Vanessa Stelzenmüller

Assessment of a Bayesian Belief Network-GIS framework as a practical tool to support marine planning.

For the UK continental shelf we developed a Bayesian Belief Network-GIS framework to visualise relationships between cumulative human pressures, sensitive marine landscapes and landscape vulnerability, to assess the consequences of potential marine planning objectives, and to map uncertainty-related changes in management measures. Results revealed that the spatial assessment of footprints and intensities of human activities had more influence on landscape vulnerabilities than the type of landscape sensitivity measure used. We addressed questions regarding consequences of potential planning targets, and necessary management measures with spatially-explicit assessment of their consequences. We conclude that the BN-GIS framework is a practical tool allowing for the visualisation of relationships, the spatial assessment of uncertainty related to spatial management scenarios, the engagement of different stakeholder views, and enables a quick update of new spatial data and relationships. Ultimately, such BN-GIS based tools can support the decision-making process used in adaptive marine management.

20 years of the German Small-Scale Bottom Trawl Survey (GSBTS): A review

AbstractThe German Small-scale Bottom Trawl Survey (GSBTS) was initiated in 1987 in order to provide complementary investigations to the International Bottom Trawl Survey (IBTS) in the North Sea, using the same methodology but focussing high-intensity sampling on selected survey areas. Over the last 20 years, the initial number of 4 survey areas (10 × 10 nautical miles; “Boxes”) has been increased to 12, which are distributed over the entire North Sea. This paper describes the survey methods of the GSBTS, summarizes the scientific outcome of the first 20 years, and suggests that international fisheries research institutions would join the GSBTS.The major outcomes of the survey include to date:— Documentation changes in the distribution of fish species and in species assemblages (e.g. changes in species richness, shifts in the southern species component).— Geostatistical evaluation of GSBTS data.— Analysis of spatial scale effects: the relevance of GSBTS survey results for interpreting large-scaled abundance and distribution data from the IBTS.— Description of benthic habitats, composition of invertebrate fauna and its variability.— Process studies, especially investigation of predator-prey interactions between fish through analyses of stomach contents.— Characterization of the typical hydrographic conditions in the survey areas and their variability, and description of the nutrient supply.— Observations of seabirds and their feeding habits.— Analysis of the effects of different parameters on catch rates for bottom fish and on the estimates of abundance indices (e.g. vessel and gear effects, towing time, hydrographic conditions, time of day, number of hauls per area). In continuing this interdisciplinary survey with simultaneous sampling of all faunal and environmental compartments and especially in making it an international effort, we see the possibility of contributing data for the implementation of the ecosystems approach to fisheries management. Particularly, the following aspects can be addressed and would further increase the scientific value of the GSBTS:— Combining the survey data with highly resolved data from the commercial fishery to separate the effects of fishing from natural variability.— Further interdisciplinary analyses of the entire data set. Main aspects include benthos-fish-bird-community changes over time and their relation to historic fisheries impacts, and the coupling of biological and physical habitat characterisation.— Collection of accompanying data (phyto-, zoo- and ichthyoplankton data) in order to make the GSBTS a true ecosystem survey in detecting temporal changes in nearly all major levels of the food web.

A spatially explicit risk approach to support marine spatial planning in the German EEZ

An ecosystem approach to marine spatial planning (MSP) promotes sustainable development by organizing human activities in a geo-spatial and temporal context. (1) This study develops and tests a spatially explicit risk assessment to support MSP. Using the German exclusive economic zone (EEZ) of the North Sea as a case study area, current and future spatial management scenarios are assessed. (2) Different tools are linked in order to carry out a comprehensive spatial risk assessment of current and future spatial management scenarios for ecologic and economic ecosystem components, i.e. Pleuronectes platessa nursery grounds. With the identification of key inputs and outputs the suitability of each tool is tested. (3) Here, the procedure as well as the main findings of the spatially explicit risk approach are summarised to demonstrate the applicability of the framework and the need for an ecosystem approach to risk management techniques using geo-spatial tools.

Effects of survey scale and water depth on the assessment of spatial distribution patterns of selected fish in the northern North Sea showing different levels of aggregation

Abstract Geostatistics was employed to investigate spatial structuring of herring, cod, dab, haddock and whiting at different spatial scales in the northern North Sea. Additionally, a structural analysis of the maximum water depth was carried out to assess habitat associations of fish. Linear, spherical, exponential and Gaussian models were fitted to the semivariograms, showing clear spatial autocorrelations. At the smaller scale, spatial structuring was weak for haddock, herring and dab, increasing at the greater spatial scale, with the exception of whiting. Mean catch rates, estimated classically and geostatistically, were in good agreement. Corresponding variances were clearly reduced at both spatial scales, when accounting for spatial distribution of the fish. At the greater survey scale a high level of habitat association was detected for haddock and whiting, while a poor habitat association was found for cod, dab and herring. The smaller scale seems to be the threshold at which spatial structuring of “cpue” could have marked influence on estimation error. Thus, survey scale is important when analysing spatial patterns and estimating mean biomass indices, and a sound analysis of relations in spatial structuring of fish and habitat conditions is essential to derive more precise estimates.

A risk-based approach to cumulative effect assessments for marine management

Marine ecosystems are increasingly threatened by the cumulative effects of multiple human pressures. Cumulative effect assessments (CEAs) are needed to inform environmental policy and guide ecosystem-based management. Yet, CEAs are inherently complex and seldom linked to real-world management processes. Therefore we propose entrenching CEAs in a risk management process, comprising the steps of risk identification, risk analysis and risk evaluation. We provide guidance to operationalize a risk-based approach to CEAs by describing for each step guiding principles and desired outcomes, scientific challenges and practical solutions. We reviewed the treatment of uncertainty in CEAs and the contribution of different tools and data sources to the implementation of a risk based approach to CEAs. We show that a risk-based approach to CEAs decreases complexity, allows for the transparent treatment of uncertainty and streamlines the uptake of scientific outcomes into the science-policy interface. Hence, its adoption can help bridging the gap between science and decision-making in ecosystem-based management.

Co-location of passive gear fisheries in offshore wind farms in the German EEZ of the North Sea: A first socio-economic scoping

Worldwide the renewable energy sector is expanding at sea to address increasing demands. Recently the race for space in heavily used areas such as the North Sea triggered the proposal of co-locating other activities such as aquaculture or fisheries with passive gears in offshore wind farms (OWFs). Our interdisciplinary approach combined a quantification of spatial overlap of activities by using Vessel Monitoring System and logbook data with a stakeholder consultation to conclude and verify on the actual feasibility of co-location. In the German Exclusive Economic Zone (EEZ) of the North Sea up to 90% of Danish and 40% of German annual gillnet fleet landings of plaice overlapped with areas where OWFs are developed. Our results indicated further that the international gillnet fishery could lose up to 50% in landings within the North Sea German EEZ when OWF areas are closed entirely for fisheries. No spatial overlap was found for UK potters targeting brown crab in the German EEZ. We further identified a number of key issues and obstacles that to date hinder an actual implementation of co-location as a measure in the marine spatial planning process: defining the legal base; implementation of safety regulations; delineation of minimum requirements for fishing vessels such as capacities, quotas, technical equipment; implementation of a licensing process; and scoping for financial subsidies to set up business. The stakeholder consultation verified the scientific findings and highlighted that all those points need to be addressed in a planning process. In the German EEZ we have shown that the socio-economic importance of spatial overlap varies within planning boundaries. Therefore we recommend an interdisciplinary bottom-up approach when scoping for suitable areas of co-location. Hence, an informed marine spatial planning process requires comprehensive and spatial explicit socio-economic viability studies factoring in also ecological effects of OWFs on target species.

A GIS-based tool for an integrated assessment of spatial planning trade-offs with aquaculture.

The increasing demand for protein from aquaculture will trigger a global expansion of the sector in coastal and offshore waters. While contributing to food security, potential conflicts with other traditional activities such as fisheries or tourism are inevitable, thus calling for decision-support tools to assess aquaculture planning scenarios in a multi-use context. Here we introduce the AquaSpace tool, one of the first Geographic Information System (GIS)-based planning tools empowering an integrated assessment and mapping of 30 indicators reflecting economic, environmental, inter-sectorial and socio-cultural risks and opportunities for proposed aquaculture systems in a marine environment. A bottom-up process consulting more than 350 stakeholders from 10 countries across southern and northern Europe enabled the direct consideration of stakeholder needs when developing the GIS AddIn. The AquaSpace tool is an open source product and builds in the prospective use of open source datasets at a European scale, hence aiming to improve reproducibility and collaboration in aquaculture science and research. Tool outputs comprise detailed reports and graphics allowing key stakeholders such as planners or licensing authorities to evaluate and communicate alternative planning scenarios and to take more informed decisions. With the help of the German North Sea case study we demonstrate here the tool application at multiple spatial scales with different aquaculture systems and under a range of space-related development constraints. The computation of these aquaculture planning scenarios and the assessment of their trade-offs showed that it is entirely possible to identify aquaculture sites, that correspondent to multifarious potential challenges, for instance by a low conflict potential, a low risk of disease spread, a comparable high economic profit and a low impact on touristic attractions. We believe that a transparent visualisation of risks and opportunities of aquaculture planning scenarios helps an effective Marine Spatial Planning (MSP) process, supports the licensing process and simplifies investments.

Eine Thünen-Evaluierung von fisch- und fischereibezogenen Indikatoren der EU Meeresstrategie-Rahmenrichtlinie (MSRL)

Dieser Bericht stellt ein Bewertungsverfahren fur die nationalen Indikatoren der Meeresstrategie-Rahmenrichtlinie (MSRL) vor, welche fischokologische Aspekte der Meeresumwelt oder die Auswirkungen von Fischerei erfassen sollen. Die Bewertung der MSRL-Indikatoren wurde vorgenommen, um den derzeit noch stattfindenden Auswahlprozess und die Operationalisierung der Indikatoren durch eine fachliche Einschatzung zu unterstutzen. Es wurden insgesamt 23 MSRL-Indikatoren nach einem international erprobten Bewertungssystem gegen 15 Kriterien bewertet. Diese Kriterien berucksichtigten die Datenqualitat, die Management-Praktikabilitat und die konzeptionellen Qualitaten jedes Indikators. Die 15 Kriterien erlaubten somit eine genauere Betrachtung moglicher Defizite und die gezielte Erarbeitung von Empfehlungen zur Verbesserung der vorgestellten Indikatoren. Die exemplarische Bewertung durch die sieben Thunen-Expertinnen und -Experten zeigte, dass Indikatoren aus dem Fischereimanagement und den fischereiwissenschaftlichen Forschungsreisen grundsatzlich sehr gut bewertet wurden. Dies liegt daran, dass viele Indikatoren aus dem Fischereimanagement schon seit Jahrzehnten etabliert sind, als wissenschaftlich abgesichert gelten, sowie einen hohen Grad internationaler Abstimmung und eine relativ gute Datengrundlage aufweisen. Die Bewertungen von Indikatoren zu dem Zustand von Nahrungsnetzen oder benthischen Lebensraumen, sowie der Beifangintensitaten von Seevogeln und Meeressaugetieren wurden als schlechter eingeschatzt. Dies lag zum einen an der bisher mangelhaften Festlegung von Zielvorgaben (benthische Lebensraume), unzureichenden bzw. unprazisen technischen Beschreibungen der Indikatoren und ihrer Messgrosen (Nahrungsnetze), sowie fehlender internationaler Abstimmung (Nahrungsnetze & benthische Lebensraume). Fur Beifange von Seevogeln und Meeressaugetieren fiel die Bewertung aufgrund der geringen Datenverfugbarkeit negativ aus. Um die Indikatoren mit schlechter Bewertung zu operationalisieren, sollte die technische Entwicklung auf internationaler Ebene vorangetrieben (Nahrungsnetze) und die Datengrundlagedurch intensiviertes Monitoring verbessert werden (benthische Lebensraume, Beifangindikatoren). Ein wesentlicher Teil der ausstehenden Arbeiten betrifft Bewertungsmethoden, sowie Bestimmung und Festlegung von Grenz- bzw. Zielwerten. Zwar liegen fur viele Indikatoren Bewertungrschlage aus der wissenschaftlichen Literatur vor, es bedarf aber einer finalen politischen Abstimmung.