Salmon hatchery return data, 1975-2016

This dataset contains salmon return data by release site to Alaska fisheries enhancement projects, as reported by operators. More details on this dataset can be found in the Alaska Fisheries Enhancement Annual Report, 2016 (http://www.adfg.alaska.gov/FedAidPDFs/RIR.5J.2017.04.pdf). This harvest data is simply how many fish were harvested by a hatchery operator in their harvest area, and is not necessarily the number of hatchery-origin fish in that harvest. The original data is contained in ADFG_Obtained_AKReturns.xlsx. The included RMarkdown script (Hatchery_returns_reformatting.Rmd) reformats these data, and assigns region information based on the release site used by the hatchery. The reformatted file is "hatchery_returns.csv". The "Project" column generally denotes the release site. "CatchType" indicates what kind of harvest project the harvested fish were a part of. This distinguishes both by sector (commercial, subsistence, sport fish), gear (for commercial sector fish), and fish caught for brood stock or cost-recovery. In some early years, the harvest was not broken out by gear, and only an estimate for generalized commercial catch was derived - these are assigned the CatchType of "commerical other." A CatchType of "other" indicates that the type of catch did not fit easily into the other categories. Negative numbers in the catch values for this dataset are real. Sometimes when a sample of fish is taken at the hatchery or the escapement to a system where a hatchery is located, not all the fish may originate from that hatchery. The fish may be wild fish from the system or hatchery fish from another hatchery. The negative numbers are there to reduce the total of hatchery fish that were counted in the brood stock or escapement by those non-hatchery fish, where non-hatchery fish are known to exist in the harvest.本数据集收录了由项目运营商上报的、针对阿拉斯加渔业增效项目（Alaska Fisheries Enhancement Projects）的按放流站点划分的鲑鱼回归数据。有关本数据集的更多详情，可参阅2016年《阿拉斯加渔业增效年度报告》（Alaska Fisheries Enhancement Annual Report，链接：http://www.adfg.alaska.gov/FedAidPDFs/RIR.5J.2017.04.pdf）。本次收录的捕捞数据仅指孵化场运营商在其作业捕捞区内的捕捞渔获量，并非该捕捞作业中源自孵化场的鲑鱼总数。原始数据存储于ADFG_Obtained_AKReturns.xlsx文件中。附带的RMarkdown脚本（Hatchery_returns_reformatting.Rmd）可对上述数据进行格式重整，并依据孵化场使用的放流站点分配区域信息。格式重整后的文件为"hatchery_returns.csv"。"Project"列通常代表放流站点。"CatchType"字段用于标识被捕捞鲑鱼所属的捕捞项目类型，其区分维度包括作业类型（商业捕捞、自给捕捞、休闲垂钓）、渔具（针对商业捕捞作业）以及为亲鱼采集或成本回收而捕捞的渔获。在部分早期年份，捕捞数据未按渔具类别拆分，仅能获取通用商业捕捞量的估算结果——此类数据的CatchType字段被赋值为"commerical other"。当"CatchType"字段为"other"时，表示该捕捞类型无法归入上述其他类别。本数据集捕捞数值中的负数均为有效记录。在孵化场采样或对孵化场所在水系的洄游渔获进行采样时，采样所得渔获未必全部源自该孵化场：这些渔获可能是该水系的野生鲑鱼，或是来自其他孵化场的孵化场源鲑鱼。此处设置负数的目的，是在已知捕捞作业中存在非孵化场源鲑鱼的情况下，从亲鱼采集或洄游渔获统计的孵化场鱼总数中扣除此类非目标渔获的数量。