In the cluster analysis, the Strait of Belle Isle unit (X3-4) is quickly isolated from the others, no doubt because of its insufficient sample size (n = 29). Next, the semiclosed coastal environments of the southern Gulf (Chaleur Bay and Northumberland Strait) branch off, followed by the maritime estuary. The units poorest in species are also the least similar since they are quickly isolated from the compact cluster in the dendrogram. The next groups to be differentiated are the deep channels, the Magdalen Shelf, the Natashquan unit, the Lower North Shore complex, Newfoundland and the Anticosti complex. Except for the Strait of Belle Isle, which does not fit neatly into the scheme, the cluster analysis reveals an upstream-downstream gradient (estuary-Gulf), a north-south gradient and a depth gradient (shelf-channels).

This typology is shown on the map adjoining the dendrogram. It is also tempting to try to interpret the positions of the Anticosti complex and Natashquan area on the dendrogram. The Anticosti complex roughly corresponds to a zone rich in rare species, which may be linked to its location in a marine blind alley, so to speak, with complex circulation (Anticosti gyre) and high productivity. The Natashquan sector, on the other hand, is in an area of cold-water upwelling, which could explain its uniqueness in terms of fish species.



Jacques Leclerc