Salmon age, sex, and length data from Westward and Southeast Alaska, 1979-2017

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 westward and southeast Kodiak. 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 the original data file (ASL DATA EXPORT.csv), a reformatting script that reformats the original data file into a consistent format (ASL_Formatting_SoutheastKodiak.R), and the reformatted dataset as a .csv file (ASL_formatted_SoutheastKodiak.csv).年龄、性别与体长数据可提供种群动态信息，用以阐明种群趋势的发生机制与变化态势。此类数据能够帮助研究人员估算种群增长率、年龄级分布及种群人口统计学特征。掌握种群人口统计学特征、增长率与变化趋势，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重要。因此，此类数据对于阿拉斯加鲑鱼渔业这类高价值渔业而言尤为关键。本数据集涵盖了从科迪亚克岛西部与东南部的商业性、自给性鲑鱼捕捞年度采样及相关研究项目中收集的年龄、性别与体长数据。数据集涵盖5种鲑鱼的数据：奇努克鲑（chinook）、狗鲑（chum）、银鲑（coho）、粉鲑（pink）及红鲑（sockeye）。年龄估算通过观察鱼鳞或硬骨结构（如耳石（otoliths，即耳部骨骼））完成。鱼鳞通常从鱼体左侧侧线上方区域采集。随后将鱼鳞或硬骨结构粘贴于涂胶卡片上，并压覆于醋酸纤维膜上以留存印痕。通过计数淡水生长环与海水生长环（即年轮）的数量，以估算鱼的年龄（以年为单位）。年龄采用欧洲记法（European Notation）记录，该方法可同时记录淡水与海水生长环数量。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，其年龄将记录为1.3。鱼类总年龄为前后两个数字之和再加1，以补偿骨骼沉积与幼鱼孵化之间的时间差，因此该示例中的鱼总年龄为5岁。鱼类性别通过观察外部形态（如头部与腹部形状）或内部生殖器官进行判定。体长以毫米为单位测量，通常测量起点为眼部中点，终点为尾鳍分叉处。本数据包包含原始数据文件（ASL DATA EXPORT.csv）、将原始数据文件重格式化为统一标准的格式化脚本（ASL_Formatting_SoutheastKodiak.R），以及已完成格式化的数据集文件（ASL_formatted_SoutheastKodiak.csv）。