scholarly journals Cod-end selectivity for sole (Solea solea) and plaice (Pleuronectes platessa) in North Sea pulse-trawl fisheries : Best Practices II - WP4 selectivity

2018 ◽  
Author(s):  
Pieke Molenaar ◽  
◽  
Chun Chen
Keyword(s):  
Best Practices ◽  
North Sea ◽  
Pleuronectes Platessa ◽  
Solea Solea ◽  
Trawl Fisheries

scholarly journals Can economic and biological management objectives be achieved by the use of MSY-based reference points? A North Sea plaice (Pleuronectes platessa) and sole (Solea solea) case study

2008 ◽  
Vol 65 (6) ◽  
pp. 1069-1080 ◽  
Author(s):  
Graham M. Pilling ◽  
Laurence T. Kell ◽  
Trevor Hutton ◽  
Peter J. Bromley ◽  
Alex N. Tidd ◽  
...  
Keyword(s):  
North Sea ◽  
Single Species ◽  
Reference Points ◽  
Pleuronectes Platessa ◽  
Management Objectives ◽  
Employment Conditions ◽  
Trade Offs ◽  
Solea Solea ◽  
Biological Management

Abstract Pilling, G. M., Kell, L. T., Hutton, T., Bromley, P. J., Tidd, A. N., and Bolle, L. J. 2008. Can economic and biological management objectives be achieved by the use of MSY-based reference points? A North Sea plaice (Pleuronectes platessa) and sole (Solea solea) case study. – ICES Journal of Marine Science, 65: 1069–1080. We examined the biological and economic impact of changing from management based on single-species limit reference points to one based on alternative targets, using the multispecies multifleet North Sea flatfish fishery. The robustness of reference points was tested against identified changes in plaice and sole biology. Current ICES single-species limit and precautionary biomass and fishing mortality reference points were seldom consistent with each other. Although they were generally robust to biological uncertainty, fishing at Fpa for sole could lead to stock collapse under one biological scenario. Adoption of alternative targets would reduce reliance on current reference points as stocks moved to a more sustainable state. Maximum sustainable yield (MSY), maximum economic yield (MEY), and maximum employment conditions implied different effort levels in the two fleets modelled, and different profits. Ftarget could be achieved with equal effort reductions in both fleets. Changes in stock biology affected the fishing effort required to maximize employment within the fishery, whereas MSY, Fmax, and MEY targets were robust to this uncertainty. Resulting profits and yields did vary widely, however. The selection of target reference points therefore requires stakeholders to define fishery objectives explicitly, against which targets can be evaluated for the resulting trade-offs between risk to stocks, yield, employment, and other social objectives.

scholarly journals Mitigating seafloor disturbance of bottom trawl fisheries for North Sea sole Solea solea by replacing mechanical with electrical stimulation

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0228528 ◽  
Author(s):  
A. D. Rijnsdorp ◽  
J. Depestele ◽  
O. R. Eigaard ◽  
N. T. Hintzen ◽  
A. Ivanovic ◽  
...  
Keyword(s):  
North Sea ◽  
Benthic Community ◽  
Bottom Trawl ◽  
Beam Trawl ◽  
Electrode Arrays ◽  
Physical Disturbance ◽  
Trawl Fishery ◽  
Solea Solea ◽  
The Impact ◽  
Trawl Fisheries

Ecosystem effects of bottom trawl fisheries are of major concern. Although it is prohibited to catch fish using electricity in European Union waters, a number of beam trawlers obtained a derogation and switched to pulse trawling to explore the potential to reduce impacts. Here we analyse whether using electrical rather than mechanical stimulation results in an overall reduction in physical disturbance of the seafloor in the beam-trawl fishery for sole Solea solea. We extend and apply a recently developed assessment framework to the Dutch beam-trawl fleet and show that the switch to pulse trawling substantially reduced benthic impacts when exploiting the total allowable catch of sole in the North Sea. Using Vessel Monitoring by Satellite and logbook data from 2009 to 2017, we estimate that the trawling footprint decreased by 23%, the precautionary impact indicator of the benthic community decreased by 39%, the impact on median longevity of the benthic community decreased by 20%, the impact on benthic biomass decreased by 61%, and the amount of sediment mobilised decreased by 39%. The decrease in impact is due to the replacement of tickler chains by electrode arrays, a lower towing speed and higher catch efficiency for sole. The effort and benthic physical disturbance of the beam-trawl fishery targeting plaice Pleuronectes platessa in the central North Sea increased with the recovery of the plaice stock. Our study illustrates the utility of a standardized methodological framework to assess the differences in time trends and physical disturbance between gears.

Survival of undersized plaice (Pleuronectes platessa), sole (Solea solea), and dab (Limanda limanda) in North Sea pulse-trawl fisheries

2017 ◽  
Vol 74 (6) ◽  
pp. 1672-1680 ◽  
Author(s):  
K. J. van der Reijden ◽  
P. Molenaar ◽  
C. Chen ◽  
S. S. Uhlmann ◽  
P. C. Goudswaard ◽  
...  
Keyword(s):  
Overall Survival ◽  
Processing Time ◽  
Fish Length ◽  
High Survival ◽  
Fishing Vessel ◽  
Fishing Trip ◽  
Pleuronectes Platessa ◽  
Solea Solea ◽  
Species Specific ◽  
Trawl Fisheries

Abstract The European Commission landing obligation, including species-specific “high survival” exemptions, has established a need for accurate discard survival estimates. This study presents the first discard survival estimates on-board Dutch commercial pulse trawlers. During seven, six, and one fishing trip(s), respectively, undersized plaice (Pleuronectes platessa), sole (Solea solea), and dab (Limanda limanda) were collected, assessed for vitality and subsequently monitored up to 21 days. Uncorrected for any potential impacts from predation, tagging, research-related handling, or holding conditions overall survival for plaice (n = 349), sole (n = 226), and dab (n = 187) was assessed as 15% [95% CI: 11–19%], 29% [95% CI: 24–35%], and 16% [95% CI: 10–26%] respectively. Survival was mainly effected by water temperature and factors linked to the fishing vessel. Fish length was not found to affect survival. Catch processing time and haul duration affected plaice survival but not sole. Vitality index, which averages reflex impairment and external damage scores, correlated with survival and may be developed as a proxy for discard survival. Compared to tickler-chain beam trawlers, pulse trawlers showed relatively higher discard survival under fishing conditions pertinent to these studies.

Otolith increments in European plaice (Pleuronectes platessa) reveal temperature and density-dependent effects on growth

2018 ◽  
Vol 75 (5) ◽  
pp. 1655-1663 ◽  
Author(s):  
Peter van der Sleen ◽  
Christoph Stransky ◽  
John R Morrongiello ◽  
Holger Haslob ◽  
Melita Peharda ◽  
...  
Keyword(s):  
Environmental Factors ◽  
North Sea ◽  
Bottom Temperature ◽  
Growth Data ◽  
Mixed Effect ◽  
Pleuronectes Platessa ◽  
Growing Season Length ◽  
The North ◽  
Growth Variation ◽  
The North Sea

Abstract European plaice (Pleuronectes platessa) is a commercially important flatfish species in the North Sea. Yet, the environmental factors that affect the growth of plaice remain unresolved. Here we examine the drivers of plaice growth variation by using a large archive of otoliths from female plaice collected in the northeastern part of the North Sea from 1993 to 2015, providing growth data over the period 1985–2014. We developed a series of increasingly complex mixed-effect models to explore intrinsic (within individual) and extrinsic (environmental factors: bottom temperature and plaice density) sources of growth variation. We analysed juvenile (0 and 1 year) and (sub)adult (≥2 years) growth separately due to different habitat utilization across life stages. Juvenile growth was positively correlated with bottom temperature, whereas growth of adults was negatively correlated with bottom temperature. Correlations for both were strongest during autumn (September to October). For juveniles, the temperature–growth relationship likely reflects a response to growing season length while for adults it could reflect temperature-dependent changes to metabolic rate or food availability. For both juveniles and adults, we also found inverse relationship between population density and growth. We suggest that the approach used in this study can find a much wider application in European waters.

scholarly journals Different bottom trawl fisheries have a differential impact on the status of the North Sea seafloor habitats

2020 ◽  
Vol 77 (5) ◽  
pp. 1772-1786 ◽  
Author(s):  
A D Rijnsdorp ◽  
J G Hiddink ◽  
P D van Denderen ◽  
N T Hintzen ◽  
O R Eigaard ◽  
...  
Keyword(s):  
North Sea ◽  
Management Strategies ◽  
Demersal Fish ◽  
Time Interval ◽  
The North ◽  
The Status ◽  
Fisheries Conservation ◽  
The North Sea ◽  
The Impact ◽  
Trawl Fisheries

Abstract Fisheries using bottom trawls are the most widespread source of anthropogenic physical disturbance to seafloor habitats. To mitigate such disturbances, the development of fisheries-, conservation-, and ecosystem-based management strategies requires the assessment of the impact of bottom trawling on the state of benthic biota. We explore a quantitative and mechanistic framework to assess trawling impact. Pressure and impact indicators that provide a continuous pressure–response curve are estimated at a spatial resolution of 1 × 1 min latitude and longitude (∼2 km2) using three methods: L1 estimates the proportion of the community with a life span exceeding the time interval between trawling events; L2 estimates the decrease in median longevity in response to trawling; and population dynamic (PD) estimates the decrease in biomass in response to trawling and the recovery time. Although impact scores are correlated, PD has the best performance over a broad range of trawling intensities. Using the framework in a trawling impact assessment of ten métiers in the North Sea shows that muddy habitats are impacted the most and coarse habitats are impacted the least. Otter trawling for crustaceans has the highest impact, followed by otter trawling for demersal fish and beam trawling for flatfish and flyshooting. Beam trawling for brown shrimps, otter trawling for industrial fish, and dredging for molluscs have the lowest impact. Trawling is highly aggregated in core fishing grounds where the status of the seafloor is low but the catch per unit of effort (CPUE) per unit of impact is high, in contrast to peripheral grounds, where CPUE per unit of impact is low.

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