Daily escapement counts from Tanada Creek and Long Lake weirs, Alaska, 1974-2014

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 near the mouths of rivers where salmon spawn 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. These counts usually represent a sample, and are expanded to represent a 24h period. 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 from Tanada Creek and Long Lake in the Copper River region of Alaska.

从海洋环境洄游至淡水溪流的成熟鲑鱼数量，被定义为洄游量（escapement）。洄游量数据即对这类溯河洄游鱼类的计数结果，是衡量产卵鲑鱼种群丰度的通用指标。此类数据对渔业管理具有重要意义，因为多数鲑鱼捕捞活动均发生在河流河口附近——鲑鱼会在此轮洄游过程中于该处产卵。洄游量数据的采集途径多样，固定监测项目会安排观测人员驻守于淡水河道沿线，对通过堰坝溯河而上的鲑鱼进行计数。此类计数通常仅为抽样结果，需经比例推算以覆盖完整的24小时时段。总体而言，洄游量计数结果并非种群总丰度，而是反映种群丰度的一项指标。调查通常会安排在产卵高峰时段开展，多集中于夏季；对于银鲑（Coho salmon）而言，也可在秋季进行调查。本数据集涵盖阿拉斯加州铜河区域内塔纳达溪与长湖的鲑鱼洄游量数据。