NEUROETHOLOGICAL STUDY OF SALMON HOMING

Hime鲑鱼(湖中的Sockeye鲑鱼，Oncorhynchus Nerka；在北美被称为kokanee)通过Chuzenji湖(日本赤木县日光)迁徙，成熟后返回他们的家乡河流。在这项研究中，作为了解鲑鱼归巢的嗅觉机制的一步，我们检测了(1)嗅球对不同河流水域的脑电(EEG)反应，以及(2)使用新开发的Y-迷宫选择家庭用水的行为能力。结果发现：(A)电生理分析表明，大马哈鱼能够区分两条相邻河流(家河和非家河)入海口的水域；(B)从实验行为分析来看，鱼更喜欢家水而不是家外水；(C)家水的这种偏好以及上游行为在嗅觉器官受损后受到严重破坏。因此，本研究为鲑鱼归巢的实验行为分析开辟了一条新的途径。

Hime salmon (lacustrine form of sockeye salmon, Oncorhynchus nerka ; known as kokanee in North America) migrate through Lake Chuzenji (Nikko, Tochigi Prefecture, Japan), and return to their home river when matured. In this study we examined, as a step towards understanding the olfactory mechanism for salmon homing, (1) electroencephalographic (EEG) response from the olfactory bulb to various river waters and (2) behavioral ability to choose the home water by using a newly developed Y-maze. As the results we found that (a) from electrophysiological analyses the hime salmon can discriminate between waters at the mouths of two neighboring rivers (home river and non-home river), (b) from experimental behavioral analyses the fish prefer the home water to the non-home water, and (c) this preference of the home water as well as the upstream-going behavior are severely damaged after lesioning the olfactory sense organ. (d) Thus, the present study opens a new way for experimental behavioral analyses of the salmon homing.