Atlantic mackerel and horse mackerel egg survey: Dutch participation May and June 2010

Every three years an international Atlantic survey is carried out by different European institutes to monitor the spatial and seasonal distribution of Atlantic mackerel and horse mackerel. During this survey mackerel and horse mackerel eggs are sampled using a plankton torpedo or bongo nets. The survey covers the whole spawning area and season. It starts along the Portuguese coast in February and continues until July when the waters west of Scotland are sampled. The mackerel and horse mackerel egg survey is coordinated by the ICES working group for mackerel and horse mackerel egg surveys (WGMEGS). England and France started the egg survey in the western area in 1977. The Netherlands participates since 1983. Nowadays participating countries and sampling area have expanded. In 2010 the following countries participated in this survey: Faeröer Islands, Germany, Iceland, Ireland, Norway, Portugal, Scotland, Spain and The Netherlands

KB WOT Fisheries 2018: maintaining excellence and innovation in fisheries research

The KB WOT Fisheries programme is developed to maintain and develop expertise needed to carry out the Dutch statutory obligations in fisheries monitoring and advice. The KB WOT Fisheries programme developed for 2018 reflects the scientific and management needs of the WOT fisheries programme. The strength of KB WOT Fisheries lies in the top-down development of the programme while allowing bottomup input, with calls for proposals, to ensure innovation and improvement. To avoid missing research priorities relevant to WOT and LNV needs, the programme is built from a closed call for proposals to WOT Fisheries project leaders. But these WOT project leaders are requested to seek input from other Wageningen Marine Research scientists to ensure innovation. The KB WOT Fisheries programme will fund 17 projects in 2018 which will focus on monitoring and remote sensing of (shell) fish in marine and freshwater ecosystems, new methods and tools for surveys, discard and catch sampling and investigating the effects of fisheries. International exchange of new expertise and developments, as well as continuous quality assurance (for collecting, storage and analyses of data), forms a major part of the programm

Haringlarvensurveys seizoen 2008-2009: reisverslagen en resulaten

In de periode september 2008 tot en met januari 2009 zijn er door IMARES drie haringlarvensurveys uitgevoerd met de Tridens. In september zijn het Buchan gebied en centrale Noordzee bemonsterd en in december en januari de zuidelijke Noordzee en het oostelijk Kanaal. De weersomstandigheden tijdens de surveys waren, met uitzondering van de januari reis, goed. Tijdens alle reizen is er een goede verspreide bemonstering van het gehele gebied gewees

Atlantic mackerel and Horse mackerel egg survey 2016: Dutch participation on board FV Atlantic Lady: May

From 10 till 25 May 2016 IMARES carried out a mackerel and horse mackerel egg survey on board the FV Atlantic Lady. This survey was part of the international mackerel and horse mackerel egg survey coordinated by ICES. The Redersvereniging voor de Zeevisserij (RVZ) asked IMARES to carry out this survey. Numbers of mackerel eggs in the samples were low, lower compared to previous surveys. Most mackerel eggs were found along the 200m depth contour of the continental slope. Most of the adult mackerel had running or newly developing (in between batches) gonads. Few mackerel had gonads which were spent. Numbers of horse mackerel eggs were extremely low. A few horse mackerel eggs were found along the 200m depth contour on the most southern transects. Adult horse mackerel caught had running or newly developing gonads

Don’t put all your eggs in one basket! : reproductive strategies and fecundity regulation in temperate marine teleosts

In fisheries management the spawning stock biomass (SSB) is an important indicator of the status of exploited fish stocks. Knowledge on the reproductive biology is essential to estimate SSB. A large variety of reproductive strategies is found. In marine fish two extreme strategies are known, capital spawners which have a determinate fecundity (no de novo oocyte recruitment during spawning), and income spawners which have an indeterminate fecundity (de novo oocyte recruitment during spawning). In this thesis fecundity regulating mechanisms are studied in commercial fish species with contrasting life history. In capital spawning plaice Pleuronectes platessa and herring Clupea harengus , which spawn in autumn and/or winter, oocyte maturation starts around April when daylight length increases. Both species recruit a high number of oocytes which are down-regulated in the course of time in relation to the available energy. After the summer feeding period, when energy levels are highest, plaice shows a second recruitment phase. In herring, no difference was observed in the oocyte development between autumn and winter spawners, although winter spawners continue developing oocytes and spawn fewer but larger eggs. The income breeding horse mackerel Trachurus trachurus utilises food resources during spawning although the first batch of spawned eggs is developed on stored energy. Food availability, through the body condition, is the most important factor regulating fecundity. In situations where food is available during the spawning season traditional determinate spawners may switch to a pseudo-indeterminate fecundity style. In conclusion this thesis shows that fecundity type of marine fish females is not fixed at the species level but represents a plastic response to the environment through food availability and energy allocation.</p

Atlantic mackerel and horse mackerel egg survey 2013: Dutch participation

In 2013 the international Atlantic mackerel and horse mackerel egg survey was performed. This year the entire spawning area was sampled by 10 institutes from 9 different countries: Faeröer Islands, Germany, Iceland, Ireland, Norway, Portugal, Scotland, Spain and The Netherlands. Sampling started in February along the Portuguese coast and continued until July west of Scotland. The Dutch institute IMARES participated in the survey in May and June on board ‘RV Tridens’. IMARES covered the area of the Northern Bay of Biscay and Southern Celtic Sea once each month

PMR Monitoring natuurcompensatie Voordelta. Perceel Vis: Jaarrapport 2009

In juni 2008 is in de Voordelta een Bodembeschermingsgebied ingesteld als compensatie voor de aanleg van de Tweede Maasvlakte. Naar verwachting zal de instelling van dit gebied leiden tot een toename van het benthos ter plaatse. De doelstelling van het onderzoek is vast te stellen welke veranderingen er in de periode 2009-2013 zullen optreden in de visgemeenschap. In deze rapportage worden bevindingen gepresenteerd van de eerste bemonsteringen na de instelling van het Bodembeschermingsgebied, in het voorjaar en late zomer van 2009

North Sea mackerel egg survey: dutch participation may and June 2011

Every three years an international North Sea survey is carried out by two European institutes, Institute for Marine Research (IMR) from Norway and Institute for Marine Resources and Ecosystem Studies (IMARES) from the Netherlands, to monitor the spatial and seasonal distribution of North Sea mackerel. In 2011 the North Sea mackerel egg survey was performed. The entire spawning area was sampled by IMR, Norway and IMARES, The Netherlands. The whole spawning area was sampled three times. IMARES covered the complete sampling area in the first period, in the second period IMR covered the northern part and IMARES the southern part of the spawning area. The third period the whole spawning area was covered by IMR. In total 190 ichthyoplankton samples were taken with a Gulf VII plankton torpedo with a Seabird CTD mounted on top. Additionally, adult fish samples for the estimation of fecundity and atresia were taken using a pelagic trawl. The survey was successful and IMARES managed to sample all but 3 of the planned stations. Numbers of mackerel eggs found in the samples were comparable to 2008. Total mackerel egg production in 2011 was 116*1012 and Spawning Stock Biomass (SSB) was estimated at 165*103 tons, which is slightly higher compared to 2008. Highest egg production was found in the first sampling week and it is possible that the beginning of mackerel spawning is missed

Review of the spatial and temporal distribution by life stage for 19 North Sea fish species

Considering the increase in human activity in the North Sea, particularly cargo shipping and the rapidly expanding construction and operation of oil platforms and wind farms, as well as the continued use of the area for military purposes, fisheries and sand extraction, there is a growing concern about the potentially harmful impacts of such anthropogenic activities on marine life. Particular concerns have been raised about the effect of loud impulse sounds and high noise levels, which may affect marine animal life in different ways: habitat use, such as feeding and migration, and reproduction patterns may be disturbed. In the extreme case animals may suffer from sub-lethal or lethal physical damage such as hearing loss and disrupted swim ladders. Knowledge of the spatial distribution and seasonal patterns in the presence of different life stages of marine species is therefore critical for assessing to what extent the dispersion of marine life overlaps with the distribution of human activities and for estimating how potentially harmful impacts can be mitigated both spatially and temporally. The aim of this desk study is consequently to provide a concise overview of existing information on seasonal patterns in the dispersion of fish species in the North Sea, in particular by highlighting the knowledge gaps