• Effect of gillnet twine thickness on capture pattern and efficiency in the Northeast-Arctic cod (Gadus morhua) fishery 

      Brinkhof, Ilmar; Herrmann, Bent; Larsen, Roger B.; Brinkhof, Jesse; Grimaldo, Eduardo; Vollstad, Jørgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-15)
      Gillnets are among the most common fishing gears worldwide. They are often made of thin twine, which is prone to wear and tear, limiting the lifespan of the gillnet. This increases gillnet turnover, and consequently increased risk of gear discarding, gear loss, ghost fishing and marine pollution. This might be mitigated by increasing twine thickness, and thereby breaking strength. However, the ...
    • Effect of grid section design on trawl size selectivity 

      Sistiaga, Manu; Herrmann, Bent; Brinkhof, Jesse; Larsen, Roger B. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-12)
      Sorting grids are introduced in trawl fisheries to improve size selectivity and reduce the variability of results obtained with sorting devices constructed of netting e.g., codends. Grids are rigid or semi-rigid structures where the bar spacing defines the sizes of fish that can pass through. However, for size selection to occur, fish need to be oriented towards the grid in specific ways, which ...
    • Effect of lifting the sweeps on bottom trawling catch efficiency on the Northeast arctic cod trawl fishery 

      Sistiaga, Manu Berrondo; Grimaldo, Eduardo; Herrmann, Bent; Larsen, Roger B.; Tatone, Ivan (Research report; Forskningsrapport, 2014)
      Fuel consumption and environmental concerns have led bottom trawlers fishing for cod (Gadus morhua) in the Barents Sea to use semi-pelagic doors. However, this change may affect fish herding and consequently the catch efficiency of the gear. In this study we compared the catch efficiency of two different setups where the sweep length with bottom contact was different. This setup also enabled us to ...
    • The effect of long-term use on the Catch efficiency of Biodegradable gillnets 

      Grimaldo, Eduardo; Herrmann, Bent; Jacques, Nadine; Kubowicz, Stephan; Cerbule, Kristine; Su, Biao; Larsen, Roger B.; Vollstad, Jørgen (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-05)
      The effect of long-term use on the catch efficiency of biodegradable gillnets was investigated during commercial fishing trials and in controlled lab aging tests. The relative catch efficiency between biodegradable and nylon gillnets was evaluated over three consecutive fishing seasons for Atlantic cod (Gadus morhua) in Norway. The biodegradable gillnets progressively lost catch efficiency over time, ...
    • The effect of Nordmøre grid length and angle on codend entry of bycatch fish species and shrimp catches 

      Larsen, Roger B.; Sistiaga, Manu Berrondo; Herrmann, Bent; Brinkhof, Jesse; Tatone, Ivan; Santos, Juan (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06-18)
      The Nordmøre grid is regarded as an efficient bycatch reducing device and is used in various shrimp trawl fisheries globally. However, in some shrimp fisheries bycatch remains a problem that seriously impacts commercial trawl activities. This study tested and compared the performance of two versions of the Nordmøre grid in the Northeast Arctic Deepwater Shrimp (Pandalus borealis) fishery; a standard ...
    • The effect of semi-pelagic trawling on american plaice (hippoglossoides platessoides) by-catch reduction in the northeast arctic shrimp fishery 

      Sistiaga, Manu Berrondo; Grimaldo, Eduardo; Herrmann, Bent; Larsen, Roger B. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017)
      The present study reports results of a small-scale preliminary experiment to evaluate whether lifting trawl doors and sweeps from the seabed can lead to a reduction of by-catch in the Northeast Arctic shrimp trawl fishery. We carried out a catch comparison and catch ratio analysis between two gear configurations: one with trawl doors and sweeps on the seabed (traditional rigging) and the other with ...
    • Effect of the Nordmøre grid bar spacing on size selectivity, catch efficiency and bycatch of the Barents Sea Northern shrimp fishery 

      Larsen, Roger B.; Herrmann, Bent; Sistiaga, Manu; Brinkhof, Jesse; Cerbule, Kristine; Grimaldo Vela, Eduardo Enrique; Lomeli, Mark JM (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-27)
      The introduction of the Nordmøre grid in shrimp trawls has reduced the bycatch of non-target species. In the Norwegian Northern shrimp (Pandalus borealis) fishery, the mandatory selective gear consists of a Nordmøre grid with 19 mm bar spacing combined with a 35 mm mesh size diamond mesh codend. However, fish bycatch in shrimp trawls remains a challenge and further modifications of the gear that ...
    • Effect of the T90-codend on the catch quality of cod (Gadus morhua) compared to the conventional codend configuration in the Barents Sea bottom trawl fishery 

      Jensen, Tonje Kristin; Brinkhof, Jesse; Lindberg, Stein-Kato; Tobiassen, Torbjørn Inge; Heia, Karsten; Olsen, Stein Harris; Larsen, Roger B.; Esaiassen, Margrethe (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-18)
      The aim of this study was to compare the catch quality of Northeast Atlantic cod (Gadus morhua) in the Barents Sea bottom trawl fishery caught using the conventional configuration (a sorting grid followed by a diamond mesh (T0) codend) and a T90° turned mesh codend (T90) without a grid. Twenty hauls were conducted, consisting of 10 hauls with the conventional configuration and 10 hauls with the ...
    • Effect of three different codend designs on the size selectivity of juvenile cod in the Barents Sea shrimp trawl fishery 

      Herrmann, Bent; Sistiaga, Manu Berrondo; Larsen, Roger B.; Brinkhof, Jesse (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-31)
      Shrimp trawlers often use a Nordmøre sorting grid ahead of a small mesh codend to avoid bycatch of juvenile fish while allowing shrimps to be efficiently caught. However, small fish can pass through the grid to enter the codend and risk being retained. The risk of retention for fish of different sizes depends the size selection in the Nordmøre grid and the size selection in the subsequent codend, ...
    • Escape rate for cod (Gadus morhua) from the codend during buffer towing 

      Brinkhof, Jesse; Herrmann, Bent; Larsen, Roger B.; Sistiaga, Manu Berrondo (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-30)
      The high abundances of Northeast Arctic cod (Gadus morhua) in the Barents Sea have led to the development of a new fishing tactic called buffer towing. On factory trawlers, the trawl is deployed immediately after taking the catch onboard, a tactic used to ensure a continuous supply of fish is being processed. If the desired amount of fish is caught before the catch from the previous haul has been ...
    • Field demonstration of a novel towed, area bubble-plume zooplankton (Calanus sp.) harvesting approach 

      Grimaldo, Eduardo; Leifer, Ira; Gjøsund, Svein Helge; Larsen, Roger B.; Jeuthe, Henrik (Research report; Forskningsrapport, 2010)
      This paper presents field experiment results of using a new technology to harvest copepods (Calanus sp.) in the ocean by bubble upwelling. Two largo-scale bubble rafts, a 21 m2 and a flexible 75 m2 bubble raft with tow parallel and perpendicular sparger elements, respectively, were field tested in areas with high, upper 25-m water column Calanus densities. Measured bubble-driven upwelling velocities ...
    • Fishing efficiency of biodegradable PBSAT gillnets and conventional nylon gillnets used in Norwegian cod (Gadus morhua) and saithe (Pollachius virens) fisheries 

      Grimaldo, Eduardo; Herrmann, Bent; Vollstad, Jørgen; Su, Biao; Føre, Heidi Moe; Larsen, Roger B.; Tatone, Ivan (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-10)
      Fishing trials were carried out to compare the relative fishing efficiency of gillnets made of a new biodegradable resin (polybutylene succinate co-adipate-co-terephthalate, PBSAT) with conventional (nylon) nets. The fishing trials covered two consecutive fishing seasons (2016 and 2017) for cod (<i>Gadus morhua</i>) and saithe (<i>Pollachius virens</i>) in northern Norway. Results generally showed ...
    • Ghost fishing efficiency by lost, abandoned or discarded pots in snow crab (Chionoecetes opilio) fishery 

      Cerbule, Kristine; Herrmann, Bent; Grimaldo, Eduardo; Brinkhof, Jesse; Sistiaga, Manu; Larsen, Roger B.; Bak-Jensen, Zita (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-07)
      Marine pollution by lost, abandoned or otherwise discarded fishing gear (ALDFG) often has negative impact on the ecosystem through plastic pollution and continuous capture of marine animals, so-called “ghost fishing”. ALDFG in pot fisheries is associated with high ghost fishing risk. The snow crab (Chionoecetes opilio) pot fishery is conducted in harsh weather conditions increasing the risk of ...
    • Governance implications for the implementation of biodegradable gillnets in Norway 

      Standal, Dag; Grimaldo, Eduardo; Larsen, Roger B. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-15)
      Gillnets are among the most widely used fishing gear in global fisheries because of their simplicity, high operability, catch efficiency and low entrance cost for fishermen. In Norway, the Northeast Atlantic (NEA) cod (<i>Gadus morhua</i>) fishing industry represents the most important economic single species fishery and the gillnet fishery accounts for 24% of the national total allowable catch (TAC) ...
    • Hooked on Longline Proceedings from a workshop on long-lining in Reykjavik October 19th and 20th 2010 

      Henriksen, Edgar; Larsen, Roger B.; Margeirsson, Svein; Pol, Mike; Rindahl, Lasse; Thomsen, Bjarti; Vidarsson, Jonas (Research report; Forskningsrapport, 2010-12-31)
      In this report are published presentations held at an international workshop in Reykjavik on various aspects of longline fishing. Issues related to market conditions, different technological aspects regarding gear technology and handling of fish, profitability in fishing operations and fish processing as well as aspects of the management were presented. There are also proposals for follow-up of ...
    • Internasjonal teineteknologi sett opp mot norske forhold Kan canadisk teineteknologi være et altenativ i det norske torskefiskeriet? 

      Rindahl, Lasse; Henriksen, Edgar; Larsen, Roger B. (Research report; Forskningsrapport, 2011-07-11)
      Pa tross av at det har vrert jobbet mye med utvikling av teine i Norge har dette redsk.apet ik.ke oppnadd tilstrekkelige fangstrater tit a fa innpass i kommerSielt fiskeri, selv om prinsippet med teinedrift er 0nsket av fiskelinii?linga. Malsetningen med dette prosjek.tet var a vurdere om det finnes teinefiskerier andre steder i verden med en teknologi som vii Vii?re mulig a overf0re til norske ...
    • Is there a limit to the potential effects of shortening lastridge ropes on the size selectivity of diamond mesh codends? 

      Sistiaga, Manu; Herrmann, Bent; Brinkhof, Jesse; Larsen, Roger B.; Santos, Juan; Stepputtis, Daniel; Brinkhof, Ilmar; Jacques, Nadine; Cerbule, Kristine; Petetta, Andrea; Cuende, Elsa; Kvalvik, Liz Beate Kolstad (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-21)
      Shortening codend lastridge ropes can be an effective fishing gear modification to improve the size selection properties in diamond mesh codends. Lastridge ropes attached to codend selvedges withstand the longitudinal forces created by the catch building up and therefore, prevent the codend meshes from closing. However, the extent to which the lastridge ropes should be shortened to maximize the ...
    • A life after Research? First Release of Harp Seals (Phoca groenlandica) after Temporary Captivity for Scientific Purposes 

      Blanchet, Marie-Anne; Acquarone, Mario; Biuw, Martin; Larsen, Roger B.; Nordøy, Erling Sverre; Folkow, Lars (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-08)
      Three wild-caught female harp seals (Pagophilus groenlandicus) from the Greenland Sea stock were brought into temporary captivity in connection with a controlled validation study on energetics. The two pups and one adult were kept in two indoor and outdoor experimental facilities approved by the Norwegian Animal Research Authority. They were trained daily using operant conditioning to participate ...
    • Make it simpler and better: T90 codend improves size selectivity and catch efficiency compared with the grid-and-diamond mesh codend in the Northeast Atlantic bottom trawl fishery for gadoids 

      Brinkhof, Jesse; Larsen, Roger B.; Herrmann, Bent (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-08)
      The use of a sorting grid followed by a size-selective codend with minimum 130 mm mesh size is compulsory in the Northeast Atlantic demersal trawl fishery targeting cod (Gadus morhua), haddock (Melanogrammus aeglefinus), and saithe (Polachius virens). However, sorting grids cause some disadvantages, which possibly can be solved by removing the grid and improving codend selectivity, thus making the ...
    • Managing size selectivity: the relevance of compulsory and alternative selection devices in the Northeast Atlantic bottom trawl fishery 

      Brinkhof, Jesse; Sistiaga, Manu; Herrmann, Bent; Grimaldo Vela, Eduardo Enrique; Larsen, Roger B. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-10-14)
      Two decades of use of the compulsory selectivity gear configuration in the Northeast Atlantic bottom trawl fishery, which consists of a rigid sorting grid followed by a diamond mesh codend, have revealed problems with performance and efficiency. Size selectivity gear alternatives to this configuration are being pursued, and recent studies of codends with shortened lastridges have reported promising ...