They concentrated on actual shrimp growth over disease….
The US SPF exclusion system concentrated genetically on breeding in disease prevention (that’s why it is called Specific Pathogen Free!) and that was the technology pushed into SE Asia.
Unfortunately growth of actual shrimp was secondary consideration in US to diseases. Who is to say why dialogue was controlled by US shrimp disease experts? Profit motive? Fear of diseases being good business in farming….
Anyway in China shrimp growth more important genetic trait than to be disease.
Shrimp farming in China initially started commercially in Taiwan before moving to vannamei and mainland China.