Two mass-balance ecosystem models representing the Strait of Georgia today and one hundered years ago were constructed using the Ecopath software. Fisheries literature and statistics from the 1980s -- 1990s were used as input for the present day model, while the one hundred year model was constructed using traditional and local environmental knowledge, historical information and scientific literature from the last 100 years. The main difference beteen the two models was the relative abundance of functional groups, though the species therein also differed. Baleen whales, Mysticeti, extirpated in the Strait in the early 1900s, and sturgeons, Acipenser transmontanus, perhaps close to a similar fate, were thus included in the one hundred year model. In November 1997 the two pilot models were presented and discussed at a multidisciplinary workshop and suggested improvements incorporated. The Strait of Georgia five hundred years ago, prior to human contact, was reconstructed in three scenarios, consisting of increasing the top-predator biomass of the one hundred year model by 10%, 20%, and 30%, respectively, omitting catches and keeping the same primary production as in the one hundred year model. The models representing past states were relatively easy to balance, but the flow characteristics of the 500 years ago models did not correspond to theoretical estimates.