Compilation of North Atlantic albacore tuna (Thunnus alalunga) fork length frequencies in 2 centimeter intervals from catches in the North Atlantic for the period 1956-2010

The development of the ecosystem approach and models for the management of ocean marine resources requires easy access to standard validated datasets of historical catch data for the main exploited species. They are used to measure the impact of biomass removal by fisheries and to evaluate the models skills, while the use of standard dataset facilitates models inter-comparison. North Atlantic albacore tuna is exploited all year round by longline and in summer and autumn by surface fisheries and fishery statistics compiled by the International Commission for the Conservation of Atlantic Tunas (ICCAT). Catch and effort with geographical coordinates at monthly spatial resolution of 1° or 5° squares were extracted for this species with a careful definition of fisheries and data screening. In total, thirteen fisheries were defined for the period 1956-2010, with fishing gears longline, troll, mid-water trawl and bait fishing. However, the spatialized catch effort data available in ICCAT database represent a fraction of the entire total catch. Length frequencies of catch were also extracted according to the definition of fisheries above for the period 1956-2010 with a quarterly temporal resolution and spatial resolutions varying from 1°x 1° to 10°x 20°. The resolution used to measure the fish also varies with size-bins of 1, 2 or 5 cm (Fork Length). The screening of data allowed detecting inconsistencies with a relatively large number of samples larger than 150 cm while all studies on the growth of albacore suggest that fish rarely grow up over 130 cm. Therefore, a threshold value of 130 cm has been arbitrarily fixed and all length frequency data above this value removed from the original data set.海洋渔业资源管理的生态系统方法及相关模型研发，亟需可便捷获取的、经标准化验证的主要捕捞物种历史捕捞数据集。此类数据集可用于量化渔业活动对生物量移除造成的影响，并评估模型性能；同时，标准化数据集的使用也有助于实现不同模型间的相互比对。大西洋长鳍金枪鱼（North Atlantic albacore tuna）全年均有延绳钓捕捞作业，夏季与秋季则辅以表层网具捕捞，相关渔业统计数据由大西洋金枪鱼养护国际委员会（International Commission for the Conservation of Atlantic Tunas, ICCAT）汇编整理。本数据集针对该物种提取了带地理坐标的捕捞量与捕捞努力量数据，时间分辨率为月度，空间分辨率为1°或5°的网格单元；提取过程中明确界定了渔业类型，并开展了数据筛查工作。1956年至2010年期间，共计界定了13类渔业作业类型，涉及的捕捞渔具包括延绳钓、曳绳钓、中层拖网及活饵垂钓。但需注意，ICCAT数据库中可获取的空间化捕捞努力量数据仅占总捕捞量的一小部分。此外，本数据集还依据前述渔业作业类型界定标准，提取了1956年至2010年的捕捞体长频率数据；该部分数据的时间分辨率为季度，空间分辨率范围为1°×1°至10°×20°。体长测量的分组尺度存在差异，分为1厘米、2厘米或5厘米的组距（叉长，Fork Length）。数据筛查过程中发现，存在大量体长超过150厘米的异常样本，但所有针对长鳍金枪鱼生长特性的研究均表明，该物种体长极少超过130厘米。因此，研究人员设定130厘米为阈值标准，将所有超出该阈值的体长频率数据从原始数据集中剔除。