The “Large Scale Survey System” (L-triple-S) is a software system for marine stock assessment and research through analysis of multi-frequency acoustic data


Illustration in article by Tommy Thorseth

LSSS is designed for marine stock assessment and for use within marine research. The system is for post-processing of acoustical data from multi-frequency echo sounders. The development started in 2002 in collaboration with the Institute of Marine Research (IMR). The product and courses are available via MAREC. MAREC offers software packages and related services for training, installation, and support/maintenance.

The primary strength of LSSS is to offer rapid interpretation of large amounts of data. All functionality has been built with the intention of enabling a typical user to interpret one full day of survey data in about 2 hours. Key features include:

  • Preprocessing algorithms such as noise removal, school detection, species identification
  • Fast  loading and visualization of multi-frequency acoustic data
  • Dynamic interpretation at different zoom levels

Data processing is done by passing datagrams through a chain of independent processing modules. This modular design provides a high degree of flexibility. A special editor is used for selecting which modules to use as well as configuring individual modules. Complete configurations can be stored to file and used later. The modularity of the system also allows experienced users to use their own processing algorithms by implementing new modules.

The processing modules currently include:

  • Bottom detection
  • Noise quantification and removal
  • Convolution and filtering
  • Formation of combination echograms
  • Categorisation
  • Region (school) detection

A main feature of LSSS is statistical categorisation. A special system is used for defining categories by selecting data samples representative for each category. New data can then be categorised based on the properties of the training data. The categorisation produces a new type of datagrams which can be viewed on screen or written to file.

LSSS continues to be in active development and has more than 100 registered users. More information: