Trends in landings of fish species potentially affected by climate change in Portuguese fisheries

Fisheries are an important source of food, with a high economic value and social significance. The present worrying situation of the world fisheries is the result of the interaction between different factors (e.g. climatic variations, natural oscillations, technological innovation), but the greatest challenges are overfishing and climate change. The species richness of the Portuguese coast is generally higher than that found in northern Europe and similar to that of the Mediterranean, since many species have their southern or northern distribution limits along the Portuguese coast. The zoogeographic importance of this latitudinal area has long been recognized, representing the transition between north-eastern Atlantic warm-temperate and cold-temperate regions, which makes the Portuguese coast an area of great sensitivity to the detection of climate change. Official landing data for commercial species that have the Portuguese coast as their distribution limit were analysed together with sea surface temperature for the period of 1927–2011. In general, landings of species with affinity for temperate waters presented a decreasing trend, whereas species with affinity for subtropical/tropical waters showed an increasing trend. These variations were associated with variation in temperature: lower landings of temperate species occurred mainly in warm years, whereas landings of subtropical/tropical species presented an opposite trend, with higher landings in warm years. Preparing for the impacts of climate change is crucial for the sustainability of fisheries. Management should take into consideration information about environmental factors that affect species distribution and abundance.     

Impact of climate warming upon the fish assemblages of the Portuguese coast under different scenarios

Impact of sea-surface warming upon the fish assemblages of the Portuguese coast was assessed under two scenarios, the A2 and the B2 scenarios (Special Report on Emission Scenarios), which when coupled with a regional circulation model HadRM3 predict 1 and 2°C of sea-surface warming until the year 2100. Species richness increased in the Portuguese coast. In both scenarios, there was a latitudinal gradient in the amount of lost and gained species, increasing from north to south. An anomaly in the latitudinal gradient of species richness was detected in the southernmost area, which presented the lowest species richness of all areas, in the A2 scenario, and appears to be particularly vulnerable to climate change. Very few species were totally eliminated from Portuguese waters. For the Portuguese coast as a whole, there were more new than lost species, in both scenarios. Most of the new species were commercially important species, in the majority subtropical in the north and tropical in the south, mainly demersal and reef-associated. Reef-associated species also increased in relative importance. A commercial opportunity for fisheries may arise from climate warming, since most of the new species were commercial species and not many commercial species were lost. An increasing gradient from north to south was detected in the colonization of new species of herbivores, planktivores, and omnivores, as well as lower mean trophic level, which might have consequences for the future of trophic webs.     

长江口中华鲟自然保护区及临近水域鱼类种类组成现状

为了解长江口中华鲟自然保护区及其临近水域鱼类种类组成的现状,2004~2008年利用底拖网、插网、定置网和刺网等多种网具对该水域的鱼类组成状况进行了较为系统的调查。共调查到鱼类105种,隶属于18目43科86属,鱼类种类组成以鲈形目和鲤形目为主;生态类型中海洋鱼类和淡水鱼类各37种,河口定居性鱼类25种,洄游性鱼类6种;鱼类种类组成处于长江下游至东海的过渡类型,鱼类食性以底栖生物、有机碎屑和浮游动物食性为主,凶猛性鱼类较少。与以往调查资料相比,调查水域鱼类物种数有所减少,一些重要的物种更是濒临绝迹。保护区水域鱼类不仅具有较高的物种多样性、河口代表性、稀有性和很高的科研价值,同时其生态系统也较为脆弱,并已受到严重威胁,保护区的保护工作显得尤为重要.     

Environmental influence on commercial fishery landings of small pelagic fish in Portugal

Small pelagic fishes are particularly abundant in areas with high environmental variability (zones of coastal upwelling and areas of tidal mixing and river discharge), and because of this, their abundance suffers large inter-annual and inter-decadal fluctuations. In Portugal, the most important species in terms of landings are European sardine, Atlantic horse mackerel and Atlantic chub mackerel. Small pelagic fish landings account for 62.8 % of the total fish biomass and represent 32.7 % of the economical value of all catches. We have investigated trends in landings of these small pelagic fishes and detected the effects of environmental factors in this fishery. In order to explain the variability of landings of small pelagic fishes, we have used official landings (1965–2012) for trawling and purse seine fisheries and applied generalized linear models, using the North Atlantic Oscillation index (NAO) (annual and winter NAO index), sea surface temperature (SST), wind data (strength and North–South and East–West wind components) and rainfall, as explanatory variables. Regression analysis was used to describe the relationship between landings and SST. The models explained between 50.16 and 51.07 % of the variability of the LPUE, with the most important factors being winter NAO index, SST and wind strength. The LPUE of European sardine and Atlantic horse mackerel was negatively correlated with SST, and LPUE of Atlantic chub mackerel was positively correlated with SST. The use of landings of three important species of small pelagic fishes allowed the detection of variations in landings associated with changes in sea water temperature and NAO index.     

中国海洋捕捞渔业温室气体排放时序分析与因素分解

综合渔获量规模、作业方式结构、作业方式能耗强度和燃油排放系数等因素对温室气体排放的影响,在对2006～2011年海洋捕捞渔业温室气体排放核算和时序分析基础上,利用LMDI方法对温室气体排放进行了因素分解。结果表明：海洋捕捞渔业温室气体排放量呈现出稳定的增长趋势,平均每年温室气体排放量增长2666万t;拖网、刺网两种作业方式产生的温室气体占相应年份海洋捕捞渔业温室气体排放量的比重最大,约占80%,且温室效应最强。渔获量规模效应是驱动我国海洋捕捞渔业温室气体排放的最主要因素。建议通过采取“捕捞配额”或实施较长期的禁渔休渔制度来降低渔获量总量,不仅有利于保护海洋渔业资源,还能减少温室气体排放,也可以通过建立海洋捕捞生态补偿制度的方式来调整作业方式结构向低温室气体排放转变     

崇西湿地冬季潮滩鱼类种类组成及多样性分析

根据2006年冬季在崇西湿地进行的光滩和草滩插网渔获调查,首次对冬季长江口潮滩鱼类种类组成、多样性及相关环境因子作了分析。结果表明：冬季崇西湿地潮滩鱼类主要由淡水小型鱼类组成,共23种,隶属7科,20属。光滩和草滩插网的最大优势种皆为油,两种网具的渔获种类组成具一定的相似性。在一个潮周期内,3种多样性指数D、H′ 和J值波动范围较大,小汛潮时多样性指数比其它潮汛低。白天和晚上潮水的鱼类种类数无显著变化（P>0.5）,但在个体数和生物量上白天较晚上潮水高（P<0.5）。水温、潮汐大小对潮滩鱼类丰度影响较大,而与盐度相关较小。此外,天气状况也是影响潮滩鱼类的一个重要因子。总之,潮滩鱼类的种类组成和多样性受到各种环境因子的综合影响。     

长江口及邻近水域渔业资源监测现状分析

长江口及邻近水域是我国多种重要鱼类产卵、索饵、育肥的优良场所和洄游通道,对于该水域渔业资源进行有效监测是开展资源评估和养护的基础.以渔业资源监测的4种常见途径,即注册制度、问卷调查及访问调查、直接监测和报告制度为框架,对照总结了这一水域各种监测项目的发展水平和缺陷,特别针对依赖于渔业的调查和独立于渔业的调查,详细分析了渔业观察员项目、科考船、采样调查设计、渔业声学调查、标志放流、鱼卵仔稚鱼调查等环节的发展现状.在此基础上对现有监测项目的发展完善提出改进建议,旨在为该水域后续建立科学合理的渔业资源监测体系积累基础参考资料.     

Direct and indirect effects of climate and fishing on changes in coastal ecosystem services: a historical perspective from the North Sea

Humanity depends on the marine environment for a range of vital ecosystem services, at global (e.g. climate regulation), regional (e.g. commercial fisheries) and local scales (e.g. coastal defence and recreation). At the same time, marine ecosystems have been exploited for centuries, and many systems today are under stress from multiple sources. Recent studies have shown how both climate change and fishing have caused long-term changes in the marine environment. However, there is still poor understanding of how these changes influence change in coastal ecosystem services. In this paper, an integrated modelling approach is used to assess how the final delivery of marine ecosystem services to coastal communities is influenced by the direct and indirect effects of changes in ecosystem processes brought about by climate and human impacts, using fisheries of the North Sea region as a case study. Partial least squares path analysis is used to explore the relationships between drivers of change, marine ecosystem processes and services (landings). A simple conceptual model with four variables—climate, fishing effort, ecosystem process and ecosystem services—is applied to the English North Sea using historic ecological, climatic and fisheries time series spanning 1924–2010 to identify the multiple pathways that might exist. As expected, direct and indirect links between fishing effort, ecosystem processes and service provision were significant. However, links between climate and ecosystem processes were weak. This paper highlights how path analysis can be used for analysing long-term temporal links between ecosystem processes and services following a simplified pathway.     

The role of environmental and fisheries multi-controls in white seabream (Diplodus sargus) artisanal fisheries in Portuguese coast

Evaluating the effects of fishing and environmental factors on fish populations are fundamental tenets of fisheries science. In this study, we assess associations between environmental variables (sea surface temperature; North Atlantic Oscillation index; upwelling; wind magnitude; westerly winds; northerly winds; river discharge) and fishing variables (fishing effort) in Diplodus sagus catch rates accounting for regional analyses (northwest coast; southwest coast and Algarve—Algarve south coast). Different time series models for data fitting (multi-model approach) were used. The models were lagged, according to species fishing recruitment age based on the hypothesis that fisheries catches depend on larvae recruitment and survivorship. D. sargus catch rates across areas were unrelated to fishing effort but correlated to environmental variables, with seasonal events explaining much of the variability in trends. On the northwestern coast, the catch rates were mainly set by sea surface temperature (SST) and wind magnitude; however, southwestern coast catch rates were set by NAO winter. On the south coast, only one statistical model (SST, upwelling and westerly winds) associated spring conditions with D. sargus catch rates. The multi-model approach revealed autumn, winter and spring seasonal effects to be related with northwest, southwest and Algarve coastal catch rates, respectively, indicating a possible coastal longitudinal gradient related with given periods of spawning and larval availability. The metadata analysis yielded different results from the regional analyses. In summary, marine resource management should take regional environment characteristics and variability into account when determining sustainable catch rates in given areas for species with high habitat site fidelity.     

赤水河赤水市江段鱼类资源现状

根据2011～2013年赤水河赤水市江段的渔获物调查数据,对该江段的鱼类资源现状进行了研究。调查期间共采集到鱼类58种,隶属于3目10科47属。唇(Hemibarbus labeo)、中华倒刺鲃(Spinibarbus sinensis)、蛇鮈(Saurogobio dabryi)、瓦氏黄颡鱼(Pelteobagrus vachelli)、大鳍鳠(Mystus macropterus)、吻鮈(Rhinogobio typus)、粗唇鮠(Leiocassis crassilabris)、银鮈(Squalidus argentatus)、鲤(Cyprinus carpio)、鳜(Siniperca chuatsi)、切尾拟鲿(Pseudobagrus truncates)、鲫(Carassius auratus)和鲇(Silurus asotus)等13种为调查江段的主要优势种类,它们在渔获物中的总数量百分比和总重量百分比分别为92.61%和93.82%。从捕捞规格来看,目前赤水市江段主要经济鱼类均以小型个体为主,平均体长多在200 mm以下,平均体重多在100 g以下,与历史调查数据相比,捕捞规格小型化趋势较为明显。建议相关部门加快渔民转产安置工作,争取早日实现赤水河流域全面禁渔,并建立流域统一协调管理机制,切实保护好赤水河这一长江上游珍稀特有鱼类的最后庇护所。     

金沙江一期工程蓄水前后绥江段鱼类群落多样性特征

为探索流域梯级水电开发对鱼类群落多样性影响,于2011年(蓄水前)和2015年(蓄水后)对金沙江下游绥江断面进行渔业资源调查,分析鱼类群落结构特征。结果表明,绥江段共计采集鱼类60种,隶属于5目12科,其中长江上游特有鱼类12种。蓄水前以瓦氏黄颡鱼(Pelteobagrus vachelli)、圆口铜鱼(Coreius guichenoti)、光泽黄颡鱼(Pelteobagrus nitidus)为优势种类;蓄水后以草鱼(Ctenopharyngodon idellus)、鳙(Aristichthys nobilis)、鲢(Hypophthalmichthys molitrix)为优势种类。与蓄水前相比,鱼类群落Margalef丰富度指数、Shannon-Weiner多样性指数、Pielou均匀度指数均呈现下降趋势,但无显著性差异(P0.05)。根据生态类群分析,静水缓流型鱼类由蓄水前54%增加到蓄水后的71%,河道洄游型鱼类从39%减少到20%,江湖洄游型鱼类蓄水前后变化不大。丰度生物量比较曲线显示,蓄水前绥江段鱼类群落未受到干扰,而蓄水后受到严重干扰。库区蓄水后总生物量有明显增加趋势,但优势种类趋于小型化、种类结构单一化。为科学保护金沙江下游流域鱼类生物多样性,建议成立鱼类保护区、开展梯级生态调度和加强流域环保预警研究等措施。     

Artisanal fisheries of the Itaparica reservoir,São Francisco River,Brazil: socioeconomic profile,environmental dynamics,and management recommendations

Currently, artisanal fisheries in fresh water reservoirs have been losing ground to commercial fish farming and a great deal of fishery resources are being threatened by human interventions, such as reservoir management and increasing net-cage aquaculture. This study aims to understand the impacts of environmental changes on fishery resources and analyse the migratory fish breeding season as a missing link for fishery management in the semi-arid area of the São Francisco River Basin. Among the 870 fishermen operating in the Pernambuco part of the Itaparica Reservoir, 10% were interviewed and affirmed that fish stocks have been compromised due to the closed fishing period’s incoherence, exotic species insertion, and changes to the river flow caused by reservoir construction and operation. A significant correlation was observed between the Reproductive Activity Index (RAI) and precipitation (p?=?0.745) as well as between the RAI and the river’s flow (p?=??0.909). This shows how important it is to consider both the semi-arid climate setting and reservoir operation in determining the closed period which should safeguard fish reproduction. Monitoring the fish reproduction period and research on the reproductive biology of native fish species is needed in the São Francisco River Basin’s different stretches in order to guarantee valuable fish stocks and fisheries maintenance. Integrated action between the fish resource users, civil society, and federal bodies/agencies is essential in order to mitigate impacts and improve fish production systems, not only in Brazil, but in other regions experiencing a similar scenario.     

基于鱼类完整性指数的黄浦江水生态系统评价

黄浦江是连接太湖与长江口的一条多功能平原感潮河流,流经上海市中心城区,干流长113.4 km。为从生态学角度揭示其污染程度,采用鱼类生物完整性指数(F-IBI)对其水生态系统的健康状况作了评价。2013年11月和2014年7月,采用地笼网、三层刺网和拖网对黄浦江7个断面作了相同努力量的样本采集,共获鱼类8 816尾。经鉴定有38种,隶属于6目12科,其中鲤形目24种,鲈形目7种,鲇形目4种。通过区分度分析和关联度筛选,构建了由9个指标组成的F-IBI评价体系。结果表明,黄浦江上游水生态系统总体上处于"好"状态,中游及河口处于"一般"至"差"之间,而下游则较"差"。春季各有3个江段"好"或"差",1个江段"一般";秋季有4个江段"一般",2个江段"差",仅有1个江段"好"。评价还表明,黄浦江上游的3大支流中,由于承接太湖来水的斜塘呈"差",导致了为上海市提供约30%原水的松浦大桥断面呈"差"或"一般"状态。因此,保护淀山湖乃至太湖水质,是确保黄浦江上游水源地原水安全的关键。     

崇明北滩鱼类群落生物多样性初探

对1994~2003年崇明北滩鱼类群落进行了研究,用多种指数对该群落生物多样性进行了描述。该群落共有鱼类33种,分别隶属于10目19科29属。生态类型为江海洄游鱼类、河口鱼类和海水鱼类,小型鱼类占绝对优势。群落优势种为凤鲚、棘头梅童鱼和小黄鱼。多样性特征值年间平均指标为：Margalef指数0.84,Wilhm改进指数1.51,Pielou指数0.63,McNaughton指数0.67。崇明北滩鱼类群落经济鱼类趋于小型化,生物多样性呈下降趋势。水环境污染及工程建设的不利影响应得到重视,无选择性网具的使用应受到严格控制。     

Mercury in twelve Mediterranean trawl fishes of Israel

Total mercury concentration was investigated in the edible portion (muscle tissue) of twelve commercial trawl fishes. Samples were collected by a commercial trawl from five stations along the Mediterranean coast of Israel at depths from 32.9 – 91.4 m.The range and average mercury concentrations for both individual and composite samples of ten species are tabulated. The range of total lengths and weights for each species is also given. For two species only one composite sample was obtained.Sufficient data were obtained for five species to discuss the variation of mercury concentration with length, with depth and by station. Mercury concentration was found to increase with length for Saurida undosquamis, Trachurus mediterraneus, Upeneus moluccensis and Pagellus erythrinus. The correlation between mercury concentration and total length in Mullus barbatus was low. The mercury concentration of this species appeared to increase with depth. Mercury concentration in the fishes examined is discussed in regard to their position in the food web, depths and distribution along the shore.     

Quantifying changes to historic fish habitat extent on north coast NSW floodplains,Australia

Global degradation of coastal ecosystems is influencing the provision of ecosystem services, including fisheries maintenance services. Degradation of the Australian coastal zone and its resources following European occupation has been recognised for some time. This includes the loss of ecologically important coastal wetlands, which have strong trophic and habitat links to fisheries. In NSW, structural flood mitigation works are a principle driver of the decline of coastal wetlands; however, little action has been taken to quantify the extent of decline due to limited information of the pre-European settlement extent of coastal wetlands. We use spatial data sets in GIS to quantify prime fish habitat and calculate the loss of fish habitat for the large coastal floodplains of northern NSW, which are significant contributors to the commercial and recreational fisheries of NSW. The technique is validated by comparison with early maps of wetland distribution. We identified pre-European distribution of available fish habitat of approximately 477,000 ha, of which 87,000 ha was identified as prime fish habitat. Approximately 62,000 ha of prime fish habitat was impacted by drainage of the coastal floodplains in association with flood mitigation works which intensified in the mid-1950s and were largely completed by 1971, equating to a loss of approximately 72 % of prime fish habitat. The declining value of the ecosystem services provided by prime fish habitat following drainage is likely to be substantial. Some actions have taken place to restore the functions of this habitat although significant opportunities remain to reverse this decline through management actions that restore natural drainage and reinstate tidal exchange. These actions become even more important as pressures on coastal wetlands increase with climate change and associated sea-level rise.     

Climate change and food security: a Sri Lankan perspective

There is growing concern in Sri Lanka over the impact of climate change, variability and extreme weather events on food production, food security and livelihoods. The link between climate change and food security has been mostly explored in relation to impacts on crop production or food availability aspects of food security, with little focus on other key dimensions, namely food access and food utilization. This review, based on available literature, adopted a food system approach to gain a wider perspective on food security issues in Sri Lanka. It points to several climate-induced issues posing challenges for food security. These issues include declining agriculture productivity, food loss along supply chains, low livelihood resilience of the rural poor and prevalence of high levels of undernourishment and child malnutrition. Our review suggests that achieving food security necessitates action beyond building climate resilient food production systems to a holistic approach that is able to ensure climate resilience of the entire food system while addressing nutritional concerns arising from impacts of climate change. Therefore, there is a pressing need to work towards a climate-smart agriculture system that will address all dimensions of food security. With the exception of productivity of a few crop species, our review demonstrates the dearth of research into climate change impacts on Sri Lanka’s food system. Further research is required to understand how changes in climate may affect other components of the food system including productivity of a wider range of food crops, livestock and fisheries, and shed light on the causal pathways of climate-induced nutritional insecurity.     

巢湖流域河流鱼类群落的时空分布

基于2013年4月和10月对巢湖流域66个河道样点的调查数据,初步研究了巢湖流域河流鱼类群落的时空变化特征。主要研究结果显示,鱼类多样性无显著性的水系间、生态分区间的变化,但随季节和河流级别显著变化:10月份的个体数显著高于4月份,2级河流的物种数和个体数均显著大于1级、3级和4级河流。鱼类群落结构的季节动态显著,随生态分区显著变化,但不受水系、河流级别的显著影响。在二级生态分区水平上,仅西南森林生态亚区的鱼类群落结构与其他5个生态亚区的显著差异;宽鳍鱲、吻虾虎鱼等在西南森林生态亚区具有更高多度,而鲫、鰐、鲤等物种在其他生态亚区多度更高。     

Resilience thinking applied to fisheries management: perspectives for the mullet fishery in Southern-Southeastern Brazil

The mullet fishery system encompasses a complex arrange of ecological and socioeconomic factors interacting in multiple scales on the Southern-Southeastern Brazilian coast. Similarly, to other fisheries in developing countries, overfishing and poor governance have been threatening the resilience of the mullet fishery. In this paper, we explore aspects related to fisheries management from the perspective of the concept of resilience. The industrial and artisanal fishery sectors represent the different stakeholders. The main issues of concern are related to failures in the fisheries management to properly address equity in resource access and resource use sustainability among stakeholders. Asymmetry in technology and political and economic power affect food security and income generation especially for subsistence and small-scale fishing. Despite changes in rules-in-use, overfishing and conflicts between resource users are still relevant. Fishery dynamics and resource availability are greatly affected locally by forces such as pollution, urbanization, non-selective fishing, and regionally, by the El Niño Southern Oscillation (ENSO), and industrial (purse-seine) fishery. Considering the influence of ENSO on this fishery, a time span of at least 7 years to investigate this system could provide better answers to improve the management. Effective resilient fisheries should rely on three aspects. First, there should be a flexible fish allocation system based on ecosystem variability. Secondly, fish allocation should prioritize food security and poverty alleviation. Thirdly, a monitoring system should be implemented that takes into consideration ecosystem, fisheries and human dimensions to support a flexible and adaptive fisheries management, with resilient fisheries as an ultimate goal.     

Fishers’ perceptions of climate change,impacts on their livelihoods and adaptation strategies in environmental change hotspots: a case of Lake Wamala,Uganda

Fisheries resources support livelihoods of fishing communities but are threatened by over-exploitation, habitat degradation, pollution, invasive species and climate change. Unlike the other threats, climate change has received limited consideration and reducing its risks requires appropriate adaptation strategies. This study used quantitative and qualitative methods to generate knowledge on fishers’ perceptions of climate change, changes in climate variables and their impacts on livelihoods, adaptation strategies, constraints to adaptation and required interventions to promote adaptation strategies that would enable fishers to build resilience to sustain their livelihoods. We found that fishers were aware of changes in climate conditions manifested by unpredictable seasons, floods and droughts. Fishing remained the main livelihood activity. However, the dominance of fishes had changed from Nile tilapia (Oreochromis niloticus L.) to the African catfish (Clarias gariepinus Burchell). Floods and droughts were associated with damage to gears, boats, landing sites and changes in fish catches and sizes, income from fishing and fish consumption. The fishers adapted by increasing time on fishing grounds and changing target species and fishing gear among other things. Some innovative fishers diversified to high-value crops and livestock. This increased their income beyond what was solely earned from fishing which provided an incentive for some of them to quit fishing. Livelihood diversification was enhanced by use of communications technology, membership of social groups, increasing fishing days and fishing experience. Adaptation was, however, constrained by limited credit, awareness and access to land, which require interventions such as improving access to credit, irrigation facilities, appropriate planting materials and awareness raising. We identified adaptation strategies, which if promoted and their constraints addressed, could increase resilience of fishers to the influence of climate change and sustain their livelihoods.