Integrated Age-based Krill Model Fish Res 2015

FAO Area 48.1, CCAMLR Area 48.1, Antarctic Peninsula, South Shetland Islands, South Orkney Islands

Stock assessments to estimate the status and productivity of biological populations are a central tool in the management of the harvesting of living resources. These methods are used to determine sustainable catch levels that can be demonstrated to meet long-term management criteria.

The Isaacs-Kidd Midwater Trawl (IKMT) is used to collect deep water biological specimens larger than those taken by standard plankton nets. The mouth of the net is attached to a wide, V-shaped, rigid diving vane that keeps the mouth of the net open and maintains the net at depth for extended periods

The Multiple Opening/Closing Net and Environmental Sensing System (MOCNESS) uses a stepping motor to sequentially control the opening and closing of individual nets to obtain discrete depth tow data. The MOCNESS uses underwater and shipboard electronics for controlling the device. The electronics system continuously monitors the functioning of the nets, frame angle, horizontal velocity, vertical velocity, volume filtered, and selected environmental parameters such as salinity and temperature.

The EM 3000 multibeam echo sounder is a very high resolution seabed mapping and inspection system with respect to high accuracy and resolution. The minimum operating depth is from less than 1 m below its transducers, and in typical sea water conditions the system operates to more than 150 m depth (less in warm water and more in fresh water). Small dimensions and low weight makes the system portable and easy to install. This allows use on survey launches and subsea vehicles to 1500 m water depth. The EM 3000 system has a very high ping rate of up to 40 Hz, a large number of measurements per ping (typically about 120), 1.5 degrees beamwidth, and electronic pitch stabilization of the transmit beam. 100% coverage of the bottom is achievable at vessel speeds of about 10 knots in shallow waters with acrosstrack coverage of up to four times depth beneath the transducers with a basic system. At longer range the achievable coverage may be up to 200 m, and 100% coverage is achievable with vessel speeds up to 20 knots. The EM 3000 may be configured to use two sets of transducers (Sonar Heads). This increases the shallow water coverage to up to ten times the depth, and the number of measurements per ping to typically 220. With an angular coverage sector of nominally 200 degrees the dual system also allows surveying to the water surface along shorelines, river banks and man-made structures. The system sonar frequency is 300 kHz allowing small dimensions, good range capability and high tolerance to turbid waters. Integrated seabed acoustical imaging capability (like a sidescan sonar) is included as standard. A nearfield mode is available for increased resolution at very short ranges (less than 4 m). A combination of phase and amplitude bottom detection algorithm is used, resulting in a measurement accuracy of 5 cm RMS being achievable practically independent of beam pointing angle. The EM 3000 multibeam system was in production from 1996 to 2004 and was replaced with the EM 3002.

various vessels ranging in size (20-40 ft length) chartered for cetacean surveys when a NOAA small boat is not available.