Sunday, January 15, 2012

Meet me whale mate

Another ' what is it' moment but honestly don't click and enlarge.
It's the vertebrae of a basking shark.  They've been overfished thanks to their highly valued fins and are now on the Convention on International Trade in Endangered Species. They don't reproduce quickly, having low fertility, are slow growing, long lived but slow to mature.

This is what a basking shark does best.  Lazes at the surface of the sea with mouth  (what a north and south it is)  open, filter feeding on zooplankton. In one hour they can filter enough water to fill an Olympic-size swimmig pool.

They are the second largest fish behind whale sharks but not much is known about their habits. Pregnant females and and young have never been spotted and they disappear for half the year. Scientists have tagged them but since they live for 50 years or more and the tags fall off after a year, it's hard to follow their migration patterns.

Which is where this section of vertebrae comes in.  Like tree rings, the vertebrae consists of distinct layers of tissue laid down sequentially over an individual's life time in an alternating light/dark banding pattern.  Using vertebrae from sharks that have stranded on beaches, scientists are looking for a radioactive isotope from nuclear bomb blasts set off in the l950s. the residue which fell all over us and the ocean.  Different areas of the ocean have different ratios of stable carbon and nitrogen isotopes so when overlain on a map of the ocean, they create distinct isotope patches and when the whales eat the plankton in these patches it shows up in the layers and in time will enable scientists to map their migration pathways.
Knowing where and when they go will help form a plan of conservation that will also help whale sharks and great whites thanks to the research of Li Ling Hamady.

As you can see in this map, colour variations represent different ratios of nitrogen isotopes in the ocean.


Elephant's Child said...

I hope that Li Ling Hamady always has sufficient funding to carry out this valuable research. I really hope so.

River said...

I would be hoping that someone would invent a tag that doesn't fall off in a year.
I hope also that funding for this research is always available.

JahTeh said...

EC, when you look at the size and all they want to take is the fin, it's disgraceful. I'll never eat shark fin soup.

River, it just shows how huge our oceans are when something this big can disappear for half the year. I'm old enough to remember being taught that the Pacific ocean was a vast flat plain, a dead zone devoid of life. I posted a long time ago on how a whale carcass falling to the sea bed was a bonanza of food for the deep critters.

River said...

The Pacific as a flat plain?
A dead zone devoid of life?
Who would teach such a thing?

Jayne said...

They are such magnificently beautiful creatures *sigh* so gorgeous to look at.
Hope further research is gained to save these lovely beings.

JahTeh said...

River, it all went the way of the dinosaur with the discovery of Plate Tectonics and the deep diving machines with cameras.

Jayne, I can't understand why it is that they can take just the fin and not get a bit of extra cash for the whole lot but then they aren't flying under the "research" flag.

Middle Child said...

The size is amazing - you akways come up with really interesting stuff - .

JahTeh said...

My mind is like a sink drainer, it catches everything.