Gear Description

The Multiple Opening/Closing Net and Environmental Sampling System is an electronically controlled discrete depth sampler. This is one of several sampling systems that were developed to obtain vertically discrete plankton samples. These systems consist of a frame with a series of up to 10 nets that are sequentially opened and closed remotely from the ship using electronic signals sent down the towing wire. Most of these systems also telemeter net condition (depth, attitude, flow) and environmental data (temperature, conductivity) up the towing wire. Messiah, Bioness (Sameoto et al. 1980), and MOCNESS (Weibe et al. 1976) are examples of such systems. The MOCNESS is currently most widely used and can be purchased in sizes with openings of 0.25, 1.0, and 10.0 m2. These systems have greatly improved the ability to investigate the vertical distribution of fish eggs and larvae. They have also been used to obtain replicate samples within a particular depth horizon, to investigate small scale variability in distribution and condition of ichthyoplankton. Nets can be opened and closed as they encounter hydrographic features (e.g. thermoclines) of interest and to relate these to concurrently collected fish eggs and larvae.