China national fisheries acoustic conference
Posted on Friday, 5 November 2010 | Permalink
What: China national fisheries acoustic conference
When: 12-15 Nov 2010
Where: South China Sea Fisheries Research Institute
Chinese fisheries acoustic people in freshwater and marine environments will participate in the second national conference. Myounghee Kang from Myriax will have two morning sessions on the 14th and 15th of November, 2010.
List of sessions (14 and 15 Nov 2010, morning)
Presenter: Myounghee Kang
14 Nov 2010, morning
This study is about a four dimensional analysis of multivariate data sets for artificial reefs off the coast of Shimonoseki, Yamaguchi prefecture. Visualization in Eonfusion application integrates data sets such as: fish school data from an echosounder; environmental data from CTD; artificial reef information; sediment data; bathymetry and coastal line data. The relationships between the quantitative environmental factors and their effect on the characteristics of fish schools around the reef are clearly shown. This multi-dimensional analysis method demonstrates a better way to understand the space and time characteristics of fish schools around artificial reefs.
The aim for this presentation is to count the number of fish, to estimate the length of target fish, and to filter a certain size of fish. The techniques of background subtraction, image processing or smoothing, target detection algorithm and target filtering, and fish tracking are illustrated. The data set is a mix of Chinook and Sockeye salmon from the Kenai river, Alaska, USA.
The multiple frequency technique called dB differencing is used to differentiate the mean volume backscatter of species using multiple frequencies. The basic idea is that target strength is dependent on frequency for different species. For example this technique has been used to distinguish two species of scatterers (e.g. fish and zooplankton). This technique will be demonstrated using Echoview.
15 Nov 2010, half-morning
There are several single target detection methods in Echoview. The detection methods are based on different echosounder algorithms. Precise single target detection methods will be elucidated.
Fish track detection is used to identify groups of single targets that show a pattern of systematic movement. The targets grouped into a fish track are assumed to have been generated by a single object moving through space. Echoview's α-β Fish Tracker algorithm implements a fixed coefficient filtering method as presented in Blackman (1986) and discussed by Dawson and Mulligan (2000). A practical example for fish tracking will be demonstrated.
Echoview’s current capability for analyzing ME70 data is precisely described in two categories: split beam data analysis and multibeam data analysis. In particular, the visualization and analysis of schools in three dimensions and school tracking are illustrated using fish school echoes observed in Bering Sea during the summer of 2008 and 2009.
Other Echoview features will also be demonstrated.
