Why do young Pacific bluefin tuna repeatedly dive to depths through the thermocline?
Why do young Pacific bluefin tuna repeatedly dive to depths through the thermocline?
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DOI：
10.1111/j.1444-2906.2007.01307.x
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发表时间：
2007-02-01
影响因子：
1.9
通讯作者：
Yamada, Harumi
中科院分区：
文献类型：
--
作者：
Kitagawa, Takashi;Kimura, Shingo;Yamada, Harumi
在东海放流了一条带有档案标签的太平洋蓝鳍金枪鱼幼鱼。时间序列数据的深度，环境和腹膜温度为9条鱼，每128秒记录，进行了分析。我们的目标是描述每月的潜水模式的变化，在3月至6月期间的环境热结构和发生的喂养事件，并讨论可能的原因，为什么蓝鳍金枪鱼反复潜水到温跃层以下的深度在他们的保温机制。结果表明，该鱼平均每隔1.2 h就在温跃层中反复下潜，且3 - 5月下潜频率较高。然而，潜水频率和周期性下降，在6月，当梯度变得陡峭。相比之下，6月份喂食事件增加。这些结果表明，从3月到5月，蓝鳍金枪鱼反复潜水，因为食物生物量不足的表面，他们停止进行重复潜水在6月时，食物变得更容易在表面，除了低太阳辐射造成的低能见度。此外，这些鱼的传热时间范围很长，它们的腹膜温度可能是通过短暂的潜水来维持的。潜水的周期性可能导致腹膜温度波动较小，表明潜水是一种行为性体温调节。
Young Pacific bluefin tuna Thunnus orientalis with archival tags were released in the East China Sea. Time-series data for depth, and ambient and peritoneal temperatures for nine fish, recorded every 128 s, were analyzed. Our objectives were to describe monthly changes in diving patterns in relation to the ambient thermal structure and the occurrence of feeding events during March-June, and to discuss possible reasons why bluefin tuna repeatedly dived to depths below the thermocline in terms of their thermoconservation mechanisms. It was found that the fish repeatedly dived through the thermocline at intervals of 1.2 h on average, and the dive frequency was high during March-May. However, the dive frequency and periodicity decreased in June, when the gradient became steeper. In contrast, feeding events increased in June. These results indicate that from March to May, bluefin tuna repeatedly dive because food biomass is inadequate at the surface, and they stop undertaking repeated dives in June when food becomes more readily available at the surface, in addition to low visibility caused by low solar radiation. Further, the range of heat transfer times for these fish was so long that their peritoneal temperature was probably maintained by engaging in brief dives. The periodicity of dives may lead to a lower fluctuation in the peritoneal temperature, suggesting that the dives are a kind of behavioral thermoregulation.