Stock structure and resource management of hairtail <Emphasis Type="Italic">Trichiurus japonicus</Emphasis> based on seasonal broods around the Bungo Channel,Japan

Declines in landings of the hairtail Trichiurus japonicas indicate the need for more effective management of this species. Hairtail spawning peaks occur twice yearly in the Bungo Channel, in spring and autumn. Relationships between hairtail stock and brood seasonality were examined to determine if an association between either and a decline in landings existed. Stock assessments show that the biomass of both spring and autumn hairtail broods from within and around the Bungo Channel are decreasing, with a rapid reduction in spring-brood stock abundance after 2007 largely responsible for decreased landings. Yield and spawning per recruitment analyses indicate current fishing pressure to be higher than several reference points. We suggest that fishing pressure needs to be reduced by at least 20% of the current level for this fishery to remain sustainable, as the projected stock abundance and catch demonstrate that the current fishing pressure is unsustainable. Analysis of time-series data of recruits per spawning revealed spring-brood recruitment to have been strong in year classes 2003 and 2005. Of various options available for improved management of this fishery, we propose that fishing pressure should be reduced in the years following the appearance of strong year classes to increase future biomasses and landings.     

Conservation of small hairtail <Emphasis Type="Italic">Trichiurus japonicas</Emphasis> by using hooks with large artificial bait: effect on the trolling line fishery

Overfishing has reduced the stock of hairtail Trichiurus japonicus around the Bungo Channel, Japan. To determine whether using larger bait in the trolling line fishery could avoid catching small/undersize hairtail, we developed and trialled a new large artificial bait (a soft plastic bait, 6 inches long). A traditional lure with natural bait (type-1), a new lure of the new artificial bait hook without natural bait (type-2), and a new lure with natural bait (type-3) were tested in fishing operations around the Bungo Channel. Compared with type-1, type-2 and type-3 caught fewer undersized and immature female individuals. The number of fish caught, yield, and composition of commercial size grades per recruitment were calculated from field data for each lure and compared. The catch sizes (number of fish per recruitment) were smaller for type-2 and type-3 than for type-1, but yield per recruitment was higher for type-3 than for type-1. Compared with type-1, type-2 and type-3 caught more large individuals, which are more valuable. The newly developed artificial bait conserves hairtail stocks by targeting larger fish, which is economically beneficial for the hairtail trolling line fishery.     

The neglected role of religion in fisheries management

Religion and spirituality have long played important roles in fishery systems around the world, and yet are often neglected in modern fisheries management and research. We review current literature and analyse the major small‐scale fishery on Lake Tanganyika, Africa, to highlight how religion may mediate fishing behaviours. Our study surveyed 154 fishers across 11 landing sites in Tanzania, followed by 15 semi‐structured interviews with key informants including fishery officers and local religious leaders. We identified key connections between religious beliefs/practices and fisher perceptions, behaviour and compliance with harvest restrictions and regulations. We demonstrate that better understanding and accounting for religious dimensions is critical for engaging with fishery stakeholders more effectively and managing global fisheries more sustainably.     

Socio-cultural context of fishers’ participation in coastal resources management in Anini-y,Antique in west central Philippines

The vicious cycle of poverty, overfishing and resource degradation in coastal communities in the Philippines calls for action that will address the problem of declining fish catch and degraded fish habitats. The literature has shown that an efficient and effective coastal management program can be instrumental in approaching this problem. In order to secure food and livelihood of fishers, the Southeast Asian Fisheries Development Center/Aquaculture Department collaborated with the local government of Anini-y, Antique to develop a sustainable utilization of natural marine resources through sea ranching of abalone within the Nogas Island marine protected area. Establishing a marine protected area is a means of conserving natural stocks while sea ranching is considered an effective strategy that can increase fishery resources. The two management schemes are considered as effective coastal resources management strategies. The success of a sea-ranching project is dependent not only on biophysical but also on socioeconomic factors as determinants of community participation and cooperation. A social assessment was conducted to determine the fishers’ socio-cultural characteristics, their perceptions of their coastal resources and knowledge on how to effectively manage these coastal resources. The fishers’ awareness on fishing regulations and the extent of their participation in community's coastal resources management activities were also determined. Data were collected from a household survey using a semi-structured questionnaire, focus group discussions and in-depth interviews with key informants. The fishers generally scored low in almost all aspects of their socioeconomic wellbeing. Most fishers perceived that their coastal resources were in a bad condition which they attributed to illegal and commercial fishing, increasing number of fishers and the poor enforcement of fishery regulations. However, the weighted mean scores of their knowledge on coastal resources management, awareness to fishery regulations and participation in community coastal resource management activities were average. This implied that fishers when trained and developed can become potential partners for effective coastal resources management programs.     

把不确定性引入生物学参考点F0.1和Fmax的估计以评估东海带鱼渔业资源

东海带鱼(Trichiurus haumela)是东海区重要经济鱼类之一,目前还没有研究在生物学参考点F0.1和Fmax的估计中引入不确定性并在此情况下对东海区带鱼渔业资源进行量化评估。文章应用蒙特卡罗模拟方法研究了渔业数据中不同水平的不确定性和不同初次捕捞年龄对F0.1和Fmax估计的影响,用其与现在的捕捞死亡系数Fcur做比较,初步评估了东海带鱼渔业资源。计算结果表明,高水平的不确定性将会增加在F0.1和Fmax估计中的差异,从而使其被定义为过度捕捞的可能性减小。经过比较表明,F0.1比Fmax是一更好的参考点,且东海区带鱼渔业明显处于过度捕捞状态。不同初次捕捞年龄下单位补充量渔获量的变化情况的研究表明,增大初次捕捞年龄可以减小现在的捕捞死亡率大于参考点死亡率的概率,从而增大初次捕捞年龄可以改善现在捕捞过度的资源状况。     

Variation in productivity of a key snapper,Chrysophrys auratus,fishery related to recruitment and fleet dynamics

Abstract Temporal variation in production of the Chrysophrys auratus (Forster) fishery of Northern Spencer Gulf, South Australia, between 1984 and 2009 was investigated using commercial fishery statistics and estimates of age and size structures from market sampling. Fishery production was divisible into two periods, i.e. from 1984 to early 2000s and the middle to late 2000s. During the former, cycles in production were relatable to variable fishable biomass. Age structures that displayed considerable differences in age class strength reflected interannual variation in juvenile recruitment, which resulted in high variability in the strength of year classes entering the fishery. Periodic strong year classes were the major influence on fishable biomass as they passed through the population over numerous years. For the latter period, fishery statistics were conflicting as catches and effort were relatively low, whilst the estimates of catch per unit effort (CPUE) were consistently high. These statistics reflect a considerable change to the structure of the fishery that involved a reduction in number of fishers and fishing effort. The fishery statistics may indicate hyperstability, with CPUE estimates remaining high despite declining biomass because of the aggregative behaviour of the fish and the efficiency of remaining fishers.     

Empowerment and regulation – dilemmas in participatory fisheries science

Using a perspective from the sociology of knowledge, this study identifies some ‘dilemmas of participatory research’. We look at how social relationships between fishers and scientists develop around the exchange of fishers’ knowledge in particular institutional contexts. We survey the general types and global examples of fisher–scientist relationships in terms of how they approach the integration of fishers’ and scientists’ knowledge. Based on an empirical study of three European cases of participatory research, we then discuss five dilemmas that tend to characterize fisher–scientist relationships. These dilemmas centre on the relationship between fisheries research, fishery regulations and fishers as subjects of both regulation and participatory research endeavours. We argue that these dilemmas – experienced by both scientists and fishers – express an underlying tension between ‘empowering’ fishers to support the effective management of the fishing commons and the bureaucratic need to regulate the fishery as an industry.     

Local knowledge surveys with small-scale fishers indicate challenges to sawfish conservation in southern Papua New Guinea

1. Sawfish (Pristidae) are considered to be among the most threatened families of elasmobranch (sharks and rays). There is a need to gather information on the status of poorly known sawfish populations to assist in global recovery initiatives.
2. This study used interviews with local fishers to investigate the presence of sawfish in southern Papua New Guinea (PNG) and their interactions with and uses and values for small-scale fishers.
3. A range of sawfish size classes are still encountered throughout southern PNG, while juvenile largetooth sawfish Pristis pristis were additionally reported in the freshwater reaches of all rivers surveyed. Reports of large size classes in estuarine and marine environments provide an optimistic outlook that sawfish populations persist throughout southern PNG.
4. Most fishers that catch sawfish retain them for various uses including consumption and for the sale of meat, fins and occasionally rostra. Negative population trends including decreases in catch frequency and/or size classes were reported by 66% of interviewees, with the largest declines being reported in the Kikori River. The increasing technical capacity of small-scale fishers, their preference for gillnetting and the emerging market for teleost swim bladder (a high-value fishery product) present a major ongoing threat to sawfish in southern PNG. Furthermore, the tendency of fishers to kill or remove rostra from entangled sawfish results in high fishing mortality regardless of any use by the fisher.
5. This study indicates that considerable community engagement will be necessary to manifest any legislative actions or increased enforcement on international trade regulations for sawfish in PNG. This is due to traditional land and waterway ownership values throughout PNG and the local perception of sawfish as a traditional food resource rather than an animal of intrinsic biodiversity value as perceived by global conservationists. Future research should consider exploring culturally appropriate conservation initiatives that are likely to achieve engagement and participation from local fishers.

     

Biological and socioeconomic implications of recreational boat fishing for the management of fishery resources in the marine reserve of Cap de Creus (NW Mediterranean)

A survey of coastal recreational boat fishing was conducted in summer 2006 in the marine reserve of Cap de Creus (NW Mediterranean) to assess the biological and socioeconomic implications of this leisure activity. Recreational boat fishers employ four different fishing techniques: bottom fishing rod, fluixa, trolling and surface fishing rod. Although the targeted species depend on the fishing method used, a total of 33 fish species were identified in the catch (8 were pelagic or benthopelagic and the rest were demersal). Fishing effort was high since fishers fished an average of 4 h/day, 8 days/month and nearly 6 months/year. Apart from the highly varied exploitation of the fauna, recreational fishing in Cap de Creus has a large economic effect on the local economy since the majority of fishers were visitors who were spending holidays in one of the villages belonging to the Park, where most of expenditures related to angling activities were made. Overall, results highlight the pressure that recreational boat fishing exerts on fish communities, particularly on littoral, demersal ones. Considering these biological and socioeconomic implications, the competition between recreational and artisanal fishers for littoral resources and the low level of compliance with the current sport fishing regulations, the implementation of a comprehensive management strategy in Mediterranean costal areas is needed.     

Fisher's preferences and trade‐offs between management options

Failure to understand the potential responses of fishers to management measures creates a significant risk of revisiting the familiar scenario of perverse and unintended consequences of those measures. This paper reports on a choice experiment survey to evaluate fisher's preferences for various management measures proposed under the EU Common Fisheries Policy (CFP) reform process, but the conclusions have wider relevance as similar measures are used by comparable fleets in fisheries globally. The survey was conducted with fishers involved in mixed pelagic and demersal fisheries in Ireland, pelagic fisheries in Denmark and demersal fisheries in Greece. Fisheries management policies were characterized by five attributes designed both to cover the principal CFP reform proposals and to integrate ecological, social, economic and institutional factors affecting fisher's decisions. The study uses a random utility modelling framework to reveal the preferences of the fishers across the alternative policy attributes. Results show that while there are generally preferences both for healthy stocks and for maintaining the importance of fishing to the local community, strong interfishery preference differences exist. These differences are most notable in relation to a discard ban and to the use of individual transferable fishing rights, favoured in Denmark, but not in Ireland for instance. The strength of these interfishery differences supports the assertion that there are no panaceas in fisheries management and that solutions should be tailored within the context of specific fisheries. Not doing so could create a significant risk of inappropriately managed fisheries that may lead to unsustainable outcomes.     

Trade‐offs in triple‐bottom‐line outcomes when recovering fisheries

Almost all environmental management comes at an economic cost that may not be borne equitably by all stakeholders. Here, we investigate how heterogeneity in catch and profits among fishers influences the trade‐off among the triple‐bottom‐line objectives of recovering a fish population, maximizing its economic value and distributing restrictions equitably across fishers. As a case‐study, we examine management reform of an ecologically and economically important coral reef fishery operating within the Great Barrier Reef Marine Park. Using a simulation model, we find that total profitability of the fishing industry is 40% lower if recovery plans are equitable when compared to the most economically efficient plan. However, efficient recovery plans were typically highly inequitable because they required some fishers to cease fishing. Equity was defined according to different norms, and the efficiency loss was greatest when catch losses were shared equally across fishers rather than in proportion to their historical catch. We then varied key social, economic and biological parameters to identify cases when equity and efficient recovery would trade‐off most strongly. Recovery plans could be both efficient and equitable when heterogeneity in fisher's catches and individual catch efficiencies was lower. If fishers were homogenous then equitable plans could have maximal economic efficiency. These results emphasize the importance of considering heterogeneity in individual fishers when designing recovery plans. Recovery plans that are inequitable may often fail to gain stakeholder support, so in fisheries with high heterogeneity we should temper our expectations for marked increases in profits.     

南海区双船大网目拖网网囊网目对带鱼的选择性

大网目拖网是我国海洋渔业捕捞带鱼的重要渔具。为提高拖网网囊选择性, 本研究在南海区采用套网法对双船大网目拖网 4 组网目尺寸(30、35、40 和 45 mm)的网囊进行实验, 在双重拔靴法的架构下, 拟合选择性参数、比较选择性的差异、估算捕捞方式指标。结果表明, 随着网目尺寸的增大, 网囊对带鱼的 50%选择体长增大, 对带鱼幼鱼个体的选择率显著下降, 带鱼幼鱼的渔获比例也呈下降趋势。结合带鱼最小可捕规格(23.0 cm)管理规定, 结果还表明网目尺寸为 40 mm 的网囊选择性较差, 其对带鱼的抛弃率大于 93%。为了进一步提高带鱼拖网渔业的资源养护水平, 还需要开展更多的选择性实验。     

Sustainability of fishers’ communities in tropical island fisheries from the perspectives of resource use and management: a comparative study of Pohnpei (Micronesia), Mafia (Tanzania), and Guimaras (Philippines)

The fisheries structure, fishing gear, fishing vessels and their ownership, landing sites and markets, as well as fisheries management and fishers’ participation were surveyed in three tropical islands: Pohnpei (Micronesia), Mafia (Tanzania), and Guimaras (Philippines), covering 127 fishers. Labour-intensive gear, including purse seines and ring nets, characterised Mafia fisheries. Fibre-reinforced plastic (FRP) boats characterised Pohnpei fisheries, and canoes with nonmarine engines were characteristic of Guimaras fisheries. Wooden plank boats with large crews were only seen in Mafia. From a gear/vessel ownership perspective, the fisher categories present were gear fishers, gear-vessel fishers, employers, and casual labour fishers. Casual labour fishers and employers were only apparent in Mafia. The fisheries in Pohnpei had a relatively early age of entry, which was attributed to the urban markets available and family cohesion, while community organisation-based management of these fisheries was weak. Mafia and rural Guimaras fishers depended on middlemen, due to the distance of the market. Deteriorating subsistence-related fishery dependency means that the Guimaras fishers’ community is at risk. The high shared gear/vessel ownership rates and levels of affiliation to community organisations in Mafia reflect government’s timely community sustainability enhancement initiative. Based on our analyses, we propose the “fishers’ community sustainability” concept. The sustainability of a fisher’s community can be judged on (1) the age of entry to the fisheries, (2) the monetary profits made at fish markets and through marketing, (3) the cohesion among the fishers, and (4) the level of subsistence-related dependency on the fishery. The fishery is key to community sustainability, thus ensuring fishery-dependent life. It is essential to consider the above indicators of fishers’ community sustainability during fisheries development.     

Perceptions of resource users and managers towards fisheries management options in Kenyan coral reefs

Abstract  The perceptions of Kenyan resource users and managers towards gear and area management were examined through face-to-face interviews to identify areas of agreement and disagreement and compare with compliance. Opinions were sought about gears that sustained fish catch, gears discouraged by the government and traditional leaders, and the benefits of area management were sought. There was good agreement among most groups and traditional leaders about the gears discouraged by government, with beach seines and spear guns the most commonly listed. This indicates good agreement between government and traditions, promoted by recent government legislation, but compliance was poor since nearly two-thirds of fishers used these recently prohibited gears. This was due, in part, to lesser agreement concerning gears that promote a sustainable fishery, with spear guns and beach seines scaled low, but moderately supported in this respect by those fishers that use these gears. These gears persist because of the lack of shared evidence about the yields and sustainability of the various gears and social and economic aspects, such as increased competitiveness and decreased costs of the gears. There is evidence that beach seines lower yields but this gear persists because it is more competitive and has lower costs to the user than the other gears. Spear guns also persist because young and poor fishermen, who cannot afford costs associated with other gears, use them. Government employees scaled the benefits of area, and particularly closed area, management, higher than fishers, which is an issue of conflict but, nonetheless, has good compliance because of the long history of closed area management. For both types of management, shared perceptions alone were insufficient to achieve high compliance, and active enabling and enforcement by managers is needed.     

Flume tank and in situ trials for verification of static and dynamic methods for gear depth and underwater behavior of hairtail trolling lines

We investigated the underwater shapes of trolling lines for the improvement of hairtail fishing efficiency. Two sets of experiments were carried out, one on a small scale, where flume tank tests of four models were scaled down by a ratio of 1:10 and trolled at different speeds, and another at full scale, comprising a survey on board a commercial fleet. In situ trials were conducted off the coast of Jeju Island, South Korea, at 33°27′57.528″N, 126°55′48.846″E, a potential fishing ground for hairtail fishing. The full-scale gear was set by altering sinker weights whilst changing the length of the warp line at different towing speeds. A dynamic method using a mass-spring technique and full-scale gear was developed. External and internal forces that govern the motion of the gear were considered. A non-linear differential equation of motion was developed, solved by a fourth-order Runge–Kutta method at a time step of 5?×?10^?4 s for each trial. A static method was also developed using full-scale gear to predict the equilibrium gear configuration under all fishing conditions. The dynamic method better predicts the actual underwater performance of trolling line gear in real time.     

Changes in albacore tuna habitat in the northeast Pacific Ocean under anthropogenic warming

Albacore tuna are widespread in the North Pacific Ocean and the basis of an important commercial fishery. These fish live mainly within a fairly narrow thermal niche range defined by sea surface temperature (SST) isotherms between 14 and 19°C. Because the fish's thermal range coincides with strong latitudinal temperature gradients off the northwest coast of North America, there is a great deal of seasonal and interannual variability in the distribution of these fish, and a significant potential for a new habitat in this region with anthropogenic climate change. We use historical catch and effort data from the Canadian troll fleet to define the fish's thermal niche, and document observed shifts in distribution associated with interannual climate variability. We then use an ensemble of climate model simulations from the Coupled Model Intercomparison Project to estimate northward extension of the potential habitat under anthropogenic warming scenarios. A potential new habitat is about half a million square kilometres even under a moderate mitigation scenario. Estimates are smaller for some months of the year in which the fishery is conducted, but as well as opening up new regions, the length of season in which the fishery is active may be extended in the northern part of the range. However, much of the potential new habitat will be in oceanic waters with relatively low productivity. Our estimated area of potential habitat is based on the fish's thermal niche and assumes that other biologically important factors such as food will not be limiting.     

Combining fishers’ knowledge and cost‐effective monitoring tools in the management of marine recreational fisheries: A case study of the squid and cuttlefish fishery of the Ría of Vigo (NW Spain)

A new methodology based in the use of fishers’ knowledge and cost‐effective tools to obtain information about marine recreational fisheries (MRF) is presented. The squid and cuttlefish fishery of the Ría of Vigo (NW Spain) was selected because it is managed in a data‐poor environment. In‐depth interviews (57) were conducted with fishers, collecting ecological and socio‐economic information. A cartography of fishing grounds based on their knowledge was obtained, while the intensity of effort and catches was mapped by the monitoring of two vessels with low‐cost GPS data loggers. The 102 shore anglers and 248 recreational boats catch 8 t/year of European squid Loligo vulgaris and 11 t/year of common cuttlefish Sepia officinalis (11% of total catches on these species in the area). Shore anglers fish from 11 ports, while boat fishers use 14 fishing grounds (covering 30 km²). Most of the catches (86%) are landed by boats, and their CPUE is higher in the outer part of the Ría of Vigo. The use of fishers’ knowledge and cost‐effective monitoring is encouraged to obtain information for the management of MRF. Given the economic contribution of MRF (260,000 €/year in direct expenses), this activity should be considered in the regulations.     

The quandary of quota management in the Torres Strait rock lobster fishery

Islanders, commercial non‐indigenous fishers and Papua New Guinea fishers share the tropical rock lobster fishery, Panulirus ornatus (Fabricius) in Torres Strait. As the fishery is in the process of moving from input to output controls, a pre‐implementation understanding of indigenous fishers' perceptions of the potential impact of different quota management systems is gained. This study, based on workshops and interviews, considers the impact of competitive quota, community quota and a hybrid system with individually tradeable quota (ITQ), and broadens the current biological focus of fisheries management through consideration of economic, social and cultural aspects. The perceived quota system impact on indigenous lobster fishers largely mirrors the experience internationally, with unlimited access and self‐determination considered most important. The heterogeneity of the indigenous sector increases the management complexity for this fishery, but needs to be taken into consideration if unexpected consequences of the chosen quota management system are to be avoided.     

Opportunities to improve fisheries management through innovative technology and advanced data systems

Fishery‐dependent data are integral to sustainable fisheries management. A paucity of fishery data leads to uncertainty about stock status, which may compromise and threaten the economic and food security of the users dependent upon that stock and increase the chances of overfishing. Recent developments in the technology available to collect, manage and analyse fishery‐relevant data provide a suite of possible solutions to update and modernize fisheries data systems and greatly expand data collection and analysis. Yet, despite the proliferation of relevant consumer technology, integration of technologically advanced data systems into fisheries management remains the exception rather than the rule. In this study, we describe the current status, challenges and future directions of high‐tech data systems in fisheries management in order to understand what has limited their adoption. By reviewing the application of fishery‐dependent data technology in multiple fisheries sectors globally, we show that innovation is stagnating as a result of lack of trust and cooperation between fishers and managers. We propose a solution based on a transdisciplinary approach to fishery management that emphasizes the need for collaborative problem‐solving among stakeholders. In our proposed system, data feedbacks are a key component to effective fishery data systems, ensuring that fishers and managers collect, have access to and benefit from fisheries data as they work towards a mutually agreed‐upon goal. A new approach to fisheries data systems will promote innovation to increase data coverage, accuracy and resolution, while reducing costs and allowing adaptive, responsive, near real‐time management decision‐making to improve fisheries outcomes.     

Balanced harvesting can emerge from fishing decisions by individual fishers in a small‐scale fishery

Catching fish in proportion to their productivity, termed balanced harvesting, has been suggested as a basis for the ecosystem approach to fishing. Balanced harvesting has been criticized as uneconomical and unachievable because of the level of micromanagement it would require. Here, we investigate the consequences of allowing a fixed number of fishers in a small‐scale fishery to choose what size fish to attempt to catch. We examine this from a game‐theoretic perspective and test our predictions using an agent‐based model for fishers’ decisions coupled with a size‐spectrum model for the dynamics of a single fish species. We show that small‐scale gillnet fishers, operating without size‐based regulations, would end up catching small and large fish in proportion to their productivity, in other words balanced harvesting. This is significant because it shows that, far from being unachievable, balanced harvesting can emerge without external intervention under some circumstances. Controls are needed to prevent overfishing, but minimum size regulations alone are not sufficient to achieve this, and actually reduce the sustainable yield by confining fishing to a relatively unproductive part of the size‐spectrum. Our findings are particularly relevant for small‐scale fisheries in areas where there is poverty and malnutrition because here provision of biomass for food is more important than the market value of the catch.