Alaska crustacean age determination study: band count and endocuticle measurements across three shell conditions of terminally molted snow crab, 2016-2018

These data are part of a crustacean age determination project. Specifically, these data describe production of band count estimates and endocuticle measurements from zygocardiac ossicles across new, old, and very old shell class terminally molted snow crab. The data set consists of two comma separated files exported from a Microsoft excel workbook. "Shell_Condition_and_Endocuticle_Measurements" data consists of 1. three independent band count estimates for each standardized zygocardiac ossicle thin section examined including the shell condition and animal size, and 2. structure and endocuticle measurements. "Endocuticle_Measurements" data consists of two sets of endocuticle measurements taken independently from the same thin sections. Sixty large (>80 mm carapace width, the minimum harvestable size in the commercial fishery) terminally molted male snow crab (20 each of three shell condition classes: new shell, old shell, and very old shell) were haphazardly collected during the NMFS Eastern Bering Sea crab and groundfish bottom trawl survey in July 2016. Crab were frozen whole at sea. Carapace width and shell condition data were collected, gastric mill ossicles were removed, cleaned and preserved for at least one week in preservative prior to being processed for the experiment.

本数据集为甲壳类动物年龄鉴定项目的一部分。具体而言，本数据集记录了针对新壳、旧壳、极旧壳三类终末蜕壳雪蟹的标准化心胃骨（zygocardiac ossicles）薄片所开展的生长纹计数估算结果与内表皮（endocuticle）测量数据。
本数据集包含两份从Microsoft Excel工作簿导出的逗号分隔格式文件。其中"Shell_Condition_and_Endocuticle_Measurements"数据集包含两部分内容：1. 对每一份经标准化处理的心胃骨薄片开展的3组独立生长纹计数估算结果，同时附带壳况与个体尺寸信息；2. 组织结构与内表皮测量数据。"Endocuticle_Measurements"数据集包含针对同批次薄片开展的2组独立内表皮测量数据。
2016年7月，在美国国家海洋渔业局（NMFS）东白令海雪蟹与底层鱼类底拖网调查中，随机采集了60只体型达标（甲壳宽＞80mm，为该商业渔业的最小可捕捞尺寸）的终末蜕壳雄性雪蟹，其中新壳、旧壳、极旧壳三类壳况各20只。
所有雪蟹均在海上进行整只冷冻保存。
研究人员记录了雪蟹的甲壳宽度与壳况信息，随后摘取其胃磨骨，经清洗后置于保存液中保存至少一周，再开展后续实验处理。