Search

Fishing is well known to curtail the size distribution of fish populations. This paper reports the discovery of small-scale spatial patterns in length appearing in several exploited species of Celtic Sea demersal 'groundfish'. These patterns match well with spatial distributions of fishing activity, estimated from vessel monitoring records taken over a period of 6 years, suggesting that this 'mobile' fish community retains a persistent impression of local-scale fishing pressure. An individual random-walk model of fish movement best matched these exploitation 'footprints' with individual movement rates set to Electronic supplementary material The online version of this article (doi:10.1007/s00227-015-2665-1) contains supplementary material, which is available to authorized users., Author(s): Francisco de Castro[sup.1] , Samuel Shephard[sup.1] , Sarah B. M. Kraak[sup.1] [sup.2] [sup.3 ] [sup.4] , David G. Reid[sup.3] , Keith D. Farnsworth[sup.1] Author Affiliations: (1) School of Biological [...]

The EU deploys technical measures (TMs) to avoid unwanted catches—here, overquota catches and juveniles of commercial species—including gear specifications and closures. In 2012, the European Commission had asked its advisory committee, Scientific, Technical, and Economic Committee for Fisheries (STECF), to evaluate the TMs and provide recommendations for improvement. In 2012–2013, STECF judged that the TMs had failed to achieve their objectives and identified approaches for improvement: (1) regionalization and move away from top-down management; (2) bottom-up results-based management to internalize the costs to the resource into individual businesses; and (3) abandon threshold percentages of bycatch leading to perverse incentives. In 2014, the new EU Common Fisheries Policy came in force, with a landing obligation (LO), and regionalization. In 2019, the new TM regulation (TMR) came in force. Besides sets of regional baseline measures, the TMR allows for regional proposals for amendments and results-based bottom-up approaches ("the good"). However, the LO is not enforced, therefore, not providing the incentive for change in fishing practices; and despite avoidance strategies being available regional, innovative bottom-up practices are still rare ("the bad"). TMs still contain threshold percentages ("the ugly"). The onus for bottom-up initiatives is on the industry, although new governance structures are needed to facilitate this. [ABSTRACT FROM AUTHOR]

Background: The field of behavioural economics holds several opportunities for integrated fisheries management and conservation and can help researchers and managers alike understand fisher behaviour and decision-making. As the study of the cognitive biases that influence decision-making processes, behavioural economics differentiates itself from the classical field of economics in that it does not assume strictly rational behaviour of its agents, but rather looks for all mechanisms that influence behaviour. This field offers potential applications for fisheries management, for example in relation to behavioural change, but such applications require evidence of these mechanisms applied in a fisheries context. Thus, we have developed a systematic literature review protocol focusing on the primary question: "Which behavioural economics mechanisms influence fisher behaviour?" The aim is to provide a comprehensive overview of these different mechanisms and how they have been applied in the study of fisher behaviour. Methods and expected outputs: The review protocol was developed in close collaboration with the International Council for the Exploration of the Sea (ICES) Working Group on Maritime Systems (WGMARS). WGMARS members were therefore considered the key stakeholders for this study, and were consulted to develop a suitable systematic review question and methodology. Three academic databases will be searched using a customized Boolean keyword search string. Research articles deemed eligible for inclusion in the systematic review are those that studied the influence of behavioural-economics mechanisms on the behaviour of marine fishers in any location, and at any scale. Insights from this literature will be collated in order to provide an overview of the relevant behavioural-economics mechanisms and actions, how effective these mechanisms are and at what scale, geographic region and in which fisheries sector they have been applied. Any fisheries management implications identified by the studies under review will also be outlined. Finally, it will be recorded whether or not ethical considerations were made in the reviewed literature, so that in the discussion it will be possible to reflect on the ethics of conducting behavioural-economics research and policy actions in a fisheries context. [ABSTRACT FROM AUTHOR]

This article describes a method for the quantitative analysis of fish behaviour relative to selection devices in trawl gears. Based on video observations, the method estimates probabilities for a given event to happen and establishes behavioural tree diagrams representing and quantifying behavioural patterns in relation to the selection device under assessment. Double bootstrapping is used to account for the uncertainty originating from a limited number of fish observations and the natural variation in fish behaviour. The method is used here to supplement standard analysis of catch data for the performance assessment of a flatfish excluder (FLEX). The Baltic Sea trawl fishery targeting cod (Gadus morhua) provides the pilot case. Results obtained by comparing catches with and without FLEX installed revealed that >75% of bycaught flatfish individuals escaped through the device, while no evidence was found that catches of cod in the targeted sizes were reduced. The behavioural analysis produced values of escape efficiency comparable to those obtained in the catch analysis. Furthermore, it revealed that ∼80% of the flatfish went calmly into the excluder, while most of the roundfish displayed avoidance swimming reactions. The method provides quantitative information of fish behaviour that can be relevant for developing and optimizing selection devices. [ABSTRACT FROM AUTHOR]

When size-selective fishing removes faster-growing individuals at higher rates than slower-growing fish, the surviving populations will become dominated by slower-growing individuals. When this "Rosa Lee phenomenon" is ignored, bias may occur in catch and stock projections. In a length-and-age-based model we quantified the effects through simulations of a simplified fishery on a stock that resembles Western Baltic cod. We compared outcomes of runs with and without taking account of the Rosa Lee phenomenon in scenarios of changes in fishing mortality. We found that, when only fishing rate was changed, the biases in predictions of spawning-stock biomass (SSB), yield and catches of undersized fish were relatively small (<10% in absolute values). When the selectivity parameters of the gear were increased, the bias in the prediction of the catches of undersized fish was very substantial (+120 to 160%). When the selectivity parameters were decreased, the biases in the predictions of SSB, yield and catches of undersized fish, were substantial (25–50% in absolute values). With slower mean growth the biases became more pronounced. We conclude that in short-term forecasts, medium-term projections, and MSE simulations featuring selectivity changes, the Rosa Lee phenomenon should be accounted for, ideally by using length-based models. [ABSTRACT FROM AUTHOR]

Despite regular reforms, problems under the EU's Common Fisheries Policy (CFP) persist. In order to identify priorities for future reforms of the policy, we developed an analytical framework consisting of 17 criteria and specifying indicators, derived from scientific, wider fisheries, and common resources literature. We applied the framework to the CFP governance system, its regulations, institutions, and processes at EU as well as member state level. The results show that the CFP does not fully meet any of the 17 criteria for an effective resource policy. Its performance was assessed as "neutral" regarding 10 criteria and "negative" regarding seven criteria. Trend analysis shows that there is a slightly positive trend regarding the CFP's performance, with five criteria trending positively, 11 showing a neutral trend and only one criterion trending negatively (simplicity of rules). The analysis identified five criteria which are performing badly and have not improved over time: simplicity of rules, user‐pays principle, resource efficiency, accountability, and compliance mechanisms. Future reforms of the CFP should first and foremost address these criteria while continuing efforts to improve the CFP's performance regarding other criteria. The evaluation of the CFP demonstrates the applicability of the analytical framework which can also be applied to other multilevel fisheries governance systems. Moreover, the results can inform reforms of Regional Fisheries Management Organisations. Like the CFP, these institutions manage transboundary fisheries and have not effectively addressed the issues of resource rent capture and resource efficiency. [ABSTRACT FROM AUTHOR]

We consider the problem of regulating the rate of harvesting a natural resource, taking account of the wider system represented by a set of ecological and economic indicators, given differing stakeholder priorities. This requires objective and transparent decision making to show how indicators impinge on the resulting regulation decision. We offer a new scheme for combining indicators, derived from assessing the suitability of lowering versus not lowering the harvest rate based on indicator values relative to their predefined reference levels. Using the practical example of fisheries management under an “ecosystem approach,” we demonstrate how different stakeholder views can be quantitatively represented by weighting sets applied to these comparisons. Using the scheme in an analysis of historical data from the Celtic Sea fisheries, we find great scope for negotiating agreement among disparate stakeholders. [ABSTRACT FROM AUTHOR]

In situations of declining or depleted fish stocks, exploiters seem to have fallen prey to the Tragedy of the Commons, which occurs when the maximisation of short-term self-interest produces outcomes leaving all participants worse off than feasible alternatives would. Standard economic theory predicts that in social dilemmas, such as fishing from a common resource, individuals are not willing to cooperate and sacrifice catches in the short term, and that, consequently, the resource is overharvested. However, over the last decades, a multitude of research has shown that humans often achieve outcomes that are 'better than rational' by building conditions where reciprocity, reputation, and trust help to overcome the temptations of short-term self-interest. The evolution of the natural human tendency to cooperate under certain conditions can be explained, and its neuro-physiological and genetic bases are being unravelled. Nevertheless, fisheries management still often deploys top-down regulation and economic incentives in its aim to regulate fisher behaviour, and under-utilizes the potential for spontaneous responsible fisher behaviour through setting conditions that enhance natural cooperative tendencies. Here I introduce this body of knowledge on how to overcome the Tragedy of the Commons to the audience of fisheries scientists, hoping to open up novel ways of thinking in this field. I do this through a series of thought experiments, based on actual published experiments, exploring under what conditions responsible and cooperative fisher behaviour can be expected. Keys include reputation-building and indirect reciprocity, face-to-face communication, knowledge on the state of the resource, and self-decision on rules and sanctions. [ABSTRACT FROM AUTHOR]

Scientists feel discomfort when they are asked to create certainty, where none exists, for use as an alibi in policy-making. Recently, the scientific literature has drawn attention to some pitfalls of simulation-based fisheries management-strategy evaluation (MSE). For example, while estimates concerning central tendencies of distributions of simulation outcomes are usually fairly robust because they are conditioned on ample data, estimates concerning the tails of distributions (such as the probability of falling below a critical biomass) are usually conditional on few data and thus often rely on assumptions that have no strong knowledge base. The clients of scientific advice, such as the European Commission, are embracing the mechanization of the evaluation of proposed Harvest Control Rules against the precautionary principle and management objectives. Where the fisheries management institutions aim for simple answers from the scientists, giving ‘green/red light’ to a proposed management strategy, the scientists are forced into a split position between satisfying the demands of their advisory role and living up to the standards of scientific rigour. We argue against the mechanization of scientific advice that aims to incorporate all relevant processes into one big model algorithm that, after construction, can be run without circumspection. We rather encourage that fisheries advice should be a dynamic process of expert judgement, incorporating separate parallel concurrent, lines of scientific evidence, from quantitative and qualitative modelling exercises and factual knowledge of the biology and the fishery dynamics. This process can be formalized to a certain degree and can easily accommodate stakeholder viewpoints. [ABSTRACT FROM AUTHOR]

Catchability is crucial for the economic performance of fisheries and their management. However, in many bio-economic simulation models it is assumed to be either constant or it is largely ignored, despite the fact that it is known to vary due to technical, environmental and behavioral factors. Such variation can cause the relationship between effort and fishing mortality to be nonlinear. This paper provides evidence for the possibility of nonlinear optimizing behavior from the Dutch beam trawl fishery, provides a methodology for estimating the curvature of the resulting relation, and a simple way of implementing these processes within a bio-economic model. Moreover, it shows the influence of a nonlinear relationship between effort and fishing mortality in a model of effort management (EU long-term flatfish management plan). [ABSTRACT FROM AUTHOR]

Pastoors, M. A., Poos, J. J., Kraak, S. B. M., and Machiels, M. A. M. 2007. Validating management simulation models and implications for communicating results to stakeholders. – ICES Journal of Marine Science, 64: 818–824.Simulations of management plans generally aim to demonstrate the robustness of the plans to assumptions about population dynamics and fleet dynamics. Such modelling is characterized by specification of an operating model (OM) representing the underlying truth and a management procedure that mimics the process of acquiring knowledge, formulating management decisions, and implementing those decisions. We employ such a model to evaluate a management plan for North Sea flatfish proposed by the North Sea Regional Advisory Council in May 2005. Focus is on the construction and conditioning of OMs, key requirements for such simulations. We describe the process of setting up and validating OMs along with its effects on the ability to communicate the results to the stakeholders. We conclude that there is tension between the level of detail required by stakeholders and the level of detail that can be provided. In communicating the results of simulations, it is necessary to make very clear how OMs depend on past perceptions of stock dynamics. [ABSTRACT FROM PUBLISHER]

Previous studies have shown (1) that stickleback males enjoy increased mating success when their nest is concealed, (2) that males reduce their courtship in the face of predation risk to a lesser extent when their nest is concealed, and (3) that eggs in concealed nests have higher hatching chances. Here we test the prediction that male sticklebacks prefer to establish a territory at a site with a macrophyte under which they can conceal their nest. We planted macrophytes at half of the potential nest sites at two depths, in a section of a channel in which sticklebacks naturally occur. Subsequently, we found significantly more nests with eggs at the sites concealed by macrophytes than at the control sites, suggesting that wild sticklebacks preferred to build their nests at sites that offer concealment. At the shallow depth, males occupying a site with a macrophyte were larger and redder than males at control sites, but not at the deeper level. This suggests that males of higher competitive ability and greater conspicuousness were more likely to settle at shallow sites where predation risk by the grey heron is high. [ABSTRACT FROM AUTHOR]

Marine litter is a global concern. Since most of the litter sinks, understanding the composition of benthic marine litter is crucial for addressing this concern. However, high costs of seafloor monitoring inhibit such understanding. Consequently, benthic marine litter in the Baltic Sea has not been comprehensively addressed yet. Here we present data from 2377 hauls, which collected 6828 litter items and 2412 kg on the Baltic seafloor during six years of the Baltic International Trawl Survey (BITS) by seven nations. Our results show lower percentages of plastic (35%) than the widely cited world average (70%) and less fishery-originated litter (2.2-5.6%) than was previously reported for the Baltic Sea (4-24%). Natural products, mostly residuals of burnt coal, were identified as the most common litter category (42-57%) and were largely ignored in the past. Our results highlight the importance of using several evaluation metrics, particularly number of items, weight and encounter probability., (Copyright © 2019 Elsevier Ltd. All rights reserved.)