Direct acoustic sizing of pelagic fishes for improved catch selectivity
Informations
- Funding country
Norway- Acronym
- -
- URL
- -
- Start date
- 1/1/2016
- End date
- 12/31/2020
- Budget
- 927,543 EUR
Fundings
| Name | Role | Start | End | Amount |
|---|---|---|---|---|
| Marine Resources and the Environment (MARINFORSK) - call 2016 | Grant | - | - | 927,543 EUR |
Abstract
This project has developed knowledge and methods to enable the estimation of the length of medium sized pelagic fish prior to them being caught. The project uses broadband echosounders to detect echoes from parts of individual fish and from this estimates their length. The project has demonstrated the method using fish-like artificial targets, dead tethered fish, free-swimming fish in large cages, and wild fish in the open ocean. The aim of the project was to develop methods and knowledge that can improve the size selectivity of commercial fishing operations and hence reduce fish discarding and unwanted by-catch. The measurements on artificial targets and dead fish showed that the method can measure the length of fish that are longer than about 20 cm with an accuracy of about 2 cm when using a broadband signal of 160 to 260 kHz. Some types of acoustic pulse are better than others at measuring fish size and the project has developed recommendations around this for use in the field. A procedure for automating the processing of the acoustic data has been developed that will facilitate the use of acoustic remote sizing in operational situations. A procedure that removes the need to know the orientation of fish relative to the echosounder has also been developed - this eases the implementation of the sizing method in operational situations.