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Testing the Dual frequency IDentification SONar (DIDSON) as a monitoring tool of the attraction effect of aquaculture cages on wild fish in a marine environment



The dual frequency identification sonar (DIDSON) technology is a non-invasive method of observing behavior of wild fish surrounding the aquaculture farm sites. Traditional methods, like gill nets, can result in high fish mortality. This project tested the DIDSON protocol established for a freshwater lake environment at a marine aquaculture site. This project established a protocol for the marine environment including the challenges related to tidal water level changes. Once the protocol was developed, it was used to determine how well wild fish, including benthic fish and lobster, can be visualized. The size, abundance and timing of wild fish movements around net cages in relation to the tide, time of day and water temperature was analyzed.


This project assessed the efficacy of the DIDSON to detect changes in benthic invertebrates (e.g., lobster) and wild fish habitat use around marine fish farms, established operational protocols and data analysis procedures, and provided advice for future DIDSON surveys. For example, to achieve optimal imaging of benthic organisms like lobster on the sea floor, the DIDSON may be installed near the sea floor (i.e., 1 to 2 m above the sea floor) and tilted downwards in an approximately 15° angle. Furthermore, the project results demonstrated that the DIDSON technology is a good candidate for use in further monitoring and research on the interactions between wild fish and marine finfish aquaculture sites.



Program Name

Program for Aquaculture Regulatory Research (PARR)


2016 - 2017

Principal Investigator

Eva Enders
Research Scientist, Freshwater Institute

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