Movements of dead fish in rivers
Background: The aim of telemetry studies is often to determine the fate and mortality rates of ish. A moving ish is usually regarded as alive and a long-term stationary ish as dead—and the site where it became stationary as the site where it died. Downstream transport of dead ish in rivers can lead...
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Online Access: | http://hdl.handle.net/11250/2443710 https://doi.org/10.1186/s40317-017-0122-2 |
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ftninstnf:oai:brage.nina.no:11250/2443710 2023-05-15T13:28:22+02:00 Movements of dead fish in rivers Havn, Torgeir Børresen Økland, Finn Teichert, Maxim A.K. Heermann, L. Borcherding, J Sæther, Stein Are Tambets, M. Diserud, Ola Håvard Thorstad, Eva Bonsak Germany 2017 application/pdf http://hdl.handle.net/11250/2443710 https://doi.org/10.1186/s40317-017-0122-2 eng eng urn:issn:2050-3385 http://hdl.handle.net/11250/2443710 https://doi.org/10.1186/s40317-017-0122-2 cristin:1462519 Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no CC-BY 5 Animal Biotelemetry Telemetri Telemetry VDP::Zoologiske og botaniske fag: 480 VDP::Zoology and botany: 480 Journal article Peer reviewed 2017 ftninstnf https://doi.org/10.1186/s40317-017-0122-2 2021-12-23T07:16:59Z Background: The aim of telemetry studies is often to determine the fate and mortality rates of ish. A moving ish is usually regarded as alive and a long-term stationary ish as dead—and the site where it became stationary as the site where it died. Downstream transport of dead ish in rivers can lead investigators to mistake dead ish for live ish. We examined downstream movements of 60 dead Atlantic salmon smolts and 55 dead European silver eels, equipped with radio transmitters and released at hydropower stations in three German rivers. Results: Overall, dead smolts drifted up to 2.4 km downstream and dead eels up to at least 30.1 km downstream. Smolts released in an Archimedes screw turbine drifted up to 1.1 km and eels up to at least 5.1 km downstream. Most smolts stopped moving further downstream within 1 week after release, whereas the eels (or their transmitters) moved downstream over several weeks, or even months, after release. However, the distance moved varied considerably also within species and among release sites. Eighteen (30%) dead smolts and nine (16%) dead eels moved upstream or disappeared from the rivers, indicating that they had been taken by scavengers. Some of these (four smolts and one eel) had recordings, indicating that they had been taken out of the river by birds. Conclusions: Fish can drift considerable distances downstream after they have died in a river. This can make it dificult to identify dead ish, and the exact site and time of death from telemetry studies. Furthermore, dead ish can be moved within the river, or taken out of the river, by scavengers. These results are relevant for studies of mortality at power stations, but also for studies of tagged ish in rivers in general. When designing telemetry studies and interpreting telemetry data, investigators should keep in mind that dead ish (or their transmitters) may drift downstream. Investigators may also consider if it is useful to release dead ish as a control groups when planning and performing ish mortality studies. Keywords: Mortality estimate, Telemetry, Radio tag, Atlantic salmon, Salmo salar, European eel, Anguilla anguilla, Smolt, Silver eel, Downstream drift Article in Journal/Newspaper Anguilla anguilla Atlantic salmon European eel Salmo salar Norwegian Institute for Nature Research: Brage NINA Animal Biotelemetry 5 1 |
institution |
Open Polar |
collection |
Norwegian Institute for Nature Research: Brage NINA |
op_collection_id |
ftninstnf |
language |
English |
topic |
Telemetri Telemetry VDP::Zoologiske og botaniske fag: 480 VDP::Zoology and botany: 480 |
spellingShingle |
Telemetri Telemetry VDP::Zoologiske og botaniske fag: 480 VDP::Zoology and botany: 480 Havn, Torgeir Børresen Økland, Finn Teichert, Maxim A.K. Heermann, L. Borcherding, J Sæther, Stein Are Tambets, M. Diserud, Ola Håvard Thorstad, Eva Bonsak Movements of dead fish in rivers |
topic_facet |
Telemetri Telemetry VDP::Zoologiske og botaniske fag: 480 VDP::Zoology and botany: 480 |
description |
Background: The aim of telemetry studies is often to determine the fate and mortality rates of ish. A moving ish is usually regarded as alive and a long-term stationary ish as dead—and the site where it became stationary as the site where it died. Downstream transport of dead ish in rivers can lead investigators to mistake dead ish for live ish. We examined downstream movements of 60 dead Atlantic salmon smolts and 55 dead European silver eels, equipped with radio transmitters and released at hydropower stations in three German rivers. Results: Overall, dead smolts drifted up to 2.4 km downstream and dead eels up to at least 30.1 km downstream. Smolts released in an Archimedes screw turbine drifted up to 1.1 km and eels up to at least 5.1 km downstream. Most smolts stopped moving further downstream within 1 week after release, whereas the eels (or their transmitters) moved downstream over several weeks, or even months, after release. However, the distance moved varied considerably also within species and among release sites. Eighteen (30%) dead smolts and nine (16%) dead eels moved upstream or disappeared from the rivers, indicating that they had been taken by scavengers. Some of these (four smolts and one eel) had recordings, indicating that they had been taken out of the river by birds. Conclusions: Fish can drift considerable distances downstream after they have died in a river. This can make it dificult to identify dead ish, and the exact site and time of death from telemetry studies. Furthermore, dead ish can be moved within the river, or taken out of the river, by scavengers. These results are relevant for studies of mortality at power stations, but also for studies of tagged ish in rivers in general. When designing telemetry studies and interpreting telemetry data, investigators should keep in mind that dead ish (or their transmitters) may drift downstream. Investigators may also consider if it is useful to release dead ish as a control groups when planning and performing ish mortality studies. Keywords: Mortality estimate, Telemetry, Radio tag, Atlantic salmon, Salmo salar, European eel, Anguilla anguilla, Smolt, Silver eel, Downstream drift |
format |
Article in Journal/Newspaper |
author |
Havn, Torgeir Børresen Økland, Finn Teichert, Maxim A.K. Heermann, L. Borcherding, J Sæther, Stein Are Tambets, M. Diserud, Ola Håvard Thorstad, Eva Bonsak |
author_facet |
Havn, Torgeir Børresen Økland, Finn Teichert, Maxim A.K. Heermann, L. Borcherding, J Sæther, Stein Are Tambets, M. Diserud, Ola Håvard Thorstad, Eva Bonsak |
author_sort |
Havn, Torgeir Børresen |
title |
Movements of dead fish in rivers |
title_short |
Movements of dead fish in rivers |
title_full |
Movements of dead fish in rivers |
title_fullStr |
Movements of dead fish in rivers |
title_full_unstemmed |
Movements of dead fish in rivers |
title_sort |
movements of dead fish in rivers |
publishDate |
2017 |
url |
http://hdl.handle.net/11250/2443710 https://doi.org/10.1186/s40317-017-0122-2 |
op_coverage |
Germany |
genre |
Anguilla anguilla Atlantic salmon European eel Salmo salar |
genre_facet |
Anguilla anguilla Atlantic salmon European eel Salmo salar |
op_source |
5 Animal Biotelemetry |
op_relation |
urn:issn:2050-3385 http://hdl.handle.net/11250/2443710 https://doi.org/10.1186/s40317-017-0122-2 cristin:1462519 |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1186/s40317-017-0122-2 |
container_title |
Animal Biotelemetry |
container_volume |
5 |
container_issue |
1 |
_version_ |
1766403682522365952 |