Plays a role in the catabolism of L-fucose, a sugar that is part of the carbohydrates that are attached to cellular glycoproteins. Catalyzes the dehydration of L-fuconate to 2-keto-3-deoxy-L-fuconate by the abstraction of the 2-proton to generate an enediolate intermediate that is stabilized by the magnesium ion (PubMed:24697329).