what is the meaning of "since when~"?

Question

i am student who studies english.
i dont know the meaning of "since when"

--> The IWC introduce a ban on whale hunting in 1892, effective from 1986, since when whale stocks appear to have recoverd.

in this sentence, what is the meanig of "since when"

could you tell me????? //// ^_^

Answer 1

It sounds like an incorrect term to me. They might have meant to say "The IWC introduced a ban on whale hunting in 1892, effective until 1986, at which time whale stocks appear to have recovered."
Also "at which time" can simply be stated "when"

Answer 2

From that point in time whale stocks appear to have recovered~~

Answer 3

Dear asker,from the context you can easily understand that since when means starting from1892 or1986 upto now the whale stocks appear to have recovered.That is all.
hope you read this and that it helps

Answer 4

Since when means - since that time, whale stocks have recovered.
or - After that time, whale stocks have recovered

any use?