When it comes to fish, frozen is better. At least if you're concerned about climate change impacts, you should buy frozen. According to expert Peter Tyedmers: "In many cases, your better choice overall, from an environment or energy–related perspective, might be frozen product from afar, regardless of the distance."
I know this goes against the common belief that fresh seafood is better. It's time to stretch your mind a bit.
Fresh seafood is wonderful, especially when you're privileged to eat something that just came out of the water. But "fresh" fish shipped by air and delivered to you days later is not the same thing. The rot sets in as soon as the animal dies, and good chilling only slows down (doesn't prevent) the decline. Good handling and fast transport helps forestall the rot, but at what cost? AT THE COST OF WARMING THE PLANET.
Take one example. Copper River salmon shipped by air all over the US is an environmental abomination. Other salmon is just as good, and shipped frozen by barge it's better for the planet.
Smart seafood people know that properly handled and quick-frozen fish is actually better than so-called "fresh" fish that has sat on ice for several days.
Will we re-investigate frozen fish now that there's a new reason to be pro-frozen? I don't know, the "fresh" dogma is fairly entrenched. But we should.