CDEENA originally proposed a comparative analysis of changes in the structure and function of Northwestern Atlantic shelf ecosystems to determine how these may have affected the productivity of living resources. To this end, CDEENA would bring together the expertise of field scientists and modellers to:

(1)	describe the changes in time and space,
(2)	identify and fill critical data gaps in the knowledge base and
(3)	develop models to investigate ecosystem-level hypotheses (i.e. environmental variation, predation, fishing effects) concerning changes in reproduction, mortality, growth and feeding of cod and other species.

The failure of the collapsed groundfish stocks to recover in the 1990's is explained by changes in the ecosystems of the NW Atlantic (e.g. changes in trophic structure) between pre-collapse (mid-1980s) and post-collapse (mid-1990s) periods driven by a combination of biological, fishing and environmental variation.

CDEENA focuses on the five following ecosystems:

(1) The Newfoundland and Labrador Shelf (NAFO 2J3KLNO),   (2) The northern Gulf of St. Lawrence (NAFO 4RS),   (3) The southern Gulf of St. Lawrence (NAFO 4T),   (4) The eastern Scotian Shelf (NAFO 4VsW),   (5) The western Scotian Shelf (NAFO 4X).

CDEENA focuses on the three following periods:

(1)	The 1970s, prior to the extension of jurisdiction (1977) and the subsequent recovery of groundfish stocks,
(2)	The mid-1980s, the peak of the recovery, and prior to the groundfish collapses of the early 1990s in virtually all areas,
(3)	The present, where the collapsed groundfish stocks have failed to recover in most areas.

The CDEENA Program is supported financially by the Department of Fisheries and Oceans Canada Science Strategic Research Program.