dividing Caspian see between bordering countries

[fooladi]

I'm looking for Non-political solutions by only using mathematics and geometry for dividing Caspian see between bordering countries
thanks

 

[mmm4444bot]

Divide the sea into areas which are proportional to the relative size of the bordering countries.

 

[fooladi]

how do this? it's shape is not simple Circle and where is its center?
so i think curve lines must use for dividing it :idea: but how?
these maps are perhaps my final answer. but the way to solve it is?