- Lamb: 1407.4
- Beef: 978.4
- Pork: 906.3
- Pig (what's the difference with pork?): 824.5
- Fish: 413.8
- Turkey: 310.9
- Broiler Chicken (what makes it "broiler"): 285.4
Interestingly, some fruits and vegetables rank fairly high, as well, with bananas, blueberries, strawberries, and cherries (unfortunately all the fruits used in smoothies) producing more carbon per serving than chicken.
Of course, this is just one datapoint and I'm sure there are some fairly large margins of error on those numbers. Nevertheless, if you can't go 100% vegan, it looks eating more poultry and fish and less beef, pork, and lamb is the way to go.