Vertical migration of Coregonid larvae in the first two months of development |
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| Authors: | Andrea R Ventling-Schwank Hans Jürg Meng |
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| Institution: | 1. Limnological Research Center, Swiss Federal Institute for Environmental Science and Technology (EAWAG), CH-6047, Kastanienbaum, Switzerland
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| Abstract: | Using an acoustic system in a 9 m deep enclosure, the daily vertical distribution patterns of whitefish larvae were studied from hatching to the age of two months. Four patterns of daily vertical distribution and migration were observed in accordance to different developmental stages: - Newly hatched larvae dispersed in the enclosure during the day and congregated at the water surface at night.
- After 2 weeks of age larvae stayed close to the water surface during day and night.
- At 15 to 18 mm length, larvae showed distinct vertical migration at dawn and dusk, they stayed close to the surface during the day and dispersed at night.
- At 28 mm length the depth pattern was reversed. These fish frequented greater depths during the day than at night.
No relation was found between larval depth distribution or vertical migration and food availability or water temperature. Low levels of solar radiation triggered the dawn and dusk vertical migration behaviour of the more developed larvae. Possible reasons for the different behaviour patterns occurring over time are discussed. |
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