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Cedar - A very common wood used to grill fish, poultry and various meats such as pork and beef. White or Red Cedar are the species most often available, which provide a distinctive natural and aromatic flavoring for a variety of foods. Salmon and other types of fish are often grilled or smoked using Cedar.


http://www.recipetips.com/glossary-term/t--37486/grilling-or-smoking-wood.asp

A google search revealed a lot of sources of cedar chips for smoking.