In the US, the country of origin must be stated on the packaging. This doesn't really help in the case of seafood, as the origin location specifies where it was processed and canned, not necessarily where it was harvested.

There are lots of 'country of origin marking' laws that are exploited or ignored by producers and vendors. US Customs turns a blind eye to it, unfortunately.

It is all laid out in Title 19, Part 134 of the US Code of Federal Regulations, if you are up for a read.

[link to www.gpo.gov]