Comparison of acoustic biomass densities (s_V) related to distance from eddy centre and depth.

<p>The three panels show data for the three depth categories; A. surface layer (0–100 m), B. mid water (101–600 m) and C. deep water (Deep, ≥600 m). In each panel distance from centre are categorized in R1<9 km, 9≤R2<37 km, R3≥37 and day (D) and night (N) data are presented.</p

Number and weight of fish species caught at three trawl stations in the Norwegian Sea.

<p>Catch (numbers, n and weight, w) composition from the Norwegian Sea eddy interior (station positions are indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030161#pone-0030161-g002" target="_blank">Figure 2</a>) as a result of targeted trawling on high acoustic densities in the DSL (#1) and on surface concentration (#2 and 3).</p

Acoustic, satellite, and CTD data comparisons from a transect through the Norwegian Sea eddy.

<p>Panel A shows anomalies in SAR back scatter (dB) overlaid with ADCP current velocity vectors (m/s, 0–600 m) along the cruise track in November 2009. Colours along the track illustrate change in biomass density at surface (accumulated S_V over the layer 15–100 m – blue is the lowest observed S_V and red is the highest). White circles delineate eddy centre, periphery and outside (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030161#s4" target="_blank">Material and Methods</a>). Panel B shows the variation in average biomass density (S_V) in the surface scattering layer (15–100 m, red), intermediate depths (101–600 m, green), deep water (601–1000 m, blue), and the entire water column (black). Panel C shows the depth distribution of biomass (S_V, dB) at 38 kHz over time along the indicated transect through the eddy centre. Water density contours calculated from CTD casts are overlaid on the acoustic data.</p

Acoustic, satellite, and ADCP comparisons from a transect through the Iceland Basin eddy.

<p>Panel A: ship track (black line) through multiple eddies as detected by satellite altimetry anomalies (colour scale in cm) in June 2004. Panels B and C: co-occurrence between the satellite altimetry anomalies (cm) of two of the eddies and the wheel structured acoustic record (panel F and G, showing S_V at 18 kHz, colour scale in dB) of two anticyclonic eddies. Water current velocity vectors (m/s, 0–600 m) along the cruise track are indicated by the blue arrows (panels B and C). Panels D and E illustrate the variation in biomass density (s_V) in the upper depth layer (150–450 m, red), intermediate depths (451–850 m, green), deep water (>850 m, blue), and entire water column (black). Vertical line in D, F indicate sunset. Sunrise is taking place prior to the start of the horizontal axis in E, G.</p

Oceanographic sampling and the origin of the water masses of the Norwegian Sea eddy.

<p>Panel A shows cruise tracks with acoustic sampling and CTD casts overlaid on anomalies in the SAR back scatter (dB); blue dots are inside the eddy and red dots along the outer periphery. Red diamonds illustrate net sampling locations. Panel B shows the difference in density (kg/m³) of water inside the eddy (solid blue line, average of all blue stations in panel A) and in the outer periphery of the eddy (solid red line, average of all red stations in panel A). Samples from nearby coastal (stippled blue) and offshore waters (stippled red) allow evaluation of the origin of the water masses in the eddy.</p