The Quality of Marks Obtained under Different Regimes of Salmon Otolith Marking
The method of creating otolith marks using specific regimes of rearing water temperature, feeding and photoperiod has been described in many works (including Brothers 1984, 1985; Volk et al. 1987; Brothers 1990; Akinicheva and Rogatnykh 1997). This method allows the creation of marks during the peri...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.532.1052 http://www.npafc.org/new/publications/Technical Report/TR5/page 94-97(Kudzina).pdf |
| Summary: | The method of creating otolith marks using specific regimes of rearing water temperature, feeding and photoperiod has been described in many works (including Brothers 1984, 1985; Volk et al. 1987; Brothers 1990; Akinicheva and Rogatnykh 1997). This method allows the creation of marks during the period of juvenile growth in the hatchery, and has been used for the purpose of identification of large managed stocks of fish produced by artificial reproduction. Thermal marks have been created through rearing the embryos and larvae under the temperature that are periodically different from the background, i.e. from water temperature supplied before the time of marking. Decreased water temperature results in slowing down calcium metabolism in fish creating a clear dark stripe. Returning to the background temperature restores the otolith calcium sedimentation rate where every new stripe becomes quite wide to frame out the next doubled dark stripe obtained via the next water temperature decrease (Akinicheva and Rogatnykh 1997). The perfect case for marking is when two water supply systems occur in a hatchery- «cold » and «warm » with a difference no less than 3°C. Total (100%) marking is possible if warming occurs in the hatchery. Malkinsky Salmon Hatchery (Bolshaya River basin, West Kamchatka) uses thermal water from Malkinsky geothermal outfall for the purpose of warming the cold water from the river. Hatchery incubation and rearing the fry and juveniles usually takes place under the higher water temperature that are never observed in nature (+7-10°C). Thermal otolith marking has been used in Malkinsky Hatchery since 1995 (Vasylkov 1995, 1996). The schemes of marking suggested in Figs. 1, 2 were used on sockeye and chinook salmon in order to create a mark resulting from an 8-hour period water temperature decrease. The image of the mark for 1995 looks like III I II, and |
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