Coherence in abundance of blue crab populations along the Atlantic coast

The blue crab (Callinectes sapidus) occurs throughout the Atlantic coast of the United States and serves as an important component of estuarine and coastal ecosystems, often coupling benthic and pelagic food webs.  The species also supports important commercial fisheries in many states throughout its range.  Over the past two decades there have been declines in landings and survey indices for many blue crab populations along the Atlantic coast.  Here we analyze fishery-dependent data from Florida to New York to assess patterns of coherence in landings time series.  Intervention analysis was used to correct for reporting changes in individual time series.  Multivariate statistical analyses, including dynamic factor analysis, were used to assess the similarity of time series as a function of their geographic separation.  These analyses quantified the role of common environmental drivers, such as NAO and system-specific winter temperatures, in explaining common responses in the time series.  We report the extent to which observed declines can be explained by exploitation and by environmental drivers.  Understanding the mechanisms behind these declines is important for the sustainable management of both the fisheries and the ecosystems in which these populations occur.