A correction to “Estimating seabed pressure from demersal trawls, seines and dredges based on gear design and dimensions”†

Eigaard, Ole Ritzau; Bastardie, François; Breen, Mike; Dinesen, Grete E.; Hintzen, Niels T.; Laffargue, Pascal; Mortensen, Lars O.; Nielsen, J. Rasmus; Nilsson, Hans C.; O’Neill, Fiona; Polet, Hans; Reid, David G.; Sala, Antonello; Sköld, Mattias; Smith, Chris; Sørensen, Thomas Kirk; Tully, Oliver; Zengin, Mustafa; Rijnsdorp, A.D.

doi:10.1093/icesjms/fsw116

Cited by 17 publications

(26 citation statements)

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“…In particular, habitats formed by slow growing and long-lived specimens such as sea pens, hydroids, or corals, have a high vulnerability to fishing and even reduced fishing effort may cause considerable damage to these species, preventing their recovery (Troffe et al, 2005;Greathead et al, 2014). Moreover, the impacts of trawl fishing gears on the seabed differ depending on the sediment compositions and on bottom trawl target species (Pranovi et al, 2001(Pranovi et al, , 2005Eigaard et al, 2016). Gear characteristics (e.g., changes in number, the size of meshes in the cod end net, modification of the design of the doors, and other parts of the trawl net) also possibly affected the level and the type of damage by trawling gear on megabenthos.…”

Section: Discussionmentioning

confidence: 99%

Local Ecological Knowledge Indicates Temporal Trends of Benthic Invertebrates Species of the Adriatic Sea

et al. 2017

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In the Adriatic Sea, shifts in benthic community structure have been attributed to multiple stressors, from the effects of climate change to the impacts of commercial fishing. Some fishing practices, such as bottom trawling, have caused a widespread decline in exploited fish stocks. Bottom trawling is also expected to have negative impacts on benthic habitats, usually structured by and hosting a large array of invertebrate species, which provide important ecological services to fish and commercial invertebrate stocks. However, in contrast to commercial species for which long-term time series of the abundance exist, data on these habitat-forming invertebrates are scarce, as they are usually caught as bycatch and discarded. Therefore, there is great uncertainty about their long-term trends, and if these populations are stable or declining. Here we used interview surveys conducted with bottom-trawling fishers of the central Adriatic Sea to gather local ecological knowledge on megabenthos abundance occurring in their fishing domain, as an alternative source of information to conventional fisheries data. We interviewed 44 fishers, from the most important ports of the Marche region of Italy, to understand how megabenthic species have changed in abundance within the area since the 1980s. Specifically, we asked fishers to provide qualitative abundance scores for 18 invertebrate species in five phyla (Porifera, Cnidaria, Bryozoa, Mollusca, and Echinodermata) based on their recollection of these species' presence in bycatch. We stratified responses in homogeneous temporal periods and geographic sectors of the study area, and analyzed their response with mixed effect ordered logistic regression models in order to evaluate spatiotemporal changes in the perceived abundance of each species. Our analysis suggests that the abundance of the sponge Geodia cydonium, the molluscs Pecten jacobaeus, Atrina fragilis, Neopycnodonte cochlear, and the group of holothurians, have declined. From fishers' perceptions, only the bryozoan Amathia semiconvoluta has increased. Local ecological knowledge can provide important information on environmental change and can highlight species and ecosystems at risk when conventional scientific data are scarce or absent. This approach can be expanded to other regions of the Adriatic and broader Mediterranean Sea to reconstruct change of this heavily exploited marine region.

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Section: Discussionmentioning

confidence: 99%

Local Ecological Knowledge Indicates Temporal Trends of Benthic Invertebrates Species of the Adriatic Sea

et al. 2017

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“…Translating those to catches per swept km 2 based on estimates of hourly swept area by Eigaard et al. (2016b) led to similar or even higher values for trawlers (seines 90–109 mm: 161.4 kg; seines ≥110 mm: 274.8 kg; trawls 90–109 mm: 267.1 kg; trawls ≥110 mm: 360.0 kg). In other words, seiners are able to fish on a larger area in shorter time, but trawling collects more fish from an area than seining.…”

Section: Discussionmentioning

confidence: 91%

“…The collected data were used to indicate how appropriate the legislative grouping of seines and trawls is and how challenged the two fisheries will be in meeting the objectives of the landing obligation.Total catches per hour were larger for seiners using mesh sizes ≥110 mm than for trawlers. Translating those to catches per swept km 2 based on estimates of hourly swept area byEigaard et al (2016b) led to similar or even higher values for trawlers (seines 90-109 mm: 161.4 kg; seines ≥110 mm: 274.8 kg; trawls 90-109 mm: 267.1 kg; trawls ≥110 mm: 360.0 kg). In other words, seiners are able to fish on a larger area in shorter time, but trawling collects more fish from an area than seining.…”

mentioning

confidence: 93%

Fishing profiles of Danish seiners and bottom trawlers in relation to current EU management regulations

Noack

Frandsen

Wieland

et al. 2017

Fisheries Management Eco

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Danish seines and bottom trawls operate differently and have different catching processes. Both gears belong to the same legislative category in European fisheries, but different management strategies in other countries and criticism by fishers on grouping Danish seines and trawls together indicate disagreement on current gear classification. This study compared both gears in terms of their fishing characteristics and catches of commercial species based on 16 years of observer data. Danish seining is a specialised fishing method that targeted few species but with higher total catch rates than bottom trawlers. Bottom trawling is a more all‐purpose fishing method that targets a larger number of species, and bottom trawlers use larger engines than Danish seiners. A generalised additive mixed model indicated that catch rates of flatfish are generally higher for Danish seines, and catch rates of roundfish species are higher for trawlers. The results do not directly suggest a separation of the gears in terms of legislation as the quantities of fish below current minimum size were similar, but for example future survival studies may reach different conclusions. Additional factors were found to be important in determining catches of both gears.

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“…Thus, it can be assumed that a complex relationship between the environmental parameters such as natural disturbances (sediment reworking due to wave impact and tidal currents) and the sediment type is controlling the persistence of TM. Moreover, the used trawling gear is of importance as the penetration depth depends on the weight of the gear [21], which also influences the persistence of TM, making the relationship even more complex.…”

Section: Introductionmentioning

confidence: 99%

“…In the German EEZ (North Sea), beam trawls (TBB) and bottom otter trawls (OTB) are common trawling gears for catching demersal fish [22,23]. The weights of such gears are variable (up to several tons) and usually, the size of the gear is related to the size of the vessel (i.e., engine power) [21]. The penetration depth of the otter doors can be up to 35 cm in muddy sediments (≤ 10 cm in sandy sediments) and beam trawls have a penetration depth of ≤10 cm on both, muddy and sandy sediments [21].…”

Section: Introductionmentioning

confidence: 99%

Identifying Trawl Marks in North Sea Sediments

et al. 2020

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The anthropogenic impact in the German Exclusive Economic Zone (EEZ) is high due to the presence of manifold industries (e.g., wind farms, shipping, and fishery). Therefore, it is of great importance to evaluate the different impacts of such industries, in order to enable reasonable and sustainable decisions on environmental issues (e.g., nature conservation). Bottom trawling has a significant impact on benthic habitats worldwide. Fishing gear penetrates the seabed and the resulting furrows temporarily remain in the sediment known as trawl marks (TM), which can be recognized in the acoustic signal of side-scan sonars (SSS) and multibeam echo sounders (MBES). However, extensive mapping and precise descriptions of TM from commercial fisheries at far offshore fishing grounds in the German EEZ are not available. To get an insight into the spatial patterns and characteristics of TM, approximately 4800 km2 of high-resolution (1 m) SSS data from three different study sites in the German EEZ were analyzed for changes in TM density as well as for the geometry of individual TM. TM were manually digitalized and their density per square kilometer was calculated. In general, TM density was highest in August and October. Moreover, different gear types could be identified from investigating individual TM in SSS data. Beam trawl marks were observed to have widths of up to 22 m whereas otter board marks showed widths up to 6 m. The persistence of TM was estimated to 2–7 days minimum for all three sites based on the SSS data from 2015–2019. A maximum persistence could be defined at one site (Dogger Bank) and it was five months for the investigation period 2016–2017. Besides the main factors driving TM degradation (wave-base impact, sediment-type), different methods for TM detection (SSS, MBES, under-water video) are discussed. The study provides valuable information on the physical impact of bottom trawling on the seabed and can support existing monitoring strategies.

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A correction to “Estimating seabed pressure from demersal trawls, seines and dredges based on gear design and dimensions”†

Abstract: A correction to "Estimating seabed pressure from demersal trawls, seines and dredges based on gear design and dimensions". -

Cited by 17 publications

References 0 publications

Local Ecological Knowledge Indicates Temporal Trends of Benthic Invertebrates Species of the Adriatic Sea

Local Ecological Knowledge Indicates Temporal Trends of Benthic Invertebrates Species of the Adriatic Sea

Fishing profiles of Danish seiners and bottom trawlers in relation to current EU management regulations

Identifying Trawl Marks in North Sea Sediments

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