Data for: An efficient protocol and data set for automated otolith image analysis

• Main Authors: Malde, Ketil, Myers, Savannah Carolyn, Thorsen, Anders, Godiksen, Jane Aanestad, Handegard, Nils Olav
• Format: Dataset
• Language: unknown
• Published: Institute of Marine Research 2019
• Subjects: Arctic; Arctic cod; Gadus morhua; Northeast Arctic cod
• Online Access: https://dx.doi.org/10.21335/nmdc-1826273218; http://metadata.nmdc.no/metadata-api/landingpage/56fa1f8685d94b833c6ce00461bdb39e

The northeast Arctic cod (Gadus Morhua) is the world's largest cod stock and it supports a large fishery in addition to being an important component of the Barent Sea ecosystem. Management of this stock uses an age-based analytical assessment model, and an accurate estimation of the age structure of the fish populations is essential. The age of individual cod is determined by manually examining the layered structure of otoliths. Image-based methods have been tried to age otoliths with varying results, but recent developments in automatic image analysis techniques have been shown to be effective in similar situations. The objective of this paper is to describe a method to efficiently image a manually broken otolith (avoiding the cross-sectioning and molding process) and to describe the organization and acquisition of imaged broken otolith images with associated metadata for a collection of northeast Arctic cod otoliths. A single lens reflex camera was used for capturing photos of the broken otoliths. A total of six images were taken for each subject, consisting of three images in the first position with three different light exposures and three images in the second position with three different light exposures. This results in a simple and efficient procedure for capturing clear, satisfactory, and reproducible images of broken fish otoliths, and a more straightforward and less labor intensive alternative to the commonly used methods that involve cross-sectioning and molding of the otolith.