Seminars

The effect of ocean environmental conditions on the distribution of summer flounder (Paralichthys dentatus):  Spatio-temporal modelling comparisons using R-INLA

Speaker: Dr. Patrick Sullivan
Affiliation:
Cornell University     
Title:
The effect of ocean environmental conditions on the distribution of summer flounder (Paralichthys dentatus):  Spatio-temporal modelling comparisons using R-INLA.
Abstract: The spatial distribution of summer flounder (Paralichthys dentatus) relative abundance changes over time with changes in environmental covariates, such as bottom depth, bottom salinity, bottom temperature and sea surface temperature (SST). A range of conditional autoregressive (CAR) models were explored using the R-INLA frame work, while accounting for random effects arising from over dispersion as well as spatio-temporal autocorrelation. Summer flounder relative abundance data is estimated over an irregular lattice of survey strata. Alternative model assumptions applied to survey observations taken during the fall and spring are explored. Relative abundance data and associated oceanographic covariates were collected during NMFS fall and spring bottom trawl surveys. Results indicate that the distribution of summer flounder stock is correlated with a regional climate-driven changes in both bottom temperature as well as sea surface temperature depending on season. An analysis of 1991-2014 NMFS survey data suggests that a 1°C increase in SST during the fall season can increase relative abundance by about 11%, whereas in the spring a 1°C increase in SST can increase relative abundance by 34% even after accounting for over-dispersion and spatio-temporal autocorrelation. Model performance was improved by allowing for the estimation of the spatial autocorrelation parameter rho and including a second-order random walk in time. The R-INLA package provides a flexible platform for hierarchical Bayesian spatial and temporal modeling.
Host: Alex Illich, Steve Murawski, USF CMS

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