DAY 8 – GANSBAAI SHARK TRIP – OCEANS 1

Great  White Shark’s imminent extinction, but they are essential to the food chain.

The University of earth team goes to Gansbaai near Cape town to see the great white shark from a cage inside the water. The marine scientists Mary from Shark Diving Company joins them to explain what is happening that is endangering the great white.

Sharks have their own personality and how they regard the bait is all due to what mood they are in or their personality. The bait is not food for the sharks. The shark cage diving does not make shark is more likely to attack humans. Shark bodies need to work at about 27 degrees which mean they have to eat high fatty food to maintain their body temperature. Sharks are very migratory by nature.

Sharks have many threats to their survival. The nets catch thousands. There is also a shortage of food. They eat seals and fish. they have incredibly low genetic diversity as 89% of the shark come from the same ancestor. There are only 4 maternal lineages. Only 333 white sharks effective population. It is generally considered that there must be at least 500 mating pairs to survive, so it is possible that it is already in an extinction spiral. Sharks are identified by the trailing edge of their dorsal fin.

Beach nets and drum lines are a massive threat to shark.( also dolphins). Dr. Andriotti has developed a shark repellent which looks like a big kelp bed with magnets. It has 100% success at repelling shark and kills no sea life. There is another electro magnetic repellent but not a good idea to depend on electricity.

Shark has a couple of extra sense – the lateral line allows them to detect vibrations in the ocean. Jelly like anculae lorenzini, black dots n its nose.  jelly like canals which detect magnetic energy and so they use them to navigate around the world using the poles magnetism.

We are changing the chemistry of the ocean with all the chemicals. The PH is lowering so the coral bleaches. Coral reefs are the most diverse ecosystems. Mary does not believe that we understand the consequences of what we have done.

Sharks are apex predators with no enemy except orcas. They regulate everything below them in the food chain. So the negative effect will ripple down the food chain. Fish diminish once the shark are gone. They keep the ocean clean.

MARY’S WISH LIST

Stop shark fishing.

Stop fishing with trawlers and commercial boats. Except for small-scale fishermen.

Stop the inhumane practice of shark fin removal.

Great White Sharks die if put in captivity. We can’t put them into a breeding program. We need to protect them before it is too late.

There are only between 3000 to 5000 Great White Sharks left in the whole world. Sharks always return inshore because they are coastal predators. A shark can swim 22 000 kilometers in as little as 8 months.

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