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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Improving accuracy of direct and maternal genetic effects in genomic evaluations using pooled boar semen: a simulation study
Maiorano, Amanda M. ; Assen, Alula ; Bijma, Piter ; Chen, Ching Yi ; Silva, Josineudson Augusto Ii Vasconcelos ; Herring, William O. ; Tsuruta, Shogo ; Misztal, Ignacy ; Lourenco, Daniela A.L. - \ 2019
Journal of Animal Science 97 (2019)8. - ISSN 0021-8812 - p. 3237 - 3245.
genomic prediction - maternal ability - multiple sire - prediction accuracy

Pooling semen of multiple boars is commonly used in swine production systems. Compared with single boar systems, this technique changes family structure creating maternal half-sib families. The aim of this simulation study was to investigate how pooling semen affects the accuracy of estimating direct and maternal effects for individual piglet birth weight, in purebred pigs. Different scenarios of pooling semen were simulated by allowing the same female to mate from 1 to 6 boars, per insemination, whereas litter size was kept constant (N = 12). In each pooled boar scenario, genomic information was used to construct either the genomic relationship matrix (G) or to reconstruct pedigree in addition to G. Genotypes were generated for 60,000 SNPs evenly distributed across 18 autosomes. From the 5 simulated generations, only animals from generations 3 to 5 were genotyped (N = 36,000). Direct and maternal true breeding values (TBV) were computed as the sum of the effects of the 1,080 QTLs. Phenotypes were constructed as the sum of direct TBV, maternal TBV, an overall mean of 1.25 kg, and a residual effect. The simulated heritabilities for direct and maternal effects were 0.056 and 0.19, respectively, and the genetic correlation between both effects was -0.25. All simulations were replicated 5 times. Variance components and direct and maternal heritability were estimated using average information REML. Predictions were computed via pedigree-based BLUP and single-step genomic BLUP (ssGBLUP). Genotyped littermates in the last generation were used for validation. Prediction accuracies were calculated as correlations between EBV and TBV for direct (accdirect) and maternal (accmat) effects. When boars were known, accdirect were 0.21 (1 boar) and 0.26 (6 boars) for BLUP, whereas for ssGBLUP, they were 0.38 (1 boar) and 0.43 (6 boars). When boars were unknown, accdirect was lower in BLUP but similar in ssGBLUP. For the scenario with known boars, accmat was 0.58 and 0.63 for 1 and 6 boars, respectively, under ssGBLUP. For unknown boars, accmat was 0.63 for 2 boars and 0.62 for 6 boars in ssGBLUP. In general, accdirect and accmat were lower in the single-boar scenario compared with pooled semen scenarios, indicating that a half-sib structure is more adequate to estimate direct and maternal effects. Using pooled semen from multiple boars can help us to improve accuracy of predicting maternal and direct effects when maternal half-sib families are larger than 2.

Brominated flame retardants in animal derived foods in the Netherlands between 2009 and 2014
Gebbink, Wouter A. ; Lee, Martijn K. van der; Peters, Ruud J.B. ; Traag, Wim A. ; Dam, Guillaume ten; Hoogenboom, Ron L.A.P. ; Leeuwen, Stefan P.J. van - \ 2019
Chemosphere 234 (2019). - ISSN 0045-6535 - p. 171 - 178.
Eggs - Fish - HBCDD - Meat - Milk - PBDE

Polybrominated diphenylethers (PBDEs), hexabromocyclododecanes (HBCDDs) and tetrabromobisphenol A (TBBPA) were monitored in various foods from terrestrial and aquatic animal origin (>850 samples), collected in the Netherlands between 2009 and 2014. The terrestrial samples included meat/fat from 7 animal species (including bovines, pigs, broilers and sheep), bovine milk and hen eggs. Dominant PBDE congeners in these samples were BDE-47, -99, -100, -153 and -183. The meat/fat generally contained the highest ∑PBDE concentrations compared to eggs and milk, with meat from deer, horse and sheep containing the highest concentrations. Generally declining ∑PBDE concentrations were observed between 2009 and 2014, however, this was only significant in pig meat and hen's eggs. The aquatic samples included fillets from 18 species (including herring, haddock and salmon), brown crab parts, shrimp and mussels, and the highest ∑PBDE concentrations were seen in body parts of brown crab, herring, mackerel, salmon and sea bass (on wet weight basis). Patterns generally contained more congeners (i.e., BDE-28, -49 and -66) additional to the aforementioned congeners found in terrestrial samples. Herring, sea bass and brown crab (body parts) contained among the highest PBDE concentrations. TBBPA was only detected in 3 individual samples (bovine and broiler meat and haddock), while α-HBCDD was the dominant diastereomer detected in several terrestrial and aquatic samples. When detected, TBBPA and HBCDD concentrations were generally in the same order as ∑PBDE concentrations in the same sample types.

Multispecies hybridization in birds
Ottenburghs, Jente - \ 2019
Avian Research 10 (2019)1. - ISSN 2053-7166
Adaptation - Admixture - Genomics - Introgression - Network analysis - Phylogenetics - Speciation

Hybridization is not always limited to two species; often multiple species are interbreeding. In birds, there are numerous examples of species that hybridize with multiple other species. The advent of genomic data provides the opportunity to investigate the ecological and evolutionary consequences of multispecies hybridization. The interactions between several hybridizing species can be depicted as a network in which the interacting species are connected by edges. Such hybrid networks can be used to identify 'hub-species' that interbreed with multiple other species. Avian examples of such 'hub-species' are Common Pheasant (Phasianus colchicus), Mallard (Anas platyrhynchos) and European Herring Gull (Larus argentatus). These networks might lead to the formulation of hypotheses, such as which connections are most likely conducive to interspecific gene flow (i.e. introgression). Hybridization does not necessarily result in introgression. Numerous statistical tests are available to infer interspecific gene flow from genetic data and the majority of these tests can be applied in a multispecies setting. Specifically, model-based approaches and phylogenetic networks are promising in the detection and characterization of multispecies introgression. It remains to be determined how common multispecies introgression in birds is and how often this process fuels adaptive changes. Moreover, the impact of multispecies hybridization on the build-up of reproductive isolation and the architecture of genomic landscapes remains elusive. For example, introgression between certain species might contribute to increased divergence and reproductive isolation between those species and other related species. In the end, a multispecies perspective on hybridization in combination with network approaches will lead to important insights into the history of life on this planet.

Occurrence of perfluoroalkyl substances (PFASs) in a large number of wild and farmed aquatic animals collected in the Netherlands
Zafeiraki, Effrosyni ; Gebbink, Wouter A. ; Hoogenboom, Ron L.A.P. ; Kotterman, Michiel ; Kwadijk, Christiaan ; Dassenakis, Emmanouil ; Leeuwen, Stefan P.J. van - \ 2019
Chemosphere 232 (2019). - ISSN 0045-6535 - p. 415 - 423.
PFOS - PFOA - eel - Fish food safety - EQS
A range of perfluoroalkyl substances (PFASs) was analysed in marine fish, farmed fish, crustaceans, bivalves and European eel caught in (mostly) Dutch waters, or purchased at Dutch markets (approximately 250 samples, collected between 2012 and 2018). ΣPFAS levels were highest in eels collected from rivers and lakes (average 43.6 ng/g and max 172 ng/g), followed by shrimps collected near the Dutch coast (average 6.7 and max. 33 ng/g ww), and seabass (average 4.5 and max. 9.4 ng/g ww). Most of the farmed fish (e.g. trout, catfish, turbot, salmon, tilapia, pangasius) were among the lowest contaminated samples in this study (averages ranged from 0.06 to 1.5 ng/g ww). Geographically, levels in marine fish from the northern North Sea (e.g. haddock, whiting, herring) were lower than in the central and southern North Sea (e.g. cod and flatfish). Concerning eel, no substantial geographical differences were found (apart from two distinct locations). The contamination pattern was similar in all species, where PFOS mostly dominated the profile, and other long-chain PFASs being frequently detected. Short-chain PFASs were rarely found. PFOS concentrations in eel varied from 3.3 ng/g (close to the North Sea) to 67 ng/g ww in eel caught from Ghent-Terneuzen canal. The majority of detected PFOS levels in eels (93%) and 1 shrimp sample from Eems-Dollard exceeded the EU Environmental Quality Standard (EQS) for surface water of 9.1 μg/kg ww. Other samples (e.g. shrimps, bivalves, flounder), subject to the EQS, did not exceed this level.
North Sea Herring and Pelagic Ecosystem Survey (HERAS) report for R/V TRIDENS, 26 June - 21 July 2017 and 25 June - 20 July 2018
Couperus, A.S. - \ 2019
Wageningen Marine Research (Report / Wageningen Marine Research 19.001) - 24 p.
Understanding ontogenetic and temporal variability of Eastern Baltic cod diet using a multispecies model and stomach data
Kulatska, Nataliia ; Neuenfeldt, Stefan ; Beier, Ulrika ; Elvarsson, Bjarki Þór ; Wennhage, Håkan ; Stefansson, Gunnar ; Bartolino, Valerio - \ 2019
Fisheries Research 211 (2019). - ISSN 0165-7836 - p. 338 - 349.
Diet composition - Length selection - Multi-species model - Predator-prey interactions

Size of predator and prey determines, to a large extent, predator-prey interactions in aquatic systems. Understanding the relationship between predator and prey size in the individual predator's food selection process is a cornerstone of ecological modelling. Stomach content data are used to inform such models, as they provide prey species specific information about the predator diet in the wild. These data are strongly relevant as direct observations of species trophic interactions, but they have limitations, and are costly. Our objective was to develop and test a model which is able to predict changes in the Baltic cod diet by reconstructing the dynamics of cod and its prey, herring and sprat, populations, their length distributions, and parametrizing trophic interactions between them. We analysed time-series of cod stomach data and built an age-length structured multispecies model using Gadget. Both observed and predicted diets of smaller (juvenile) cod consisted mainly of benthos, while larger cod fed mostly on fishes (herring and sprat). Our model could predict the main patterns in species and length composition of cod diet. We also identified important knowledge gaps, especially on benthos dynamics and processes affecting prey availability and predator preference.

Downs recruitment survey 2018: herring larvae survey in the Southern North Sea and German Bight in april
Damme, C.J.G. van - \ 2018
Wageningen Marine Research (Report / Wageningen Marine Research Report 18.007) - 21 p.
Herring larvae surveys 2017 : survey reports and results
Damme, C.J.G. van; Blom, E. ; Vries, M. de - \ 2018
Wageningen Marine Research (Report / Wageningen Marine Research Report 18.008) - 28 p.
Investigation of echosounder finger prints of Dutch pelagic freezer trawlers (SEAT II) evaluation of the SEAT II joint-industry project : evaluation of the SEAT II joint-industry project
Sakinan, Serdar ; Haan, Dick de; Burggraaf, Dirk ; Fassler, Sacha - \ 2018
IJmuiden : Wageningen Marine Research (Wageningen Marine Research rapport C020/18) - 44
The SEAT algorithm aims at classifying different fish species using relative frequency response acquired by downward looking echosounders operating at multiple frequencies. The performance of the system has been being evaluated on three Dutch freezer trawlers: Fishing Vessel (FV) SCH302 Willem van der Zwan, FV SCH6 Alida and FV SCH24 Afrika. One of these vessels (FV Alida SCH6) operates a mixture of SIMRAD EK60 & EK80 software while others operate only Simrad EK80. As reported by these vessels, the classification accuracy of the SEAT software has been reduced particularly at the later stages of the project. To investigate this problem these vessels collected acoustic data in close range of each other while targeting herring in the summer of 2017 at east of Shetland isles. Using this dataset together with calibration data, a statistical comparison was conducted. Furthermore, potential discrepancies between Simrad EK60 and EK80 systems were examined using data collected during herring assessment survey HERAS of Fishing Research Vessel (FRV) TRIDENS in July 2017. This dataset included recordings of both systems in alternating mode enabling a ping to ping comparison. It was found that two serious software bugs were likely to have influenced the calibration procedure of the EK80 software. One of these impacted the comparison of HERAS FRV Tridens records and lead to Sv gain offsets of 1.76 dB. After the correction, the measured acoustic intensities were comparable between EK60 and EK80 implying that the interchangeable application of these tools on board SCH6 should not affect species classification and measurements should be similar between vessels either using EK60 or EK80 given the instruments are calibrated correctly. The calculated relative frequency responses from the acoustic recordings of these three fishing vessels showed that FV Willem van der Zwan SCH302 and FV Alida SCH6 were found reasonably coherent, but FV Afrika SCH24 was different. These differences are associated with lower mean backscatter values of the 38 kHz channel.Similar analysis conducted in the earlier phases of this project where frequency response calculated from data collected by FV Alida SCH6 to investigate the discrepancies in the received horse mackerel frequency response and its expected fingerprints (Fassler, 2016 Annex 1). His results showed that the contribution of the 120 kHz data on the classification of varied with location and increased above latitude 52. In addition, this contribution was much lower for shoals detected in the English Channel (Fassler, 2016). Fassler (2016) also suggested that water pressure may affect the morphology of swimbladdered species and may explain the variability between shoals detected on the Atlantic Ocean and in the English Channel. The depth related effects found in different cases suggests that water depth has to be accounted for as an additional variable for each location. As suggested by Fassler (2016), these results may gain significance when the number of datasets increases.The results of the investigations presented here show that further post-processing of calibration records may improve the data quality hence the classification outputs. Particularly the unexpected reduction in the classification performance after 2016 can be improved by rolling back all the SEAT settings to an original state followed by proper calibrations settings. It is also recommended to maintain the latest software versions to ensure equipment are operating efficiently and consistent across the vessels. Regular tests with vessels fishing in close range as in the case of the summer of 2017 is a useful approach to test species recognition and to compare overall performance of the classification algorithm.
Shifts in North Sea forage fish productivity and potential fisheries yield
Clausen, Lotte W. ; Rindorf, Anna ; Deurs, Mikael van; Dickey-Collas, Mark ; Hintzen, Niels T. - \ 2018
Journal of Applied Ecology 55 (2018)3. - ISSN 0021-8901 - p. 1092 - 1101.
Bottom-up effects - Fisheries management - Fisheries yield - Forage fish - Functional complementarity - Maximum sustainable yield - Portfolio effect - Recruitment - Small pelagic fisheries - System productivity
1. Forage fish populations support large scale fisheries and are key components of marine ecosystems across the world, linking secondary production to higher trophic levels. While climate-induced changes in the North Sea zooplankton community are described and documented in literature, the associated bottom-up effects and consequences for fisheries remain largely unidentified.
2. We investigated the temporal development in forage fish productivity and the associated influence on fisheries yield of herring, sprat, Norway pout and sandeel in the North Sea. Using principal component analysis, we analysed 40 years of recruitment success and growth proxies to reveal changes in productivity and patterns of synchroneity across stocks (i.e. functional complementarity). The relationship between forage fish production and Calanus finmarchicus (an indicator of climate change) was also analysed. We used a population model to demonstrate how observed shifts in productivity affected total forage fish biomass and fisheries yield.
3. The productivity of North Sea forage fish changed around 1993 from a higher average productivity to lower average productivity. During the higher productivity period, stocks displayed a covariance structure indicative of functional complementarity. Calanus finmarchicus was positively correlated to forage fish recruitment, however, for growth, the direction of the response differed between species and time periods. Maximum sustainable yield (MSY) and the associated fishing mortality (Fmsy) decreased by 33%–68% and 26%–64%, respectively, between the higher and lower productivity periods.
4. Synthesis and applications. The results demonstrate that fisheries reference points for short-lived planktivorous species are highly dynamic and respond
rapidly to changes in system productivity. Furthermore, from an ecosystem-based fisheries management perspective, a link between functional complementarity and productivity, indicates that ecosystem resilience may decline with productivity. Based on this, we advise that system productivity, perhaps monitored as forage fish growth, becomes an integral part of management reference points; in both single species and ecosystem contexts. However, to retain social license of biological advice when fish catch
opportunities are reduced, it is crucial that shifts in productivity are thoroughly documented and made apparent to managers and stakeholders.
Instead of eating herring we should eat algae!
Janssen, M.G.J. - \ 2017
Wageningen :
algae
What makes algae a sufficient food?
Data from: Shifts in North Sea forage fish productivity and potential fisheries yield
Clausen, Lotte W. ; Rindorf, Anna ; Deurs, Mikael van; Hintzen, N.T. - \ 2017
maximum sustainable yield - functional complimentarity - bottom-up effect - small pelagic fisheries - fisheries - regime shift - recruitment - growth
Forage fish populations support large scale fisheries and are key components of marine ecosystems across the world, linking secondary production to higher trophic levels. While climate-induced changes in the North Sea zooplankton community are described and documented in literature, the associated bottom-up effects and consequences for fisheries remain largely unidentified. We investigated the temporal development in forage fish productivity and the associated influence on fisheries yield of herring, sprat, Norway pout and sandeel in the North Sea. Using principal component analysis, we analysed 40 years of recruitment success and growth proxies to reveal changes in productivity and patterns of synchroneity across stocks (i.e. functional complementarity). The relationship between forage fish production and Calanus finmarchicus (an indicator of climate change) was also analysed. We used a population model to demonstrate how observed shifts in productivity affected total forage fish biomass and fisheries yield. The productivity of North Sea forage fish changed around 1993 from a higher average productivity to lower average productivity. During the higher productivity period, stocks displayed a covariance structure indicative of functional complementarity. Calanus finmarchicus was positively correlated to forage fish recruitment, however, for growth, the direction of the response differed between species and time periods. Maximum sustainable yield (MSY) and the associated fishing mortality (Fmsy) decreased by 33%–68% and 26%–64%, respectively, between the higher and lower productivity periods. Synthesis and applications. The results demonstrate that fisheries reference points for short-lived planktivorous species are highly dynamic and respond rapidly to changes in system productivity. Furthermore, from an ecosystem-based fisheries management perspective, a link between functional complementarity and productivity, indicates that ecosystem resilience may decline with productivity. Based on this, we advise that system productivity, perhaps monitored as forage fish growth, becomes an integral part of management reference points; in both single species and ecosystem contexts. However, to retain social license of biological advice when fish catch opportunities are reduced, it is crucial that shifts in productivity are thoroughly documented and made apparent to managers and stakeholders.
Winter distribution of plaice (Pleuronectes platessa) and lemon sole (Microstomus kitt) larvae in the English Channel and North Sea inferred from the 2016 IBTS sampling
Pernak, M. ; Giraldo, C. ; Huwer, B. ; Damme, C.J.G. van; Nash, R. ; Klopmann, M. ; Ritchie, L. ; Loots, C. - \ 2017
Although most fish species spawn during spring, ensuring a temporal coincidence of their larvae with the planktonic bloom, several spawn during winter. During the International Bottom Trawl Survey (IBTS), the MRN (Midwater Ring Net) sampling is performed each year during winter (January-February) all over the eastern English Channel (EEC) and North Sea. Until now, MRN data have been mainly used for stock assessment of North Sea Herring. Hence, the aim of the present study is to focus on others species (especially flatfishes) found in samples collected in 2016 and to determine spatial patterns in larval fish assemblages in relation to environmental conditions.
Brexit and the Dutch Fishing Industry
Turenhout, Mike ; Hamon, Katell ; Hintzen, Niels ; Poppe, Krijn - \ 2017
EuroChoices 16 (2017)2. - ISSN 1478-0917 - p. 24 - 25.
Brexit has become a reality, and not only at the negotiation table in Brussels. In the fishing industry, Brexit has created uncertainty over access to fishing grounds and national allocations of EU Total Allowable Catches (TACs) by fish species. This uncertainty is already affecting investment decisions.
Each EU Member State has its own Exclusive Economic Zone (EEZ), which is a sea area defined in International Law that extends up to 200 nautical miles from the coast of the EU Member State. Within the EU, Member States have equal access to EU fishing grounds. Dutch fisheries are highly dependent on the UK EEZ, where (pelagic) trawlers in particular, targeting herring and mackerel, are highly active (Figure 1). The other types of trawlers (so called bottom trawlers) target species like plaice, sole and common shrimp. They fish mainly in the North Sea, partly in the UK EEZ although less so than the pelagic trawlers.
Improving Larvae Survey Indices: a case study of North Sea herring
Damme, Cindy van - \ 2017
Overview of the international fishing activities on the Central Oyster Grounds and Frisian Front : update with Dutch, British, Danish, German, Belgian, Swedish and French data for 2010-2015
Buisman, Erik F.C. ; Hintzen, Niels T. ; Hamon, Katell G. - \ 2017
Wageningen : Wageningen Economic Research (Wageningen Economic Research memorandum 2017-078) - 25
In response to a request to Wageningen University & Research from the Dutch Ministry of Economic Affairs, an update of the data and analysis on the value of the fishing activities of the Dutch, British, Danish, German, Belgian, Swedish and French fishing fleets on the proposed closed areas on the Central Oyster Grounds and Frisian Front was prepared. This report uses the method presented in Chapter 5 of Effects of seabed protection on the Frisian Front and Central Oyster Grounds (Van Oostenbrugge et al. 2015) to update the reports already published by Wageningen Economic Research on fishing activity on the proposed closed areas on the Central Oyster Grounds and Frisian Front (Oostenbrugge, Bartelings et al. 2013, Oostenbrugge and Hamon 2014, van Oostenbrugge and Hamon 2014, Oostenbrugge, Turenhout et al. 2016, Oostenbrugge, Turenhout et al. 2016). The effort, value and landings by the Dutch, British, Danish, German, Belgian, Swedish and French fishing fleets are presented for a five-year period (2010-2015) and show variations over the last years without a clear trend. Value of landings and gross value added of the Dutch, British and Belgian fleets have been fluctuating over the past years but there was a clear upward trend for Danish and German fleets. Sweden and France have not been active in the area over the 2010-2015 period. Main target species of the Central Oyster Grounds and Frisian Front are plaice and sole mostly targeted by the beam trawl fleet, and sprat (largest in volume) targeted by the Danish fleet. The other demersal fleets also catch some nephrops and herring.
Variation that can be expected when using particle tracking models in connectivity studies
Hufnagl, Marc ; Payne, Mark ; Lacroix, Geneviève ; Bolle, Loes J. ; Daewel, Ute ; Dickey-Collas, Mark ; Gerkema, Theo ; Huret, Martin ; Janssen, Frank ; Kreus, Markus ; Pätsch, Johannes ; Pohlmann, Thomas ; Ruardij, Piet ; Schrum, Corinna ; Skogen, Morten D. ; Tiessen, Meinard C.H. ; Petitgas, Pierre ; Beek, Jan K.L. van; Veer, Henk W. van der; Callies, Ulrich - \ 2017
Journal of Sea Research 127 (2017). - ISSN 1385-1101 - p. 133 - 149.
Ensemble - Lagrangian approach - Marine protected areas - Model intercomparison - Ocean circulation - Renewable energy - Variability - Wind park

Hydrodynamic Ocean Circulation Models and Lagrangian particle tracking models are valuable tools e.g. in coastal ecology to identify the connectivity between offshore spawning and coastal nursery areas of commercially important fish, for risk assessment and more for defining or evaluating marine protected areas. Most studies are based on only one model and do not provide levels of uncertainty. Here this uncertainty was addressed by applying a suite of 11 North Sea models to test what variability can be expected concerning connectivity. Different notional test cases were calculated related to three important and well-studied North Sea fish species: herring (Clupea harengus), and the flatfishes sole (Solea solea) and plaice (Pleuronectes platessa). For sole and plaice we determined which fraction of particles released in the respective spawning areas would reach a coastal marine protected area. For herring we determined the fraction located in a wind park after a predefined time span. As temperature is more and more a focus especially in biological and global change studies, furthermore inter-model variability in temperatures experienced by the virtual particles was determined. The main focus was on the transport variability originating from the physical models and thus biological behavior was not included. Depending on the scenario, median experienced temperatures differed by 3. °C between years. The range between the different models in one year was comparable to this temperature range observed between modelled years. Connectivity between flatfish spawning areas and the coastal protected area was highly dependent on the release location and spawning time. No particles released in the English Channel in the sole scenario reached the protected area while up to 20% of the particles released in the plaice scenario did. Interannual trends in transport directions and connectivity rates were comparable between models but absolute values displayed high variations. Most models showed systematic biases during all years in comparison to the ensemble median, indicating that in general interannual variation was represented but absolute values varied. In conclusion: variability between models is generally high and management decisions or scientific analysis using absolute values from only one single model might be biased and results or conclusions drawn from such studies need to be treated with caution. We further concluded that more true validation data for particle modelling are required.

Detection of low numbers of microplastics in North Sea fish using strict quality assurance criteria
Hermsen, E. ; Pompe, R. ; Besseling, E. ; Koelmans, A.A. - \ 2017
Marine Pollution Bulletin 122 (2017)1-2. - ISSN 0025-326X - p. 253 - 258.
We investigated 400 individual fish of four North Sea species: Atlantic Herring, Sprat, Common Dab, and Whiting on ingestion of > 20 μm microplastic. Strict quality assurance criteria were followed in order to control contamination during the study. Two plastic particles were found in only 1 (a Sprat) out of 400 individuals (0.25%, with a 95% confidence interval of 0.09–1.1%). The particles were identified to consist of polymethylmethacrylate (PMMA) through FTIR spectroscopy. No contamination occurred during the study, showing the method applied to be suitable for microplastic ingestion studies in biota. We discuss the low particle count for North Sea fish with those in other studies and suggest a relation between reported particle count and degree of quality assurance applied. Microplastic ingestion by fish may be less common than thought initially, with low incidence shown in this study, and other studies adhering to strict quality assurance criteria.
North Sea Herring and Pelagic Ecosystem Survey (HERAS) report for R/V TRIDENS
Couperus, A.S. ; Fassler, S.M.M. - \ 2016
Wageningen Marine Research (Internal report 16.012) - 25 p.
Sexual dimorphism in livestock species selected for economically important traits
Heide, E.M.M. van der; Lourenco, D.A.L. ; Chen, C.Y. ; Herring, W.O. ; Sapp, R.L. ; Moser, D.W. ; Tsuruta, S. ; Masuda, Y. ; Ducro, B.J. ; Misztal, I. - \ 2016
Journal of Animal Science 94 (2016)9. - ISSN 0021-8812 - p. 3684 - 3692.
Beef cattle - Broiler chickens - Genetic correlation - Genomic selection - Purebred pigs - Sex difference

Most breeding companies evaluate economically important traits in males and females as a single trait, assuming genetic correlation of 1 between phenotypes measured in both sexes. This assumption may not be true because genes may be differently expressed in males and females. We estimated genetic correlations between males and females for growth and efficiency traits in broiler chickens, growth traits in American Angus beef cattle, and birth weight and preweaning mortality in purebred pigs; therefore, each trait was treated differently in males and females. Variance components were estimated in single- and multiple-trait models, jointly or separated into both sexes. Furthermore, we calculated traditional and genomic evaluations, and we correlated EBV or genomic EBV (GEBV) from joint and separate evaluations for males and females. For broiler chickens, genetic correlations ranged from 0.86 to 0.94. For Angus cattle, genetic correlations ranged from 0.86 to 0.98 for early growth traits and were less, ranging from 0.68 to 0.84, for postweaning gain. In pigs, genetic correlations ranged from 0.98 to 0.99 for birth weight and from 0.71 to 0.73 for preweaning mortality. For some models in all 3 animal species, the joint and separate analyses had different heritabilities. Despite differences in heritability, the correlations within the sex-specific trait EBV and between the sex-specific and the joint trait EBV were very strong, regardless of the model or inclusion of genomic information. Males and females differed for traits measured late in the animal’s life; however, strong traditional EBV correlations and also GEBV correlations indicate that considering the traits equal in males and females may have no negative impact on selection.

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