Rights-based Fisheries Management: An Environmentalist Perspective

Fisheries management regimes take many forms, but most fail to designate shares of the catch. This failure creates strong incentives for individuals to maximize their share without regard to long-term sustainability, because the benefits of conservation actions do not accrue to individuals. The competition to maximize catch usually entails excessive capital investments in fishing vessels and gear and intense fishing pressure, resulting in overfishing, high bycatch rates, and the use of large, efficient types of gear that can harm habitat. Managers respond by increasing regulations, but this often exacerbates perverse incentives. In addition, many fisheries could be producing more value than the current system permits, i.e. large quantities of fish are landed during short seasons, forcing fishermen to sell for low prices. Conservation and economic problems facing fisheries can be addressed in an integrated way, by designating access privileges (specifying shares of the catch) to individuals, harvest cooperatives, fishing sectors, communities, or other appropriate entities. Designated Access Privilege (DAP) systems demonstrably end the competition to maximize catch and often result in better conservation and financial performance. The cost of implementing these systems can be relatively high and has been a barrier to better management. However, this doesn’t have to be so. Fisheries could accept investments from a variety of sources and use a portion of the increased financial performance to repay recoverable grants and loans. The key to protecting fish stocks, habitats, and the communities that depend on them will be to implement DAPs that are appropriate for each fishery or community, making investments in sustainability, and creating financing mechanisms that are themselves sustainable, drawing on the increased value that DAP fisheries can produce.     

The Emergence of Access Controls in Small-Scale Fishing Commons: A Comparative Analysis of Individual Licenses and Common Property-Rights in Two Mexican Communities

Addressing global fisheries overexploitation requires better understanding of how small-scale fishing communities in developing countries limit access to fishing grounds. We analyze the performance of a system based on individual licenses and a common property-rights regime in their ability to generate incentives for self-governance and conservation of fishery resources. Using a qualitative before-after-control-impact approach, we compare two neighbouring fishing communities in the Gulf of California, Mexico. Both were initially governed by the same permit system, are situated in the same ecosystem, use similar harvesting technology, and have overharvested similar species. One community changed to a common property-right regime, enabling the emergence of access controls and avoiding overexploitation of benthic resources, while the other community, still relies on the permit system. We discuss the roles played by power, institutions, socio-historic, and biophysical factors to develop access controls.     

我国热带金枪鱼围网人工集鱼装置特征及随附鱼群行为

金枪鱼围网渔船使用人工集鱼装置(FADs)可以增加对金枪鱼随附鱼群的捕捞能力,而大规模投放FADs引起的生态问题在数十年间引起了国际社会的广泛关注。因此,开发高效集鱼能力并降低生态影响的FADs是金枪鱼围网渔业面临的挑战。由于缺乏大量试验研究,目前对FADs和捕捞物种之间相互关系的理解极其有限。本研究通过对从事金枪鱼围网捕捞生产的船长进行问卷调查,从渔民经验的角度总结了FADs的投放现状、结构设计、捕捞和生态特性,以及随附鱼群的行为特征等,并基于一致性指数(IoC)对调查内容的认知差异进行量化。结果表明: 我国金枪鱼围网船单船每年平均投放的FADs数量为(102±37),丢失数量为(72±15)。FADs的集鱼效果优于天然流木,水下悬挂结构是吸引金枪鱼的主要原因,且悬挂吸引物(如漂带)有助于诱集金枪鱼集群。FADs投放后金枪鱼的首次出现时间平均约32 d,此后的1个月内集群量趋于稳定;海龟或鲨鱼被FADs网状结构缠绕的情况偶有发生。被调查者对“生物附着对集群效果的影响”和“优化FADs隐蔽性的意愿”两个问题的反馈具有较高的一致性(IoC均为0.73),对“筏体结构类型对集群效果影响”的反馈答案分歧较大(IoC=0.34)。当前FADs的设计存在低隐蔽性和导致非目标鱼种高脆弱性的弊端。研究结果可为开发生态效应和捕捞效益兼具的生态友好型FADs提供科学依据。     

福建南日岛南部水域鱼类群落结构及多样性

为探究南日岛南部水域鱼类群落结构及多样性特征,在2009年冬季,2010年春季与夏季于南日岛南部海域展开了3个航次的渔业资源综合调查.采用Bray-Curtis聚类方法,对南日岛南部海域鱼类群落进行划分,并在此基础上分析了不同群落鱼类种类数、数量密度、生态类群和多样性特征,讨论了水团变化对鱼类群落格局划分及多样性特征的影响。结果显示:春季调查海域的鱼类可划分为北部沿岸群落和南部近海群落,这两个种群种类数分别是27和32种,密度分别为7.47×103尾/km2和24.34×10~3尾/km~2,多样度H'值分别为2.71和1.97,南部近海群落中暖水种数量密度均高于北部沿岸群落,而暖温种相反。与春季不同,夏季由西至东划分为西部沿岸群落和东部近海群落,种类数分别为55和27种,密度分别为329.24×10~3尾/km~2和106.47×103尾/km2,H'值分别为1.97和1.62,西部沿岸群落中沿岸种和近海种数量密度均高于东部近海群落。冬季调查海域鱼类可划分为北部沿岸群落和南部近海群落,种类数分别为25和32种,密度分别为9.96×10~3尾/km~2和28.85×10~3尾/km~2,H'值分别为2.45和2.33,南部近海群落暖水种与暖温种数量密度均高于北部沿岸群落。冬、春季时,海峡暖水影响的海域鱼类种类数、数量密度、多样度以及暖水种的数量密度均高于浙闽沿岸水控制的海域;夏季,西部沿岸径流影响的海域鱼类种类数、数量密度、多样度以及暖水种的数量密度均高东部海峡暖水影响的海域。可见鱼类群落分布特征与季节性变化的水团有关。     

Beyond biodiversity: fish metagenomes

Biodiversity and intra-specific genetic diversity are interrelated and determine the potential of a community to survive and evolve. Both are considered together in Prokaryote communities treated as metagenomes or ensembles of functional variants beyond species limits.Many factors alter biodiversity in higher Eukaryote communities, and human exploitation can be one of the most important for some groups of plants and animals. For example, fisheries can modify both biodiversity and genetic diversity (intra specific). Intra-specific diversity can be drastically altered by overfishing. Intense fishing pressure on one stock may imply extinction of some genetic variants and subsequent loss of intra-specific diversity. The objective of this study was to apply a metagenome approach to fish communities and explore its value for rapid evaluation of biodiversity and genetic diversity at community level. Here we have applied the metagenome approach employing the barcoding target gene coi as a model sequence in catch from four very different fish assemblages exploited by fisheries: freshwater communities from the Amazon River and northern Spanish rivers, and marine communities from the Cantabric and Mediterranean seas.Treating all sequences obtained from each regional catch as a biological unit (exploited community) we found that metagenomic diversity indices of the Amazonian catch sample here examined were lower than expected. Reduced diversity could be explained, at least partially, by overexploitation of the fish community that had been independently estimated by other methods.We propose using a metagenome approach for estimating diversity in Eukaryote communities and early evaluating genetic variation losses at multi-species level.     

The effects of fishing on the diversity,biomass and trophic structure of Seychelles’ reef fish communities

A fishery independent underwater visual census technique was used to assess the effects of fishing on the diversity, biomass and trophic structure of the diurnally active non-cryptic reef-associated fish communities of the Seychelles. One hundred and thirty four species associated with three significantly different types of reef habitat were censused at one unfished ground and in six fishing grounds subject to different fishing intensity and the biomass of several species targeted by the fishery. The diversity of families containing target species (lutjanidae, lethrinidae) was significantly higher at unfished and lightly fished sites as was the total biomass of the fish community and the biomass of piscivorous, piscivorous/invertebrate feeding and herbivorous trophic groups. However, there was no indication that the biomass of non-target species increased in response to the removal of their predators by fishing. The findings of this study are significant for fishery managers because they suggest that the intensive differential cropping of top predators will not necessarily lead to increases in the biomass and productivity of their prey.     

Scale-dependant control of motile epifaunal community structure along a coral reef fishing gradient

Large-scale fishing is mostly conducted using towed gears that reduce the biomass and diversity of benthic invertebrates. However, it is impossible to differentiate between the physical disturbance effect of towed gears from the effect of fish predator removal upon benthic invertebrate communities. Here we explore the impact of fish removal alone on the community structure of small motile coral reef invertebrates (epifauna) along a subsistence fishing intensity gradient in the Lau group, Fiji. We deployed settlement plates at three areas in each of six fishing grounds and examined the density and class richness of the motile epifaunal communities and the associated algal communities in relation to the structure of fish and benthic communities. Motile epifaunal density was unrelated to fishing intensity. However, at smaller inter-area scale (0.5-10 km) motile epifaunal density was negatively related to plate algal biomass, whereas at the larger inter-fishing-ground scale (4-180 km) motile epifaunal density was positively related to the rugosity (substrate complexity) of the surrounding benthos. The class richness and diversity (Margalef's d) of motile epifaunal communities were negatively related to fishing intensity, but unrelated to grazing intensity, rugosity or algal biomass at either scale. Benthic community structure varied significantly with fishing intensity; hard-coral cover was lower and turf-algal cover was higher at high fishing pressure. The variation in benthic community structure was associated with variation in fish community structure, which in turn varied with fishing intensity. Motile epifaunal community structure upon plates was linked to the structure of the surrounding benthic community, but was not directly linked to the plate algal community. We suggest the decline in richness of the motile epifauna community along the fishing gradient is attributable to either to exploiter-mediated coexistence or the reduction in ‘habitat quality’ of the surrounding benthos. At the large spatial scale substrate complexity is the key determinant of motile epifaunal density, suggesting predation by fishes plays an important structuring role at this scale. Assuming that rugosity is inversely related to predation risk then this study represents the first evidence for spatial-dependence on the top-down (predation) vs. bottom-up (algal biomass) control of community structure. We argue fisheries exploitation, in the absence of a physical disturbance can negatively influence motile epifaunal community structure at large spatial scales.     

Resilience of predators to fishing pressure on coral patch reefs

Numbers and biomass of piscivorous fish and their predation on other fish may often be high in undisturbed coral reef communities. The effects of such predation have sometimes been studied by removal of piscivores (either experimentally or by fishermen). Such perturbations have usually involved removal of large, highly vulnerable, mobile piscivores that are often actively sought in fisheries. The effects of fishing on smaller, demersal, semi-resident piscivores have been little studied. We studied such effects on the fish communities of patch reefs at Midway atoll by experimentally removing major resident, demersal, piscivorous fishes. First, four control reefs and four experimental reefs were selected, their dimensions and habitats mapped, and their visible fish communities censused repeatedly over 1 year. Census of all control and experimental reefs was continued for the following 39 months, during which known piscivores were collected repeatedly by hand spearing. Records were kept of catch and effort to calculate CPUE as an index of predator density. Spearfishing on the experimental reefs removed 2504 piscivorous fish from 12 families and 43 taxa (mostly species). The species richness of the catch did not show an overall change over the duration of the experiment. Spearman rank correlation analysis showed some unexpected positive correlations for density in numbers and biomass of major fished piscivorous groups (especially lizardfish) over the experiment. Only two relatively minor fished piscivorous taxa declined in abundance over the experiment, while the overall abundance of piscivores increased. Visual censuses of fish on the experimental reefs also failed to show reduction of total piscivores over the full experimental period. No significant trend in the abundance of lizardfish censused over the full period was apparent on any of the control reefs. The high resilience of piscivores on these experimental reefs to relatively intense fishing pressure could result from their protracted recruitment seasons, high immigration rates, cryptic habits, or naturally high abundances. A major factor was the high immigration rates of lizardfish, replacing lizardfish and other less mobile piscivores removed from the reefs by spearing. On the fished reefs, the removed lizardfish population replaced itself >20 times during the experiment; other piscivorous taxa replaced themselves only 5 times.     

Fish by‐catch in shrimp beam trawls in the northern South China Sea

The by‐catch of shrimp beam trawl fisheries in the northern South China Sea were estimated during the 2005–2006 and 2012–2013 fishing seasons. A total of 98 hauls from three important shrimp fishing grounds were used in the analyses. A total of 119 by‐catch species were captured, compared with only 15 target species. The ratio of by‐catch to shrimp ranged from 1.01 to 13.90. The dominant standard length (SL) range of fish by‐catch was 51–100 mm. The percentage of juveniles in the total catch of some fish species was high (e.g. 100% for A. aneus).     

人工集鱼装置对热带金枪鱼类行为模式的影响

金枪鱼类会聚集在漂浮物周围,人类依据该行为特性研制出人工集鱼装置(fish aggregation devices,FADs)诱集金枪鱼,从而使金枪鱼围网的产量和捕捞效率大幅提高.但目前科学界仍不确定FADs为何能够吸引金枪鱼以及其广泛使用是否会对金枪鱼资源和大洋中上层生态系统产生潜在影响.针对这些问题,国外学者展开了大量以FADs周围金枪鱼为研究对象的个体行为学试验.本文归纳并整理了过去30多年中较可靠和经典的相关试验,从金枪鱼的趋向性行为、集群行为、随附行为、摄食行为和垂直移动行为5个方面分别阐述了漂流FADs和锚泊FADs下金枪鱼的行为模式,并对国内今后开展相关研究的重点方向和注意事项进行了展望.     

FAD: Fish Aggregating Device or Fish Attracting Device? A new analysis of yellowfin tuna movements around floating objects

Tropical tuna are known to associate with floating objects. Because fish are easier to detect and to catch when around these objects, fishermen have extensively deployed a large number of artificial floating objects in the tropical oceans. Although such objects are referred to as Fish Aggregating Devices (FADs), there is yet no strong evidence that fish do show an aggregative behaviour around them. The high probability of finding tuna around FADs may be the result of an aggregation process (high density of fish because fish stay for a long time around FADs) as well as an attraction process (high flow of fish through FADs). We analysed the movements of 14 yellowfin tuna, Thunnus albacares, in relation to FADs moored in the Indian and Pacific Oceans (corresponding to all the published tracking data) to determine whether the observed movement patterns resulted from an aggregation or an attraction process. Tuna appeared to be attracted by FADs. In general, they did not stay for long close to the FADs reached, and so did not aggregate there. Some FADs may nevertheless act as Fish Aggregating Devices. The possible reasons why tuna associate with floating objects are discussed in the light of these results.     

Community Based Fisheries Management and Fisher Livelihoods: Bangladesh Case Studies

Poor fishers in Bangladesh have been disadvantaged by policies that favored powerful people leasing fishing rights. Community-based management was expected to improve fisher access, livelihoods, and the sustainability of fisheries. The impacts of community management in three floodplain waterbodies differed according to the environment and property rights. Where a set of fishers jointly held exclusive rights to a small enclosed lake they increased production by stocking fish and shared the returns. This strategy is productive but attracts competition for profits and fish consumption was unchanged. Access to capture fisheries in floodplain waterbodies enables the poor to catch diverse small fish for their consumption. Yet sustainability requires limits on fishing. Fish sanctuaries were respected, yet catches per day fell when more people from several villages increased fishing effort in a large wetland, while a tightly knit community restored the fishery in a smaller floodplain. Community organizations will need recognition of their long-term use rights to overcome future threats.

基于栖息地指数的东太平洋黄鳍金枪鱼渔场预报

黄鳍金枪鱼是东太平洋海域重要的金枪鱼种类之一,也是我国金枪鱼延绳钓的主要捕捞对象之一。根据2011年东太平洋海域(20°N—35°S、85°W—155°W)延绳钓生产统计数据,结合表温(SST)和海面高度(SSH)的遥感数据,采用频次分析法获得黄鳍金枪鱼分布的SST和SSH适宜范围;运用一元非线性回归方法,以渔获量为适应性指数,按季度分别建立了基于SST和SSH的长鳍金枪鱼栖息地适应性指数,采用算术平均法获得基于SST和SSH环境因子的栖息地指数综合模型,并用2012年各月实际作业渔场进行验证。结果显示,黄鳍金枪鱼渔场多分布在SST为24—29℃、SSH为0.3—0.7 m的海域。采用一元非线性回归建立的各因子适应性指数模型在统计上均为显著(P0.05)。经与2012年实际生产情况比较,作业渔场预报准确性达66%以上。研究获得栖息地指数模型可为金枪鱼延绳钓渔船寻找中心渔场提供参考。     

Bycatch species composition over time by tuna purse-seine fishery in the eastern tropical Atlantic Ocean

Within the Ecosystem-based fisheries management framework, we evaluated the changes over time in bycatch species of the European tuna purse-seine fishery operating in the eastern Atlantic Ocean. Bycatch data was collected during two scientific observer programs conducted in the late 1990s and in the late 2000s. Over these two time periods, we compared the temporal trends in bycatch species composition, the probability of occurrence of functional groups per fishing set, the spatio-temporal species richness and the potential impact on several species listed in the red list of the International Union for Conservation of Nature (IUCN). The analyses were performed separately on the two main fishing modes of the fleet, i.e. sets on free-swimming school sets and on fish aggregating devices (FADs). Owing data quality constraints, we did not estimate bycatch rates. Ours results showed that the species composition of sharks caught on FADs decreased over time. The total species richness was higher for FAD sets than for free-swimming school sets (87 vs. 61 species respectively), such difference is common between fishing modes worldwide. For the species catalogued as threatened by the IUCN, in free-swimming schools, 25.5 % of the species caught during first period increased to 30.4 % during second period, while for FAD-fishing the increase was from 28.8 % during first period to 34.9 % in second period. Ours findings suggest that tropical tuna purse-seine fisheries should include ecosystem-based governance of bycatch. Effective tuna management will require a combination of technological improvements for mitigating incidental catch of vulnerable species, best use of byproduct species, regulations in fishing practices and in spatial distribution of fishing effort, and international agreements that, together, can monitor and manage bycatch, reducing the negative fishing effects on the epipelagic ecosystem biodiversity.     

A plan for fisheries management in the lakes drained by the Oulujoki river

Freshwater fishery management is treated as a dynamic system comprising environment protection and improvement, fishing, fishery resources allocation, fish stocking programs and marketing policy. The aims of the plan are to increase the economic value of the catch and to protect the professional fishery. Fisheries statistics, catch per unit effort data and other material were collected during 1972–1976. The total allowable catch (TAC) for the most important fish species was estimated with MSY and population analysis models. The results of fish stockings were studied by tagging and population analysis calculations. Fishing of vendace and non-valuable species (perch, roach, smelt) can be increased, but the fishing pressure on other species should not be raised above the present level. Restrictions on whitefish fishing are needed in some areas. A balanced multispecies fishery is desirable, and suggestions are given for the composition of the fishing gear. Fish stocking can make possible a larger and more valuable catch, but at present its profitability is rather low. The stocking results are strongly affected by the fishery and the gear composition.     

The consequences of balanced harvesting of fish communities

Balanced harvesting, where species or individuals are exploited in accordance with their productivity, has been proposed as a way to minimize the effects of fishing on marine fish communities and ecosystems. This calls for a thorough examination of the consequences balanced harvesting has on fish community structure and yield. We use a size- and trait-based model that resolves individual interactions through competition and predation to compare balanced harvesting with traditional selective harvesting, which protects juvenile fish from fishing. Four different exploitation patterns, generated by combining selective or unselective harvesting with balanced or unbalanced fishing, are compared. We find that unselective balanced fishing, where individuals are exploited in proportion to their productivity, produces a slightly larger total maximum sustainable yield than the other exploitation patterns and, for a given yield, the least change in the relative biomass composition of the fish community. Because fishing reduces competition, predation and cannibalism within the community, the total maximum sustainable yield is achieved at high exploitation rates. The yield from unselective balanced fishing is dominated by small individuals, whereas selective fishing produces a much higher proportion of large individuals in the yield. Although unselective balanced fishing is predicted to produce the highest total maximum sustainable yield and the lowest impact on trophic structure, it is effectively a fishery predominantly targeting small forage fish.     

Fishing at Rio Grande (Brazil): Ecological niche and competition

This study is an ecological analysis of the use of resources by two potentially competitive groups, the commercial and recreational fishermen of Rio Grande, located on the border of the States of SÃo Paulo and Minas Gerais. Tourism at Rio Grande was intensified after the construction of the hydroeletric plant of Marimbondo in 1974, and local fishermen have complained about its interference. Values of niche dimensions, such as fishing periods, grounds, and prey caught were obtained through data gathered at landing points. Local and recreational fishermen usually fish in different parts of the river and catch different fish, because they use different gear. However, in transition months between the wet and dry seasons, when fish are less abundant, there is conflict or competition related to fishing grounds, reinforced by the territorial fishing rights of local longline fishermen in this period. We show how ecological concepts, such as niche and competition, may help to understand strategies of exploitation by human groups, fundamental information for the management of tropical areas.     

人工集鱼装置对热带金枪鱼类摄食模式的影响研究进展

热带金枪鱼类具有聚集在漂浮物体周围的行为特性,形成的集群表现稳定,可捕性较高。以此特性,金枪鱼围网渔业研制并投放了大量的人工集鱼装置(Fish Aggregation Device,FAD)用于聚集并捕捞金枪鱼。然而,大规模出现的FAD会使某些海域海面漂浮物的密度迅速增加,从而在一定程度上人为地改变了金枪鱼的表层栖息环境,对金枪鱼种群具有一系列可能的潜在负面影响,摄食模式的改变就是其中之一。归纳并综合了近年来国内外关于FAD对金枪鱼类摄食模式影响的相关研究,从摄食行为、日摄食量、饵料种类与组成以及生态位宽度4个方面对比了随附于FAD的金枪鱼和自由状态下同类的不同,发现大多情况下FAD的存在会使金枪鱼的摄食模式发生一定的改变。最后,归纳了过往实验存在的不足,对今后研究的发展方向进行了展望。     

Impacts of predator depletion by fishing on the biomass and diversity of non-target reef fish communities

 An understanding of the indirect effects of fishing on predator-prey relationships is required for the development of valid multispecies yield models for reef fisheries and for determining the factors governing fish community structure at larger scales. We used an underwater visual census technique to examine the indirect effects of fishing on the biomass and diversity (species richness) of reef fishes in a series of ten traditional Fijian fishing grounds (qoliqoli) subject to a range of fishing intensities. All members of the families Chaetodontidae (butterflyfishes), Labridae (wrasses), Lutjanidae (snappers), Mullidae (goatfishes), Scaridae (parrotfishes) and the sub-family Epinephelinae (groupers and coral trout) which could be reliably identified were censused. Each species censused was assigned to one of three trophic groups: herbivore, invertebrate feeder or piscivore. The biomass of all piscivorous fishes and of large (>30 cm) piscivorous fishes differed significantly between qoliqoli and was significantly correlated with fishing intensity. However, the biomass of piscivorous fishes was not correlated with the biomass or diversity of their potential prey (which were not targeted by the fishery). This suggested that the indirect effects of fishing did not have an important bearing on fish diversity or biomass and that predation by the target species did not play an important role in structuring these Fijian reef fish communities. The results contrast with those from a number of studies at smaller scales and provided further indications that the structure of reef fish communities is not governed by a single dominant process, but by a range of processes which operate on different scales in different circumstances. Accepted: 29 July 1996