as well as other organizations involved in shark protection such as the FAO (Food and Agricultural Organization), will have at their disposable a valuable aid to identify white sharks. By removing their basis of argumentation, it will take the wind out of the sails of nations who until now have opposed protecting white sharks, claiming they were not identifiable in trade.

The easy-to-use application of bi-organelle tests also enables large-scale monitoring of commodities in which parts of white sharks are presumed.

Although initially the bi-organelle test for white sharks will most likely only be applied by nations who have already placed white sharks under protection, it still has the potential of being implemented worldwide as soon as white sharks enjoy global protection. A recent attempt on the part of CITES nations to put white sharks on Appendix II of the CITES lists failed at least partly because no reliable and economical methods were available to identify products made from protected sharks.

In the future this very reliable and easy-to-use technique of bi-organelle, pentaplex PCR tests can be adapted to protect other animal and even plant life and so serve to control global trade with these species.

May be published only by indicating the source: Shark Info



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last change: 06-04-2016 10:48