The Baltic cod - An unexpected journey

Stefanie Haase*, Kate McQueen, Monica Mion, Uwe Krumme, Michele Casini, Karin Hüssy, Annelie Hilvarsson, Hans Jakob Olesen

*Corresponding author for this work

Research output: Contribution to conferencePosterResearch

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Abstract

Worrying trends such as deteriorating condition, decreasing growth rates and diminished distribution range have been observed in the eastern Baltic cod stock in recent years. However, the mechanisms underlying these changes are still poorly understood. In an effort to better understand the observed changes in this stock, since 2016 >23,000 eastern Baltic cod have been externally tagged with T-bar anchor tags and released into the Baltic Sea, as part of the international project TABACOD. In addition, 1260 cod have also been tagged using data storage tags (DSTs) which record high-resolution measurements of temperature and pressure. The conventional external tagging provides new data on the growth and movement of recaptured cod, but perhaps the most intriguing insights into Baltic cod ecology come from recaptured DST tagged cod. Although the number of returned DSTs to date is still rather low (N=23), each one provides a wealth of valuable new data. The unexpected results which have already been revealed by the returned DSTs include information on seasonal migration patterns which would not have been identified from the conventional external tagging alone. Additionally, we found examples of cod vertical movement patterns that aligned with moon phase, potentially following lunar-related changes in prey distribution. We have also gained direct evidence of the predation on one unlucky cod by a cormorant, through a DST recovered in a colony by an ornithologist. This DST indicates very shallow, inshore movements of Baltic cod. Such discoveries provide new pieces of the puzzle, which will help us to better understand Baltic cod ecology, formulate new hypotheses, and guide future research.
Original languageEnglish
Publication date2019
DOIs
Publication statusPublished - 2019
Event5th International Conference on Fish Telemetry - Clarion Hotel Tyholmen, Arendal, Norway
Duration: 24 Jun 201928 Jun 2019
Conference number: 5
https://www.5thicft.org/

Conference

Conference5th International Conference on Fish Telemetry
Number5
LocationClarion Hotel Tyholmen
CountryNorway
CityArendal
Period24/06/201928/06/2019
Internet address

Cite this

Haase, S., McQueen, K., Mion, M., Krumme, U., Casini, M., Hüssy, K., ... Olesen, H. J. (2019). The Baltic cod - An unexpected journey. Poster session presented at 5th International Conference on Fish Telemetry, Arendal, Norway. https://doi.org/10.13140/RG.2.2.13591.21923
Haase, Stefanie ; McQueen, Kate ; Mion, Monica ; Krumme, Uwe ; Casini, Michele ; Hüssy, Karin ; Hilvarsson, Annelie ; Olesen, Hans Jakob. / The Baltic cod - An unexpected journey. Poster session presented at 5th International Conference on Fish Telemetry, Arendal, Norway.
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title = "The Baltic cod - An unexpected journey",
abstract = "Worrying trends such as deteriorating condition, decreasing growth rates and diminished distribution range have been observed in the eastern Baltic cod stock in recent years. However, the mechanisms underlying these changes are still poorly understood. In an effort to better understand the observed changes in this stock, since 2016 >23,000 eastern Baltic cod have been externally tagged with T-bar anchor tags and released into the Baltic Sea, as part of the international project TABACOD. In addition, 1260 cod have also been tagged using data storage tags (DSTs) which record high-resolution measurements of temperature and pressure. The conventional external tagging provides new data on the growth and movement of recaptured cod, but perhaps the most intriguing insights into Baltic cod ecology come from recaptured DST tagged cod. Although the number of returned DSTs to date is still rather low (N=23), each one provides a wealth of valuable new data. The unexpected results which have already been revealed by the returned DSTs include information on seasonal migration patterns which would not have been identified from the conventional external tagging alone. Additionally, we found examples of cod vertical movement patterns that aligned with moon phase, potentially following lunar-related changes in prey distribution. We have also gained direct evidence of the predation on one unlucky cod by a cormorant, through a DST recovered in a colony by an ornithologist. This DST indicates very shallow, inshore movements of Baltic cod. Such discoveries provide new pieces of the puzzle, which will help us to better understand Baltic cod ecology, formulate new hypotheses, and guide future research.",
author = "Stefanie Haase and Kate McQueen and Monica Mion and Uwe Krumme and Michele Casini and Karin H{\"u}ssy and Annelie Hilvarsson and Olesen, {Hans Jakob}",
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Haase, S, McQueen, K, Mion, M, Krumme, U, Casini, M, Hüssy, K, Hilvarsson, A & Olesen, HJ 2019, 'The Baltic cod - An unexpected journey' 5th International Conference on Fish Telemetry, Arendal, Norway, 24/06/2019 - 28/06/2019, . https://doi.org/10.13140/RG.2.2.13591.21923

The Baltic cod - An unexpected journey. / Haase, Stefanie; McQueen, Kate; Mion, Monica; Krumme, Uwe; Casini, Michele; Hüssy, Karin; Hilvarsson, Annelie; Olesen, Hans Jakob.

2019. Poster session presented at 5th International Conference on Fish Telemetry, Arendal, Norway.

Research output: Contribution to conferencePosterResearch

TY - CONF

T1 - The Baltic cod - An unexpected journey

AU - Haase, Stefanie

AU - McQueen, Kate

AU - Mion, Monica

AU - Krumme, Uwe

AU - Casini, Michele

AU - Hüssy, Karin

AU - Hilvarsson, Annelie

AU - Olesen, Hans Jakob

PY - 2019

Y1 - 2019

N2 - Worrying trends such as deteriorating condition, decreasing growth rates and diminished distribution range have been observed in the eastern Baltic cod stock in recent years. However, the mechanisms underlying these changes are still poorly understood. In an effort to better understand the observed changes in this stock, since 2016 >23,000 eastern Baltic cod have been externally tagged with T-bar anchor tags and released into the Baltic Sea, as part of the international project TABACOD. In addition, 1260 cod have also been tagged using data storage tags (DSTs) which record high-resolution measurements of temperature and pressure. The conventional external tagging provides new data on the growth and movement of recaptured cod, but perhaps the most intriguing insights into Baltic cod ecology come from recaptured DST tagged cod. Although the number of returned DSTs to date is still rather low (N=23), each one provides a wealth of valuable new data. The unexpected results which have already been revealed by the returned DSTs include information on seasonal migration patterns which would not have been identified from the conventional external tagging alone. Additionally, we found examples of cod vertical movement patterns that aligned with moon phase, potentially following lunar-related changes in prey distribution. We have also gained direct evidence of the predation on one unlucky cod by a cormorant, through a DST recovered in a colony by an ornithologist. This DST indicates very shallow, inshore movements of Baltic cod. Such discoveries provide new pieces of the puzzle, which will help us to better understand Baltic cod ecology, formulate new hypotheses, and guide future research.

AB - Worrying trends such as deteriorating condition, decreasing growth rates and diminished distribution range have been observed in the eastern Baltic cod stock in recent years. However, the mechanisms underlying these changes are still poorly understood. In an effort to better understand the observed changes in this stock, since 2016 >23,000 eastern Baltic cod have been externally tagged with T-bar anchor tags and released into the Baltic Sea, as part of the international project TABACOD. In addition, 1260 cod have also been tagged using data storage tags (DSTs) which record high-resolution measurements of temperature and pressure. The conventional external tagging provides new data on the growth and movement of recaptured cod, but perhaps the most intriguing insights into Baltic cod ecology come from recaptured DST tagged cod. Although the number of returned DSTs to date is still rather low (N=23), each one provides a wealth of valuable new data. The unexpected results which have already been revealed by the returned DSTs include information on seasonal migration patterns which would not have been identified from the conventional external tagging alone. Additionally, we found examples of cod vertical movement patterns that aligned with moon phase, potentially following lunar-related changes in prey distribution. We have also gained direct evidence of the predation on one unlucky cod by a cormorant, through a DST recovered in a colony by an ornithologist. This DST indicates very shallow, inshore movements of Baltic cod. Such discoveries provide new pieces of the puzzle, which will help us to better understand Baltic cod ecology, formulate new hypotheses, and guide future research.

U2 - 10.13140/RG.2.2.13591.21923

DO - 10.13140/RG.2.2.13591.21923

M3 - Poster

ER -

Haase S, McQueen K, Mion M, Krumme U, Casini M, Hüssy K et al. The Baltic cod - An unexpected journey. 2019. Poster session presented at 5th International Conference on Fish Telemetry, Arendal, Norway. https://doi.org/10.13140/RG.2.2.13591.21923