|Document Type:||Journal Article|
|Title:||Estimation of the relative contributions of climatic vs. other factors to changes in salmon productivity in the North Pacific region|
|Author:||Brigitte Dorner, Kendra R. Holt, R. M. Peterman, Chris E. Jordan, D. P. Larsen, Anthony R. Olsen, Omar I. Abul-Aziz|
|Keywords:||ocean conditions,salmon monitoring,climate change,confounding,sampling design,productivity changes,stock assessment|
We used empirically based simulation modelling of 48 sockeye salmon (O. nerka) populations to examinehow reliably alternative monitoring designs and fish stock assessment methods can distinguish betweenchanges in density-dependent versus density-independent components of productivity and identify therelative contribution of a climate-driven covariate. We explored a wide range of scenarios for ocean andfreshwater conditions and the response of salmon productivity (adult recruits per spawner) to thoseconditions. Our results show that stock assessments based on historical relationships between salmonproductivity and climate-driven oceanographic conditions will likely perform poorly when those rela-tionships change, even when such changes are anticipated and incorporated into stock assessment modelsin a timely manner. Estimating the relative importance of climate-driven oceanographic influences as adriver of sockeye productivity will be difficult, especially if climatic changes occur rapidly and concur-rently with other disturbances. Thus, better understanding of the mechanisms by which climatic changesand other drivers influence salmon productivity may be essential to avoid undesirable management out-comes. As well, an expansion of monitoring of juvenile salmon abundances on more salmon stocks isneeded to help distinguish the effects of different drivers.