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

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.

东北北极鳕鱼（Gadus Morhua）是全球规模最大的鳕鱼种群，不仅支撑了大规模捕捞渔业，同时也是巴伦支海生态系统的重要组成部分。针对该种群的管理采用基于年龄的分析评估模型，而精准估算鱼类种群的年龄结构是此项管理工作的必要前提。个体鳕鱼的年龄需通过人工观察耳石（otolith）的层状结构来确定。此前已有研究尝试利用图像法开展耳石年龄鉴定工作，但所得结果参差不齐；近年来自动图像分析技术的进步已在类似场景中被证实具备良好应用效果。本研究旨在提出一种可高效拍摄人工断裂耳石的方法（无需进行切片与铸模流程），并阐述东北北极鳕鱼耳石样本集的断裂耳石图像的组织、采集流程及其关联元数据（metadata）。本研究采用单镜头反光照相机拍摄断裂耳石的图像：每个样本共拍摄6张照片，其中第一拍摄位置采用3种不同曝光参数拍摄3张，第二拍摄位置同样以3种不同曝光参数拍摄3张。该流程可简洁高效地获取清晰、优质且可复现的断裂鱼类耳石图像，相较于传统的耳石切片与铸模方法，更为简便且劳动强度更低。