Blar i Brage IMR 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, ... -
A vessel specific bias in echo sounder recordings during trawling
Handegard, Nils Olav; Hjellvik, Vidar (ICES CM Documents;2004/R:35, Working paper, 2004) -
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 ... -
Adaptive Management of living Marine Resources by integrating different data sources and key ecological parameters (ADMAR)
Handegard, Nils Olav (Conference object, 2010-09-18) -
Adaptive management of living marine resources by integrating different data sources and key ecological processes (ADMAR): A joint effort by IMR and CEES
Handegard, Nils Olav; Stenseth, Nils Christian; Dankel, Dorothy Jane; Durant, Joël M.; Eikeset, Anne Maria; Enberg, Katja; Hjermann, Dag Ø.; Huse, Geir; Pennington, Michael; Skern-Mauritzen, Mette; Stige, Leif Christian; Subbey, Samuel; Vølstad, Jon Helge (ICES CM documents;2010/R:26 Poster;, Working paper, 2010-09) -
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. ... -
Akustikk og fiskeåtferd: korleis kan vi observera åtferd og kva finn vi ut?
Handegard, Nils Olav (Conference object, 2010-09-15) -
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 ... -
Behavioral responses of herring (Clupea harengus) to 1–2 and 6–7 kHz sonar signals and killer whale feeding sounds
Doksæter, Lise; Godø, Olav Rune; Handegard, Nils Olav; Kvadsheim, Petter H.; Lam, Frans-Peter A.; Donovan, Carl; Miller, Patrick J. O. (Journal article; Peer reviewed, 2009-01)Military antisubmarine sonars produce intense sounds within the hearing range of most clupeid fish. The behavioral reactions of overwintering herring (Clupea harengus) to sonar signals of two different frequency ranges ... -
Behavioral responses of herring (Clupea harengus) to 1–2 and 6–7 kHz sonar signals and killer whale feeding sounds
Doksæter, Lise; Godø, Olav Rune; Handegard, Nils Olav; Kvadsheim, Petter H.; Lam, Frans-Peter A.; Donovan, Carl; Miller, Patrick J. O. (Journal article; Peer reviewed, 2009-01)Military antisubmarine sonars produce intense sounds within the hearing range of most clupeid fish. The behavioral reactions of overwintering herring (Clupea harengus) to sonar signals of two different frequency ranges ... -
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 ... -
Capelin migration and spawning dynamics [4/3 - 6/4, 2002]
Slotte, Aril; Gjøsæter, Harald; Handegard, Nils Olav; Rist, Frøydis ([Toktrapport/Havforskningsinstituttet];Nr. 8, Working paper, 2002) -
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 ... -
Climate-fish relations in Norwegian waters
Stiansen, Jan Erik; Loeng, Harald; Svendsen, Einar; Pettersson, L.H.; Johannessen, Johnny A.; Furevik, Tore; Handegard, Nils Olav; Fredo, O. (Fisken og havet, Research report, 2002)Climate variability and change in the Arctic and Sub-Arctic regions have become increasingly important issues over the past few decades. The goal of the Arctic Climate Impact Assessment (ACIA) is to evaluate and synthesize ... -
Correcting for avoidance in acoustic abundance estimates for herring using a generalized linear model
Hjellvik, Vidar; Handegard, Nils Olav; Ona, Egil (ICES CM documents, Working paper, 2006)When a research vessel passes over a herring school or layer, the herring may avoid the vessel by swimming downwards and horizontally. The fish may also change its orientation, which may alter its mean target strength. ... -
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 ...