Estimating the spatial position of marine mammals based on digital camera recordings

Estimating the spatial position of organisms is essential to quantify interactions between the organism and the characteristics of its surroundings, for example,predator–prey interactions, habitat selection, and social associations. Because marine mammals spend most of their time under water and may appear at the surface only briefly, determining their exact geographic location can be challenging.Here, we developed a photogrammetric method to accurately estimatethe spatial position of marine mammals or birds at the sea surface. Digital recordings containing landscape features with known geographic coordinates can be used to estimate the distance and bearing of each sighting relative to the observation point. The method can correct for frame rotation, estimates pixel size based on the reference points, and can be applied to scenarios with and without a visible horizon. A set of R functions was written to process the images and obtain accurate geographic coordinates for each sighting. The method is applied to estimate the spatiotemporal fine-scale distribution of harbourporpoises in a tidal inlet. Video recordings of harbour porpoises were made from land, using a standard digital single-lens reflex (DSLR) camera, positioned at a height of 9.59 m above mean sea level. Porpoises were detected up to a distance of ~3136 m (mean 596 m), with a mean location error of 12 m. The method presented here allows for multiple detections of different individuals within a single video frame and for tracking movements of individuals based on repeated sightings. In comparison with traditional methods, this method only requires a digital camera to provide accurate location estimates. It especially has great potential in regions with ample data on local (a)biotic conditions, to help resolve functional mechanisms underlying habitat selection and other behaviors in marine mammals in coastal areas

An overview of the impacts of fishing on seabirds, including identifying future research directions

Knowledge of fisheries impacts, past and present, is essential for understanding the ecology and conservation of seabirds, but in a rapidly changing world, knowledge and research directions require updating. In this Introduction and in the articles in this Themed Set “Impacts of fishing on seabirds”, we update our understanding of how fishing impacts seabird communities and identify areas for future research. Despite awareness of the problems and mitigation efforts for >20 years, fisheries still negatively impact seabirds via the effects of bycatch, competition, and discards. Bycatch continues to kill hundreds of thousands of seabirds annually, with negative population-level consequences. Fisheries for forage fish (e.g. anchovy, sandeel, and krill) negatively impact seabirds by competing for the same stocks. Historically, discards supplemented seabird diets, benefitting some species but also increasing bycatch rates and altering seabird community composition. However, declining discard production has led to potentially deleterious diet switches, but reduced bycatch rates. To improve research into these problems, we make the following recommendations: (1) improve data collection on seabird–vessel interaction and bycatch rates, on fishing effort and vessel movements (especially small-scale fleets), and on mitigation compliance, (2) counter the current bias towards temperate and high-latitude ecosystems, larger-bodied species and particular life stages or times of year (e.g. adults during breeding), and (3) advance our currently poor understanding of combined effects of fisheries and other threats (e.g. climate change, offshore renewables). In addition, research is required on under-studied aspects of fishing impacts: consequences for depleted sub-surface predators, impacts of illegal, unreported and unregulated fishing, artisanal and emerging fisheries, such as those targeting mesopelagic fish, have received insufficient research attention. Some of these shortfalls can be overcome with new tools (e.g. electronic monitoring, remote sensing, artificial intelligence, and big data) but quantifying and addressing fishing impacts on seabirds requires greater research investment at appropriate spatio-temporal scales, and more inclusive dialogue from grassroots to national and international levels to improve governance as fishing industries continue to evolve

Broedsucces van kustbroedvogels in de Waddenzee in 2007 en 2008

Voor het derde en vierde opeenvolgende jaar werd het broedsucces van een aantal kustbroedvogels in de Waddenzee bepaald. Van Eider, Scholekster, Kluut, Kokmeeuw, Zilvermeeuw en Visdief, alsmede van Kleine Mantelmeeuw en Noordse Stern werd informatie verzamelen over het nestsucces en uitvliegsucces (het uiteindelijke broedsucces). Kennis over de jaarlijkse variatie in broedresultaten bij de verschillende soorten is van belang als een early warning systeem om de 'kwaliteit' (het reproducerend vermogen) van de vogelpopulaties in de Waddenzee te volgen en de achterliggende processen van populatieveranderingen te doorgronden. Directe aanleiding voor het project vormde de evaluatie van de effectiviteit van het nieuwe schelpdiervisserijbeleid en de mogelijke gevolgen voor de voedselvoorziening van schelpdieretende vogels

Harbour porpoises (Phocoena phocoena) in the Marsdiep area, the Netherlands: new investigations in a historical study area

Na de terugkeer van bruinvissen in de Nederlandse kustwateren is er in 2010 een haalbaarheidsonderzoek uitgevoerd om na te gaan of het opnieuw de moeite waard zou kunnen zijn om bruinvissen in het Marsdiep te bestuderen. De aantallen bruinvissen die in het voorjaar van 2011 werden gezien waren groot, maar weken niet wezenlijk af van wat er, op basis van zeetrektellingen bij Huisduinen, aan aantallen bruinvissen in de afgelopen vier seizoenen werd gezien. De door Verwey waargenomen verplaatsing van bruinvissen "met het getijde mee" kon tijdens ons onderzoek niet worden bevestigd

Scavenger communities and fisheries waste : North Sea discards support 3 million seabirds, 2 million fewer than in 1990

Every year fisheries discard >10 million tonnes of fish. This provides a bounty for scavengers, yet the ecological impact of discarding is understudied. Seabirds are the best-studied discard scavengers and fisheries have shaped their movement ecology, demography and community structure. However, we know little about the number of scavenging seabirds that discards support, how this varies over time or might change as stocks and policy change. Here, we use a Bayesian bioenergetics model to estimate the number of scavenging birds potentially supported by discards in the North Sea (one of the highest discard-producing regions) in 1990, around the peak of production, and again after discard declines in 2010. We estimate that North Sea discards declined by 48% from 509,840 tonnes in 1990 to 267,549 tonnes in 2010. This waste had the potential to support 5.66 (95% credible intervals: 3.33-9.74) million seabirds in the 1990s, declining by 39% to 3.45 (1.98-5.78) million birds by 2010. Our study reveals the potential for fishery discards to support very large scavenging seabird communities but also shows how this has declined over recent decades. Discard bans, like the European Union's Landing Obligation, may reduce inflated scavenger communities, but come against a backdrop of gradual declines potentially buffering deleterious impacts. More work is required to reduce uncertainty and to generate global estimates, but our study highlights the magnitude of scavenger communities potentially supported by discards and thus the importance of understanding the wider ecological consequences of dumping fisheries waste.Publisher PDFPeer reviewe

Baseline studies North Sea wind farms: Lot 5 marine birds in and around the future sites Nearshore Windfarm (NSW) and Q7

Dit rapport beschrijft de zeevogelgemeenschap die zich in de loop van het jaar bevindt in een zeegebied voor de Noord-Hollandse kust, waar in de nabije toekomst twee windmolenparken gebouwd zullen worden, de zogenaamde Nearshore Windfarm (NSW) en het windmolenpark Q7. Om deze ¿T-nul¿ situatie te kunnen vastleggen zijn de zeevogels gedurende acht weken, verspreid door het jaar, geïnventariseerd vanaf een speciaal daartoe ingezet schip. Er werd hierbij steeds een gebied geïnventariseerd dat ruimschoots groter was dan de beide toekomstige windmolenparken samen. Hierdoor konden de vogelaantallen binnen en buiten de contour van de windmolenparken worden vergeleken, rekening houdend met de ruimtelijke patronen die zeevogelverspreidingen in het gebied laten zien. In de nul-situatie, dus nog voordat er windturbines in gebied staan, is niet gebleken dat de aangewezen gebieden voor de turbines qua vogelbevolking afwijken van de omgeving. T-één studies (na de bouw) zullen moeten uitwijzen of dat in de toekomst zo zal blijven. De aantallen vogels, aanwezig in een relatief klein gebied zoals nu bestudeerd, kunnen van dag tot dag, week tot week en jaar tot jaar sterk variëren, zoals in deze studie werd vastgesteld aan de hand van langer lopende dataseries. Dit maakt dat een directe vergelijking van aantallen nu en straks minder zinvol is, dan een vergelijking van de aantallen binnen en buiten een windpark, op hetzelfde moment gemeten

Monitoring Chemical Pollution in Europe’s Seas: Programmes, practices and priorities for research

This report has been produced by the Marine Board Working Group on Existing and Emerging Chemical Pollutants (WGPOL) first convened in 2008 and tasked to examine the assessment and monitoring of existing and emerging chemicals in the European marine and coastal environment. The Working Group considered (i) existing monitoring/assessment frameworks; (ii) current monitoring practices; and (iii) new and emerging chemicals of concern and the mechanisms used to include them in current monitoring programmes. The primary conclusions and recommendations of this position paper are: 1. Fully implement state of the art environmental risk assessment procedures (combining exposure and effect assessment) to evaluate the full impact of chemical substances on the different compartments of coastal and open sea systems. 2. Further improve the coordination, cooperation and harmonization between existing monitoring efforts and those under development, to avoid duplication of effort, loss of expertise and a reduced willingness to fulfil the obligations towards regional conventions. 3. Ensure that the development and implementation of monitoring programmes for the assessment of chemicals in marine and coastal environment are based on a science-based and dynamic process. 4. Apply more resources targeted at developing appropriate approaches, tools and practices (education and training) to improve the acquisition and management of monitoring data. In addition to the above main recommendations, two further recommendations have been identified on the basis of two specific case studies which form part of this paper and which focus on the release, effects and monitoring of (i) hydrophobic and insoluble chemicals in the marine environment from merchant shipping; and (ii) chemicals released by the offshore oil-industry in the North Sea. These case studies highlighted the need to: 5. Develop a consistent, pan-European or regional (legal) framework/regulation which covers the activities of the oil and gas industry at sea. At the same time, more information and research is needed on the release and the effects of chemicals arising from offshore oil and gas activities. 6. Develop and apply state-of-the-art environmental risk assessment procedures (combining exposure and effect assessments, including on human health) to evaluate the impact of noxious liquid substances listed under MARPOL Annex II on the different compartments in coastal and open sea ecosystems

Baseline data on the harbour porpoise, Phocoena phocoena, in relation to the intended wind farm site NSW, in the Netherlands

To evaluate the possible impact of the planned Near Shore Wind farm on harbour porpoises, a baseline study has been carried out to provide a thorough description of the ecological reference situation. Three methods were used to collect baseline data on harbour porpoise in the intended wind farm area as well as reference areas. Firstly, during a whole year echolocation sounds of the animals were collected via fixed hydrophones, so-called T-PODs. This will provide information on relative density of porpoises. Secondly, bi-monthly ship-surveys were conducted to obtain an estimate for density. Finally, hydrophones were towed behind the survey ship to corroborate the visual data. These studies proved that porpoises frequently occurred in the target area and also in the control sites. Intensity of the porpoise activity was clearly higher in winter months. Observations surpass the expectations with respect to the amount of animals and recordin

The stranding anomaly as population indicator: the case of Harbour Porpoise <i>Phocoena phocoena</i> in North-Western Europe

Ecological indicators for monitoring strategies are expected to combine three major characteristics: ecological significance, statistical credibility, and cost-effectiveness. Strategies based on stranding networks rank highly in cost-effectiveness, but their ecological significance and statistical credibility are disputed. Our present goal is to improve the value of stranding data as population indicator as part of monitoring strategies by constructing the spatial and temporal null hypothesis for strandings. The null hypothesis is defined as: small cetacean distribution and mortality are uniform in space and constant in time. We used a drift model to map stranding probabilities and predict stranding patterns of cetacean carcasses under H-0 across the North Sea, the Channel and the Bay of Biscay, for the period 1990-2009. As the most common cetacean occurring in this area, we chose the harbour porpoise <i>Phocoena phocoena</i> for our modelling. The difference between these strandings expected under H-0 and observed strandings is defined as the stranding anomaly. It constituted the stranding data series corrected for drift conditions. Seasonal decomposition of stranding anomaly suggested that drift conditions did not explain observed seasonal variations of porpoise strandings. Long-term stranding anomalies increased first in the southern North Sea, the Channel and Bay of Biscay coasts, and finally the eastern North Sea. The hypothesis of changes in porpoise distribution was consistent with local visual surveys, mostly SCANS surveys (1994 and 2005). This new indicator could be applied to cetacean populations across the world and more widely to marine megafauna