Modelling habitat preference and estimating the spatial distribution of Australian Sea Lions (Neophoca cinerea); "A first exploration "

Managing the Australian sea lion (Neophoca cinerea) population and mitigating its interactions with commercial fisheries, requires an understanding of their spatial distribution and habitat preference at sea. Numerous wildlife telemetry devices have been attached to individual seals from different colonies, providing a detailed insight into there movement and activities. However, as data are only available from some individuals from 16 of 40 colonies in South Australia, these data represents only a small proportion of the population. Moreover, some colonies are poorly represented. To estimate the spatial distribution of the entire South Australian population, one can first investigate why individuals visit certain places and use this information to predict the spatial distribution for other regions lacking data. In this study we fit Generalized Additive Mixed Models (GAMMs) to wildlife telemetry data collected from adult female Australian sea lions to investigate the species’ habitat preference for the variables distance to the colony, depth and slope. The results show that in general they have a higher preference for shallow areas, places close to the colony and a steep slope, but they also display large individual variability. Preference for these variables does not seem to differ between individuals of different sizes. In some of the most western colonies, some individuals seem to spend more time further away from the colony, but apart from this, there is no apparent effect of the longitudinal capture position on preference. The predicted spatial distribution is largely driven by the distance from the departure colony and the actual distribution of individuals among the different colonies. Although depth and slope does seem to effect their distribution to some extent, the most important variables that explain fine-scale foraging activities at-sea are probably missing. Future studies using GPS transmitters attached to animals, that yield high resolution locations and more detailed environmental data, in combination with the analytical technique presented here, should provide more insight there foraging decisions. This should eventually also improve the spatial prediction of the population as a whole

Discard sampling of Plaice (Pleuronectes platessa) and Cod (Gadus morhua) in the North Sea by the Dutch demersal fleet from 2004 tot 2008

The PVis discard data used in the analysis presented in this report clearly shows where and when most discarding takes place. Although previous analysis (Aarts & van Helmond 2007) and the latest Flatfish Benchmark Assessment (2009), indicate that the data cannot be incorporated into the ICES stock assessment, it still provides an important reference points that can be used to evaluate the current DCR discard estimates and methods used. In 2009 Wageningen IMARES started a new DCR sampling program. The most remarkable difference with the previous program is the integration of self-sampling next to a less intensive observer program. We encourage this initiative, since the increase of discard data available over space and time will be of great value, but strongly recommend clarity of sampling procedures, thorough training and intensive communication with fishermen. Hence, inaccurate data on discards will have a significant impact on future management strategies

Grey seals (Halichoerus grypus) in the Dutch North sea: population ecology and effects of wind farms

This study was setup to gain an understanding of the possible effects of large-scale development of wind farms in Dutch waters on grey seals (Halichoerus grypus). This should be considered a first step in doing so as up until now relatively little was known about the species in Dutch waters. The study was carried out in the framework of WE@SEA a foundation aimed at acquiring knowledge in the field of offshore wind energy

Gerichte visserij op wolhandkrab in het IJsselmeer, een onderzoek naar vangstmethoden en bijvangsten

Vissers van het IJsselmeer hebben eind 2007; begin 2008 een onderzoek uitgevoerd naar de effectiviteit en bijvangsten van een gerichte visserij op wolhandkrab met behulp van aangepaste fuiken

Harbour porpoises Phocoena phocoena in the Eastern Scheldt: A resident Stock or trapped by a storm surge barrier?

Coastal protection measures are planned and executed worldwide to combat the effects of global warming and climate change, in particular the acceleration of sea level rise, higher storm surge flooding and extensive coastal inundation. The extent to which these defensive measures may impact coastal and estuarine ecosystems is still poorly understood. Since the building of a storm surge barrier, movement of harbour porpoises Phocoena phocoena in and out of the Eastern Scheldt tidal bay (SW-Netherlands) may be limited. To measure residency, porpoises stranded along the Dutch North Sea coast between 2006 and 2008 were sampled for muscle (n = 102) and bone tissue (n = 118), of which 9 muscle (8.8%) and 12 bone samples (10.2%) were collected from animals stranded within the Eastern Scheldt. Stable carbon (d13C) was analysed to get insight into the habitat use and residency of porpoises in the Eastern Scheldt. Our data showed significantly higher d13C values in the muscle of porpoises stranded within the Eastern Scheldt (µ = -17.7‰, SD = 0.4‰) compared to animals stranded along the Dutch coast (µ = -18.3‰, SD = 0.5‰). This suggests that most porpoises stranded in the Eastern Scheldt foraged there for a longer period. The distinct d13C signature of animals from the Eastern Scheldt was not observed in bone tissue, suggesting a relatively recent shift in habitat use rather than life-long residency of porpoises within the Eastern Scheldt. The high number of strandings within the Eastern Scheldt suggests a higher mortality rate compared to the Dutch coastal zone. Our study indicates that along with other changes in the physical environment, the storm surge barrier may play an important role in determining the residency of porpoises in the Eastern Scheldt, and that the area might act as an ecological trap for porpoises entering it

Onderzoek naar bijvangst bruinvissen in de Nederlandse visserij

Het aantal gestrande bruinvissen langs de Nederlandse kust is de laatste jaren sterk toegenomen. Het grootste aantal strandingen vond plaats in 2006: 546 geregistreerde dieren, waarvan naar schatting 7 - 70% stierven als gevolg van verdrinking. Intensieve studies elders en anekdotische informatie, beschikbaar voor Nederland, wijzen erop dat bruinvissen onder andere verstrikt raken in staandwantnetten. Er is echter grote variatie in de plaats en tijd dat de verschillende varianten staandwant worden ingezet. Het doel van dit vergelijkend onderzoek is om een beter beeld te krijgen van ruimtelijke en tijdelijke variatie in bruinvisstrandingen, en hoe dit samenhangt met veranderingen in het aantal bruinvissen waargenomen voor de kust en de inzet van staandwan

Habitat quality for Grey Seals in the Dutch Wadden Sea

Growth in numbers has seen the Netherlands become a strong-hold for grey seals in continental Europe. This report has the following subjects (questions posed by the Dutch Ministry): “Is a favourable status of the habitat quality of the grey seal in the Netherlands dependant on the presence of undisturbed, permanently dry breeding sites, or do the current sites, which are considered sub optimal, suffice for a long term survival of the species in the Netherlands?” and "How is the growth influenced by immigration from other areas (i.e. the UK)?

Seal monitoring and evaluation for the Luchterduinen offshore wind farm: 2. Tconstruction - 2014 report

Two seal species live in Dutch waters: the harbour seal (Phoca vitulina) and the grey seal (Halichoerus grypus). They occupy land-based sites (haul-outs) in both the Wadden Sea and the Delta region, and move between these regions along the North Sea coastal zone. Human activities, such as construction of a wind farm in this zone, may influence movement and use of the zone by the seals. Monitoring of potential impacts on seals to Luchterduinen construction was required in the permit to construct. The Luchterduinen offshore wind farm is the third wind farm development in the Dutch North Sea coastal zone (between Den Helder and Rotterdam). Pile-driving of the turbine towers occurred between 31 July and 16 October, 2014. Seals exposed to pile-driving, even at close distances o

Multi-element bioimaging of Arabidopsis thaliana roots

Better understanding of root function is central for development of plants with more efficient nutrient uptake and translocation. We here present a method for multi-element bioimaging at the cellular level in roots of the genetic model system Arabidopsis thaliana. Using conventional protocols for microscopy we observed that diffusible ions such as potassium (K+) and sodium (Na+) were lost during sample dehydration. Thus, we developed a protocol which preserves ions in their native, cellular environment. Briefly, fresh roots are encapsulated in paraffin, then cryo-sectioned and freeze dried. Samples are finally analyzed by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS), utilizing a specially designed internal standard procedure. The method can be further developed to maintain the native composition of proteins, enzymes, RNA and DNA, making it attractive in combination with other omics techniques. To demonstrate the potential of the method we analyzed a mutant of A. thaliana unable to synthesize the metal chelator nicotianamine (NA). The mutant accumulated substantially more zinc (Zn) and manganese (Mn) than the wild type in the tissues surrounding the vascular cylinder. For iron (Fe) the images looked completely different, with Fe bound mainly in the epidermis of the WT plants, but confined to the cortical cell walls of the mutant. The method offers the power of ICP-MS to be fully employed, thereby providing a basis for detailed studies of ion transport in roots. Being applicable to A. thaliana, the molecular and genetic approaches available in this system can now be fully exploited in order to gain a better mechanistic understanding of these processes