Pool cover preferences in white-spotted charr Salvelinus leucomaenis under resting and stressed conditions
2016
Yamashita, Y. | Nakamura, T. | Suzuki, N. | Sakuramoto, K.
Pool cover preferences were clarified in white-spotted charr Salvelinus leucomaenis under resting and stressed conditions. A pool was constructed in a stream and six covers were placed in various locations on the pool. Thus, covers were placed along the bank on the upper, middle, and lower parts of the pool, and along the center line of the pool at the upstream, middle, and downstream parts of the pool. The placement of the cover mouth (a hole in the cover used for access and feeding) relative to the direction of stream flow was also varied in three ways: on the side of the cover, or on the downstream- or upstream-end of the cover. Twenty charr were then introduced into the pool and the number of charr hiding under each cover was counted under resting and stressed conditions. The charr preferred covers situated in the upstream part of the pool under both resting and stressed conditions, with this tendency being more apparent under stressed conditions. When resting, charr preferred covers with the cover mouths on the sides of the pool. However, under stressed conditions, charr showed no preference for the position of the cover mouth.
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