Ecosystems Dynamics & Assessment : Current Conditions (Spring 2017)

Trends in Fall Species Distribution

Along-shelf depth trend
Trends in Fall Species Distribution

The species of the Northeast Shelf ecosystem have shown changes in distribution over recent decades. Individual species have shifted distribution for a number of reasons, and these shifts can be characterized in a number of different ways. Two metrics that have been used to characterize distribution on the NE Shelf include: 1) the position in the ecosystem along an axis oriented from the southwest to the northeast referred to as the along shelf distance; and, 2) the depth of occurrence. Along shelf distances range from 0 to 1360, which relates to positions along the axis from the origin in southwest to northeast in kilometer units. Depth ranges from 0 to -260, which relates to depth of occurrence in meters. The table below shows the species analyzed; click on a species name to see the along and depth distribution trends. The mean along shelf distance and depth of occurrence for all species by year are shown in the two graphs, with the 2016 values marked with a dashed red line. As a group, these species had an along shelf distance of approximately 870 km, they now have a distance of over 930 km. For most of the time series, the species averaged a depth of 100 m, they now average approximately 113 m.

Click species name to see the along-shelf distance and depth distribution trends.
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(File Modified Apr. 19 2017)