Free Access

Fig. 2

image

Download original image

Histograms for the different sets of data associated to haul no. 4 explained in Figure 1. The left panel histograms correspond to (a) the raw Sv data for the whole echogram (excluding sea bottom); (b) the first 100 m from the surface; and (c) the rectangular area enclosing the schools. The histograms of the averaged Sv data for the same sets are represented in the right panels (d, e and f). The red and green lines in the bottom histograms are the Gaussian PDFs fitted by the EM algorithm to the weak and strong (likely the schools) echoes. The black vertical lines in (c) and (d) represent the optimal thresholds found for both sets, −54.2 and −60.4 dB, respectively.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.