Internal injuries in whiting (Merlangius merlangus) caught by tickler-chain and pulse-trawl gears

Boute, P.G.; Rijnsdorp, A.D.; Leeuwen, J.L. van; Versteeg, W. Sarina M.; Pieters, R.P.M.; Lankheet, M.J.M.

doi:10.1016/j.fishres.2022.106351

Cited by 5 publications

(2 citation statements)

References 77 publications

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“…Exposure to electrical pulses may inflict internal injuries, such as spinal injuries and hemorrhages, which could result in a delayed mortality (De Haan et al, 2016;Soetaert et al, 2016a). Because the recorded injury rate in pulse trawl catches was low (<2.5%) in 14 dominant North Sea fish species sampled (Boute, 2022;Boute et al, 2022) it is highly unlikely that pulse-induced internal injuries will result in mass mortality. This conclusion also holds for the two species (cod, sandeel) for which higher injury rates were observed, because cod is only a small fraction of a beam trawl's catch (ICES, 2020), and because none of the sandeel exposed to a commercial pulse stimulus in a tank experiment developed internal injuries (Schram et al, 2022).…”

Section: Discussionmentioning

confidence: 99%

A Transdisciplinary Approach Towards Studying Direct Mortality Among Demersal Fish and Benthic Invertebrates in the Wake of Pulse Trawling

et al. 2022

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Between 2009 and 2020, beam trawlers in the North Sea switched to electrical stimulation to target sole (Solea solea). The transition to pulse trawling raised widespread concern about possible adverse effects of electrical stimulation on marine organisms. Environmental NGO’s and small scale fishers claimed that it would electrocute marine life and create a ‘graveyard’ in the wake of pulse trawlers. This paper uses realistic field experiments to investigate the ‘graveyard’ hypothesis. In cooperation with fishers, a field experiment was designed where we simultaneously sampled marine organisms in the wake of pulse trawlers and in untrawled control areas. The impact was quantified by estimating the direct mortality among three dominant fish species and four dominant invertebrate species. In total, nine experimental tows were conducted in two years. Direct mortality among fish and invertebrates was low (0-10%) and did not differ between the pulse trawl track and the untrawled controls. Equally, no impact of the pulse trawl was found on external damages and vitality scores. The limited effects observed are likely due to the mechanical impact of the pulse and the sampling gear. The results of experiment do not support the claim that pulse trawling results in mass mortality among marine organisms in the trawl track. Throughout the research period, the concerns of small-scale fishers on pulse fishing shifted from being focused on biological effects to political and managerial issues. This can partly be attributed to the engagement in and the results of our research and has increased its credibility and salience. By integrating fishers’ knowledge and examining their perceptions through transdisciplinary research, we were able to show the importance of untangling the intricate relation between perceived knowledge gaps and political or management related concerns.

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Section: Discussionmentioning

confidence: 99%

A Transdisciplinary Approach Towards Studying Direct Mortality Among Demersal Fish and Benthic Invertebrates in the Wake of Pulse Trawling

et al. 2022

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“…Spinal injuries caused by involuntary muscle contractions induced by pulse stimulation have been reported in several species (van Marlen et al, 2014;de Haan et al, 2016;Soetaert et al, 2016a,b). The sensitivity among fish species for pulse-induced injuries was estimated by extensive sampling of target and non-target species from catches of commercial pulse and tickler-chain beam trawlers (ICES, 2020;Boute, 2022;Boute et al, 2022). In most species, relatively low spinal injury probabilities were found in pulse-trawl catches.…”

Section: Introductionmentioning

confidence: 99%

Effect of electrical stimulation used in the pulse trawl fishery for common sole on internal injuries in sandeels

Schram

Molenaar

Soetaert³

et al. 2022

ICES Journal of Marine Science

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Electric stimulation was used in the North Sea beam trawl fishery for common sole to reduce its environmental impact. Because electrical stimulation may cause internal injuries in fish, a laboratory experiment was conducted to study the effect of pulse exposure on lesser sandeel (Ammodytes tobianus) and greater sandeel (Hyperoplus lanceolatus), important mid-trophic species in the North Sea ecosystem. We exposed 244 sandeels between two electrodes to a pulsed bipolar current for 2 s in an experimental cage with 5 cm sediment; 221 control fish were handled similarly but not exposed. The occurrence of spinal injuries and internal haemorrhages were scored using X-radiography and dissection. None of the sandeels exposed to a field strength of up to 600 V m–1 showed spinal injury or haemorrhage. Equal numbers of minor spinal abnormalities were found in exposed and control fish. In the absence of spinal injuries, we estimated by bootstrapping the field strength below which spinal injuries are unlikely to occur, i.e. the lower limit threshold, and the corresponding limit dose–response relationship between field strength and injury probability. We conclude that it is unlikely that pulse trawl fishery will have an ecologically significant adverse effect on the population abundance of sandeels, because of the low probabilities of exposure and injury.

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Electrotrawling can improve the sustainability of the bottom trawl fishery for sole: a review of the evidence

Rijnsdorp,

Boute,

Tiano

et al. 2024

Rev Fish Biol Fisheries

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Between 2009 and 2021 almost the complete beam trawl fleet of the Netherlands switched from conventional beam trawls (BT) to pulse trawls (PT) using electrical stimulation to catch sole, Solea solea. Electric fishing, being banned in the EU in 1988, was made possible in 2006 under a derogation. Over the years stakeholders expressed concern about ecosystem effects. Here we review the research conducted. PT improved the selectivity of the fishery and reduced the ecological side effects. PT caught more sole per hour fishing but less discards and benthos than BT. The transition to PT reduced the surface area swept (lower towing speed), sediment depth of disturbance and associated benthic impacts, as well as fuel consumption. Laboratory experiments with 9 fish and 17 benthic invertebrate species showed that exposure to a commercial bipolar pulse stimulus did not result in harmful effects except in cod. Autopsy of cod sampled from PT revealed that 40% had an internal injury. Injury rates in other roundfish species was low (< 2%) and absent in flatfish. Electrical-induced impacts on biogeochemistry were not observed. The transition increased competition with other fishers which fed the resentment against PT. Governance arrangements under which the number of temporary licenses expanded, undermined legitimacy of the gear, resulting in a ban in 2021. Although questions about the ecological impact of electrical stimulation remain, adverse effects are considered negligible in comparison with the benefits.

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Internal injuries in whiting (Merlangius merlangus) caught by tickler-chain and pulse-trawl gears

Cited by 5 publications

References 77 publications

A Transdisciplinary Approach Towards Studying Direct Mortality Among Demersal Fish and Benthic Invertebrates in the Wake of Pulse Trawling

A Transdisciplinary Approach Towards Studying Direct Mortality Among Demersal Fish and Benthic Invertebrates in the Wake of Pulse Trawling

Effect of electrical stimulation used in the pulse trawl fishery for common sole on internal injuries in sandeels

Electrotrawling can improve the sustainability of the bottom trawl fishery for sole: a review of the evidence

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