Adapting benchmarks of biological status for persistent changes in productivity and variability in exploitation history with a focus on data-limited populations (Conservation Units) of Chum Salmon in southern BC

The PST Chum Annex requires biological benchmarks to inform the development of fishery reference points for PST related fisheries; including the lower fishery reference point for the Johnstone Strait fisheries as well as subsequent terminal fisheries. Biological benchmarks for data-limited populations have been proposed and are currently being applied to Conservation Units (CUs, population units of biological assessment under Canada’s Wild Salmon Policy) of Chum Salmon in southern BC. However, recent simulation modelling has shown that those benchmarks, which are derived from time-series of spawner abundances alone, are associated with high probabilities of extirpation under low and/or declining stock productivity (Holt and Folkes, in review). In addition, previous unpublished studies suggest these benchmarks may be higher than necessary to achieve conservation objectives when exploitation rates are low (cited in Fair et al. 2010). For this project, we will (1) identify candidate benchmarks for data-limited CUs and revised versions that account for persistent changes in productivity and variability in exploitation rate history, (2) evaluate them against benchmarks based on data-intensive methods, and (3) apply them to chum management units (through component CUs) within the context of the PST Chum Annex.