Daily salmon escapement counts from the OceanAK database, Alaska, 1921-2017

The number of mature salmon migrating from the marine environment to freshwater streams is defined as escapement. Escapement data are the enumeration of these migrating fish as they pass upstream, and are a widely used index of spawning salmon abundance. These data are important for fisheries management, since most salmon harvest occurs in freshwater rivers during this migration. Escapement data are collected in a variety of ways. Stationary projects utilize observers stationed along freshwater corridors who count salmon as they pass upriver through weirs or past elevated towers. Sonar equipment placed in the river can also give a stationary escapement count. These counts usually represent a sample, and are expanded to represent a 24h period. Escapement data can also be collected using aerial surveys, where observers in an aircraft provide an index to estimate escapement. In general, escapement counts do not represent total abundance, but instead an index of abundance. Surveys are usually timed to coincide with peak spawning activity, generally in the summer, but in the case of Coho salmon in the fall as well. This dataset contains salmon escapement data extracted from the Alaska Department of Fish and Game's OceanAK database, and contains data from multiple regions in Alaska.

成熟鲑鱼从海洋洄游至淡水溪流的数量，被定义为洄游亲体量（escapement）。洄游亲体数据是对这些溯河洄游鱼类的计数结果，是评估产卵鲑鱼种群丰度的常用指标。此类数据对渔业管理至关重要，因为绝大多数鲑鱼捕捞都发生在该洄游阶段的淡水河道中。洄游亲体数据的采集方式多种多样：固定监测站点会安排观测人员沿淡水河道值守，统计通过拦鱼堰或高架观测塔的溯河鲑鱼数量；布设在内河的声呐设备也可完成固定站点式的洄游亲体计数。此类计数通常仅为抽样结果，需通过推算拓展为单日（24h）的总量。洄游亲体数据也可通过航空调查采集，航空器上的观测人员可通过观测获取估算洄游亲体量的相关指标。总体而言，洄游亲体计数并非种群总丰度的直接统计结果，而是种群丰度的替代指标。调查通常会安排在产卵活动的峰值时段，多为夏季，对于银鲑（Coho salmon）而言也可在秋季开展。本数据集包含从阿拉斯加渔猎部（Alaska Department of Fish and Game）的OceanAK数据库中提取的鲑鱼洄游亲体数据，涵盖阿拉斯加多个区域的相关信息。