John Trochta1
1SAFS
April 11, 2017 9:00 (PST): FSH 105
An investigation of popular hypotheses on the survival of Pacific herring in Prince William Sound, Alaska using Bayesian model selection
We investigate how changing environmental conditions may impact Pacific herring (Clupea pallasii) population dynamics in Prince William Sound, Alaska. The Prince William Sound herring collapsed in the early 1990’s and have yet to recover from low abundance that has remained below the lower regulatory threshold (i.e. for closing fishing) of 20,000 metric tons. This event continues to motivate herring research, especially in improving the predictability of herring biomass dynamics. There is large uncertainty in these dynamics, where we seek to improve biomass estimates by including covariates from physical and ecological data in a Bayesian age-structured assessment model of herring biomass. Indicators of potential environmental effects (i.e. sea surface temperature, air temperature, freshwater discharge, and sea level) and species interactions (i.e. pink salmon, humpback whales, and pollock) are modeled as covariates impacting either adult or juvenile survival in the assessment model. This effort will build upon previous hypothesis testing and reviews that examined the causes of both herring collapse and recovery failure by synthesizing both old and new hypotheses with updated data, as well as new data sets. Our results help to determine which effects may be most significant, while further improving the utility of herring stock assessment models in being able to simulate biomass dynamics under different environmental conditions.