Overview of the Dutch recreational fisheries for ICES WGSMRF 2009

The new European Union commission decision of 6 November 2008 adopts a multiannual Community programme pursuant to Council Regulation (EC) No 199/2008 establishing a Community framework for the collection, management and use of data in the fisheries sector and support for scientific advice regarding the common fisheries policy (2008/949/EC). This programme includes the collection of data for recreational fisheries

Use of high resolution sonar for near-turbine fish observations (DIDSON) - We@Sea 2007-002

In this study we investigate small scale distribution of pelagic fish within a windfarm by means of a high resolution sonar (DIDSON, Dual frequency IDentification SONar; Soundmetrics). In addition we assess the bias of small scale variations induced by the effects of wind turbines (monopiles) on distribution of the pelagic fish community in the hydro acoustic surveys carried out on the OWEZ Near Shore Wind farm (NSW)

Trekgedrag van schieraal rondom het Zaangemaal in Zaandam. DIDSON metingen

Het Zaangemaal is één van de twee gemalen, die het belangrijkste boezemsysteem van Hollands Noorderkwartier, de Schermerboezem, bemalen. Parallel aan het gemaal ligt een historisch sluisje, welke mogelijk gebruikt kan worden om aal voor het gemaal op te vangen en door het sluisje langs het gemaal te sturen, om op deze manier schade aan vis te voorkomen. Dit onderzoek maakt onderdeel uit van een proef van het Hoogheemraadschap om te onderzoeken of vismigratie via deze historische sluis kan worden omgeleid langs het gemaal. Met behulp van de akoestische camera DIDSON is tijdens twee dagen gemeten of schieraal intrekt in dit historische sluisje in Zaandam

Session C5: Behavioural Patterns of Migrating Silver Eel at a Hydro Power Station in the River Meuse

Abstract: In order to provide efficient downstream passage for migrating silver eel and to reduce mortality or obstruction rates at barriers, a better understanding of behavioural patterns for migrating silver eels is necessary. To study behavioural patterns of downstream migrating silver eels which are confronted with a hydropower station – weir – ship lock complex in the river Meuse a telemetry experiment was performed. This study used four detection stations (NedapTrail-System®) covering the river bed, two stations up and downstream the HPS, two stations up and downstream the weir and two stations in separated fishways. In all, 148 silver eels were surgically implanted with Nedap-transponders in 2010. 121 eels continued migration showing a great variety of individual behavioural patterns. The majority, 68%, of the eels passed through the turbines either immediately or after recurrence or avoidance behaviour, 15% eels migrated over the weir and it was assumed that 14% of the eels migrated using shiplocks either directly or after returning behaviour at the hydropower station complex. A great number of silver eels (36-38%) approaching the hydropower station (HPS) – weir complex, did not follow the current of the river and were firstly detected at the weir while all the water was guided through the turbines. This suggests either an active avoidance behaviour at a greater distance independent to river discharge or a passive behavioural result of eels that could not detect the main current near the complex. Other eel showed immediate passage (32%) or hesitated to pass the complex or turned around after presumably following the river flow (29-31%)

Gedrag van schieraal rond een viswering met stroboscooplampen bij gemaal IJmuiden. DIDSON metingen

Om de sterfte van uittrekkende schieraal in het gemaal van IJmuiden in het Noordzeekanaal te verminderen heeft Rijkswaterstaat Noord-Holland een meerjarig en multidisciplinair onderzoek uitgezet om effectieve maatregelen te kunnen nemen en te testen op effectiviteit

Silver eel mortality during downstream migration in the Meuse: comparing telemetry study 2010-2012 to 2002-2006

During the descend to sea, silver eel face different hazards causing migration delay or mortality (e.g. dams, hydropower stations (HPS), weirs, ship locks, fisheries, predation). In 2010 fisheries was closed from September – November 30th and from April 1th 2011 the commercial eel fisheries in the river Meuse was closed for a undetermined period, due to dioxin pollution. To compare general mortality percentages with earlier studies (2002 and 2004), additional telemetry studies were carried out in 2010 and 2011. Compared to earlier studies more detection stations were used to estimate the mortality of the migration silver eel. This report attempts to answer two research questions: 1) Did the closure of the fisheries starting in 2010 result in a lower mortality rate for downstream migrating silver eel in the Meuse compared to previous studies in 2002-2006? 2)What is the delayed and direct Hydro power station (HPS) mortality for migrating silver eel in the Meuse during 2010-2012? In 2010 a batch of 150 female silver eel with surgically implanted transponders was released in the river Meuse and they could be followed with an array of detection stations of the Nedap TrailTM System. From the detection data mortality estimations were obtained. The present report is restricted to analysing migration routes and mortality estimations for the batch released in 2010. In accordance with the methodology used in 2002 (16 – 26% mortality) and 2004 (25 – 34% mortality) there was no big difference found in mortality estimations in 2010 (13 – 26% mortality). A comparison between the methodology used in previous studies (13 – 26% mortality) and new mortality estimations using more detection stations (22-25%) suggests that a more precise mortality estimation must be found in the upper limits of the mortality ranges derived from previous studies. Based on telemetry we found a minimum percentage of delayed and direct mortality of at least 20% of the migrating batch (121 eel). This percentage was corrected for other factors causing mortality (e.g. natural mortality, disease, predation etc.)

Bemonsteringsplan de Zandmotor : werkplan maart 2012

Tussen maart 2011 en oktober 2011 hebben Rijkswaterstaat en de provincie Zuid Holland bij Kijkduin een schiereiland in de vorm van een haak aangelegd, de Zandmotor. Het schiereiland steekt één kilometer ver in zee en is langs de strandkant twee kilometer breed. Bij aanleg was de oppervlakte 128 hectare. De Zandmotor is een pilotproject en de ontwikkeling van de Zandmotor zal worden gevolgd, zowel de verspreiding van het zand, als ontwikkelingen in flora en fauna rond de Zandmotor. Door wind, golven en stroming verspreidt het zand van de Zandmotor zich langs de kust tussen Hoek van Holland en Scheveningen, waardoor dit deel van kust op “natuurlijke wijze” aan zal groeien

Jaarrapportage Passieve Vismonitoring Zoete Rijkswateren: fuik- en zalmsteekregistraties in 2009

In dit rapport worden de gegevens van de passieve monitoring van de visstand in de zoete rijkswateren, die in 2009 zijn verzameld, gepresenteerd. Voor de passieve monitoring wordt op 29 locaties, normaliter in de periode april tot en met november, door beroepsvissers hun vangst op twee manieren geregistreerd. Sinds 1993 wordt een vangstregistratie van de commerciële fuikenvisserij op aal bijgehouden. Naast de doelsoort aal worden ook van de bijgevangen vissoorten de aantallen en lengtes geregistreerd