Experiments were carried out in 2007 and 2008 on discard reducing techniques in flatfish beam trawling onboard FRV “Tridens” in close cooperation with the fishing industry. A total of 38 gear tests were conducted in which modified beam trawls were compared in pair with a conventional 12 m beam trawl. The modifications consisted of a T90 aft part and various Square Mesh Panels (SMPs) in the bottom sheet, top sheet and combinations of both, and variations of a Benthos Release Hole with a guiding V-panel in the bottom sheet. It was found that a panel in the bottom sheet with 160 mm mesh size appeared to perform best without releasing too many marketable fish. The panel should extend relatively far aft just in front of the codend here the netting is offground. Panels placed only in the top sheet are not very suitable in reducing benthos ycatches. In addition the Benthos Release Hole with guiding device seems to be effective in reducing such bycatches. The cooperation between fishermen and scientists worked very well and created better mutual understanding. Further work is advocated to optimise the design of these devices. It is expected that such devices will get wider application in the Dutch beam trawling sector

Buyvoets, E.

Helmond, A.T.M., van

Marlen, B., van

Dutch

Het tegengaan van vermeende negatieve ecosysteemeffecten van vistuigen, vooral boomkorren, is een belangrijk doel van het huidige visserijbeleid. Een van deze effecten is de weggooi (EN: ‘discards’) van ondermaatse vis (vooral schol) te verminderen. Daarnaast neemt de bereidheid bij consumenten en de vishandel af om producten af te nemen uit visserijen met een intensieve bodemberoering. De kottersector heeft deze signalen opgepakt en is zich terdege bewust van het belang aan deze maatschappelijke kritiek tegemoet te komen. Gefinancierd door Productschap Vis is door IMARES een project opgezet onder de titel: “Vermindering ‘discards’ in de kottervisserij door technische aanpassingen van de netten (VDTN)”, met als doel door netaanpassingen de hoeveelheid ‘discards’ in de boomkorvisserij te verminderen.Experiments were carried out in 2007 and 2008 on discard reducing techniques in flatfish beam trawling onboard FRV “Tridens” in close cooperation with the fishing industry. A total of 38 gear tests were conducted in which modified beam trawls were compared in pair with a conventional 12 m beam trawl. The modifications consisted of a T90 aft part and various Square Mesh Panels (SMPs) in the bottom sheet, top sheet and combinations of both, and variations of a Benthos Release Hole with a guiding V-panel in the bottom sheet. It was found that a panel in the bottom sheet with 160 mm mesh size appeared to perform best without releasing too many marketable fish. The panel should extend relatively far aft just in front of the codend here the netting is offground. Panels placed only in the top sheet are not very suitable in reducing benthos ycatches. In addition the Benthos Release Hole with guiding device seems to be effective in reducing such bycatches. The cooperation between fishermen and scientists worked very well and created better mutual understanding. Further work is advocated to optimise the design of these devices. It is expected that such devices will get wider application in the Dutch beam trawling sector

Name not available

Reduction of discards by technical modifications of beam trawls

Wageningen Yield 

69 Report number C003/09 Haul Gear test Date P gear test S gear control Objective

69 Report number C003/09 Table 11: Summary of trials in week 22,

Catch comparison of a 12 m pulse beam trawl with a conventional tickler chain beam trawl. RIVO-Report C043b/05

Catch comparison of a prototype 7 m electrical beam trawl and a conventional tickler chain beam trawl. RIVO internal report 99.006b,

Experiments in 1999 on a 7 m beam trawl with electrical stimulation. RIVO-report C028/01,

Figure 10: Comparison of discard fish – trials

Figure 11: Comparison of discard fish – trials

Figure 12: Comparison of discard fish – trials

Figure 13: Comparison of sole < MLS – trials

Figure 14: Comparison of sole < MLS – trials

Figure 15: Comparison of sole < MLS – trials

Figure 16: Comparison of plaice < MLS – trials

Figure 17: Comparison of plaice < MLS – trials

Figure 18: Comparison of plaice < MLS – trials

Figure 19: Comparison of benthos – trials

Figure 20: Comparison of benthos – trials

Figure 21: Comparison of benthos – trials

Figure 25: Comparison of sole > MLS – trials

Figure 26: Comparison of sole > MLS – trials

Figure 27: Comparison of sole > MLS – trials

Figure 28: Comparison of plaice > MLS – trials

Figure 29: Comparison of plaice > MLS – trials

Figure 31: Comparison of gross earnings – trials

Figure 32: Comparison of gross earnings – trials

Figure 33: Comparison of gross earnings – trials

Figure 34: Comparison of earnings from sole catches – trials

Figure 35: Comparison of earnings from sole catches – trials

Figure 36: Comparison of earnings from sole catches – trials

Figure 37: Comparison of earnings from plaice catches – trials

Figure 38: Comparison of earnings from plaice catches – trials

Figure 39: Comparison of earnings from plaice catches – trials

Figure 5: Positions fished in 2007(Period 1) and

Figure 6: Net drawing of conventional gear 52 of 69 Report number C003/09 Total bycatch weight

Figure 7: Comparison of total bycatch weight – trials

Figure 8: Comparison of total bycatch weight – trials

Figure 9: Comparison of total bycatch weight – trials

Length/weight relationships for 88 species of fish encountered in the North East Atlantic.

Mortality in megafaunal benthic populations caused by trawl fisheries on the Dutch continental shelf in the North Sea.

Performance of pulse trawling compared to conventional beam trawling. RIVO-report Nr.

Period 1 (MOD = modified gear; CON = conventional gear) 60 of 69 Report number C003/09

Period 2 (MOD = modified gear;

Period 3 (MOD = modified gear; CON = conventional gear) Report number C003/09 61 of 69 sole

Reducing the benthos by-catch in flatfish beam trawling by means of technical modifications.

Report number C003/09 29 of 69 Haul Gear test Date P gear test S gear control Objective

Report number C003/09 31 of 69 Haul Gear test Date P gear test S gear control Objective

Report of the Working Group on Ecosystem Effects of Fishing Activities.

Research on by-catch reduction in a beam trawl (Onderzoek naar vermindering van de bijvangst van een boomkortuig). RIVO Rapport C030/05.

T90 Std Comparison T90 with standard net, both with 90 mm cod-ends. Some loss of marketable sole, few losses in undersized sole, and plaice (also marketable), clear reduction in benthos catch

Table 10: Summary of trials in week 21,

Table 12: Summary of trials in week 45,

Table 13: Summary of trials in week 50,

Table 14: CPUE for total bycatches – experiments Period 1,

Table 15: CPUE for total bycatches – experiments Period 2,

Table 16: CPUE for total bycatches – experiments Period 3,

Table 17: CPUE for discard fish – experiments Period 1,

Table 18: CPUE for discard fish – experiments Period 2,

Table 19: CPUE for discard fish – experiments Period 3,

Table 20: CPUE for sole < MLS – experiments Period 1,

Table 21: CPUE for sole < MLS – experiments Period 2,

Table 22: CPUE for sole < MLS – experiments Period 3,

Table 23: CPUE for plaice < MLS – experiments Period 1,

Table 24: CPUE for plaice < MLS – experiments Period 2,

Table 25: CPUE for plaice < MLS – experiments Period 3,

Table 26: CPUE for benthos – experiments Period 1,

Table 27: CPUE for benthos – experiments Period 2,

Table 28: CPUE for benthos – experiments Period 3,

Table 29: CPUE for landings – experiments Period 1,

Table 30: CPUE for landings – experiments Period 2,

Table 31: CPUE for landings – experiments Period 3,

Table 32: CPUE for sole > MLS – experiments Period 1,

Table 33: CPUE for sole > MLS – experiments Period 2,

Table 34: CPUE for sole > MLS – experiments Period 3,

Table 35: CPUE for plaice > MLS – experiments Period 1,

Table 36: CPUE for plaice > MLS – experiments Period 2,

Table 37: CPUE for plaice > MLS – experiments Period 3,

Table 38: Total Gross Earnings per hour – experiments Period 1,

Table 39: Total Gross Earnings per hour – experiments Period 2,

Table 40: Total Gross Earnings per hour – experiments Period 3,

Table 41: Gross Earnings on sole – experiments Period 1,

Table 42: Gross Earnings on sole – experiments Period 2,

Table 43: Gross Earnings on sole – experiments Period 3,

Table 44: Gross Earnings on plaice – experiments Period 1,

Table 45: Gross Earnings on plaice – experiments Period 2,

Table 46: Gross Earnings on plaice – experiments Period 3,

Table 47: Average price in € per kg in various market grades (year 2007), used in the economic calculations (source:

Table 7: Summary of trials in week 44,

Table 8: Summary of trials in week 45,

Table 9: Summary of trials in week 49,

Technical modifications to reduce the by-catches and impacts of bottom gears on non-target species and habitats. In: Kaiser,

The capacity of benthos release panels to reduce the impacts of beam trawls on benthic communities.

The effects of different types of fisheries on the North sea and Irish sea benthic ecosystems. EU-project AIR2-CT94-1664 (IMPACT-II),

The effects of fishing on marine ecosystems.

Vissen met tegenwind, Advies Task Force Duurzame Noordzeevisserij,

Reduction of discards by technical modifications of beam trawls

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