A reader lends his expertise to the question:
I’m a marine fisheries biologist who just returned from a research trip on a commercial fishing vessel in the Gulf of Maine. I have tremendous respect for the intelligence of fish; they are smarter than most can think, and Culum Brown overlooks some research that shows fish can remember information for more than a year. I do have some doubts over whether they feel pain, but I am convinced they can suffer.
That said, if one chooses to eat animal protein, then fish may be the most moral choice.
Wild fish are born and live in their natural environment. They are unconfined, eat natural prey, and managed in most places so that they can reproduce at least once in their lifetimes. Depending on the fishing method, during capture they may experience fatigue, crowding and surprise, among other emotions. In my long experience, only in some trawl fisheries are they crushed. Most or many fish brought to the surface are still alive. Once on deck, most suffocate because they cannot acquire oxygen from the air, but the experience has been theorized by some to be like falling asleep would be for humans. Although I’m no expert on the slaughter of pigs, cattle, or chickens, I would assume that fish suffer less than domesticated animals, over the course of their lives.
Fish provide important sources of protein around the world. I presume eliminating or reducing consumption of fish in favor of a vegetarian diet may place more pressure on limited arable land, leading to clearing that would kill or eliminate habitat for terrestrial animals. All the choices are bad, but eating wild fish may be one of the least bad choices.
In the food industry, the killing of marine animals far outnumbers the killing of all other beings. One very conservative estimate is 90 billion (yes, with a “B”) individuals killed per year. Check out the kill counter here, and watch the comparative numbers grow before your eyes.