Coherence and potential drivers of stock assessment uncertainty in Northeast US groundfish stocks

Abstract

Failure to account for the impacts of climate and ecosystem change on stock dynamics can introduce uncertainty to stock assessments that can make meeting the objective of sustainable fisheries management challenging. The increased prevalence and magnitude of uncertainty in New England groundfish stock assessments (i.e. retrospective patterns) in recent years suggest that there may be common drivers impacting these stocks that are currently unaccounted for in the stock assessment. We examined the coherence in retrospective patterns across groundfish stock assessments and evaluated candidate drivers of retrospective patterns, including large-scale climate and ecosystem change, as well as significant management and monitoring changes. We found high coherence in moving window Mohn's rho time series for groundfish within the Gulf of Maine and Georges Bank areas. Fluctuations in Gulf of Maine groundfish Mohn's rho values were most strongly related to lagged bottom temperature and spiny dogfish biomass time series, whereas fluctuations in Georges Bank groundfish Mohn's rho values were strongly related to lagged time series of warm core rings formation from the Gulf Stream. Our identification of coherence in retrospective patterns across groundfish stocks by region supports the idea of common regional drivers with climate and ecosystem changes emerging as the leading contributing factors.