Blar i forfatter "Stepputtis, Daniel"

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    • Broadening the horizon of size selectivity in trawl gears 

      Stepputtis, Daniel; Herrmann, Bent; Mieske, Bernd; Santos, Juan (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-12)
      The discussion of alternative harvest patterns in commercial fisheries has been raised by stock assessment and fishery modelers, especially in the wider context of balanced harvesting. But often, these theoretical approaches propose alternative exploitation patterns that are difficult to achieve within the current limitations in the selectivity characteristics of fishing gears, such as trawl gears. ...

    • The capability of square-meshes and fixed-shape meshes to control codend size selection 

      Bak-Jensen, Zita; Santos, Juan; Melli, Valentina; Stepputtis, Daniel; Feekings, Jordan P.; Herrmann, Bent (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-11)
      Trawl codends are commonly made of diamond-mesh netting. However, diamond-mesh codends vary in mesh geometry along its length and during fishing due to catch build up. This introduces variability in the size selection process. This phenomenon compromises the rationality of regulating exploitation patterns in trawl fisheries through adjustments in codend mesh size. One technical solution often ...

    • The efficiency of sieve-panels for bycatch separation in Nephrops trawls 

      Santos, Juan; Herrmann, Bent; Mieske, Bernd; Krag, Ludvig Ahm; Haase, Stefanie; Stepputtis, Daniel (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-11)
      This study investigated the efficiency of a sieve‐panel concept, intended to separate bycatch species from <i>Nephrops</i> (Norway lobster) in a trawl gear via mechanical and behavioural means. Four different designs of varying panel mesh size or inclination were tested in experimental fishing. For each design, the length‐dependent sieving efficiency, defined as the fraction of <i>Nephrops</i> or ...

    • 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 ...

    • Predictive framework for codend size selection of brown shrimp (Crangon crangon) in the North Sea beam-trawl fishery 

      Santos, Juan; Herrmann, Bent; Stepputtis, Daniel; Gunther, Claudia; Limmer, Bente; Mieske, Bernd; Schultz, Sebastian; Neudecker, Thomas; Temming, Axel; Hufnagl, Marc; Bethke, Eckhard; Kraus, Gerd (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-16)
      The brown shrimp (<i>Crangon crangon</i>) fishery is of great socio-economic importance to coastal communities on the North Sea. The fishery is exploited by beam trawlers often using codends with very small mesh sizes, leading to concerns about catch rates of undersized shrimp. However, little information is available on codend size selection, making it difficult to provide scientifically based ...

    • Quantifying the performance of selective devices by combining analysis of catch data and fish behaviour observations: methodology and case study on a flatfish excluder 

      Santos, Juan; Herrmann, Bent; Stepputtis, Daniel; Kraak, Sarah B. M.; Gökce, Gökhan; Mieske, Bernd (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-06)
      This article describes a method for the quantitative analysis of fish behaviour relative to selection devices in trawl gears. Based on video observations, the method estimates probabilities for a given event to happen and establishes behavioural tree diagrams representing and quantifying behavioural patterns in relation to the selection device under assessment. Double bootstrapping is used to account ...

    • Reducing cod bycatch in flatfish fisheries 

      Santos, Juan; Stepputtis, Daniel; Oesterwind, Daniel; Herrmann, Bent; Lichtenstein, Uwe; Hammerl, Constanze; Krumme, Uwe (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-12)
      Management measures to facilitate the recovery of fish stocks can lead to shifts in traditional fishing patterns and target species. In the Baltic Sea, drastic reductions in catch quota for cod (Gadus morhua) force mixed demersal trawl fisheries to avoid cod bycatch and focus on flatfish species. This study developed and tested a simple se- lection concept that aims to avoid cod bycatch in ...