Blar i Publikasjoner fra CRIStin på forfatter "Handegard, Nils Olav"

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    • A method to automatically detect fish aggregations using horizontally scanning sonar 

      Vatnehol, Sindre; Pena, Hector; Handegard, Nils Olav (Journal article; Peer reviewed, 2018)
      Pelagic fishes are a major source of protein and unsaturated fatty acids, and robust management is critical to avoid overfishing. Fisheries management is often supported by indices from scientific acoustic-trawl surveys, ...

    • Acoustic classification in multifrequency echosounder data using deep convolutional neural networks 

      Brautaset, Olav; Waldeland, Anders Ueland; Johnsen, Espen; Malde, Ketil; Eikvil, Line; Salberg, Arnt-Børre; Handegard, Nils Olav (Peer reviewed; Journal article, 2020)
      Acoustic target classification is the process of assigning observed acoustic backscattering intensity to an acoustic category. A deep learning strategy for acoustic target classification using a convolutional network is ...

    • Addressing class imbalance in deep learning for acoustic target classification 

      Pala, Ahmet; Oleynik, Anna; Utseth, Ingrid; Handegard, Nils Olav (Peer reviewed; Journal article, 2023)
      Acoustic surveys provide important data for fisheries management. During the surveys, ship-mounted echo sounders send acoustic signals into the water and measure the strength of the reflection, so-called backscatter. ...

    • Applications and analytical approaches using imaging sonar for quantifying behavioural interactions among aquatic organisms and their environment 

      Munnelly, Ryan T.; Castillo, Jose Carlos; Handegard, Nils Olav; Kimball, Matthew E.; Boswell, Kevin M.; Rieucau, Guillaume (Peer reviewed; Journal article, 2023)
      For many aquatic animals, distributional patterns, trophodynamic relationships, and reproductive activity are driven by complex biotic and abiotic ecosystem interactions that influence behaviour. Linking behavioural ...

    • Automatic interpretation of otoliths using deep learning 

      Moen, Endre; Handegard, Nils Olav; Allken, Vaneeda; Albert, Ole Thomas; Harbitz, Alf; Malde, Ketil (Journal article; Peer reviewed, 2018)
      The age structure of a fish population has important implications for recruitment processes and population fluctuations, and is a key input to fisheries-assessment models. The current method of determining age structure ...

    • Automatic interpretation of salmon scales using deep learning 

      Vabø, Rune; Moen, Endre; Smolinski, Szymon; Husebø, Åse; Handegard, Nils Olav; Malde, Ketil (Peer reviewed; Journal article, 2021)
      For several fish species, age and other important biological information is manually inferred from visual scrutinization of scales, and reliable automatic methods are not widely available. Here, we apply Convolutional ...

    • Behavioural responses of wild, spawning Atlantic cod (Gadus morhua L.) to seismic airgun exposure 

      McQueen, Kate; Skjæraasen, Jon Egil; Nyqvist, D; Olsen, Esben Moland; Karlsen, Ørjan; Meager, Justin James; Kvadsheim, Petter Helgevold; Handegard, Nils Olav; Forland, Tonje Nesse; de Jong, Karen; Sivle, Lise Doksæter (Peer reviewed; Journal article, 2023)
      Seismic airgun surveys to map petroleum deposits in the seabed may impact behaviour of marine animals over large distances. Understanding whether fish spawning behaviour is affected by this anthropogenic noise source is ...

    • Characterizing coastal cod vocalization using a towed hydrophone array 

      Seri, Sai Geetha; Schinault, Matthew Edward; Penna, Seth Michael; Zhu, Chenyang; Sivle, Lise Doksæter; de Jong, Karen; Handegard, Nils Olav; Ratilal, Purnima (Peer reviewed; Journal article, 2023)
      To better understand spawning vocalizations of Norwegian coastal cod (Gadus morhua), a prototype eight-element coherent hydrophone array was deployed in stationary vertical and towed horizontal modes to monitor cod sounds ...

    • CRIMAC - Annual Report 2020 

      Ona, Egil; Handegard, Nils Olav; Pedersen, Geir; Forland, Tonje Nesse; Tenningen, Maria; Johnsen, Espen (Research report, 2021)

    • CRIMAC cruise report: Development of acoustic and optic methods for underwater target calssification - G.O. Sars 22.11 - 03.12 2022 

      Handegard, Nils Olav; Tenningen, Maria; Bildøy, Leif; Corneliussen, Jon Even; Esmail, Kameran; Heinsdorf, Jens; Khodabandeloo, Babak; Korneliussen, Rolf; Kubilius, Rokas; Kvalvik, Liz Beate Kolstad; Osborg, Eirik Svoren; Pala, Ahmed; Pedersen, Geir; Rosen, Shale; Saltskår, Jostein; Schuster, Erik; Ulset, Ingrid; Westergerling, Eugenie Heliana Taraneh (Toktrapport;2023 - 3, Research report, 2023)
      The overarching objective of the survey is to collect data to support the CRIMAC activities and to collect data for the LoVe observatory. CRIMAC is a center of research-based innovation funded by the research council of ...

    • Data interoperability between elements of the global ocean observing system 

      Snowden, Derrick P.; Tsontos, Vardis; Handegard, Nils Olav; Zarate, Marcos; O'Brien, Kevin M.; Casey, Kenneth S.; Smith, Neville; Sagen, Helge; Bailey, Kathleen; Lewis, Mirtha; Arms, Sean (Journal article; Peer reviewed, 2019)
      The data management landscape associated with the Global Ocean Observing System is distributed, complex, and only loosely coordinated. Yet interoperability across this distributed landscape is essential to enable data to ...

    • A deep learning-based method to identify and count pelagic and mesopelagic fishes from trawl camera images 

      Allken, Vaneeda; Rosen, Shale Pettit; Handegard, Nils Olav; Malde, Ketil (Peer reviewed; Journal article, 2021)
      Fish counts and species information can be obtained from images taken within trawls, which enables trawl surveys to operate without extracting fish from their habitat, yields distribution data at fine scale for better ...

    • Deep Semi-Supervised Semantic Segmentation in Multi-Frequency Echosounder Data 

      Choi, Changkyu; Kampffmeyer, Michael; Jenssen, Robert; Handegard, Nils Olav; Salberg, Arnt-Børre (Peer reviewed; Journal article, 2023)
      Multi-frequency echosounder data can provide a broad understanding of the underwater environment in a non-invasive manner. The analysis of echosounder data is, hence, a topic of great importance for the marine ecosystem. ...

    • Deep Semi-Supervised Semantic Segmentation in Multi-Frequency Echosounder Data 

      Choi, Changkyu; Kampffmeyer, Michael; Jenssen, Robert; Handegard, Nils Olav; Salberg, Arnt-Børre (Peer reviewed; Journal article, 2023)
      Multi-frequency echosounder data can provide a broad understanding of the underwater environment in a non-invasive manner. The analysis of echosounder data is, hence, a topic of great importance for the marine ecosystem. ...

    • Detection, Localization and Classification of Multiple Mechanized Ocean Vessels over Continental-Shelf Scale Regions with Passive Ocean Acoustic Waveguide Remote Sensing 

      Zhu, Chenyang; Garcia, Heriberto; Kaplan, Anna; Schinault, Matthew; Handegard, Nils Olav; Godø, Olav Rune; Huang, Wei; Ratilal, Purnima (Journal article; Peer reviewed, 2018)
      Multiple mechanized ocean vessels, including both surface ships and submerged vehicles, can be simultaneously monitored over instantaneous continental-shelf scale regions >10,000 km 2 via passive ocean acoustic waveguide ...

    • Diversity and seasonal development of large zooplankton along physical gradients in the Arctic Barents Sea 

      Engeland, Tom Van; Bagøien, Espen; Wold, Anette; Cannaby, Heather Anne; Majaneva, Sanna Kristiina; Vader, Anna; Rønning, Jon S.; Handegard, Nils Olav; Dalpadado, Padmini; Ingvaldsen, Randi Brunvær (Peer reviewed; Journal article, 2023)
      Due to ongoing climate change, a new Arctic Ocean ecosystem is emerging. Within the framework of the Nansen Legacy project, we investigated the community composition of the large zooplankton and its seasonal development ...

    • Effects on individual level behaviour in mackerel (Scomber scombrus) of sub-lethal capture related stressors: Crowding and hypoxia 

      Anders, Neil; Howarth, Kirsten; Totland, Bjørn; Handegard, Nils Olav; Tenningen, Maria; Breen, Michael (Journal article; Peer reviewed, 2019)
      Stress to fish during harvest in wild capture fisheries is known to negatively influence subsequent survival in catches that are released. Therefore, if fisheries are to be conducted sustainably, there is a need to promote ...

    • Effects on schooling function in mackerel of sub-lethal capture related stressors: Crowding and hypoxia 

      Handegard, Nils Olav; Tenningen, Maria; Howarth, Kirsten; Anders, Neil; Rieucau, Guillaume; Breen, Michael (Journal article; Peer reviewed, 2017)
      The selectivity of fishing gears with respect to fish species and size is important, both for fisheries management and fishing operations. Purse seining is an efficient, environmentally friendly fish capture methodology ...

    • Evaluating acoustic-trawl survey strategies using an end-to-end ecosystem model 

      Holmin, Arne Johannes; Mousing, Erik Askov; Skogen, Morten D.; Hjøllo, Solfrid Sætre; Huse, Geir; Handegard, Nils Olav (Peer reviewed; Journal article, 2020)
      Fisheries independent surveys support science and fisheries assessments but are costly. Evaluating the efficacy of a survey before initiating it could save costs. We used the NORWECOM.E2E model to simulate Northeast Atlantic ...

    • Evaluation of echosounder data preparation strategies for modern machine learning models 

      Ordonez, Alba; Utseth, Ingrid; Brautaset, Olav; Korneliussen, Rolf; Handegard, Nils Olav (Peer reviewed; Journal article, 2022)
      Fish stock assessment and management requires accurate estimates of fish abundance, which are typically derived from echosounder observations using acoustic target classification (ATC). Skilled operators are regularly ...