Precision and accuracy of fish length measurements obtained with two visual underwater methods

Rochet, Marie-Joëlle and Cadiou, Jean-François and Trenkel, Verena M. (2006) Precision and accuracy of fish length measurements obtained with two visual underwater methods. Fishery Bulletin, 104(1), pp. 1-9.

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Abstract

During the VITAL cruise in the Bay of Biscay in summer 2002, two devices for measuring the length of swimming fish were tested: 1) a mechanical crown that emitted a pair of parallel laser beams and that was mounted on the main camera and 2) an underwater auto-focus video camera. The precision and accuracy of these devices were compared and the various sources of measurement errors were estimated by repeatedly measuring fixed and mobile objects and live fish. It was found that fish mobility is the main source of error for these devices because they require that the objects to be measured are perpendicular to the field of vision. The best performance was obtained with the laser method where a video-replay of laser spots (projected on fish bodies) carrying real-time size information was used. The auto-focus system performed poorly because of a delay in obtaining focus and because of some technical problems.

Item Type: Article
Title: Precision and accuracy of fish length measurements obtained with two visual underwater methods
Personal Creator/Author:
CreatorsEmail
Rochet, Marie-Joëlle
Cadiou, Jean-François
Trenkel, Verena M.
Refereed: Yes
Journal or Publication Title: Fishery Bulletin
Volume: 104
Number: 1
Page Range: pp. 1-9
Date: 2006
ISSN: 0090-0656
Issuing Agency: United States National Marine Fisheries Service
Subjects: Biology
Ecology
Fisheries
Item ID: 9002
Depositing User: Patti M. Marraro
Date Deposited: 03 Aug 2012 18:13
Last Modified: 03 Aug 2012 18:13
URI: http://aquaticcommons.org/id/eprint/9002

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