It turns out that Portugal is one of the most ecologically minded countries in the world. They ran the country for something like three days on only renewable energy just to prove that it was political will that makes the difference. It is nestled between Spain and the Atlantic Ocean. At lunch time there is something called "the workers lunch" where you can get a real meal for very little money, In Porto one of the finest small craft boat makers "Nelo" operates - kayaks, canoes and yes rowing skulls. An there is fish.
The Duro river empties into the sea near Porto -- the Duro estuary is peculiar in that the bottom sediment has less mercury than than the top.. like 7ug -1 vs < 1ug-1 usually settles to the bottom being a heavier metal. The transport in the bottom water is more dissolved that's the upper water which is attached to sediments and salt. Still gorgeous and lots of seafood. In the USA have a look at Fish and Shellfish Advisories and safe eating guidelines on EPA.gov -- if they haven't been removed by the current administration in Washington DC.