Smaller bar spacings in a Nordmøre grid reduces the bycatch of redfish (Sebastes spp.) in the offshore Northern shrimp (Pandalus borealis) fishery of eastern Canada

Araya-Schmidt, Tomas; Bayse, Shannon M.; Winger, Paul D.; Frank, Colin C.H.

doi:10.1016/j.aaf.2023.01.009

Cited by 2 publications

(3 citation statements)

References 31 publications

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“…Conversely, an increase in inclination grid angle from 30 • to 45 • and 60 • results in maximum velocity reductions of 12.6% and 8.6%, respectively, behind a circular grid when the grid bar spacing is widened from 7 mm to 11 mm and 15 mm. These observations deviate from experimental findings in the flume tank and camera observations conducted by Araya-Schmidt et al [27,30], potentially attributed to variations in grid design and testing conditions. Echoing the hypothesis of Hickey et al [31], the present study confirms that greater inclination grid angles yield increased flow velocity reductions behind the grid.…”

Section: Discussioncontrasting

confidence: 95%

“…The BRD is an essential component of the trawl codend system, which can easily allow the escape of unwanted fish and juvenile fish, which improves trawl selectivity. As emphasized earlier, the hydrodynamic performance of the BRD significantly influences the fish selection and the overall efficacy of the codend system [27,28]. In contrast to the study of Earyrs et al [8], the present study and the previous study done by Araya-Schmidt et al [29] showed reducing the grid bar spacings from 15 to 11 and 7 mm in the flume tank significantly increased the hydrodynamic performance of the BRD of the codend-BRD system and decreased the velocity deficit downstream to the BRD, which will reduce juvenile bycatch while maintaining a marine ecosystem.…”

Section: Discussionmentioning

confidence: 93%

“…This phenomenon can be attributed to the alteration of water flow dynamics resulting from an expanded solid area (comprising grid bar spacing and inclination grid angle). This, in turn, redirects the water flow pattern, increasing the deflected flow and decreasing the flow traversing through the grid [14,27]. T When grid bar spacing is increases from 7 mm to 11 mm and 15 mm, velocity reduction registers at a minor 6.1% and 4.8%, respectively, for an inclination grid angle of 30 • .…”

Section: Discussionmentioning

confidence: 99%

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Flow Field Pattern and Hydrodynamic Characteristics of a Grid Device Made with Various Grid Bar Spacings at Different Inclination Angles

Zhang,

Tang,

Thierry

et al. 2023

JMSE

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The grid is a crucial component in constructing grid-type bycatch reduction devices. The grid’s structural characteristics and orientation significantly impact the hydrodynamic characteristics and efficacy of the separation device. Therefore, it is essential to thoroughly understand the grid device’s hydrodynamic characteristics and flow field to optimize its structure. Thus, this study used CFD numerical simulation and flume tank experiments to investigate the effects of inclination grid angles and grid bar spacing on hydrodynamic forces and flow fields around a circular grid. The results indicated that the hydrodynamic forces acting on the circular grid increased with higher flow velocity and inclination grid angle, decreasing with smaller grid bar spacing. Flow velocity acceleration zones were observed at the upper and lower ends of the grid and between the grid bars. Additionally, upwelling and vortices were present at the back of the grid. It was found that an increase in the inclination grid angle accelerated the vortex and wake effects.

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Section: Discussioncontrasting

confidence: 95%

Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

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Flow Field Pattern and Hydrodynamic Characteristics of a Grid Device Made with Various Grid Bar Spacings at Different Inclination Angles

Zhang,

Tang,

Thierry

et al. 2023

JMSE

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Morphometric characteristics of Antarctic krill (Euphausia superba) and finfish bycatch in the krill fishery in the waters of South Orkney Islands during the 2022/23 fishing season

Wang,

Ma,

Wang

et al. 2024

Front. Mar. Sci.

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Determination of bar spacing of bycatch reduction devices (BRDs) should consider species composition and morphometric characteristics (particularly width) of target species krill and bycatch. This study conducted a scientific investigation of the finfish bycatch in the Antarctic krill (Euphausia superba) trawl fishery by the fishing vessel SHEN LAN in the waters surrounding the South Orkney Islands from December 24, 2022, to February 20, 2023. The results show that scientific observers sampled 676 individuals of finfish bycatch. Of these, 665 were identified to species (17 species from 8 families), while the remaining 11 specimen were juveniles of the Nototheniidae family that could not be identified to the species level. IRI (index of relative importance) calculations showed three dominant (IRI value greater than 1,000) finfish bycatch species (Champsocephalus gunnari, Pseudochaenichthys georgianus, and C. aceratus from the Channichthyidae family) and four important (IRI value between 1,000 and 100) finfish bycatch species (Electrona carlsbergi and Gymnoscopelus nicholsi from the Myctophidae family, Gobionotothen gibberifrons from the Nototheniidae family, and Notolepis coatsi from the Paralepididae family). Our study provides morphometric data (particularly body width) that is crucial to model the potential for bycatch reduction by use of bycatch reduction devices (BRDs) and to determine the appropriate candidate bar spacings for BRD sea trials. Predictions suggest that a 10 mm (the maximum body width of krill) bar spacing releases a significant amount of dominant and important bycatch species (93.94% of C. gunnari, 53.99% of P. georgianus, 76.25% of C. aceratus, and 100% of G. gibberifrons). Reduced fishing pressure would reduce the risks to dominant and important bycatch species to make the krill fishery sustainable. We recommend that future BRD sea trials should initially test a 10 mm bar spacing. If marked loss of krill is observed, wider spacings (e.g. 15 mm) must be tested.

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Smaller bar spacings in a Nordmøre grid reduces the bycatch of redfish (Sebastes spp.) in the offshore Northern shrimp (Pandalus borealis) fishery of eastern Canada

Cited by 2 publications

References 31 publications

Flow Field Pattern and Hydrodynamic Characteristics of a Grid Device Made with Various Grid Bar Spacings at Different Inclination Angles

Flow Field Pattern and Hydrodynamic Characteristics of a Grid Device Made with Various Grid Bar Spacings at Different Inclination Angles

Morphometric characteristics of Antarctic krill (Euphausia superba) and finfish bycatch in the krill fishery in the waters of South Orkney Islands during the 2022/23 fishing season

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