Ecosystems Dynamics & Assessment : Current Conditions (Spring 2017)

Kernel Density Plots of Fall Species Distribution

The habitats used by species of the Northeast Shelf ecosystem have changed over recent decades. Species have moved in response to a complex set of factors resulting in changes in distribution in respect to latitude and depth, among a number of habitat indicators. Kernel density plots provide a way of characterizing where a species is distributed by defining an area with an associated probability that a species will be found there. We compared the kernel densities for three probability levels between two time periods. The three probability levels were 25, 50, and 75% kernel densities; the 25% kernel defines the core area of the distribution whereas the 75% defines the broader use of the ecosystem. The two time periods were a base distribution period based on species distribution during the 1970s (shown as blue kernel densities) and a contemporary distribution period based on the last three years (2014-2016) for the fall survey (shown as red kernel densities). The table below shows the species analyzed.

Click on a species name to see kernel density plots.

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(File Modified Apr. 19 2017)