Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Monitoring cod catches of the Dutch demersal fleet in 2016
    Hal, R. van; Machiels, M.A.M. - \ 2017
    IJmuiden : Wageningen Marine Research (Wageningen Marine Research Report C056/17) - 29
    monitoring - cod - beam trawling - pulse trawling - demersal fisheries - marine fisheries - fish catches - north sea - gadus morhua - monitoring - kabeljauw - boomkorvisserij - pulsvisserij - demersale visserij - zeevisserij - visvangsten - noordzee - gadus morhua
    This report presents the results of the cod monitoring program 2016. The research was commissioned by the Dutch Ministry of Economic Affairs within the EZ-program Beleidsondersteunend Onderzoek. Cod catches of the vessels in the fleet segments BT2 (beam trawl and pulse trawl) and TR (otter trawls and seines) need to be monitored yearly, due to the Dutch implementation of the European cod recovery plan. The European cod recovery plan restricts the fishing effort of European fleets catching cod. Fishing effort, based on historical track records, is allocated to different gear groups. Fishing effort can be transferred between gear groups by use of conversion factors. In the Netherlands fishing effort is transferred yearly from the BT2 gear group to the TR group, based on a national conversion factor of 1:3 (BT:TR) kWdays instead of the European conversion factor of 1:16. This is because the cod catches in the Dutch TR fleet are not as high as the European conversion factor implies. In order to substantiate for the national conversion factor, the Dutch government is obliged to report cod catches per unit of effort (CpUE) of the vessels in these gear groups to the European Commission. An overview is provided of the fishing activity, the cod landings and the cod landings per unit of effort of the various gear categories in the BT2 and the TR fleet segments during the year 2016. First the cod Catch per Unit of Effort (CpUE) transition ratio between the BT2 on the one hand and the TR1C plus TR2 fleet segments on the other hand was calculated. And secondly the percentage of cod avoidance trips – trips during which 5% or less cod was caught – in the TR-fleet were calculated. The TR fleet has a higher cod CpUE on average than the BT fleet. When the cod targeted fisheries (TR1AB) are not taken into account, the CpUE effort transition ratio (TR1C+TR2): BT2 of 2016 lies between 4.2:1 and 5.7:1, depending on whether the ratio is calculated on the basis of minimum or maximum cod discards estimation by the Scientific, Technical and Economic Committee for Fisheries (STECF) respectively whereby in the minimum calculation the vessels participating in the CCTV program are excluded. Based on average discards estimations including all vessels, the ratio is 5.1:1. The percentage of cod avoidance trips, fishing trips with 5% cod or less in the total catches, in the TR1C and the TR2 fleets were 94% and 96% in 2016 respectively. These percentages are based on average STECF cod discards estimations. When minimum or maximum discards estimations are used, the calculated percentages of cod avoidance trips does not vary more than 2 or 3% from the percentage based on average estimations.
    Monitoring cod catches of the Dutch demersal fleet in 2015
    Trapman, B.K. ; Machiels, M.A.M. - \ 2016
    IJmuiden : Wageningen Marine Research (Wageningen Marine Research rapport C106/16) - 30
    cod - fisheries - fish catches - monitoring - demersal fisheries - netherlands - kabeljauw - visserij - visvangsten - monitoring - demersale visserij - nederland
    Fishing over the sides or over the stern: does it matter : comparison of two fishing methodologies in the Wadden Sea Demersal Fish Survey
    Chen, C. ; Bolle, L.J. ; Boois I.J. de, Ingeborg - \ 2016
    IJmuiden : Wageningen Marine Research (Wageningen Marine Research report C122/16) - 27
    fisheries - fishing methods - fishing gear - demersal fisheries - wadden sea - visserij - vismethoden - vistuig - demersale visserij - waddenzee
    Since 1972, the Demersal Fish Survey (DFS) in the Wadden Sea has been carried out with the RV Stern. Within a few years this vessel will be replaced by another vessel as a result of the current ship replacement policy of Rijkswaterstaat Rijksrederij. It is not yet clear which vessel will replace RV Stern. In the search for a new vessel the main question is if fishing over the sides is needed, or if fishing over the stern is possible without a major effect on catch efficiency. Especially in shallow waters, catch efficiency may be affected by fishing over the stern, because of the current created by the ship’s propeller. To be able to continue the use of the long and valuable time-series the shift in vessel should not lead to a different gear efficiency.
    Monitoring cod catches of the Dutch demersal fleet in 2014 : Investigating the effects of season and fishing gear on cod landings
    Reijden, K.J. van der; Machiels, M.A.M. ; Trapman, B.K. ; Kraan, M.L. - \ 2016
    IMARES (Report / IMARES C010/16) - 68
    cod - fish catches - monitoring - demersal fisheries - fishing gear - kabeljauw - visvangsten - monitoring - demersale visserij - vistuig
    In this report the results of the cod monitoring program are presented. This research was commissioned by the Dutch Ministry of Economic Affairs. Cod catches of the vessels in the gear groups BT2 (beam trawl) and TR (otter trawls and seines) need to be monitored yearly, due to the Dutch implementation of the European cod recovery plan. The European cod recovery plan restricts fishing efforts of European fleets that catch cod. Fishing effort, based on historical track records, is allocated to different gear groups. Fishing effort can be transferred between gear groups but then conversion factors apply. In the Netherlands fishing effort is transferred yearly from the BT2 gear group to the TR group, based on a national conversion factor of 1:3 (BT:TR) kWdays instead of the European conversion factor of 1:16, because the cod catches in the Dutch TR fleet are not as high as the European conversion factor implies. In order to substantiate for the national conversion factor, the Dutch government is obliged to report cod catches per unit of effort (CpUE) of the vessels in these gear groups to the European Commission.
    Voorbereiding van de pulsmonitoring: Vaststellen omvang van bemonsteringsprogramma
    Reijden, K.J. van der; Hintzen, N.T. - \ 2015
    IMARES (Rapport / IMARES C074/15) - 19
    pulsvisserij - demersale visserij - visserij - monitoring - bemonsteren - pulse trawling - demersal fisheries - fisheries - monitoring - sampling
    VIP Rapportage "Steekproef schattingen demersale discards aan boord" : Rapportage Validering en opwerking uitkomsten project "demersale discardverwerking"
    Verkempynck, R. ; Machiels, M.A.M. - \ 2015
    IJmuiden : IMARES (Rapport / IMARES C166/15) - 23
    discards - quota's - visserij - demersale visserij - demersale vissen - discards - quotas - fisheries - demersal fisheries - demersal fishes
    Onder de aanlandplicht zullen de discards met het quotum verrekend worden. Daarom is het nodig om het totale gewicht en de samenstelling van de discards te bepalen. In dit rapport worden drie scenario’s voorgesteld waarbij het totale gewicht en de samenstelling van vijf soorten in de discards (schol, tong, roggen, wijting en schar) geschat moet worden voor het boomkorsegment.
    Consequences of discard survival under the landing obligation : Reporting validation and reprocessing project outcomes of "demersal discard processing"
    Verkempynck, R. ; Machiels, M.A.M. - \ 2015
    IJmuiden : IMARES (Report / IMARES C176/15) - 16
    discards - bycatch - demersal fisheries - demersal fishes - survival - solea - plaice - discards - bijvangst - demersale visserij - demersale vissen - overleving - solea - schol
    This report describes the results of a short and medium term forecast over the period 2016-2019 given different scenarios of discard survival rates (10-50%) of North Sea plaice and North Sea sole. Additionally, average value of landings over the year 2019 is calculated per scenario using the landings derived from the biomass and the average price per kg of both stocks. Potential loss in average gross revenue from value of landings can be inferred from these.
    Update of "Delineating catch quotas for Dutch demersal fisheries: a theoretical pilot study"
    Poos, J.J. - \ 2015
    IJmuiden : IMARES (Report / IMARES C139/15) - 19
    demersal fisheries - fish catches - quotas - netherlands - demersale visserij - visvangsten - quota - nederland
    A reduction of unwanted catches is a key element of the Common Fisheries Policy reform proposal (EC, 2010). To achieve this, a landing obligation (or discard ban) will be introduced, prohibiting the at-sea disposal of quota-regulated species. Instead these catches shall be brought back to shore and counted against a quota, where applicable. In 2014, upon request by the ministry, more clarity was sought on how catch quotas could be calculated and what they would look like for the most relevant fish species of the Dutch demersal fishery . The report of that study (Miller et al. 2014) provided an overview of total allowable catch allocations (TAC), national quota, landings and discards statistics for some of the most-relevant quota-regulated species caught by the Dutch demersal fleet. A number of scenarios of how the new catch quotas could be calculated were presented. The theoretical implications of these alternative scenarios for the Dutch fleet were described under the assumption of no change in relative stability. In 2015, the Ministry of Economic Affairs requested an update of Miller et al. (2014), and this report is the result of that update.
    Teveel tong verspeeld, zoektocht gaat verder: IMARES presenteert tussentijdse resultaten project Netinnovatie kottervisserij (interview met Pieke Molenaar)
    Molenaar, P. - \ 2015
    Visserijnieuws 35 (2015)37. - ISSN 1380-5061 - p. 3 - 3.
    zeevisserij - tong (vis) - innovaties - vistuig - demersale visserij - visserijbeheer - marine fisheries - dover soles - innovations - fishing gear - demersal fisheries - fishery management
    Nederlandse kottervissers halen alles uit de kast om selectiever te vissen en zo met het oog op de aanlandplicht discards te sparen. Maar uit de praktijkproeven blijkt dat scheidingspanelen ook een verlies van zo'n tien procent van de tongvangst te betekenen. De zoektocht gaat verder.
    Dutch demersal fisheries
    Turenhout, Mike - \ 2015
    demersal fisheries - netherlands - pelagic fishery - mussel culture - oysters - shellfish fisheries - fishing vessels - fishing methods
    Socio-economic impact of landing obligation for the Dutch demersal fisheries
    Turenhout, Mike - \ 2015
    demersal fisheries - socioeconomics - economic impact - social impact - netherlands - landings
    Aanbodanalyse discards demersale visserij
    Goudswaard, P.C. ; Reijden, K.J. van der; Verkempynck, R. ; Poelman, M. - \ 2015
    IJmuiden : IMARES Wageningen UR (Rapport / IMARES Wageningen UR C100/15) - 24
    demersale visserij - waardeketenanalyse - discards - bijproducten - vangstsamenstelling - bijvangst - demersal fisheries - value chain analysis - discards - byproducts - catch composition - bycatch
    De aanlandplicht betekent een serieuze verandering voor de demersale visserij. Mogelijkheden voor verwerking en gebruik van discards zijn te vinden in verschillende (bestaande en nog te ontwikkelen) afzetmarkten en sectoren. Dit rapport bevat een aanbodanalyse die een inschatting kan geven van de te verwachten discards die in de Nederlandse havens aangeland gaan worden. Hiermee wordt een eerste stap gezet naar het inzichtelijk maken van de data die nodig is om toekomstige ketenmogelijkheden te ontwikkelen.
    De samenstelling van discards in de demersale visserij voor valorisatie doeleinden
    Kals, J. ; Poelman, M. ; Goudswaard, P.C. - \ 2015
    IJmuiden : IMARES Wageningen UR (Rapport / IMARES Wageningen UR C099/15) - 27
    demersale visserij - discards - bijvangst - bijproducten - vercommercialisering - vangstsamenstelling - visvangsten - eu regelingen - voedingswaarde - visproducten - demersal fisheries - discards - bycatch - byproducts - commercialization - catch composition - fish catches - eu regulations - nutritive value - fish products
    Vanaf januari 2016 wordt de discard regelgeving vanuit de EU aangepast. Dit betekent dat de sector zich moet committeren aan deze regelgeving. Hierdoor zullen de niet gewenste vangsten die op dit moment nog overboord gaan, aangeland moeten worden. Er is een traject ingezet om de kansen tot valorisatie van de discards te ontwikkelen. In een separaat traject is bepaald welke hoeveelheden van soorten er vanaf 1 januari 2016 vanuit de demersale visserij zullen worden aangeland. In voorliggend technisch rapport wordt deze analyse verder vormgegeven door een beschrijving te geven van de nutritionele waarde van de discards.
    Vallen en opstaan: update overlevingsprojecten ILVO en IMARES (interview met Karin van der Reijden)
    Reijden, K.J. van der - \ 2015
    Visserijnieuws 35 (2015)17. - ISSN 1380-5061 - p. 5 - 5.
    visserijbeleid - visserijbeheer - discards - zeevisserij - wetgeving - eu regelingen - visserij - mortaliteit - visstand - demersale visserij - dierenwelzijn - diergezondheid - fishery policy - fishery management - discards - marine fisheries - legislation - eu regulations - fisheries - mortality - fish stocks - demersal fisheries - animal welfare - animal health
    De Europese aanlandplicht is een feit. De visserijsector vreest een negatieve invloed op de bestanden door een hogere vissterfte. In de wetgeving is een uitzonderingsmaatregel voor de discardban opgenomen als vis een hoge overlevingskans heeft. Zowel in Nederland als België wordt daarom in de kottervisserij wetenschappelijk onderzocht hoe groot de overlevingskansen van gevangen vis zijn. Karin van der Reijden (WUR - IMARES) en Ruben Theunynck (ILVO) geven inzicht in de stand van zaken.
    Waardekaarten van: Outer Thames Estuary, Haisborough, Hammond and Winterton & Margate and Long Sands
    Machiels, M.A.M. - \ 2015
    IJmuiden : IMARES (Rapport / IMARES Wageningen UR C054/15) - 16
    vissersschepen - engeland - kustwateren - kaarten - taxatie - demersale visserij - schol - tong (vis) - tarbot - raja - fishing vessels - england - coastal water - maps - valuation - demersal fisheries - plaice - dover soles - turbot - raja
    Dit rapport is geschreven in opdracht van VisNed. IMARES is gevraagd om waardekaarten en tabellen te leveren van alle bodem beroerende Nederlandse visserijschepen binnen de gebieden 1) Haisborough, Hammond and Winterton, 2) Margate and Long Sands voor de Engelse kust en 3) Outer Thames Estuary.
    North Sea submarine cable disruptions and fishing activity
    Hintzen, N.T. ; Machiels, M.A.M. - \ 2014
    IJmuiden : IMARES Wageningen UR (Report / IMARES Wageningen UR C117/14-A) - 26
    noordzee - telecommunicatie - kabels - demersale visserij - boomkorvisserij - energiebesparing - innovaties - vistuig - north sea - telecommunications - cables - demersal fisheries - beam trawling - energy saving - innovations - fishing gear
    At the North Sea seafloor, numerous submarine cables are positioned that connect telecommunication networks between countries. Worldwide, human activities cause most of the cable disruptions with fisheries accounting for nearly half of all reported faults. Due to a recent increase of submarine cable disruptions in the central North Sea area, Global Marine Systems Ltd. requested IMARES to investigate a possible link between these occurrences and the recent gear switch of the Dutch –demersal beam-trawlfishing fleet.
    Discard self-sampling of Dutch bottom-trawl and seine fisheries in 2013
    Reijden, K.J. van der; Verkempynck, R. ; Nijman, R.R. ; Uhlmann, S.S. ; Helmond, A.T.M. van; Coers, A. - \ 2014
    IJmuiden : Centrum voor Visserijonderzoek (Report / CVO Wageningen UR 14.007) - 74
    discards - demersale visserij - noordzee - visvangsten - visbestand - bemonsteren - eu regelingen - gegevens verzamelen - discards - demersal fisheries - north sea - fish catches - fishery resources - sampling - eu regulations - data collection
    In the European Union, the collection of discard data is enforced through the Data Collection Regulation Framework (DCF) of the European Commission (EC). To comply with these requirements, IMARES coordinates a discards monitoring programme in collaboration with the Dutch fishing industry. Within this project, a ‘reference fleet’ of vessel owners, willing to participate in a self-sampling programme, has been recruited. Fishermen are requested to collect discard samples for a definite number of trips per year. After the discard samples are brought to shore, IMARES collects and analyses these samples. This report summarizes data from this monitoring programme of Dutch demersal fisheries operating in the North Sea in 2013.
    Delineating catch quotas for Dutch demersal fisheries: a theoretical pilot study
    Miller, D.C.M. ; Pastoors, M.A. ; Coers, A. ; Uhlmann, S.S. - \ 2014
    IJmuiden : IMARES (Report / IMARES Wageningen UR C081/14) - 21
    visserijbeleid - demersale visserij - quota's - bijvangst - discards - scenario-analyse - fishery policy - demersal fisheries - quotas - bycatch - discards - scenario analysis
    A reduction of unwanted catches is a key element of the Common Fisheries Policy reform proposal (EC, 2010). To achieve this, a landing obligation (or discard ban) will be introduced, prohibiting the at-sea disposal of quota-regulated species. Instead these catches shall be brought back to shore and counted against a quota, where applicable.
    Technological Development and Fisheries Management
    Eigaard, O.R. ; Marchal, P. ; Gislason, H. ; Rijnsdorp, A.D. - \ 2014
    Reviews in Fisheries Science & Aquaculture 22 (2014)2. - ISSN 2330-8249 - p. 156 - 174.
    individual transferable quotas - time-varying catchability - fishing power increases - trawl fishery - unit-effort - technical efficiency - demersal fisheries - mixed fisheries - fleet dynamics - north-sea
    Many marine fish stocks are overexploited and considerable overcapacity exists in fishing fleets worldwide. One of the reasons for the imbalance between resource availability and fishing capacity is technological development, which continuously increases the efficiency of the vessels—a mechanism referred to as “technological creep.” We review how the introduction of new and more efficient electronic equipment, gear design, engines, deck equipment, and catch-handling procedures influences the capture efficiency (catchability) of commercial fishing vessels. On average, we estimate that catchability increases by 3.2% per year due to technological developments, an increase often ignored in fisheries management. The documentation and quantification of technological creep improves the basis for successfully integrating the effects of technological development (and catchability changes) in fisheries management regulations and policies. Ways of counteracting the undesired effects of technological creep are discussed as are the potential management benefits from improved fishing technology. Specific suggestions are given on the selection, application, and tuning of fisheries management tools that can be used to improve the balance between harvesting capacity and resource availability.
    Species identification workshops 2012 and 2013: Gobies and Elasmobranchs
    Boois, I.J. de; Bolle, L.J. - \ 2013
    IJmuiden : IMARES (Report / IMARES Wageningen UR 13.009) - 16
    demersale visserij - elasmobranchii - pomatomidae - aquatische ecosystemen - identificatie - benthos - demersale vissen - demersal fisheries - elasmobranchii - pomatomidae - aquatic ecosystems - identification - benthos - demersal fishes
    Up until now, gobies of the genus Pomatoschistus have not been identified to the lowest taxonomic level during The Demersal Fish Survey (DFS), Sole Net Survey (SNS) and Beam Trawl Survey (BTS). It is however an abundant genus in the catches in the shallow coastal zone stations and it can be assumed that the species play a role in the coastal ecosystem. The correct identification on board is however questionable. For that reason, during the 2012 DFS extra attention has been paid to identification of Pomatoschistus species. On each of the three vessels carrying out the DFS, a Pomatoschistus expert (Cindy van Damme or Bram Couperus) was taken on board for one week. On board Stern and Schollevaar all Pomatoschistus have been identified to the species, and on board Isis part of the specimens were identified to the species, and part was taken to the lab. Samples were frozen following a protocol to keep the quality of the fish as good as possible and were taken back to the lab for identification. Main problems arose in identification of P. lozanoi and P. minutus. As even the experts did not agree, it is proposed to treat P. lozanoi and P. minutus as a group of species, and to identify the other species to the species level. From identification workshops and tests on demersal fish and benthos it became clear that specific attention should be paid to the elasmobranch species. On 20 March 2013 a dedicated species identification workshop focusing on elasmobranch species was organised for IMARES employees. Main purpose of the workshop was quality assurance of species identification of elasmobranch species. IMARES projects influenced by the quality of this species identification are i.a. the seagoing statutory task surveys, statutory task discard projects, PULSMON. The species to be identified were collected during the BTS2011 and BTS 2012 and stored in the freezer. Results are presented by expertise level of the employees. The expertise level was based on expertise and responsibilities during surveys and discard sampling. The results of the test and workshop were in line with earlier workshops focusing on fish and macrobenthos.
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