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Shark Info 2 / 02   (07-20-2002)

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  Intro:

Modern technology aids shark protection

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  Main article:

Modern technology aids white shark protection

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  Article 1:

The role of CITES in protecting and managing sharks

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  Article 2:

Shark Exhibit in Zurich

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  Article 3:

Sharks in Research and Industry

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  Article 4:

Dr. Erich Ritter's accident with a bull shark

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  Fact Sheet:

Salmon Shark

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Sharks in Research and Industry

Report by Shark Info

Migrations of the whale shark (Rhincodon typus)

One enormous problem encountered in trying to protect selected shark species is the lack of knowledge on the migratory behavior of individual species. During their migrations, sharks pay no attention to political boundaries, while unfortunately catch and usage regulations of these animals do.
In this study the migratory behavior of six whale sharks in the Sulu Sea region was registered by satellite telemetry between 7 to 128 days. Each of the animals swam a distance of 4,567 km, i.e. 8,025 km, crossing several political boundaries in their migrations. The acquired data proves the need to regulate the economy and the protection of whale sharks multilaterally, or at least on a regional level.

Source: Movements of whale sharks (Rhincodon typus) in South-east Asian waters as determined by satellite telemetry (2002). Journal of Zoology 257 pp 111-115.

Multiple paternity in the nurse shark (Ginglymostoma cirratum)

The Dry Tortugas Region of the Florida Keys represents a very important area for the reproduction of nurse sharks where many of the animals have been observed. Using molecular biological methods the paternity of 32 descendants of one mother animal were examined. Results showed that the young pups had at least four different fathers. This multiple paternity strategy most likely increases the genetic diversity of a population on a short-time basis which in turn appears to be most valuable for species with limited migratory behavior.

Source: Multiple paternity in the nurse shark, Ginglymostoma cirratum (2002). Environmental Biology of Fishes 63 pp 347-351.

Radioactive contamination from bomb tests enable age determination of large pelagic sharks

Determining the age of long-living pelagic sharks is particularly difficult. It is known that sharks take up radioactive material in their food chain and partially store it in various tissues. This is true for porbeagle sharks (Lamna nasus) who store it in their cartilaginous vertebrate tissue. Such deposits lead to measurable growth rings or bands which are characteristic for a certain time period time, similar to those of trees which reflect the relevant climate.

The growth rings found in animals from the 60s corresponded with animals found later on and thus made it possible to calibrate the growth rings of porbeagle sharks up to at least the age of 26.

Source: Bomb dating and age determination of large pelagic sharks (2002) Canadian Journal of Fisheries & Aquatic Sciences 59 pp 450-455.

A new shark species in the Parascyllium family

Registering species is difficult, even for specialists. On the one hand some species are so rare that even sighting them may be purely accidental, making it just as accidental for the relevant specialist to even find out about it. On the other hand, species can resemble each other to such a degree that they can be assessed as being a variation of one single, so-called cryptic species.

As concerns the above-mentioned species from West Australia, Parascyllium sparsimaculatum (meaning the sparsely or weakly spotted), the differences to the next similar species ascertained through morphological measurements are proven and cannot easily be recognized without mathematical aids. Up until now only three specimens of this species have been scientifically registered and published as such. The authors provide an identification key which includes and comprises those species in the group which can be confused with each other.

Source: A new parascylliid species, Parascyllium sparsimaculatum, from Western Australiua (Elasmobranchii: Orectolobiformes). Ichthyological Research, 2002, 49, pp 15-20.

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