渔获物平均营养级在渔业可持续性评价中的应用研究进展

高强度的捕捞努力量和渔业管理不力等因素导致全球范围内传统渔业资源的衰退,近年来渔获物平均营养级(MTL,mean trophic level)作为以生态系统为基础的渔业管理评价指标被普遍应用。本文在广泛收集国内外相关文献资料基础上,系统地介绍了MTL在渔业资源评价中的研究进展。已有研究显示,MTL能够利用已知渔获数据来分析,且参数化较为简便,在评价渔业可持续性中优势明显。受以渔获量作为生态系统指标、营养级(TL,trophic level)随体长的变化、渔获统计数据质量、低TL种类的过多捕捞和海域环境富营养化等因素的影响,在评估渔业资源利用状况时,需将MTL与剔除TL小于3.25物种下的3.25MTL、渔业均衡指数(FIB)等营养指标综合分析。此外,综合运用多指标,将营养指标与渔获组成、中上层鱼类与底层鱼类产量的比值、市场价格等指标结合分析,有助于掌握引起MTL变动的因素,更加全面地掌握捕捞活动下鱼类群落结构的实际变化状况。     

Landing profiles of Portuguese fisheries: assessing the state of stocks

Long‐term trends in Portuguese fisheries landing profiles of biodiversity, assemblage composition, trophic groups and marine trophic index (1950–2009) were studied to understand the evolution of the fisheries from an ecological viewpoint and evaluate the effects of fisheries on stocks. The number of species landed has increased considerably since the 1980s. This indicates an expansion of the fisheries and also a better use of the marine biodiversity for redistributing effort. Changes in the ecological composition of fisheries catches have occurred since the 1950s, with a significant shift in the middle 1980s (anchor point). Deep‐sea resources and higher trophic levels (cephalopods, large benthopelagics, flatfishes, demersal invertebrates, small‐medium and large rays, medium bathydemersal, shrimps, small benthopelagics large sharks) have increased while traditional commercial species captured by nearshore fisheries (medium and small pelagics) have decreased. Despite the decreasing trend in catches since 1988, the marine trophic index (MTI = 3.04) increased by approximately 0.2 units per decade (MTI in 2009 = 3.46). The number of collapsed, overexploited and fully exploited stocks has increased considerably over the last 20 years (>50%). Overall, the data indicate that redistributing fishing effort and targeting of deep‐sea resources may have been driven by depletion of inshore fishery stocks, which signals concern for the fishery. Marine biodiversity indexes and ecological structure of landings profiles should be considered by fishery managers when redefining new marine fisheries policy.     

Shifting trophic architecture of marine fisheries in New Zealand: Implications for guiding effective ecosystem‐based management

New Zealand has led the world in restoration of marine fisheries since the introduction of the Quota Management System in 1986, but challenges remain in minimizing the ecosystem‐level effects of industrialized fishing. We analysed existing long‐term fisheries data sets from 1931 to 2015 in New Zealand to resolve trends in important ecological properties of major exploited fish communities. Increases in community dissimilarities of catch composition in 1931 and 1972, followed by increasing total landings, highlight major expansions of fishing grounds and exploited species during these periods. Mirroring global patterns, the remarkable rise in fishing power, demand and generation of new markets in New Zealand have all contributed to this expansion. Marine Trophic Indices (MTIs) of landings have decreased together with total catch after the year 2000, reflecting smaller catches with a higher composition of lower trophic‐level species in recent years. Differences in relative abundance of species estimated between fisheries‐dependent and fisheries‐independent data were observed, where high‐value species displayed better agreement in relative abundance between data sets. Despite being under a Quota Management System, temporal development of MTI values relative to the timing of industrial expansion of fisheries was remarkably similar to those observed in the North Sea and Brazil, with a single expansion and decline. MTI values presented better long‐term stability in the US fisheries analysed. Analysis of long‐term data and the development of well‐resolved ecological baselines will be the first step towards applying EBM to New Zealand fisheries, in keeping with global trends in fisheries management.     

Fishing grounds of bottom-liners on the continental shelf of south-east Brazil

Abstract The space and depth distribution of the bottom-line fisheries on the continental shelf of south-east Brazil were analysed, and an attempt was made to identify the areas and depths where fishing effort is concentrated to delimit the main fishing grounds. Four main fishing grounds were identified based on the effort and catches between 1975 and 1985. These were, in decreasing order of importance: north of Espírito Santo state, near the Abrolhos archipelago; adjacent to Rio de Janeiro state, under the influence of Cabo Frio upwelling; north of São Paulo state, encircling Alcatrazes archipelago; and the outer edge of the Rio de Janeiro and São Paulo state continental shelves, between the Guanabara and Sepetiba bays. The concentration of the fisheries, the greater catches and the best productivity indices were found in outer and deeper areas along the edge of the continental shelf. There was a concentration of fishing effort and higher catches in deeper grounds, from the north to the south of the regional fishing area. The bathymetric distribution of the fisheries showed that they intensified from 30 m depth to the outer edge of the continental shelf. The fishery productivity indices increased towards a depth of 50 m, but fell thereafter. Fishing activities were lowest during the winter season for the whole region, but intensified during the summer-autumn or spring-summer seasons.     

应用渔业资源评估专家系统预测东海鲐年产量

利用渔业资源评估专家系统估算和预测了东海鲐年产量，实际的应用和对过去年产量的回顾预测都表明，该专家系统具有一定的实用性，其预测产量与实际产量比较接近，平均预测精度为87.8%，预测结果可供渔业生产和管理部门参考。从近十多年鲐的渔业生产和资源状况来看，鲐实际捕捞产量巳接近我们所评估的现存资源量。同时，渔获物的组成以当龄鱼为绝对多数，小型化、低龄化现象明显，说明东海鲐资源巳得到充分利用，并开始出现过度利用的迹象，资源前景并不乐观。     

Trends in trawl-targeted species landings off northern Taiwan and effects of fishing and environmental factors

Time series of landings may provide information crucial to achieving a better understanding of temporal variations in the abundances and compositions of exploited species and ecosystems. The waters off northern Taiwan, located in the southern East China Sea, are one of the most important fishing grounds for Taiwan’s coastal and neritic fisheries. Temporal variations in the abundances of the species exploited in this region are rarely studied because of the multi-gear fisheries involved. In this study, trends in the landing per unit effort (LPUE) time series for 13 trawl-targeted species (groups) off northern Taiwan from 1976 to 2007 were explored using dynamic factor analysis (DFA). Potential effects of fishing effort (number of vessels) and environmental factors [Southern Oscillation Index, sea surface temperature (SST) near northern Taiwan, and river discharge] were examined. The optimum DFA model included three common trends and three explanatory variables (excluding SST). A general decreasing pattern was identified from among the common trends, and this was observed in the LPUE time series for most of the species. Fishing effort is an important explanatory variable in the model, suggesting that it plays a critical role in explaining LPUE variations of trawl-targeted species. The common trends identified here could lead to new strategies for fisheries management, particularly where multi-gear fisheries operate and multiple species are targeted.     

Long‐term changes in fishery resources of an estuary in southwestern Atlantic according to local ecological knowledge

Long‐term changes in the abundance of fisheries resources from the Patos Lagoon estuary and adjacent coastal waters in southern Brazil have been observed. Despite this understanding, it is well known that the perception of pristine state of the environment is susceptible to inter‐generational changes, commonly known as shifting baseline syndrome (SBS). An useful approach in the reconstruction of pristine scenarios and in lack of data, as often occurs in small‐scale fisheries, is the local ecological knowledge (LEK). Temporal changes in the perception of 81 fishers with 1–63 years of fishing about the resources status were analysed. More experienced fishers reported larger catches, heavier individuals and perceived a greater number of species as "scarce" nowadays and "common" at the beginning of their careers proving the existence of a SBS among them. Over time, the number of fishing sites with very high catches decreased and fishing sites shifted from the lower towards the upper estuary. The perception of the fishers corroborated the real decreasing scenario in estuarine fisheries resources shared with industrial fishing in coastal waters. The results reinforce the utility of LEK for reconstruction of biological scenarios when no empirically obtained data are available.     

A socio-economic perspective on gear-based management in an artisanal fishery in south-west Madagascar

Abstract  Artisanal fisheries are important socially, nutritionally and economically. Poverty is common in communities dependent on such fisheries, making sustainable management difficult. Poverty based on material style of life (MSL) was assessed, livelihoods surveyed and the relationship between these factors and fishery data collected using a fish landing study were examined. Species richness, diversity, size and mean trophic level of catches were determined for six fishing gears in an artisanal fishery in south-west Madagascar. There was little livelihood diversification and respondents were highly dependent on the fishery. No relationship was found between poverty and gear use. This suggests that poverty does not have a major impact on the nature of the fishery; however, this study was dominated by poor households, so it remains possible that communities with more variation in wealth might show differences in fishing methods according to this parameter. The fishery was heavily exploited with a predominance of small fish in the catches. Beach seines caught some of the smallest fish, overlapped in selectivity with gill nets and also had the highest catch per fishers. Thus, a reduction in the number of beach seines could help reduce the catch of small fish and the overlap in selectivity among gears.     

Are the exploitation pressures on the Nile perch fisheries resources of Lake Victoria a cause for concern?

Abstract Lake Victoria is one of the African Great Lakes, and an important source of affordable protein food in the form of fish. It provides employment, income, and export earnings to the riparian communities. Despite this importance there are major concerns about the status and exploitation of the fisheries. This study assesses if current extraction rates/yield of Nile perch, Lates niloticus (L.), from Lake Victoria are sustainable for the foreseeable future. The paper reviews trends in catch and effort in the Nile perch fishery and models the expected scenarios using ECOPATH. The fishery exhibits, classic indicators of intensive fishing, erring towards overexploitation, including: (i) decline in total estimated catch of Nile perch in recent years from the peaks in the 1990s. This is coupled with a shift in contribution of catches from higher trophic level species (Nile perch) to lower trophic level (dagaa) species. (ii) Three major trends in the fishing effort are evident: (a) almost doubling of the number of fishers and fishing boats between 1990 and 2000, and the even greater expansion between 2000 and 2002; (b) a large scale increase in the number of gears operational in the lake; and (c) the propensity for use of ‘illegal’ gears. (iii) Catch‐per‐unit‐effort has declined from about 80 to 45 kg per boat day. (iv) Predictive modelling (ECOSIM) of the future of the Nile perch fisheries under a scenario of increased fishing effort suggests that the fisheries are unsustainable and will decline in the long term. It appears that the Nile perch stocks in the three riparian countries are under intense fishing pressure, and unless concerted action is taken, the potential for degradation of the resources is prevalent. In view of the importance of these fisheries, it is recommended that a precautionary approach to further intens‐ification of the fisheries is adopted until such time empirical evidence shows that the fisheries are capable of further expansion and intensification. The main options for management are devolvement of responsibilities for the fisheries to the communities, enforcement of existing regulations, improved monitoring and data collection processes, reducing post‐harvest losses and increasing the value of the products to the export market.     

Ecosystem structure and functioning of Lake Taihu (China) and the impacts of fishing

Lake Taihu is the third largest freshwater lake in China and has provided local communities with valuable fisheries for centuries. However, we have only a limited knowledge of its ecosystem. In this study, a trophic model was constructed for the Lake Taihu ecosystem. This model was used to evaluate and analyze the food web structure and other properties of this ecosystem using data covering the period from 1991 to 1995. Using the model, we evaluated the impacts on local fisheries of various management scenarios comprising two basic management regimes: (1) setting fishing mortality for the top predator (large culters, Erythroculter mongolicus and Erythroculter ilishaeformis) to 0, 0.3, 0.6, 0.9 and 1.2, and (2) adjusting overall fishing effort to 0.25, 0.5, 0.75 and 1.25 times the current level. For both scenarios, fishery profit and cost were evaluated to provide an understanding of how components of the ecosystem interact. We identified possible causes of fishery overexploitation in the lake ecosystem and described the necessity of developing ecosystem-based management. The results showed that Lake Taihu had six theoretical trophic levels (TLs), with the trophic flows primarily occurring through the first five TLs. System properties such as transfer efficiency, Finn's index, Finn's mean length, connectance index, system omnivory index, primary production/respiration ratio, and net primary production all indicated that Lake Taihu was an immature, fairly simple ecosystem in which a relatively low fraction of total primary production was utilized. At the same time, the ecosystem was also experiencing high fishing pressure. Yet despite this, the low ascendency index (25.9%) and high system overhead ratio (74.1%) indicated that the system was highly developed and relatively stable, a condition that might result from the high degree of recycling in the system. Among the harvesting strategies considered, a strategy of either decreasing the fishing mortality of the top predator (large culters) to 0.3 or, alternatively, reducing the overall effort on the system by a factor of 0.75 appeared to be most effective at increasing the efficiency of the fisheries.     

挪威海洋捕捞及渔船管理概述

本文概要介绍了挪威海洋捕捞业和渔船管理状况:2011年,捕捞量230万t,产值159亿挪威克朗(约26.8亿美元);渔民数量12 791人,渔船数量6 252艘;近10年的捕捞量基本稳定,年均捕捞量为250万t,与此同时,渔船和渔民数量则呈持续下降态势,说明挪威渔船的捕捞能力显著增强,捕捞效率明显提升。挪威的渔业管理制度和法规建设比较完善,这为控制捕捞强度、保护海洋渔业资源奠定了法律基础。挪威的经验具有借鉴意义。我国现阶段以实行渔船控制等投入控制制度为主、其他管理方式为辅的渔业资源管理制度,比较符合我国实际。实践证明,减船转产政策是控制捕捞渔船规模和降低海洋捕捞强度行之有效的措施之一。     

南沙群岛西南陆架区底拖网主要经济渔获种类组成和数量变动

根据1993-2002年南海区3省市渔业公司在南沙群岛西南陆架区底拖网的生产资料和渔业资源调查资料，分析了底拖网主要渔获种类组成和数量变动。结果表明，底拖网渔获种类组成基本相同，主要渔获经济种类有20多种，以蛇鲻属（Synodidae）、大眼鲷属（Priacanthidae）等底层鱼类为主，占总渔获物的70．9％。经济鱼类资源渔获率有明显的年间变动。底层鱼类资源除蛇鲻属和大眼鲷属外，其他种类如石斑鱼属（Serranidae）、鲱鲤属（Mullidae）、红笛鲷（L．sanguineus）、黄鳍马面纯（T．xanthopterus）、刺鲳（Psenopsis anomala）等波动很大，而中上层鱼类资源和头足类资源则相对稳定。分析认为捕捞是引起经济鱼类资源数量变动的主要原因。     

东海南部海区生态系统结构与功能的模型分析

根据1999～2002年间对东海南部海区的渔业资源和生态环境进行调查后所获得的数据和资料,应用Ecopath with Ecosim5.1软件构建了该海区生态系统的生态通道模型,基于该模型对生态系统结构特征进行了量化分析。生态通道模型由20个功能组构成,基本覆盖了东海南部海区生态系统能量流动的主要过程。分析结果表明,东海南部海区生态系统各功能组的营养级为1.00～4.23,能量流动主要由6个整合营养级构成,营养级I的利用效率颇为低下,大量初级生产力未进入更高层次的营养流动,造成生态系统下层营养流动的"阻塞"。鲹科鱼类、沙丁鱼、鳀科鱼类和其他小型鱼类的生产量较高,占鱼类总生产量的85.6%,而其他大中型肉食性鱼类的生产量都较低。混合营养分析表明,在能量从低级向高层次转化的食物网中,底层功能组起关键作用。反映系统成熟度的指标,包括较高的净初级生产力(NPP)和净初级生产力/呼吸(NPP/R),以及较低的连接指数(CI)、系统杂食指数(SOI)和Finn’s循环指数(FCI)等,均表明该海区处在一个"幼态化"的生态系统。     

The development of fisheries at Bornholm,Denmark (Baltic Sea) during 1880s–1914

For centuries the abundance of fish in the Baltic Sea has had an important role in the economy of Bornholm, Denmark. This study examines the development of Bornholm fisheries between approximately 1880s and 1914 on the basis of the first officially recorded Danish fisheries data. Several species were caught, but prior to 1914 especially herring, salmon and cod were economically most important. In the late 19th and early 20th century, the catch composition changed fundamentally due to complex interactions between biological, technological and economical factors. During the late 19th century the catches of herring increased, while the catches of salmon and cod decreased. This development coincided with the introduction of new technologies and fishing practices, including motorization of fishing vessels and the exploitation of herring in previously unexploited areas (i.e., expansion of fishing areas). In addition, the salmon fishery diminished after the introduction of driftnets, which caught large numbers of small salmon. The high catches of small salmon, in combination with other factors, probably contributed to the decline in catches of larger salmon. Each of the fisheries for the three species required different types of vessels and gear, and when catches began to drop in the salmon fishery, Bornholm fishermen were faced with two options. They could either specialise in the growing herring fishery, thereby hoping to maintain their income level, or they could pursue a strategy of risk minimization, by acquiring an income outside the fishing industry, while continuing to work part-time in the salmon and cod fisheries. This dual tendency was intensified further as marine engines and new types of vessels were introduced, raising the costs of fishing.     

Global reduction fisheries and their products in the context of sustainable limits

Globally, one‐sixth of landings from marine capture fisheries are destined for the production of fishmeal and fish oil (FMFO), which are currently overwhelming utilized by fed aquaculture. Many different species are used globally for the production of FMFO, but little concern has been given to the divergent environmental and ecological impacts of FMFO products based on species, ecosystem and fishing gear used in their capture. We evaluated the variable environmental performance of FMFO products from a wide range of fisheries whose products are either primarily intended for reduction or whose by‐products are redirected to reduction. Assessed fisheries accounted for 44% of global reduction fishery landings in 2014. Analysis was conducted on the basis of two measures: the carbon footprint (i.e., greenhouse gas [GHG] emissions) and the marine footprint (i.e., primary production required [PPR]). We found large differences between the impacts of FMFO products across the 18 reduction fisheries examined. Cumulatively, we estimate that reduction fisheries emitted 4.6 million tonnes of CO₂‐e GHGs in 2014, and appropriated over 4% of primary production in some ecosystems, demonstrating a non‐trivial impact. As demand for aquafeeds grow, the sustainable sourcing of raw material inputs will be of great importance. Results here suggest that the source of FMFO inputs can have dramatic effects on the environmental performance of fish feeds and fed aquaculture. We recommend further research on the environmental and ecological impacts of food production systems, and specifically to understand these results in relation to global production and sustainable boundaries.     

Fisheries and conservation assessment of sharks in Pacific Panama

1. In Panama, shark fisheries were initially developed in the 1980s and progressively increased in production in the 1990s mainly due to the high demand for shark fins and meat from the international Asian market. Since then, and despite the exploitation rate (average 3,514 t year^–1) and endangered status of some species, shark fisheries have seldom been studied, and official statistics are general or incomplete and not suitable for the development of appropriate conservation and management strategies.
2. To understand the dynamics of shark fisheries in Panama, field surveys were conducted between 2007 and 2009 at several landing ports of small‐scale and industrial fisheries, at fish processing plants and on‐board fishing vessels in Pacific Panama, where most of the fishing vessels of the country operate.
3. In general, it was found that the artisanal and industrial fisheries of the Pacific coast of Panama regularly exploit at least 18 species of sharks, which are also being exploited by neighbouring countries in the eastern Pacific, suggesting the importance of coordinated conservation initiatives across the multiple jurisdictions. A large number of the individuals caught were immature, implying a certain level of impact on recruitment rates. This pattern was particularly evident in species such as Sphyrna lewini, for which immature individuals represented at least 99% and 63% of the total catch by small‐scale and industrial fisheries, respectively. Catch per unit of effort analyses showed that Carcharhinus and Sphyrna species were the most exploited (representing ~80% of the catches) by industrial fisheries in Panama between 2006 and 2009, suggesting that fishery management should provide special attention to these groups.
4. It is expected that the information presented here provides a baseline to develop new regulations, including the implementation of annual quotas and fishing seasons and the protection of nursery areas, for the long‐term sustainability and conservation of sharks in Panama.

     

大西洋南部金枪鱼渔场的生产调查报告

根据随船调查材料，对大西洋南部金枪鱼延绳钓渔业从捕捞技术，渔场环境因素，渔获物情况、初加工、销售等方面做出了总结。本文着重分析了各个作业渔场的渔获情况，判断出八个中心渔场的位置，并就大眼金枪鱼在这几个中心渔场的生物学特征做了统计分析，从而为用地理信息技术预报渔场提供了实施依据。     

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.     

Just a FAD? Ecosystem impacts of tuna purse‐seine fishing associated with fish aggregating devices in the western Pacific Warm Pool Province

The western and central Pacific Ocean supports the world's largest tuna fisheries. Since the 1990s, the purse‐seine fishery has increasingly fished in association with fish aggregating devices (FADs), which has increased catches of juvenile bigeye and yellowfin tunas and vulnerable bycatch species (e.g., sharks). This has raised concerns regarding the sustainability of these species’ populations and the supporting ecosystem, but may provide improved food security of Pacific Island nations through utilisation of FAD‐associated byproduct species (e.g., wahoo). An ecosystem model of the western Pacific Warm Pool Province was used to explore the potential ecological impacts of varying FAD fishing effort (±50% or 100%) over 30 years. The ecosystem has undergone a significant change in structure since 1980 from heavy exploitation of top predators (e.g., tunas) and “fishing up the food web” of high‐trophic‐level non‐target species. The ecosystem appeared resistant to simulated fishing perturbations, with only modest changes (<10%) in the biomass of most groups, although some less productive shark bycatch species decreased by up to 43%, which had a subsequent positive effect on several byproduct species, the prey of sharks. Reduction of FAD effort by at least 50% was predicted to increase the biomass of tuna species and sharks and return the ecosystem structure to a pre‐industrial‐fishing state within 10 years. Spatial disaggregation of the model and integration of economic information are recommended to better capture ecological and economic changes that may result from fishing and/or climate impacts and to develop appropriate management measures in response.