Salmon age, sex, and length data from Lower Cook Inlet, Alaska, 1961-2014

Age, sex and length data provide population dynamics information that can indicate how populations trends occur and may be changing. These data can help researchers estimate population growth rates, age-class distribution and population demographics. Knowing population demographics, growth rates and trends is particularly valuable to fisheries managers who must perform population assessments to inform management decisions. These data are therefore particularly important in valuable fisheries like the salmon fisheries of Alaska. This dataset includes age, sex and length data compiled from annual sampling of commercial and subsistence salmon harvests and research projects in the Upper Cook Inlet. It includes data on five salmon species: chinook, chum, coho, pink and sockeye. Age estimates were made by examining scales or bony structures (e.g. otoliths - ear bones). Scales were removed from the side of the fish; usually the left side above the lateral line. Scales or bony structures were then mounted on gummed cards and pressed on acetate to make an impression. The number of freshwater and saltwater annuli (i.e. rings) was counted to estimate age in years. Age is recorded in European Notation, which is a method of recording both fresh and saltwater annuli. For example, for a fish that spent one year in freshwater and 3 years in saltwater, its age is recorded as 1.3. The total fish age is the sum of the first and second numbers, plus one to account for the time between deposition and emergence. Therefore the fish in this example is 5 years old. Fish sex was determined by either examining external morphology (eg. head and belly shape) or internal sex organ. Length was measured in millimeters, generally from mid-eye to the fork of the tail. This data package includes a .csv of ASL data (ASL_formatted_LowerCookInlet.csv) derived from an original data file (ASL_ALL.csv), a file containing location information (HEADER_ALL.csv), a file containing gear information (LUT_GEAR), and a file containing sex information (LUT_GENDER_DETERMINATION_CODE.csv). The reformatting script (ASL_Formatting_LowerCookInlet.R) draws pertinent columns from the data file and combines it with information from the metadata and locations files.年龄、性别与体长数据可提供种群动态信息，用以揭示种群趋势的发生与变化规律。此类数据能够帮助研究人员估算种群增长率、年龄层级分布与种群统计特征。掌握种群统计特征、增长率及种群趋势，对于需要开展种群评估以制定管理决策的渔业管理者而言尤为关键。因此，这类数据在阿拉斯加鲑鱼渔业这类高价值渔业中具有极高的应用价值。本数据集涵盖从库克湾上游地区商业性与自给性鲑鱼捕捞的年度采样及相关研究项目中整合得到的年龄、性别与体长数据，包含5种鲑鱼：奇努克鲑（chinook）、马苏鲑（chum）、银鲑（coho）、粉鲑（pink）与红鲑（sockeye）。年龄估算通过观察鳞片或骨质结构（如耳石（otoliths））完成。鳞片取自鱼体侧面，通常为侧线以上的左侧区域。随后将鳞片或骨质结构粘贴于涂胶卡片，并压印于醋酸纤维胶片以获取印痕。通过计数淡水年轮与海水年轮（annuli）的数量，即可估算鱼的年龄（以年为单位）。年龄采用欧洲记龄法（European Notation）记录，该方法同时记录淡水与海水年轮的数量。例如，若某条鱼在淡水环境中生活1年、海水环境中生活3年，其年龄将被记为1.3。鱼类总年龄为两个数字之和再加1，用以补偿骨组织沉积与幼体孵化出膜之间的时间差，因此上述示例中的鱼实际年龄为5龄。鱼类性别通过观察外部形态（如头部与腹部形态）或内部生殖器官确定。体长以毫米为单位测量，通常测量起点为眼中部，终点为尾鳍分叉处。本数据包包含以下文件：源自原始数据文件（ASL_ALL.csv）的ASL数据CSV文件（ASL_formatted_LowerCookInlet.csv）、包含位置信息的文件（HEADER_ALL.csv）、包含渔具信息的文件（LUT_GEAR），以及包含性别判定编码信息的文件（LUT_GENDER_DETERMINATION_CODE.csv）。格式重构脚本（ASL_Formatting_LowerCookInlet.R）从原始数据文件中提取相关列，并结合元数据与位置文件中的信息完成数据整合。