Spatial hierarchical Bayesian models for stock-recruitment analysis of pink salmon (Oncorhynchus gorbuscha)

Abstract

To improve the understanding of effects of environmental factors on spawner-to-recruit survival rates of pink salmon (Oncorhynchus gorbuscha), we developed several spatial hierarchical Bayesian models (HBMs). We applied these models to 43 pink salmon stocks in the Northeast Pacific. By using a distance-based, spatially correlated prior distribution for stock-specific parameters, these multistock models explicitly allowed for positive correlation among nearby salmon stocks in their productivities and coefficients of early summer coastal sea surface temperature (SST). To our knowledge, this is the first time that such distance-based, spatial prior probability distributions for parameters have been applied to fisheries problems. We found that the spatial HBMs produce more consistent and precise estimates of effects of SST on productivity than a single-stock approach that estimated parameters for each stock separately. Similar to earlier results using mixed-effects models for the same stocks, we found significant positive effects of SST on survival rates of northern pink salmon stocks, but weaker negative effects of SST on survival rates of southern pink salmon stocks. However, we show a smoother transition in magnitude of effects between these regions.

Cultured Atlantic salmon in nature: a review of their ecology and interaction with wild fish

“…Studies on stock-recruitment relationships suggest that salmonid populations are regulated by densitydependent mortality during early life stages after fry emerge from the spawning gravel. After that regulatory phase, mortality is influenced mainly by density-independent factors (Jonsson et al, 1998;Milner et al, 2003;Su et al, 2004), although there are also exceptions of density-dependent mortality at later stages (Unwin, 1997;Elliott and Hurley, 1998).…”

Clockwise Loops and Anticlockwise Loops Observed in a Stock-Recruitment Relationship

“…Recently, however, the importance of environmental factors has been reported in many studies. For instance, Su et al [5] noted a significant positive effect of sea-surface temperature (SST) on the survival rate of northern pink salmon stocks; conversely, they observed a weak negative effect of SST on the survival rate of southern pink salmon stocks. Sundby [6] noted that the recruitment of Atlantic cod stocks showed the different responses to the temperature changes.…”

Bayesian Models in Assessment and Management

“…With the hierarchical approach, they could account for the partial commonality in parameter values across different estuarine systems. Hierarchical models were also applied to analyze multi-stock data for pink salmon (Peterman 2004, Su et al 2004). The hierarchical approach improved the estimates of probability distributions for model parameters compared with those derived through single-stock analyses.…”