Combining fishery-independent and -dependent catch observations in a single index of abundance by allowing for spatially varying catchability 

John Best, Jim Thorson, Rick Methot, Andre Punt

October 29th, 2019 9:00 AM (PST): FSH 203

For fisheries where both fishery-independent and -dependent catch observations are available, spatiotemporally standardized indices of abundance currently use only the fishery-independent data because it is difficult to reliably standardize fishery-dependent observations. There may be an order of magnitude more fishery-dependent observations than fishery-independent observations, representing a currently unused source of information. Integrating these two types of data into a single index of abundance may increase precision, but the fishery-dependent observations would need to be standardized carefully to avoid unacceptable levels of additional bias. One approach to standardizing fishery-dependent observations in a spatiotemporal standardization model would include spatial and/or spatiotemporal random effects on catchability. A model that allows this will be presented along with preliminary simulation study results.