Gordoa Ana, Sanz Nuria, Viñas Jordi
Department of Marine Ecology, Centro de Estudios Avanzados de Blanes, Spanish National Research Council (CSIC), Blanes, Girona, Spain.
Laboratori d'Ictiologia Genètica, Departament de Biologia, Facultat de Ciències, Universitat de Girona, Girona, Spain.
PLoS One. 2015 Aug 28;10(8):e0136733. doi: 10.1371/journal.pone.0136733. eCollection 2015.
This study presents the first results on Atlantic bluefin tuna (Thunnus thynnus) individual spawning duration and its short-term temporal behavior. The study was based on direct measurements resulting from mtDNA analysis of the offspring of spawners held in transport cages during the 2013 spawning monitoring survey in Balearic waters. The number of females consisted of approximately 259 individuals with an average weight of 186 kg. The survey began on May 22 and ended on July 3. Spawning started on May 30 and was observed every night afterwards. The sampling of eggs for genetic monitoring was conducted for 9 days interspersed from the beginning of spawning to the end of the survey. A total of 946 eggs were analyzed and revealed 129 different haplotypes; 77 of these were not previously detected in the Mediterranean. A total of 69 haplotypes were observed in more than one spawning event and those with higher frequency lasted their maximum possible duration. The haplotypes present at the beginning of spawning were also identified at the end of the sampling, indicating a minimum spawning duration of 34 days, and individual annual fecundity was estimated at around 1290 eggs gr(-1). These results differed from those generally presumed until now and are indicative of a much higher fecundity. Females exhibited a regular spawning schedule but with the capacity to shift the spawning hour during the spawning season. These results were observed for the eastern population of Atlantic bluefin tuna and before extrapolating to the western population, their validity should be proved.
本研究首次呈现了关于大西洋蓝鳍金枪鱼（Thunnus thynnus）个体产卵持续时间及其短期时间行为的结果。该研究基于2013年巴利阿里海域产卵监测调查期间，对运输笼中产卵亲体后代进行线粒体DNA分析所得到的直接测量数据。雌性数量约为259只，平均体重186千克。调查于5月22日开始，7月3日结束。产卵于5月30日开始，之后每晚进行观测。从产卵开始到调查结束期间，穿插进行了9天用于基因监测的鱼卵采样。共分析了946枚鱼卵，发现了129种不同的单倍型；其中77种此前在地中海未曾被检测到。在不止一次产卵事件中观察到了总共69种单倍型，且出现频率较高的单倍型持续了其最大可能持续时间。产卵开始时出现的单倍型在采样结束时也被识别出来，这表明最短产卵持续时间为34天，个体年繁殖力估计约为1290枚卵克-1。这些结果与目前普遍推测的结果不同，表明繁殖力要高得多。雌性表现出规律的产卵时间表，但在产卵季节有能力改变产卵时间。这些结果是针对大西洋蓝鳍金枪鱼东部种群观察到的，在推广到西部种群之前，其有效性需要得到验证。
