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These data consist of raw echosounder observations collected during the Malaspina 2010 Spanish Circumnavigation Expedition (14th December 2010, Cádiz-14th July 2011, Cartagena). The cruise was divided into seven legs: leg 1 (14th December 2010, Cádiz-13th January 2011, Rio de Janeiro), leg 2 (17th January 2011, Rio de Janeiro-6th February 2011, Cape Town), leg 3 (11th February 2011, Cape Town-13th March 2011, Perth), leg 4 (17th March 2011, Perth-30th March 2011, Sydney), leg 5 (16th April 2011, Auckland-8th May 2011, Honolulu), leg 6 (13th May 2011, Honolulu-10th June 2011, Cartagena de Indias) and leg 7 (19th June 2011, Cartagena de Indias-14th July 2011, Cartagena). Echosounder observations were made from the BIO Hespérides (A-33) using two EK60 GPTs operating two hull-mounted transducers (38 and 120 kHz). A calibration was carried out prior to the start of the expedition (30th of November 2010, close to Mazarron port, water temperature c. 17 degrees C) and values of the peak transducer gain and Simrad correction factor for both frequencies were updated in the ER60 software. Data are stored in raw proprietary Simrad (Bergen, Norway) format (.raw, .idx, .bot files).
This file provides daily/per station summaries of daytime and nighttime acoustic data (omitting data recorded within 1 hour of sunrise and sunset), specifically per day and night mesopelagic average nautical area scattering coefficient (NASC 200-1000 m), average total NASC (0-1000 m), and weighted mean depths (WMD) of mesopelagic and total NASC. Migration amplitude is the difference in day and night WMD, day to night ratio is the ratio of daytime to nighttime total NASC (0-1000 m) and migration ratio is calculated from the relative drop in mesopelagic backscatter (NASC 200-1000 m) during night. For details of calculations see Klevjer et al. 2016. Note that the provided positions correspond to the fixed Malapina station at that date, not the start and end point of the data collection.