Ultrasonic Measurements in Fish-water Pipe Flows

A. C. Baker1, J. Spilde1, O. Brix1,2, R. Grüner3,4 and K-E. Froysa1

2CMR Instrumentation, Bergen, Norway, Email: kjell-eivind.froysa@cmr.no

2Dept. of Biology, University of Bergen, Norway

3Dept. of Radiology, Haukeland University Hospital, Bergen, Norway

4Dept. of Physics and Technology, University of Bergen, Norway

ABSTRACT

Christian Michelsen Research has developed a prototype fish flow meter based on electromagnetic sensors. Currently the main application for this system is the measurement of the total weight of fish pumped from a purse-seine net to the holds on board a purse-seiner. The Fish Flow Meter is capable of measuring fish flow rates up to 1000 tons/hour with an accuracy of better than 5 %. However, there remain a number of significant challenges including, determination of the average fish size and the distribution of sizes of fish caught as well as the automatic identification of species. The Fish Flow Meter alone is not necessarily the most effective solution to these problems. A possible alternative is the use of an ultrasound system to image the fish-water flow to extract information on individual fish, whilst the Fish Flow Meter measures the total quantity of fish. An experimental ultrasonic prototype has been built and tested at sea alongside the Fish Flow Meter. Results from the field tests will be presented and discussed. In parallel with sensor development, a detailed study of fish anatomy has been initiated in order to improve our knowledge of the physical properties of the flow. Initial results of this anatomical properties study are presented.

Keywords Fish, flow meter, ultrasound, computed tomography, magnetic resonance imaging