Ievgen Koliada: Fish stock estimation in shallow water by scientific echosounders
Stock estimate is one of the key issues of fisheries . Use of echosounding is a
very promising approach for fish surveys of large inland waters especially due to large
volumes surveyed in relatively short time and non-intrusiveness of the method
causing no damage to fish. The acoustical approach is similar in many respects to that
of light, but in water sound can propagate over much longer distances far beyond the
range of vision, even in environments with low visibility. In traditional echo-sounding,
a sonar beam is oriented vertically downwards to the bottom of sea or lake,
observing a depth distribution in targets of interest through the whole water column
However, the vertical beaming acoustics is inappropriate for monitoring fish in rivers
and lakes, where the depths do not exceed several meters in dimension. In this case
we use horizontal beaming acoustics. While vertical use of scientific echosounders
are being routinely used in many kinds of waters, horizontal applications in nearsurface waters are still limited due to a number of limitations caused by fish
behaviour in connection with physical problems of fish detection. This also embraces
the data analysis and the interpretation of the analysis results. The three elements,
acquisition, analysis, and interpretation constitute the method. Data acquisition
involves tasks like selection of equipment and suitable sites, mounting the
equipment, tuning the sonar parameters, and recording the data. Analysis involves
detecting the wanted information from the recorded data, while interpretation
converts this information into useful statistics.
During the present project student will be driven through all acoustic fish
stock estimation method. He will be familiar with commonly used technics and
software for this method. The acoustic measurements will be carried out in the
canyon-shaped mesotrophic Římov reservoir, Czech Republic (48˚50’N, 14˚30’E; 170
km south of Prague) using the SIMRAD EK 60 split-beam echo sounder (circular beam,
120 kHz) with a horizontally aligned transducer. Echo data will be processed with
Sonar5-Pro and with MS Excel software.