Mackerel populations and distribution around the north-western European shelf.

<p>Continental shelf marked in grey (bottom depth <250 m). North Sea and western mackerel spawning areas indicated by dots. Each dot marks an observation of 50+ eggs m⁻² day⁻¹. Data from international mackerel egg surveys (Blue = North Sea 2002–2011 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038758#pone.0038758-ICES2" target="_blank">[7]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038758#pone.0038758-ICES4" target="_blank">[34]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038758#pone.0038758-ICES5" target="_blank">[35]</a>, Green = Western areas 1977–2007 (ICES WGMEGS)). Blue rectangle marks the approximate main coverage of the international mackerel egg survey in the latter years <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038758#pone.0038758-ICES2" target="_blank">[7]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038758#pone.0038758-ICES4" target="_blank">[34]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038758#pone.0038758-ICES5" target="_blank">[35]</a>.