Search

Abstract Single species stock assessment models are, and will remain, the workhorse of fisheries management. However, they are incapable of assessing the structure and functioning of the ecosystem the fisheries operate in. This study describes the trophic structure of the southern North Sea and the flows between the nodes of its food-web. It is based on the outputs of an Ecopath food-web model of the North Sea south of the Skagerrak (ICES area VIb and c), parametrized representing the year 1991. The study also compares the southern to a whole North Sea Ecopath model (whole ICES area IV) parametrized for the same year, 1991. The two dominant flows of biomass led from primary producers to detritus, and from there into benthos. The southern North Sea differed from the whole North Sea representation in its fish community composition, primarily attributable to the biogeography of the species. Flatfish were caught more and roundfish less in the south, even with a nominally identically gear, to wit, otter trawlers. The largely different fish and catch compositions call for a specific, local management of the shallow southern North Sea's fisheries, which is based on ecosystem boundaries, rather than politically defined areas. Beyond fished stocks, food-web network indicators suggest that both systems functioned similarly, if compared to a global set of Ecopath models. They also deem the 1991 North Sea and its southern sub-part a densely woven, mature and resilient food-web. Highlights • We holistically assess the 1991 southern North Sea with an Ecopath food-web model. • Its different compartments are highly interlinked and the food-web is densely woven. • Ecological theory hence suggests high resilience of the ecosystem. • Fish community and catch composition differ from the North Sea as a whole. • Despite that, southern and total North Sea structure and function very similarly. [ABSTRACT FROM AUTHOR]

There is an increasing need for marine spatial planning in the North Sea given the multiple uses with competing objectives. Plans to increase renewable energy production by establishing offshore wind farms (OWFs) are likely to coincide with existing and planned marine protected areas (MPAs), with obvious incompatibilities relating to conservation goals. Both will restrict fishing activities to varying degrees, thus a framework is needed to assess possible trade-offs to differing stakeholders and ecosystem health. Using a spatially-explicit trophic model, ecosystem response to different types of spatial closures to fisheries was evaluated using a variety of indicators relating to ecosystem health and fisheries productivity in the southern part of the North Sea. Additionally, hypothetical MPAs designated with specific ecological objectives in mind were tested. Scenario outcomes suggest that closures may need to be accompanied with additional fisheries management measures to avoid unintended negative impacts outside the closed areas. Furthermore, size and placement of spatial closures are important factors influencing overall benefits and losses in terms of ecological health and fisheries yield. One particular hypothetical large-scale closure, designed with the goal of protecting areas with high biodiversity, performed better in terms of indicators and trade-offs than the more fragmented, currently planned and existing closures. Although model outcomes have to be treated with care, the spatially-explicit food web modeling approach will likely aid in providing a more holistic evaluation of trade-offs between conservation objectives and fishing activities, which should contribute to a more target-oriented framework for the evaluation of closed areas. • Positive impact of fishing exclusion on ecological indicators inside closed area. • Fishing effort reduction needed to counterbalance effects of effort redistributions. • Placement and size of closure most important. • Trade-offs not only between sectors, but also within food web. • Closure of area with low fishing effort and high protective value performed best. [ABSTRACT FROM AUTHOR]

Maximising the long term average catch of single stock fisheries as prescribed by the globally-legislated MSY objective is unlikely to ensure ecosystem, economic, social and governance sustainability unless an effort is made to explicitly include these considerations. We investigated how objectives to be maximised can be combined with sustainability constraints aiming specifically at one or more of these four sustainability pillars. The study was conducted as a three-year interactive process involving 290 participating science, industry, NGO and management representatives from six different European regions. Economic considerations and inclusive governance were generally preferred as the key objectives to be maximised in complex fisheries, recognising that ecosystem, social and governance constraints are also key aspects of sustainability in all regions. Relative preferences differed between regions and cases but were similar across a series of workshops, different levels of information provided and the form of elicitation methods used as long as major shifts in context or stakeholder composition did not occur. Maximising inclusiveness in governance, particularly the inclusiveness of affected stakeholders, was highly preferred by participants across the project. This suggests that advice incorporating flexibility in the interpretation of objectives to leave room for meaningful inclusiveness in decision-making processes is likely to be a prerequisite for stakeholder buy-in to management decisions. [ABSTRACT FROM AUTHOR]

The southern North Sea is the stage of conflicting objectives of beam trawlers targeting flatfish; of shrimp trawlers fishing for brown shrimp with bycatch of juvenile flatfish; and of demersal trawlers, the main fishery on cod, a key predator of shrimp and other groups. To expose trade-offs between the fleets’ objectives and to explore what a possible variant of a multispecies maximum sustainable yield (MSY) could look like, we parameterized an ecosystem model and subjected it to a range of different fishing effort levels of the three fleets. Long-term projections highlighted multiple fishing regimes that lead to catches of at least 30% of all focal stocks' single species MSYs at the same time. Trade-offs between the yields of shrimp fishers and demersal trawlers made higher simultaneous yields impossible. Besides optimizing multispecies catches, we identified effort regimes that satisfied a set of descriptors of good environmental status (GES). We found that GES can only be obtained through low efforts of beam and demersal trawlers, which cannot be aligned with our multispecies MSY variant without accepting trade-offs in fishing yields and/or conservation goals. [ABSTRACT FROM AUTHOR]

One of the most important goals in current fisheries management is to maintain or restore stocks above levels that can produce the maximum sustainable yield (MSY). However, it may not be feasible to achieve MSY simultaneously for multiple species because of trade-offs that result from interactions between species, mixed fisheries and the multiple objectives of stakeholders. The premise in this study is that MSY is a concept that needs adaptation, not wholesale replacement. The approach chosen to identify trade-offs and stakeholder preferences involved a process of consulting and discussing options with stakeholders as well as scenario modelling with bio-economic and multi-species models. It is difficult to intuitively anticipate the consequences of complex trade-offs and it is also complicated to address them from a political point of view. However, scenario modelling showed that the current approach of treating each stock separately and ignoring trade-offs may result in unacceptable ecosystem, economic or social effects in North Sea fisheries. Setting F MSY as a management target without any flexibility for compromises may lead to disappointment for some of the stakeholders. To treat F MSY no longer as a point estimate but rather as a “Pretty Good Yield” within sustainable ranges was seen as a promising way forward to avoid unacceptable outcomes when trying to fish all stocks simultaneously at F MSY . This study gives insights on how inclusive governance can help to reach consensus in difficult political processes, and how science can be used to make informed decisions inside a multi-dimensional trade-off space. [ABSTRACT FROM AUTHOR]

Abstract: The performance of the EU long-term management plan for cod stocks, in force since 2009, is analysed focusing on the human and institutional factors. The plan operates through landings quotas (TACs) and effort restrictions following a Harvest Control Rule, and deploys a novel instrument allowing Member States to ‘buy back’ or increase fishing effort for fleet segments engaged in cod-avoidance measures. The stipulated fishing mortality reductions have not been achieved. On the positive side, the ‘buy-back’ instrument has led to increased uptake of selective gear and implementation of permanent and real-time temporary closures. On the negative side, ignoring the dimension of fishers as reactive agents in the design, the impact assessment, and the annual implementation of the measures has contributed to the failure to adequately implement the plan and achieve its objectives. The main problem is that the landings quotas taken in a mixed fishery did not limit catches because fishers were incentivised to continue fishing and discard overquota catch while quota for other species was available. The effort limitations intended to reduce this effect were insufficient to adequately limit fishing mortality in targeted fisheries, although fishers experienced them as prohibiting the full uptake of other quotas. Recommendations for future plans include (i) management through catch rather than landings quotas, (ii) the internalisation of the costs of exceeding quotas, (iii) use of more selective gear types, (iv) the development of appropriate metrics as a basis for regulatory measures and for evaluations, (v) participatory governance, (vi) fishery-based management, (vii) flexibility in fishing strategy at vessel level. [Copyright &y& Elsevier]

Background and Purpose: To this day, the diagnostic and therapeutic strategy for acute lower gastrointestinal hemorrhage requiring transfusion varies among different hospitals. The purpose of this paper was to evaluate our own data on the group of patients presented and to outline our diagnostic and therapeutic regime taking into account the literature of the past 30 years.Methods: Following prospective data collection on 63 patients of a university hospital (40 male, 23 female patients) who received surgical intervention for acute lower intestinal hemorrhage requiring transfusion, we retrospectively analyzed the data. After a medical history had been taken, all patients underwent clinical examination, including digital palpation; 62 patients underwent procto-rectoscopy, 38 gastroscopy and colonoscopy, 52 patients colonoscopy only, and 45 patients gastroscopy only. Angiography was applied in 14 cases and scintigraphy in 20 cases.Results: Diagnostic procedures to localize hemorrhage were successful in 61 cases, 41 of which through endoscopy, 12 through angiography, and eight through scintigraphy. Of our group of patients, 32 suffered from a bleeding colonic diverticulum, eight from angiodysplasia, and five from bleeding small bowel diverticula. Five patients had inflammatory bowel disease and three neoplasia. Among the surgical interventions, segmental resections were performed most frequently (15 sigmoidectomies, 11 small bowel segmental resections, 11 left hemicolectomies, seven right hemicolectomies, one proctectomy). Subtotal colectomies were carried out in ten cases. The complication rate for this group of critically ill, negatively selected patients was 60.3% and the mortality rate was 15.9%.Conclusions: Examination and stabilization of the patient is directly followed by diagnostic localization. Today, we primarily rely on nonsurgical control of hemorrhage by endoscopy or angiography; the indication for surgery is mainly limited to peracute, uncontrollable, and recurrent forms. In the case of surgery, intestinal segmental resection is recommended after identification of the lesion; if the localization of colonic hemorrhage is uncertain, subtotal resection is the method of choice. For stable patients with unverifiable small-bowel hemorrhage we recommend regular re-evaluation. [ABSTRACT FROM AUTHOR]

• First to study sexual harassment as a friction to optimal utilization of human capital. • The Harvey Weinstein scandal used as a positive shock that reduced sexual harassment. • Reducing the threat of sexual harassment in the workplace improves productivity. • Performance of female fund managers increases after the Harvey Weinstein scandal. Sexual harassment, a widespread problem in the workplace, keeps female employees from optimally employing their human capital. We show that removing or diminishing this friction improves productivity. Specifically, using the male-dominated fund industry as our testing ground, we show that productivity of female mutual fund managers significantly increased after the Harvey Weinstein scandal and the onset of the #MeToo movement. Evidence from lawsuits and organizational changes at several fund companies also suggests that reducing the threat of sexual harassment improves productivity. Our results have important implications for the policy debate on workforce diversity and costs of sexual harassment. [ABSTRACT FROM AUTHOR]

• Novel approach combining species distribution models (SDMs) with Ecospace. • Performance of presence/absence- vs. abundance-based (Hurdle) SDMs are evaluated. • Presence/absence SDMs perform better than abundance-based (Hurdle) SDMs. • Results highlight how spatial distributions can drive trophic interactions. One of the most applied tools to create ecosystem models to support management decisions in the light of ecosystem-based fisheries management is Ecopath with Ecosim (EwE). Recently, its spatial routine Ecospace has evolved due to the addition of the Habitat Foraging Capacity Model (HFCM), a spatial-temporal dynamic niche model to drive the foraging capacity to distribute biomass over model grid cells. The HFCM allows for continuous implementation of externally derived habitat preference maps based on single species distribution models. So far, guidelines are lacking on how to best define habitat preferences for inclusion in process-oriented trophic modeling studies. As one of the first studies, we applied the newest Ecospace development to an existing EwE model of the southern North Sea with the aim to identify which definition of habitat preference leads to the best model fit. Another key aim of our study was to test for the sensitivity of implementing externally derived habitat preference maps within Ecospace to different time-scales (seasonal, yearly, multi-year, and static). For this purpose, generalized additive models (GAM) were fit to scientific survey data using either presence/absence or abundance as differing criteria of habitat preference. Our results show that Ecospace runs using habitat preference maps based on presence/absence data compared best to empirical data. The optimal time-scale for habitat updating differed for biomass and catch, but implementing variable habitats was generally superior to a static habitat representation. Our study hence highlights the importance of a sigmoidal representation of habitat (e.g. presence/absence) and variable habitat preferences (e.g. multi-year) when combining species distribution models with an ecosystem model. It demonstrates that the interpretation of habitat preference can have a major influence on the model fit and outcome. [ABSTRACT FROM AUTHOR]