The latest progress in echosounder technology has seen a transition from single frequency to wideband signal, yielding a drastic increase in information and resolution of acoustic data. The DABGRAF project makes use of this new technology in order to estimate size distributions in pelagic fish schools.
DABGRAF is a joint project of the Institute of Marine Research (IMR) and CMR, funded by the Norwegian Seafood Research Fund. The aim of the project is to estimate the fish size distribution of a school based on data from a sideward pointing wideband echosounder. This is of particular interest in the context of purse seine fishing, where early information on the expected fish size distribution is key to efficient and sustainable fishing.
During the project period, researcher at IMR and CMR have jointly developed a method to perform pre-catch sizing of herring and mackerel. The method consists of the following main steps:
- Resolve single fish in outskirts of schools with split beam wide band principle and a very narrow beam
- Find size related parameters echo (time and frequency domain)
- Compute statistical estimates
- Visualize estimated size in echogram
The proposed method has been implemented in a stand-alone prototype, based on the Large Scale Survey System (LSSS), and tested at sea aboard of “G.O. Sars”, IMR’s research vessel.
The method, software and project results were presented internationally at a large conference in fisheries acoustics, ICES SOMEACOUSTICS, in Nantes, France in May 2015.
This video demonstrates the main functionality of the DABGRAF prototype as presented during ICES SOMEACOUSTICS 2015, Nantes, France
- Inspection of fish school with zoom window (00:05 – 00:35), continuous update of size estimations (top right)
- Set fixed depth range to be used for size estimation (00:35 – 01:00)
- Restrict echogram to certain depth range (01:00 – 01:25)
- Free-hand drawing of region to use for size estimation (01:32 – 02:10)
- Different representation of estimated size distribution (KDE and histogram) (02:15 – 02:40)
- Change of colour scale (02:42 – 03:00)
- Night mode (03:00 – 03:15)
- Navigation in files (fast forward, rewind,…), different selection modes, general user interaction (03:20 – 04:15)
For more information, please confer the presentation slides (see “Download files”) or contact firstname.lastname@example.org.
Institute of Marine Research (IMR)/The Norwegian Seafood Research Fund (FHF)