Migration of smolts through lakes
1 Purpose:
Lakes are believed to be challenging areas for smolt navigation that result in high mortality of individuals moving through. This research aims to understand the movements of salmon and trout smolts through the three lakes Evangervatnet and Vangsvatnet in Vosso River, and Vassbygdvatnet in Aurland River. We plan to evaluate potential effects of flow and temperature from hydropower stations discharging into the lake. Our project involves tagging of smolts with acoustic transmitters with specialized sensors to understand their ecology while in these lakes and determine whether there are challenges related to hydropower. We will use predation sensor tags, which have been shown to be effective tools for monitoring the fate of smolts during the freshwater and marine migrations (FOTS 22861: Influence of lakes on the survival of migrating salmon smolts). In addition, we plan to add temperature sensors to the tags to answer a question from the management about potential critical temperature exposure (cold shock) of fish entering lakes in the early spring.
2 Distress:
The whole procedure of capture and tagging is considered to be moderately stressful. Smolts are captured by electrofishing (alternative by traps and nets if electrofishing is not possible), and undergo the same standard and widely used tagging procedure with trained researchers (SOP 05a.E, SOP 11E, SOP 12E). All fish are expected to recover from the procedure. Fish that do not recover will be euthanized. These fish are frozen if possible and returned to the lab for necropsy for further investigation to help us understand defaults.
3 Expected benefit:
The data collected on smolts in the age 2-3 years old in this research can contribute to understand the difficulties along the migration path, and in a narrower picture, gain knowledge on how to manage these rivers in relation to hydropower related issues that alter temperature and flow in the lakes during the spring migration. For future purposes, this research may also benefit similar systems in other lakes and rivers in Norway.
4 Number of animals, and what kind:
We will tag 300 salmon smolts and 250 trout smolts in Vosso and Aurland in 2022 and 2023 (total = 550).
5 How to adhere to 3R:
Acoustic tags can provide more detailed movements and behavior data compared to other tracking devices where more individuals are needed to gain the same amount of data. It is also widely used by researchers, and we have experienced low mortality. Therefore, we aim to reduce the number of animals using acoustic tags.
We have also improved our SOPs following our telemetry studies from 2020/2021, and believe we are equipped the best possible way to conduct capture - and tagging procedures.
Lakes are believed to be challenging areas for smolt navigation that result in high mortality of individuals moving through. This research aims to understand the movements of salmon and trout smolts through the three lakes Evangervatnet and Vangsvatnet in Vosso River, and Vassbygdvatnet in Aurland River. We plan to evaluate potential effects of flow and temperature from hydropower stations discharging into the lake. Our project involves tagging of smolts with acoustic transmitters with specialized sensors to understand their ecology while in these lakes and determine whether there are challenges related to hydropower. We will use predation sensor tags, which have been shown to be effective tools for monitoring the fate of smolts during the freshwater and marine migrations (FOTS 22861: Influence of lakes on the survival of migrating salmon smolts). In addition, we plan to add temperature sensors to the tags to answer a question from the management about potential critical temperature exposure (cold shock) of fish entering lakes in the early spring.
2 Distress:
The whole procedure of capture and tagging is considered to be moderately stressful. Smolts are captured by electrofishing (alternative by traps and nets if electrofishing is not possible), and undergo the same standard and widely used tagging procedure with trained researchers (SOP 05a.E, SOP 11E, SOP 12E). All fish are expected to recover from the procedure. Fish that do not recover will be euthanized. These fish are frozen if possible and returned to the lab for necropsy for further investigation to help us understand defaults.
3 Expected benefit:
The data collected on smolts in the age 2-3 years old in this research can contribute to understand the difficulties along the migration path, and in a narrower picture, gain knowledge on how to manage these rivers in relation to hydropower related issues that alter temperature and flow in the lakes during the spring migration. For future purposes, this research may also benefit similar systems in other lakes and rivers in Norway.
4 Number of animals, and what kind:
We will tag 300 salmon smolts and 250 trout smolts in Vosso and Aurland in 2022 and 2023 (total = 550).
5 How to adhere to 3R:
Acoustic tags can provide more detailed movements and behavior data compared to other tracking devices where more individuals are needed to gain the same amount of data. It is also widely used by researchers, and we have experienced low mortality. Therefore, we aim to reduce the number of animals using acoustic tags.
We have also improved our SOPs following our telemetry studies from 2020/2021, and believe we are equipped the best possible way to conduct capture - and tagging procedures.