Rationale and Follow-up on Terminating Nutrient Treatment of Morice Lake

Returns of sockeye salmon to the Morice-Nanika production system (tributary to the Skeena River) routinely exceeded 60,000 pieces prior to 1950. Between 1950 and 1955 escapements declined precipitously to only a few thousand adults and this condition has persisted to the present time (Figure 1). Shepard as well as other DFO management personnel suggested a plausible mechanism through which a sudden decline in adult sockeye returns might trigger changes in within-lake growth and survival of juvenile sockeye such that further stick declines would occur.