| | | Recent research has shown [hat simultaneous use of several discrete echo sounder frequencies (innItifrequency) not only improves fish stock estimates, but can also be used to identify species. This is because each specie has a unique acoustic frequency response. This new anil growing understanding greatly improves the value of hydroaeousiies to obtain information Scientists at die Institute of Marine Research, Norway, have shown dun | | |
| | | different species ol'/oopUiuklon and fish can be idenlilied based on multifrcqucncy acoustics. In the future, databases of 'acoustic signatures' for the different commercially interesting fish species will be established and Simrad is already developing echo sounders that can take this information into practical Single frequency echo sounders have traditionally been used to locate fish resources and to determine their size, both at population and individual level. With the high exploitation rale on limited fish i | | imerr.alioniiilv. selccme fishing has become a major topic in fisheries management. Our goal is to provide echo sounders for the internaiional iKhing Heel hems: capable of hod: species identification and accurate size estimation. Sustainable exploitation of our fisheries resources is dependeni on this information and any instrument being capable of providing such information will be a success. Our development for fishery research systems can help the industiy | | |
| | | Example: Mackerel One example is given in the echograms below where schools of mackerel are observed simultaneously at the frequencies 18, 38, 70, 120, 200 kHz using the Simrad EK.60 | | |
| | | scientific echo sounder. The schools of mackerel can be seen in the left part of the echogram. II is clear that the echo from the schools becomes Stronger with increase in frequency. | | This response is unique to mackerel and can be used to discriminate mackerel from other fish species. | | |