GEOGRAPHIC COVERAGE: From the southern Sicily platform, from Marsala up to beyond Capo Passero, and around the Maltese Islands for an area covering a total of about 2700 nm2. N30E010

Habitat characterisation; Acoustic backscatter in the water column

Acoustic backscatter sensors

Acoustic surveys of stocks of small pelagic using the scientific multi-frequency echosounder Kongsberg Simrad EK500, with hull transducers and frequencies of 38, 120 and 200 kHz. The scientific echosounder was calibrated for the 3 frequencies using acoustic transmissions in the area of the sea that extends from Marsala to Siracusa. The calibration took place in the port of Siracusa, using the method of the sampling sphere of TS. During the echogram acquisition, the data was recorded on the hard disk of a PC. With the help of the acquisition and post-elaboraion software BI500, the data was printed in real time using an HP 895cxi professional. In the second part of the research campaign, the echo-sounder Simrad EK60 was used in the vicinity of Maltese waters. This instrument was calibrated using the method of the sampling sphere. Measurements of the physical and chemical parameters of the water column using a Minisonde 4a Hydrolab (CTD). The probe was immersed into the sea using a hydro-pneumatic arm placed on the left side of the boat. Biological sampling of small pelagic organisms with pelagi monovolante net equipped with Kongsberg Simrad ITI acoustic system for the control of geometry of the net during sampling. The net systems used were Flying type Monobarca of a total length of 78 meters and a width of 22 meters, vertical and horizontal openings of width respectively 7 meters and 13 meters for an area of the aperture of 90 meters squared approximately, the front net opening was 182x800 millimeters and lateral net opening of 400 millimeters. The cable from towing made of steel was 16 millimeters of diameter, 50 meters long and with the divergence of Polyvalent type. For the employment of the system Simrad ITI, the transducers were placed in the upper part of the front opening of the net while the hydrophone, was placed on a buoy and hauled for the entire period of sampling.

Oceanography Malta Research Group, Department of Geosciences, University of Malta
Maths & Physics Building, University of Malta
Msida

MSD 2080
Malta