Over past few weeks, Stanley Park Ecology Society (SPES) has received questions from concerned citizens about the number of dead carp seen in Lost Lagoon. The Vancouver Board of Parks and Recreation directed the necropsies on a few of the fish while SPES conducted water quality testing. While the receiving lab could not pinpoint an exact cause, staff believe the fish die off is related to the overall water quality of Lost Lagoon, mainly low dissolved oxygen and high salinity (from adjacent ocean in Coal Harbour) levels.
The carp die-off occurred over the weekend of September 18, 2021. It is possible that the heavy rainfall from that weekend, which occurred after a prolonged period of drought, may have disturbed the bottom layer of anoxic water in Lost Lagoon. This lower layer of water may have mixed with upper layers decreasing dissolved oxygen levels.
Beyond this incident, SPES staff and VPB staff have been aware of the ecological issues and challenges at Lost Lagoon for some time, and over the last few years VPB staff have been exploring various feasible solutions to restore the area. Lost Lagoon is an artificially isolated body of water created in the early 1900s when the causeway was built. Formerly a tidal ecosystem, the berm built for Highway 99 turned the lagoon into a pond for recreational and aesthetic purposes. Because it is isolated, infilling, and now only approximately a metre deep (with much of the shoreline non-naturalized), it is considered an ecologically poor habitat, vulnerable to sea level rise and other events.
In order to restore the area to the point where ecology is its primary function, significant infrastructure, investment and time is needed. The Stanley Park Comprehensive Plan is currently being developed in partnership with Musqueam, Squamish and Tsleil-Waututh Nations, and the first part of this plan will be presented to the Board in early 2022.