There was plenty in this book that I already knew:
(1) we are ruining the ocean with overfishing and pollution;
(2) farmed salmon is an environmental disaster and not much use in a nutritional sense either;
(3) fishermen do a lousy job of self-policing and they blame the government for putting them out of a job but only because they can't fish as much as they'd like to;
(4) governments do a lousy job of protecting fishing stocks because fishermen are constituents, the fishing industry is an important lobby, and no politician wants to be viewed as anti-business; and
(5) the system of using any kind of flag on a ship is a terrible idea and piracy or illegal fishing is a huge problem for the fishing industry.

But there was also a lot that I didn't know or hadn't thought of:
(1) we are also ruining bays and estuaries with invasive plants and fish. We all know about carp, but I didn't know about algaes moving in when what is supposed to be there is gone or they are unwittingly brought in by ships;
(2) shrimp from Thailand or India or any other non-US or Canadian country is farmed, full of antibiotics, polluting and full of things like bleach. I promise I will only eat Maine shrimp from now on. I love shrimp but it was disgusting and depressing and I had no idea;
(3) there are some farmed fish that are just fine to eat, particularly trout and tilapia. Apparently, farmed fish that are raised in inland ponds don't have the environmental affects of those in the ocean;
(4) the Japanese, in particular, eat some disgusting things. I won't get started on whaling and my complete horror that they do this and get away with it but I learned a new term "cruel cuisine", for example, eating live cut up octopus. That is so beyond disgusting and cruel that I don't know where to begin. It's the difference between humane killing (I'm not going to argue about this) and hanging, drawing and quartering. There is just no excuse for what amounts to torture; and
(5) you can't always trust those supermarket signs about farmed, origin etc. Since I can't do anything about that, I have to make my decisions based on that information but it's infuriating to know that I could be eating something completely different and it might be farmed when I think it is wild.

I really liked the structure of Bottomfeeder with a focus on a particular food, e.g. oysters from Brittany, sushi in Japan. It's written in an engaging way. I borrowed this book from the library but I really think I need to own it. This book is basically The Omnivore's Dilemma for fish.