Session 6: Discussion/Summing Up

Session Chairs: Antonio Vázquez and Joanne Morgan

The discussion suggested that paleogeography of the Flemish Cap played an important role in shaping the ecosystem of today. In particular the fact that the Flemish Cap was neither glaciated nor exposed during the last major glaciation event appears to mean that it may have served as a refuge for marine species. The overall ecosystem of the Cap may have then served as specialized refugia in a historic sense.

The participants recognized the current oceanographic conditions are a major factor in the ecosystem of the Cap. The area has a fairly stable bottom temperature with very little seasonal or annual variability, and temperatures are in general warmer than the northern Grand Bank. The water retention times on the Cap may be longer than previously thought, but its implications for recruitment are unclear at this time. The gyre appears to play an important role in the area.  Studies of currents indicate a closer relation between the waters of the Cap and those of the Labrador Shelf and Northern Grand Bank than with the Southern Grand Bank.

There is the possibility of interchange of individuals of various populations with other areas, either as eggs and larvae or as adults leaving the Flemish Cap.  However, all of the studies presented during the Symposium that examined the relationships between most populations on the Cap and other areas found that there was little connection and that the populations on the Cap were distinguishable from those in other areas.  The exceptions to this are Greenland halibut and roughhead grenadiers which are generally found in deep waters and have a wide distribution.

The meeting noted large changes occurred in the ecosystem of the Cap during the 1990s and they have continued until the present.  There were major declines in the abundance of cod and American plaice, coincident with a decrease in their area of distribution and their move to shallower waters.  At the same time of the cod and American plaice decline, Greenland halibut spread into shallower depths on the Cap and there was a large increase in the abundance of shrimp.  Although these phenomena occurred over a similar time period, the discussion showed the cause is not necessarily the same.

Participants in the Symposium expressed particular interest in studies comparing the Flemish Cap ecosystem with other ecosystems. The discussions again brought to focus that ecosystem changes, both in time and biology, in all of the Atlantic , for example in areas off southeast and west Greenland , Labrador Shelf/Grand Banks, Scotian Shelf and Georges Bank , may show comparable patterns. They suggested that a Symposium on comparative studies of ecosystems in the Northwest Atlantic would be very worth while and of great interest, and accordingly recommended that the Scientific Council should consider this as a future area of study.