Multispecies fisheries management in the Mediterranean Sea: application of the Fcube methodology

Abstract The ecosystem approach (EA) advocates that advice should be given based on a holistic management of the entire marine ecosystem and all fisheries and fleets involved. Recent developments have advanced to multi‐species, multi‐fisheries advice, rather than on a single‐species/fleet/area stock basis, bridging the gap between existing single‐species approaches and the needs of the EA. The Fleet and Fisheries Forecast method (Fcube) method estimates potential levels of effort by fleet in mixed fisheries situations to achieve specific targets of fishing mortality. Data on effort, landings and socioeconomic parameters were used for coastal and trawl fisheries in the Aegean Sea. Results pointed out the strengths and weaknesses of alternative management strategies from both a biological and socioeconomic perspective. Fcube revealed the importance of effort control in the coastal fisheries that are still managed with no effort restrictions. The present findings, although preliminary, revealed that stringent cuts to effort and catch levels are required if EA management goals are to be met. The Fcube methodology, initially developed for mixed fisheries advice in northern European waters that are managed with TACs, also proved promising in providing advice to non‐TAC fisheries.     

The interim management procedure approach for assessed stocks: Responsive management advice and lower assessment frequency

Stock assessments are often used to provide management advice, such as a total allowable catch (TAC), to fishery managers. Many stocks are not assessed annually, and the TAC from the previous assessment is often maintained in years between assessments. We developed two interim management procedures (MPs) that update the estimate of current vulnerable biomass from a surveyed index of abundance to adjust the TAC from a previous assessment. These MPs differ in how they handle uncertainty in observed indices. Using closed‐loop simulation, we evaluated the two interim MPs (with 10‐ and 5‐year assessment intervals) against several “status quo” approaches: (1) an annual assessment, and (2) a stock assessment every 5 or 10 years with (a) fixed TACs or (b) projections between assessments. We evaluated performance across three life‐history types and six operating model scenarios. The interim MPs performed similarly to annual assessments in terms of trends in biomass and yield, regardless of the assessment interval of the interim MPs. The interim MPs often produced more yield than the Fixed TAC MP with 10‐year assessment intervals, for example, in depleted scenarios. The Fixed TAC MP performed more similarly to interim MPs when the assessment interval for the Fixed TAC MP was decreased to five years. The interim MPs can also perform well when circumstances arise that are not accounted for in the Projection MP. Our results show that interim MPs should be considered for infrequently assessed stocks or rebuilding stocks, and highlight potential cost savings of interim MPs over annual assessments.     

Does ‘race to fish’ behaviour emerge in an individual transferable quota fishery when the total allowable catch becomes non‐binding?

Successful individual transferable quota (ITQ) management requires a binding (constraining) total allowable catch (TAC). A non‐binding TAC may result in a shift back towards open access conditions, where fishers increasingly compete (‘race’) to catch their share of the total harvest. This process was examined by comparing fishing fleet behaviour and profitability in the Tasmanian southern rock lobster (Jasus edwardsii) fishery (TSRLF), Australia. Between 2008 and 2010, the TSRLF had a non‐binding TAC and effectively reverted to a regulated, limited‐entry fishery. Fishers' uncertainty about future profitability and their ability to take their allocated catch weakened the security characteristic of the ITQ allocation. The low quota lease price contributed to an increase in fleet capacity, while the more limited reduction in quota asset value proved an investment barrier, hindering the autonomous adjustment of quota towards the most efficient fishers. In the TSRLF, catch rates vary more than beach price and are therefore more important for determining daily revenue (i.e., price x catch rate) than market price. Consequently, fishers concentrated effort during times of higher catch rates rather than high market demand. This increased rent dissipation as fishers engaged in competitive race to fish to be the first to exploit the stock and obtain higher catch rates. The history of this fishery emphasizes the need for a constraining TAC in all ITQ fisheries, not only for stock management, but also to manage the security of the ITQ allocation and prevent unanticipated and undesirable changes in fisher behaviour and fishery profitability.     

Estimating and monitoring the stock size of sandfish <Emphasis Type="Italic">Arctoscopus japonicus</Emphasis> in the northern Sea of Japan

ABSTRACT:   The stock size of sandfish in the northern Sea of Japan was estimated by a virtual population analysis (VPA) and sensitivity analyses were attempted on the VPA estimate. The stock size estimates were approximately 600–900 million until 1975, but since 1976 they have rapidly decreased. In the sensitivity analyses, the estimates of absolute stock size were not sensitive against the changes in the fishing mortality coefficient for terminal age and the measurement error in catch-at-age. This suggested that the relative stock size remains almost unaffected by the error in the data used in the VPA, if the degree of catch-at-age error and the natural mortality coefficient is correct. The relationships between the biomass estimated by the VPA and the density index from Danish seine fisheries, and between the biomass and the catch per unit effort (CPUE) from the experimental survey using Danish seine nets, were also examined. The density index and the CPUE indicated significant relations with the biomass. Consequently, the CPUE is useful to monitor the relative stock size in a timely manner, and the VPA estimate and the CPUE should be utilized for adjusting the total allowable catch in the multiseasons.     

Closure strategies as a tool for fisheries management in metapopulations subjected to catastrophic events

Abstract Spatial management measures in the form of no‐take areas used in fisheries management can provide a buffer against catastrophic events. Dynamic area closures, like rotational closures, have also been used as a management tool particularly for sessile organisms. In this study, bioeconomic models are developed to investigate dynamic closure strategies for use as a management tool in the harvest of a metapopulation consisting of two local sub‐populations. The models provide an optimal strategy that maximises the sum of discounted net returns with a fixed harvest level [i.e. total allowable catch (TAC)] by opening and closing the sub‐populations of a metapopulation, subject to random negative catastrophic effects. Results showed the optimal policy for opening and closing a single exploited population depends on the degree and pattern of migration between it and other sub‐populations. When the harvest or TAC can be applied to either sub‐population, the optimal closure strategy depends on the abundance of both populations, crucially, even if they are biologically independent. The results provide insights into the management of stochastically fluctuating populations including more mobile species that are frequently not subject to no‐take controls.     

How do individual transferable quotas affect marine ecosystems?

Published papers were reviewed to assess ecosystem impacts of individual transferable quotas (ITQs) and other dedicated access systems. Under ITQs, quota shares increase with higher abundance levels, thus fishers may request lower total allowable catches (TACs) and pay for monitoring and research that improves fishery sustainability. Mortality on target species generally declines because catches are closer to TACs and because ghost fishing through lost and abandoned gear decreases. High-grading and discarding often decline, but may increase if landings (and not catches) count against ITQs and when there is little at-sea enforcement. Overall, ITQs positively impact target species, although collapses can occur if TACs are set too high or if catches are routinely allowed to exceed TACs. Fishing pressure may increase on non-ITQ species because of spillover from ITQ fisheries, and in cases where fishers anticipate that future ITQ allocations will be based on catch history and therefore increase their current catches. Ecosystem and habitat impacts of ITQs were only sparsely covered in the literature and were difficult to assess: ITQs often lead to changes in total fishing effort (both positive and negative), spatial shifts in effort, and fishing gear modifications. Stock assessments may be complicated by changes in the relationship between catch per unit effort, and abundance, but ITQ participants will often assist in improving data collection and stock assessments. Overall, ITQs have largely positive effects on target species, but mixed or unknown effects on non-target fisheries and the overall ecosystem. Favourable outcomes were linked to sustainable TACs and effective enforcement.     

Assessing the state of Greek marine fisheries resources

Annual fish landings for the Greek seas were analysed for the period 1982–2007 and classified into exploitation categories based on a catch‐based stock classification method. In 2007, about 65% of the Greek stock were characterised as overfished, 32% as fully exploited and only 3% were characterised as developing; collapsed stocks were not recorded. The cumulative percentage of fully exploited and overfished stocks has been increasing over the past 20 years suggesting overexploitation of resources. The results were contrasted against total landings, the fishing‐in‐balance index (FiB) and fishing effort, and some irregularities on the dataset were explained based on current legislation and management measures. A positive correlation between FiB and total fishing effort confirmed the expansion of the Greek fisheries up to 1994, but contraction thereafter. The results suggest that the apparently stable overall catches and decreasing effort may be deceiving, as they hide an underlying pattern of overexploitation in some of the stocks. It was concluded that the Greek fisheries are no longer sustainable and radical management measures are needed.     

Global marine yield halved as fishing intensity redoubles

There is widespread concern and debate about the state of global marine resources and the ecosystems supporting them, notably global fisheries, as catches now generally stagnate or decline. Many fisheries are not assessed by standard stock assessment methods including many in the world's most biodiverse areas. Though simpler methods using widely available catch data are available, these are often discounted largely because data on fishing effort that contributed to the changes in catches are mostly not considered. We analyse spatial and temporal patterns of global fishing effort and its relationship with catch to assess the status of the world's fisheries. The study reveals that fleets now fish all of the world's oceans and have increased in power by an average of 10‐fold (25‐fold for Asia) since the 1950s. Significantly, for the equivalent fishing power expended, landings from global fisheries are now half what they were a half‐century ago, indicating profound changes to supporting marine environments. This study provides another dimension to understand the global status of fisheries.     

Reforming the European Common Fisheries Policy: a case for capacity and effort controls

I summarize the total allowable catch (TAC) fishery management system, which forms part of the European Common Fisheries Policy (CFP) as complicated, inaccurate and ineffective. Total allowable effort (TAE), i.e. limits on fishing capacity and days‐at‐sea, provides a simpler, readily enforceable control to protect all species affected by a fishery. Fishing capacity of vessels in each region‐gear fleet could be capped through limits on engine power, gear, crew, and fittings, and/or reducing allowances of days‐at‐sea for large, powerful vessels. Two basic, fishery‐dependent indicators are put forward to assess sustainability of a fishery dependably even in the absence of fishery‐independent data. One is socio‐economic, the other is ecological. Fishery working groups within each marine region would recommend a TAE to sustain their fishery while also protecting the most critically affected species or processes. Regional working groups would supervise a consistent approach across the different fisheries in their region. A pan‐European group would set policy, implement external agreements, set rules for trading TAE if necessary and harmonize fishing opportunities across regions. To ease negotiations on TAEs with the fishing industry when an ecosystem needs to recover, I propose compensation payments funded by re‐direction of existing CFP subsidies that promote fishing.     

Fisheries management based on ecosystem dynamics and feedback control

Recently, ecosystem management has become popular for forestry, agriculture and fisheries management. Carrying capacity and maximum sustainable yield for a particular species definitely depend on population sizes of other species in the same ecosystem. Natural stock fluctuations of sardine, anchovy and chub mackerel are well known examples of large, natural fluctuations. There is a negative correlation among their fluctuations. In accordance with the cyclic advantage hypothesis for replacement of pelagic fish species (Matsuda et al., 1992), we can predict the next dominant species, despite an uncertainty in the year of the next replacement. We recommend that commercial fisheries should switch their target to the next dominant species before the stock of the present dominant species collapses. Whilst total allowable catch (TAC) of the present dominant species can be as large as we can consume, TAC after the species collapses should be much smaller than the present catch level.     

Individual transferable quotas and ecosystem‐based fisheries management: it’s all in the T

Recent articles in high‐profile journals advocating the widespread establishment of economic rights‐based approaches for managing fisheries has re‐kindled the debate over the efficacy of incentive‐based vs. regulatory‐based management approaches. Inspection of these works, written from the particular perspectives of economics, fisheries biology, or marine ecology, reveals that advocates of rights‐based regimes such as Individual Transferrable Quotas are sometimes recommending these policy instruments for quite different reasons. Hence, the advantageous attributes of rights‐based approaches from the perspective of one discipline may be quite different when seen from the perspective of another discipline. This is of concern as it exposes a tendency for particular disciplines to consider only the advantages of rights‐based approaches, such as establishing a harvest cap, but to implicitly discount the disadvantages such as less attention being paid to critical ecological and ecosystem issues.     

Understanding fisheries credit systems: potentials and pitfalls of managing catch efficiency

Following implementation in a range of other resource sectors, a number of credit‐like systems have been proposed for fisheries. But confusion exists over what constitutes these nascent ‘fisheries credit’ systems and how they operate. Based on a review of credit systems in other sectors, this study fills this gap by defining how credit systems function and what credits add to prevailing fisheries management. In doing so, we distinguish ‘mitigation’ and ‘behavioural’ fishery credits. Mitigation credits require resource users to compensate for unsustainable catches of target species, by‐catch species or damaging practices on the marine environment by investing in conservation in a biologically equivalent habitat or resource. Behavioural credit systems incentivize fishers to gradually change their fishing behaviour to more sustainable fishing methods by rewarding them with, for instance, extra fishing effort to compensate for less efficient but more sustainable fishing methods. The choice of credit system largely depends on the characteristics of specific fisheries and the management goals agreed upon by managers, scientists and the fishing industry. The study concludes that fisheries credit systems are different but complimentary to other forms of management by focusing on ‘catchability’ or gear efficiency in addition to effort or catch quota, affecting overall economic efficiency by setting specific goals as to how fish are caught. Credit systems therefore incentivize specific management interventions that can directly improve stock sustainability, conserve habitat and endangered species, or decrease by‐catch.     

Inland fish stock assessment: Applying data‐poor methods from marine systems

Inland fisheries can be diverse, local and highly seasonal. This complexity creates challenges for monitoring, and consequently, many inland fish stocks have few data and cannot be assessed using methods typically applied to industrial marine fisheries. In such situations, there may be a role for methods recently developed for assessment of data‐poor fish stocks. Herein, three established data‐poor assessment tools from marine systems are demonstrated to highlight their value to inland fisheries management. A case study application uses archived length, catch and catch‐per‐unit‐effort data to characterise the ecological status of an important recreational brown trout stock in an Irish lake. This case study is of specific use to management of freshwater sport fisheries, but the broader purpose of the paper was to provide a crossover between marine and inland fisheries science, and to highlight accessible data‐poor assessment approaches that may be applicable in diverse inland systems.     

我国海洋渔业捕捞限额制度实施试点评析与完善建议

2017—2018年我国沿海5省开展了捕捞限额制度实施试点,在实地调查的基础上,对试点渔业的捕捞限额制度实施情况进行了回顾和比较分析。试点渔业在利用专项捕捞许可制度限制捕捞准入、加强渔捞日志管理、试行观察员制度、吸纳基层渔民组织参与监管等方面进行了有益的探索。不同试点之间在实施捕捞限额管理的渔业资源种类选择、渔场和渔船及作业方式的特定性、配套制度等方面具有共性;在捕捞对象种类的单一性、渔场进入的排他性、捕捞限额分配方式、渔获量监测措施方面存在差异。目前我国实施捕捞限额制度仍存在多鱼种渔业问题、捕捞生产监测制度尚未建立、针对性资源调查监测不足、捕捞限制性措施未能有效执行、管理能力和体制不适应需求、违反管理要求的法律责任缺失等问题。建议修改《渔业法》以完善捕捞限额制度体系,加强和完善渔业资源调查、监测,建立综合性渔业数据信息系统,进一步完善基于捕捞许可制度的捕捞作业限制,建立多方参与和跨区域联合的监管机制,根据渔业特点分类设置捕捞限额及其管理机制。     

CPUE standardisation and the construction of indices of stock abundance in a spatially varying fishery using general linear models

Construction of annual indices of stock abundance based on catch and effort data remains central to many fisheries’ assessments. While the use of more advanced statistical methods has helped catch rates to be standardised against many explanatory variables, the changing spatial characteristics of most fisheries data sets provide additional challenges for constructing reliable indices of stock abundance. After reviewing the use of general linear models to construct indices of annual stock abundance, potential biases which can arise due to the unequal and changing nature of the spatial distribution of fishing effort are examined and illustrated through the analysis of simulated data. Finally, some options are suggested for modelling catch rates in unfished strata and for accounting for the uncertainties in the stock and fishery dynamics which arise in the interpretation of spatially varying catch rate data.     

Assessing and managing data‐limited ornamental fisheries in coral reefs

Coral reefs support numerous ornamental fisheries, but there are concerns about stock sustainability due to the volume of animals caught. Such impacts are difficult to quantify and manage because fishery data are often lacking. Here, we suggest a framework that integrates several data‐poor assessment and management methods in order to provide management guidance for fisheries that differ widely in the kinds and amounts of data available. First, a resource manager could assess the status of the ecosystem (using quantitative metrics where data are available and semi‐quantitative risk assessment where they are not) and determine whether overall fishing mortality should be reduced. Next, productivity susceptibility analysis can be used to estimate vulnerability to fishing using basic information on life history and the nature of the fishery. Information on the relative degree of exploitation (e.g. export data or ratios of fish density inside and outside no‐take marine reserves) is then combined with the vulnerability ranks to prioritize species for precautionary management and further analysis. For example, species that are both highly exploited and vulnerable are good candidates for precautionary reductions in allowable capture. Species that appear to be less vulnerable could be managed on a stock‐specific basis to prevent over‐exploitation of some species resulting from the use of aggregate catch limits. The framework could be applied to coral reef ornamental fisheries which typically lack landings, catch‐per‐unit‐effort and age‐size data to generate management guidance to reduce overfishing risk. We illustrate the application of this framework to an ornamental fishery in Indonesia.     

Following the chain to elusive anglers

Obtaining reliable estimates of important parameters from recreational fisheries is problematic but critical for stock assessment and effective resource management. Sampling methodologies based on traditional design‐based sampling theory, is inadequate in obtaining representative catch and effort data, social or demographical characterization, or fisher behaviour from small hard‐to‐reach components within recreational fisheries (e.g. specialized sport fisheries) that may account for the majority of the catch for some species. A model‐based approach to sampling is necessary. Researchers in other disciplines including epidemiology and social sciences routinely survey rare or ‘hidden’ populations within the general community by penetration of social networks rather than by interception of individuals. We encourage fisheries researchers to rethink survey designs and consider the social elements of recreational fishing. Employing chain‐referral methods, such as respondent‐driven sampling (RDS), may be a statistically robust and cost‐effective option for sampling elusive sub‐elements within recreational fisheries. Chain‐referral sampling methodology is outlined and an example of a complemented ‘RDS‐recapture’ survey design is introduced as a cost‐effective application to estimating total catch in recreational fisheries.     

Quantifying fishing effort: a synthesis of current methods and their applications

The need to accurately quantify fishing effort has increased in recent years as fisheries have expanded around the world and many fish stocks and non‐target species are threatened with collapse. Quantification methods vary greatly among fisheries, and to date there has not been a comprehensive review of these methods. Here we review existing approaches to quantify fishing effort in small‐scale, recreational, industrial, and illegal, unreported and unregulated (IUU) fisheries. We present the strengths and limitations of existing methods, identifying the most robust methods and the critical knowledge gaps that must be addressed to improve our ability to quantify and map fishing effort. Although identifying the ‘best’ method ultimately depends on the intended application of the data, in general, quantification methods that are based on information on gear use and spatial distribution offer the best approaches to representing fishing effort on a broad scale. Integrating fisher’s knowledge and involving fishers in data collection and management decisions may be the most effective way to improve data quality and accessibility.     

基于渔船捕捞行为特征的远洋延绳钓渔场捕捞强度计算

渔场捕捞强度信息可以为渔业资源评估和管理提供帮助。本研究结合2017年10—11月船舶自动监控系统(AutomaticIdentificationSystem,AIS)信息和同期中国中西太平洋延绳钓渔船捕捞日志数据,通过挖掘延绳钓渔船作业航速和航向特征,建立渔场作业状态识别模型,提取渔场捕捞强度信息。以3～9节为航速阈值和0°～10°及300°～360°为航向阈值,渔船作业状态识别准确率为68.29%。阈值识别和日志记录的捕捞强度信息在空间上相关性很高(0.96),基于AIS信息挖掘的渔船捕捞强度空间分布特征和实际非常相似。阈值识别和日志记录的捕捞强度信息在空间上与单位捕捞努力量渔获量(catch per unite of effort, CPUE)、渔获尾数、渔获重量和投钩数的空间相关系数均大于0.62,基于AIS信息挖掘的渔船空间捕捞强度也可替代用于渔业资源分析。     

基于CMSY和BSM的东海区重要渔业种类资源评估

有限数据方法(data-limited method)可结合少量易获得数据和相关生物学信息对渔业资源状况、生物学参考点以及生物量等进行评估,已经成为全球区域性渔业管理组织和资源评估学者的关注热点。本研究采用基于渔获量的最大可持续渔获量(catch-based maximum sustainable yield,CMSY)和基于贝叶斯状态空间的Schaefer产量模型(Bayesian Schaefer production model,BSM)评估了东海区19个重要经济种类的资源状况,并提出了基于最大可持续渔获量(maximum sustainable yield,MSY)的渔业管理建议。结果显示,19个种类中有1个种类衰竭,3个种类严重衰退,5个种类过度捕捞,5个种类轻度过度捕捞,5个种类健康。种群状态长期评估结果表明,处于生物可持续水平的鱼类种群占比已由1980年的95%下降至2019年的26%。同时对CMSY和BSM方法的结果进行了比较,整合单位捕捞努力量渔获量(catch per unit effort,CPUE)数据的BSM方法导致了置信区间较宽,并调节了生物量轨迹的变化形态...