Tonje Knutsen Sørdalen

Postdoctoral Research Scientist

Centre for Coastal Research
University of Agder
Norway

Tel. +47 93627433
Email:

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Education

Ph.D. (2019) in Marine Biology, University of Oslo
M.Sc. (2012) in Marine ecology, Norwegian University of Life Sciences (NMBU)
B.Sc. (2011) in Biology, Norwegian University of Life Sciences (NMBU)
B.Sc. (2005) in Political sciences, Norwegian University of Science and Technology (NTNU)

Areas of expertise and interest

I am a marine ecologist interested in anthropogenic influence on reproductive behavior, population dynamics and contemporary evolution in crustaceans and fish. My main approach involves combining genetic methods and field studies of behavior and life history traits to understand the eco-evolutionary consequences of different management strategies and harvesting practices. I’m currently involved in studies addressing the sustainability in harvesting wrasse species for the use as cleaner fish in salmonid aquaculture. We use mark-recapture data from in and outside marine reserves, otolith analysis and sea data to investigate how behavior of fish and fishermen relate to one another, and how populations change due to selection. I am also in the final stage of completing my PhD where I study how the fishery interacts with the European lobsters’ population dynamic, and how it affects sexual selection, reproductive strategies and mate choice.

Active projects

Population dynamics of wild wrasse populations along the Norwegian coast (led by Anne Berit Skiftesvik)

Publications

A contrastive learning approach for individual re-identification in a wild fish population

Langøy Olsen, Ø., T. Knutsen Sørdalen, M. Goodwin, K. Malde, K. Muri Knausgård & K.T. Halvorsen 2023. A contrastive learning approach for individual re-identification in a wild fish population. Proceedings of the Northern Lights Deep Learning Workshop 4, doi: 10.7557/18.6824.
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Protection from fishing improves body growth of an exploited species

Sørdalen, T.K., Halvorsen K.T. & E.M. Olsen. 2022. Protection from fishing improves body growth of an exploited species. Proceeding of the Royal Society B: Biological Sciences. doi: 10.1098/rspb.2022.1718.
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Read stories about the work in The Economist, Nature, and HERE (in Norwegian)

Unlocking the potential of deep learning for marine ecology: overview, applications, and outlook

Goodwin, Morten, Halvorsen, Kim, Jiao, Lei, Knausgård, Kristian Muri, Martin, Angela, Moyano, Marta, Oomen, Rebekah A., Rasmussen, Jeppe, Sørdalen, Tonje Knutsen, Thorbjørnsen, Susanna Huneide. 2022. Unlocking the potential of deep learning for marine ecology: overview, applications, and outlook. ICES Journal of Marine Science. doi:10.1093/icesjms/fsab255.
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Lobster reserves as a management tool in coastal waters: two decades of experience in Norway

Knutsen, J.A., A.R. Kleiven, E.M Olsen, H. Knutsen, S.H. Espeland, T.K. Sørdalen, S.H. Thorbjørnsen, J.A. Hutchings, A. Fernández-Chacón, M. Huserbråten, D. Villegas-Ríos, K.T. Halvorsen, P.J Kleiven, T.K. Langeland & E. Moland. 2022. Lobster reserves as a management tool in coastal waters: two decades of experience in Norway. Marine Policy 136: February 2022, 104908.
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Restoration of abundance and dynamics of coastal fish and lobster within northern marine protected areas across two decades

Moland, E., A. Fernández-Chacón, T.K. Sørdalen, D. Villegas-Ríos, S.H. Thorbjørnsen, K.T. Halvorsen, M. Huserbråten, E.M. Olsen, P.J. Nillos-Kleiven, A.R. Kleiven, H. Knutsen, S.H. Espeland, C. Freitas, J.A. Knutsen. 2021. Restoration of abundance and dynamics of coastal fish and lobster within northern marine protected areas across two decades. Frontiers in Marine Science. 8:674756. doi: 10.3389/fmars.2021.674756.
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Movement patterns of temperate wrasses (Labridae) within a small marine protected area

Halvorsen, K.T., T. Larsen, H.I. Browman, C.M.F. Durif, N. Aasen, L.A. Vøllestad, A. Cresci, T.K. Sørdalen, R. Bjelland & A.B. Skiftesvik. 2021. Movement patterns of temperate wrasses (Labridae) within a small marine protected area. Journal of Fish Biology. 99: 1513-1518. doi: 10.1111/jfb.14825.
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Temperate fish detection and classification: a deep learning based approach

Knausgård. K.M., Wiklund. A., Sørdalen T.K., Halvorsen K.T, Kleiven, A., Jiao, L. & M. Goodwin. 2021. Temperate fish detection and classification: a deep learning based approach. Applied Intelligence, doi: 10.1007/s10489-020-02154-9.
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Mind the depth: The vertical dimension of a small-scale fishery shapes selection on species, size and sex in wrasses

Halvorsen, K.T., T. Knutsen Sørdalen, T. Larsen, H.I. Browman, T. Rafoss, J. Albretson & A.B. Skiftesvik. 2020. Mind the depth: The vertical dimension of a small-scale fishery shapes selection on species, size and sex in wrasses. Marine and Coastal Fisheries 12: 404–422, doi: 10.1002/mcf2.10131.
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The consequences of size-selective fishing mortality for larval production and sustainable yield in species with obligate male care

Kindsvater H.K., Halvorsen K.T., Sørdalen T.K. & S.H. Alonzo. 2020. The consequences of size-selective fishing mortality for larval production and sustainable yield in species with obligate male care. Fish and Fisheries. DOI: 10.1111/faf.12491
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Marine protected areas rescue a sexually selected trait in European lobster

Knutsen Sørdalen, T., K.T. Halvorsen, L.A. Vøllestad, E. Moland & E. Moland Olsen. 2020. Marine protected areas rescue a sexually selected trait in European lobster. Evolutionary Applications, doi: 10.1111/eva.12992.
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Biometric Fish Classification of Temperate Species Using Convolutional Neural Network with Squeeze-and-Excitation

Olsvik. E., C. Trinh, Knausgård. K.M., Wiklund. A., Sørdalen T.K., Kleiven, A.R. Goodwin, M. & L. Jiao. 2019. Biometric Fish Classification of Temperate Species Using Convolutional Neural Network with Squeeze-and-Excitation. In: Wotawa F., Friedrich G., Pill I., Koitz-Hristov R., Ali M. (eds) Advances and Trends in Artificial Intelligence. From Theory to Practice. IEA/AIE 2019. Lecture Notes in Computer Science, vol 11606: 89-101. arXiv:1904.02768v1.
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Harvesting changes mating behavior in European lobster

Sørdalen, T.K., K.T. Halvorsen, H.B. Harrison, C. Ellis, L.A. Vøllestad, H. Knutsen, E. Moland & E. Moland Olsen. 2018. Harvesting changes mating behavior in European lobster. Evolutionary Applications 11:963–977. DOI 10.1111/eva.12611
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Sex- and size-selective harvesting of corkwing wrasse (Symphodus melops) cleaner fish in salmonid aquaculture.

Halvorsen, K.T., T.K. Sørdalen, L.A. Vøllestad, A.B. Skiftesvik, S.H. Espeland & E.M. Olsen. 2017. Sex- and size-selective harvesting of corkwing wrasse (Symphodus melops) cleaner fish in salmonid aquaculture. ICES Journal of Marine Science 74: 660-669.
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Impact of harvesting cleaner fish for salmonid aquaculture assessed from replicated coastal marine protected areas.

Halvorsen, K.T., T. Larsen, T. K.Sørdalen, L.A. Vøllestad, H. Knutsen & E.M. Olsen. 2017. Impact of harvesting cleaner fish for salmonid aquaculture assessed from replicated coastal marine protected areas. Marine Biology Research 13: 359-369.
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Male biased sexual size dimorphism in the nest building corkwing wrasse (Symphodus melops): implications for a size regulated fishery.

Halvorsen, K.T., T.K. Sørdalen, C.M.F. Durif, H. Knutsen, E.M. Olsen, A.B. Skiftesvik, T.E. Rustand, R.M. Bjelland & L.A. Vøllestad. 2016. Male biased sexual size dimorphism in the nest building corkwing wrasse (Symphodus melops): implications for a size regulated fishery. ICES Journal of Marine Science 73: 2586-2594.
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Genotype reconstruction of paternity in European lobsters (Homarus gammarus).

Ellis, C. D., Hodgson, D. J., André, C., Sørdalen, T. K., Knutsen, H., & Griffiths, A. G. F. 2015. Genotype reconstruction of paternity in European lobsters (Homarus gammarus). PLoS ONE 10: 1–14.
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Last updated: February 4, 2023