Grammer

First, the word is spelled "grammar".

Second, let's add a word to your sentence:

1. There are more fishers in Asia than in the rest of the world combined.

This means that if you added up all the fishers in the rest of the world the total would be less than the number of fishers in Asia. That total — minus Asia — is the "rest of the world combined."

2. There were 0.5 million fishers in 1970 increasing to about 1.2 million in 1980.

You could say it this way: Between 1970 and 1980 the number of fishers increased from 0.5 million to 1.2 million.

But the construction of the original sentence requires the use of the adverbial participle "increasing."