Observations on the effect of visual and olfactory ablation on the swimming behavior of migrating adult chum salmon,Oncorhynchus keta |
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Authors: | Kazunari Yano Akira Nakamura |
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Institution: | 1. Seikai National Fisheries Research Institute, Shimonoseki Branch, Fisheries Agency of Japan, 2-5-20, Higashiyamato-machi, 750, Shimonoseki, Japan 2. Department of Marine Electronics, Faculty of Marine Science and Technology, Tokai University, 3-20-1, Orido, Shimizu, 424, Shizuoka, Japan
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Abstract: | The behavior of chum slamon,Oncorhynchus keta, was studied using ultrasonic telemetry in the waters off the Okhotsk coast of Hokkaido from 1979 to 1981. Thirty-six adult
fish were outfitted with a 50 KHz ultrasonic transmitter provided with either a depth sensor, depth/illumination sensors,
or depth/ temperature sensors. Twenty-one of the experimental fish were used as controls and left intact. Of the remaining
fish, six had their sight destroyed, seven had their olfactory nerves severed or their nares filled with wax, one had both
senses destroyed, and one had a sham operation, but had only a shallow transverse cut made in the skin over the olfactory
nerves. Control fish and the fish with the sham operation initially swam in a horizontal zigzag pattern while fish with an
obliterated sense swam in a similar pattern but to a reduced extent. The horizontal and vertical speeds of the intact fish
were faster than those of the fish with a destroyed sense. Amplitude of vertical movements of the intact fish stretched from
surface to bottom, while fish with destroyed vision tended towards midwater. Fish without an olfactory sense tended to be
at the surface or near the bottom. Regular vertical movement would be effective in refreshing olfactory epithelia which might
become acclimated when exposed to one odor. The vertical movements can be found in the horizontal zigzag movements in coastal
and near shore migrations, as well as in the stream phase of homing. The zigzag movements, both horizontal and vertical, allow
the fish to sense the water masses and locate the correct tributary. |
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