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1.
《African Journal of Marine Science》2013,35(1):773-789
There are two types of interactions between seals and commercial fisheries in South Africa: biological (potential competition for shared resources between the two "predators") and operational (conflicts during fishing operations). Using data for the 1980s, a comparison is made of relative consumption by different predators in South African waters. Seals and fisheries are not the major consumers in the system, but they do take comparable amounts. This has resulted in calls for a reduction in the seal population, but to date, no studies have shown that reducing seal predation of commercial species will make more fish available for the fisheries. Most fisheries are subject to some form of operational interaction with seals. These interactions include consumption of catches (operational consumption), disturbance of fishing operations (operational disturbance) and damage to fishing gear (operational gear damage); they vary in degree of severity, both seasonally and regionally. Estimates of the consumption by seals from fishing operations in South Africa show it to be a minimal percentage of fishery catches and a small proportion of the total predation by seals. Preliminary calculations of overall economic losses resulting from seal interference show this to be small in comparison with the wholesale value of the catches. Seals die as a result of fishing operations, and estimates of the potential mortality through entanglement, drowning and deliberate killing indicate this mortality to be of a magnitude that should be monitored. 相似文献
2.
Antonello Sala Francesco De Carlo Gabriele Buglioni Alessandro Lucchetti 《Ocean Engineering》2011,38(5-6):804-809
A new fuel consumption monitoring system was set up for research purpose in order to evaluate the energy performance of fishing vessels under different operating conditions. The system has been tested on two semi-pelagic pair trawlers in the Adriatic Sea with an engine power of around 900 kW, and with length overall of around 30 m. Both vessels work with a gear of similar design and size, the differences between the two vessels are in the propeller design and the hull material: the first with a controllable pitch propeller (CPP) and a metal hull, the second with a fixed pitch propeller (FPP) and a wooden hull. The fuel monitoring system conceived at CNR-ISMAR Ancona (Italy) consists of two mass flow sensors, one multichannel recorder and one GPS data logger. The working time duration, the vessel speed, the total fuel consumption and the instant fuel rate were logged by the system. A typical commercial round trip for a semi-pelagic trawler consists of several fishing operations (steaming, trawling sailing, etc.). Fuel consumption rate and vessel speed data were used to identify energy performance under different vessel-operating conditions. The highest fuel demands were during the trawling (130 l/h at 4.4 kn) and the steaming (100–130 l/h at 11 kn) phases. Fuel savings of up to 15% could be obtained by reducing the navigation speed of half a knot. 相似文献
3.
《Marine Policy》2014
Fisheries management determines how much of each stock can be landed when, where and how fishing is permitted. It has been identified to strongly influence the environmental performance of the fishing industry, including fuel use. As fuel data for fisheries is scarce, especially on a detailed level, the aim of this study was to develop an approach for utilizing fleet-wide fuel data to estimate the fuel use of individual fisheries and mapping how fuel efficiency in Swedish fisheries is influenced by management. Swedish demersal trawl fisheries were studied between 2002 and 2010. Results show that the overall fuel efficiency has improved and interesting patterns between different fisheries and vessel sizes emerged. The difference in fuel efficiency per kilo landing between large and small trawlers was generally small, unless catch capacity was lowered e.g. by selective grids. Stock rebuilding was shown to be highly important for fuel efficiency, as fuel use was inversely correlated to the biomass of eastern Baltic cod. However, rebuilding can also lead to trade-offs e.g. in the case of selective trawling, where protection of depleted stocks comes at the cost of higher fuel intensity per landing. Finally, tax exemption of fuel use in fisheries was shown to maintain inefficient fisheries. These results could be used to reduce overall environmental impacts of fishing further by incorporating fuel use as an additional aspect into the fisheries management system. 相似文献
4.
Robert Kilpatrick Graeme EwingTim Lamb Dirk WelsfordAndrew Constable 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(4):486-491
Studies of the interactions of demersal fishing gear with the benthic environment are needed in order to manage conservation of benthic habitats. There has been limited direct assessment of these interactions through deployment of cameras on commercial fishing gear especially on demersal longlines. A compact, autonomous deep-sea video system was designed and constructed by the Australian Antarctic Division (AAD) for deployment on commercial fishing gear to observe interactions with benthos in the Southern Ocean finfish fisheries (targeting toothfish, Dissostichus spp). The Benthic Impacts Camera System (BICS) is capable of withstanding depths to 2500 m, has been successfully fitted to both longline and demersal trawl fishing gear, and is suitable for routine deployment by non-experts such as fisheries observers or crew. The system is entirely autonomous, robust, compact, easy to operate, and has minimal effect on the performance of the fishing gear it is attached to. To date, the system has successfully captured footage that demonstrates the interactions between demersal fishing gear and the benthos during routine commercial operations. It provides the first footage demonstrating the nature of the interaction between demersal longlines and benthic habitats in the Southern Ocean, as well as showing potential as a tool for rapidly assessing habitat types and presence of mobile biota such as krill (Euphausia superba). 相似文献
5.
《Marine Policy》2014
Fisheries statistics provided by the Hellenic Statistical Authority (HELSTAT) have been often criticized for unusual estimates in landings and fishing effort data and for limitations in the sampling methodology, although there is no study on the identification of these biased and misreporting estimates. In the present study the landings per species and fishing subarea, as well as the fishing effort data per fishing gear reported by HELSTAT were analysed over the period 1982–2010. The results showed abrupt changes of both the recorded species and species landings per subarea, spurious correlations of landings among different species groups and misreporting estimates in the number of fishing vessels per fishing gear. These might be likely attributed to: (a) differences of the HELSTAT administrative infrastructures at local scale, (b) changes in the sampling protocol followed by HELSTAT, (c) reporting faults made by HELSTAT, (d) fisheries restrictive measures at local basis, (e) other factors that increased the bias and the uncertainties of HELSTAT fisheries data and related to socio-economic (i.e. fuel price) and operational (i.e. spatial structure of the fisheries fleet) aspects and/or (f) to environmental changes that might possibly affected fisheries dynamics. The present study aims to the improvement of the effectiveness of the national fisheries statistics as pinpointed by Common Fisheries Policy in order to avoid imprecise and/or biased estimations about the state of the fisheries. 相似文献
6.
《Marine Policy》2017
Fatal entanglements in fishing gear threaten marine mammal populations worldwide. The management of entanglements of large whales, such as the North Atlantic right whale (Eubalaena glacialis), with commercial fisheries, is a challenge given the species’ small population size, economic consequences of regulations, and the general lack of data on entanglements. The U.S. Marine Mammal Protection Act (MMPA) requires development of programs to limit marine mammal entanglement in commercial fishing gear. Following a retrospective look at implementing aspects of the MMPA, a set of guiding principles were developed with associated best practices useful in reducing fatal large whale entanglement in fishing gear. Among these are: 1) involve stakeholders early in the decision making process; 2) establish a transparent management strategy that includes critical needs to guide research; 3) use a variety of tools such as an established process for receiving new information and ideas; and 4) incorporate adaptive management which considers the constraints of dynamic (rapid) changes to some fixed fishing gear. Efforts to reduce worldwide marine mammal bycatch will typically occur in a data-limited environment as experienced with U.S. Atlantic large whale entanglements. The guiding principles will remain as key tools for reducing large whale bycatch in fisheries as they build upon common practices. These insights developed over two decades of management can potentially help others to address similar bycatch problems. 相似文献
7.
《Marine Policy》2017
The fisheries management policy shift towards resource user participation in Malawi in the early 1990s resulted in mixed benefits among small-scale fishers, with many applauding the changes. This paper considers the impacts of these policy changes on government and within the fishing communities around Lake Chiuta whose fisheries co-management experience is considered successful. Benefits to the communities range from gaining government support in excluding non-local fishers using destructive fishing gear to increased household incomes and improved livelihoods, while benefits to government range from taking credit for establishing a sustainable fishery and co-management arrangements to reduced resource management costs. Community costs include financial resources and time spent by resource user representative organisations in enforcing fishing regulations. These findings enable a more balanced assessment of neoliberal claims about the benefits of delegating management responsibilities and downloading costs of management onto fishing communities and organisations. 相似文献
8.
Overcapacity in the fishing fleets is considered as the most serious threat to sustainable fisheries. More effective fishing vessels and catching gear contribute to increased catch capacity. Increased catch capacity causes environmental problems such as overexploitation and calls for larger quotas. The problem of overcapacity indicates the need for a stronger integration of technological aspects into fisheries management. This article assesses the differences in sustainability between the Norwegian ocean and coastal fishing fleets in the cod fisheries, by using systems engineering methods. Attributes of sustainability in the Norwegian cod fishing fleets are investigated, as well as acceptance criteria and performance indicators. The results show that there are huge differences in the performance between the vessel groups, and that the results of an evaluation of sustainability in the fishing fleets are dependent on which attributes are explored. Thus, the discussion may contribute to a better decision basis and improved sustainability in fisheries management. 相似文献
9.
《Marine Policy》2005,29(6):481-493
Controlling the expansion of capture capacity has been a major challenge for the fisheries management systems around the North Atlantic. Despite focused attempts to reduce this capacity in recent years in different jurisdictions, it has continued to expand. This chapter uses a case study of changes in Norwegian fisheries to help explain why this has happened. The article supports the replacement of the rational actor approach that is currently hegemonic within fisheries management by a relational approach to the analysis of capture capacity expansion. A relational approach offers new insights into the ways political, economic, and technological forces continue to fuel capacity expansion within fishing. By use of this approach the article describes how the harvest machinery comes into existence. 相似文献
10.
《Marine Policy》2014
Several tuna regional fisheries management organizations (t-RFMOs) have adopted retention requirements for skipjack, bigeye and yellowfin tunas caught by purse seine vessels to reduce discards, create disincentives to catch small fish, and incentivize the development and adoption of more selective technologies. Although retention policies in the t-RFMOs have been limited to target tunas in purse seine fisheries, some have advocated for an expansion of those policies, and t-RFMOs could consider expanding retention policies to a greater number of species and/or to other gear types. This paper discusses the benefits and costs of broader retention policies for purse seine and longline tuna fisheries in the western and central Pacific Ocean (WCPO). Using bycatch data from observers and logbooks from the U.S. purse seine and longline fleets operating in the WCPO, this paper documents the types and magnitude of fish discarded. For the purse seine fishery, this information was used to estimate direct impacts of having to off-load at the initial point of landing in key Pacific Island ports. For the longline fishery, estimates of direct impacts were limited to Honolulu and Pago Pago, American Samoa, the two primary ports where U.S. catch is landed. Expanding retention policies beyond the target tunas and to other gear types would further reduce discarding and possibly provide stronger incentives to develop and use more selective techniques. Beyond impacts to the ecosystem and fisher behavior, adopting broader retention policies may have other implications, and this paper explores those implications on vessels, processors, and communities. In general, as is the case with most direct interventions on fishing operations, there will be both benefits and costs, and the magnitude of those impacts will depend on the scope and extent of any expanded retention policy. 相似文献
11.
《Marine Policy》2016
Climate change affects ocean conditions, fish stocks and hence fisheries. In West Africa, climate change impacts on fisheries were projected to be mainly negative through multi-facet ways. However, analysis of adaptation responses of fishers to climate change impacts is scarce. This paper reviews the impacts on climate change on fisheries in West Africa and discusses the potential adaptation strategies adopted by both the artisanal and industrial fishing sectors. Overall, climate change and over-exploitation have altered species composition of fisheries catches in West Africa. The effect of ocean warming on fisheries is indicated by the increase in dominance of warmer water species in the landings, shown from an increase in Mean Temperature of Catch, in the region. Climate change induced changes in potential catch and species composition, which inherently have similar symptoms as over-exploitation, are expected to have repercussions on the economic and social performance of fisheries. Both artisanal and industrial sectors may adapt to these changes mainly through expansion of fishing ground that increases operation costs. Our results highlight that historical changes in target species are more common in industrial than artisanal fisheries. This result challenges the prevailing assumption that artisanal fisheries, given their limited movement capacity, would adapt to climate change by shifting target species and/or gear type. 相似文献
12.
《Marine Policy》2017
A feasibility study was conducted on the impacts of the new Common Fisheries Policy (CFP) rules requiring catches in regulated fisheries to be landed and counted against quotas of each Member State - the landing obligation (LO), and that catch of species subject to the LO below a minimum conservation reference size (MCRS) be restricted to purposes other than direct human consumption. The aim was to estimate the level of discarded fish likely to be covered by the new rules, the impact of the rules on EU fisheries and the regulatory challenges and responses to them. Data from EU's Scientific, Technical and Economic Committee on Fisheries (STECF) database were analysed to estimate the volume of unwanted catches produced by EU fisheries. Views were sought from policy officials and fisheries scientists through a questionnaire on the implications of the LO and the control of fisheries across Member States, and the potential adjustments that might be needed. Findings show that 11% (44,000 t) of the total catches of EU countries from which data were available are of fish under MCRS. The species with the highest volume of undersized discards associated with the lowest quota, which would potentially restrict the fishing opportunities for other quota species (i.e. choke species), are plaice and haddock with 18,000 and 14,000 t of undersized fish respectively, followed by whiting and cod with 5000 and 6000 t of undersized fish respectively. Discards data shows that the Netherlands, United Kingdom, France and Belgium will be most affected by landings for non-human markets. Findings also show that existing infrastructure at landing ports in all Member States is limited because there are currently limited facilities in place to handle animal by-products produced by the catching sector. Policy officials maintained that while they could support the fishing industry through funding programmes, it is the responsibility of fishers to ensure they have the right infrastructure to handle unwanted catches. The expectation is that the LO combined with the restriction to non-human consumption purposes will encourage fishers to internalise the costs of catching unwanted fish and motivate them to avoid unwanted catch. This will be realised if sufficient flexibility is given to fishers to find their own solutions to reducing unwanted catches. It is concluded that gear technology measures exist to enable the regulated fisheries to increase gear selectivity. 相似文献
13.
There is a growing concern with the impact of marine operations on the environment. This requires reducing fuel consumption and vessel pollution during operation. On-board computers and satellite communications will enable the operator to reduce fuel consumption and NOX emissions during vessel operations.This paper presents the results of a study on this problem and how such an on-board system could be implemented to reduce fuel consumption and engine NOX emissions. 相似文献
14.
《Marine Policy》2014
To support implementing an ecosystem approach to fisheries management, ecological risk assessment (ERA) methods have recently been developed for the continuum of data-deficient to data-rich fisheries. A semi-quantitative ERA was conducted for the Marshall Islands longline bigeye tuna (Thunnus obesus) fishery. The study used information from analyses of observer data, surveys of captains and crew and inventories of gear and equipment. Relative risks were evaluated through a consideration of phylogenetic uniqueness, risk of population extirpation, risk of species extinction and importance in ecosystem regulation. The fishery presents a highest relative risk to leatherback (Dermochelys coriacea), hawksbill (Eretmochelys imbricata), green (Chelonia mydas) and olive Ridley (Lepidochelys olivacea) sea turtle Regional Management Units that overlap with the fishery, in that order. The next highest relative risk is to affected stocks of oceanic whitetip (Carcharhinus longimanus), blue (Prionace glauca), and silky (Carcharhinus falciformis) sharks, in that sequence. Seabird bycatch is likely not problematic. There was inadequate information to assess risks to cetacean populations. Risks to stocks of market and non-market species of marine fishes with r-selected life history characteristics were not assessed. This is because estimates of critical threshold levels of local and absolute abundance and current biomass are not known for many of these stocks. Several best practice gear technology methods to mitigate problematic catch of vulnerable species groups are currently employed: monofilament leaders, whole fish for bait, single-hooking fish bait, no lightsticks, and no fishing at shallow submerged features. Setting terminal tackle below 100 m and carrying and using best practice handling and release equipment were methods identified to reduce fishing mortality and injury of vulnerable species. More information is needed to determine if weaker hooks should be prescribed to mitigate cetacean bycatch. The large benefit to sea turtles of replacing remaining J-shaped hooks with circle hooks might outweigh a possible small increase in elasmobranch catch rates. The consumption of 2024 l of fuel per tonne of landed catch, which is within the range of available estimated rates from similar fisheries, could be reduced, reducing greenhouse gas emissions, through more frequent maintenance and upgrading vessel equipment and materials. Observer data quality may be adequate to support a quantitative Level 3 ERA to determine the significance of the effect of various factors on standardized catch rates and to estimate population-level effects from fishing mortality. 相似文献
15.
Chung-Ling Chen 《Marine Policy》2012,36(2):350-357
It is widely recognized that fishing states are obliged to exercise flag state responsibility over their vessels. In an attempt to become a responsible fishing actor, Taiwan has endeavored to manage its distant water fishing fleet in accordance with international fisheries management. However, the long-standing problems of illegal, unreported and unregulated (IUU) fishing, fish laundering, and fishing overcapacity, which remained unsolved during the 1990s and early 2000s, brought its management capability into doubt. Failure to address these problems undermined the credibility of all management measures and ultimately resulted in a recommendation adopted by International Commission for the Conservation of the Atlantic Tunas (ICCAT) in 2005. This recommendation significantly affected Taiwan's distant water fishing policy. This paper examines how Taiwan assimilated this outside force into its fishing policy as a new response to international fisheries management and how fishers perceived this response. It shows that Taiwan's efforts in controlling distant water fisheries marked a big change, specifically manifest in three noticeable actions - reducing excessive bigeye-targeted efforts, deterring IUU fishing, and strengthening fisheries management. The study advises that management of small tuna vessels be effectively exercised and recommends future actions on providing subsidies for fishers to partially offset costs incurred by rule compliance, streamlining their administrative work, enhancing communication with them, putting more enforcement and meaningful penalties in place. Finally, the study indicates the existence of an interaction in the international fisheries management scheme, potentially favoring Taiwan to bargain for fishing rights and a favorable status in the participation of regional fisheries management organizations (RFMOs) in the future if it continues to exercise effective control of distant water fisheries. 相似文献
16.
渔用合成纤维及其网线和绳索是构成渔具的基本要素，其强度性能对渔具的力学性能、渔获性能、使用寿命和制造成本具有重要作用。为了满足海洋渔业不断发展的需要，我国陆续颁布了一批国家及行业质量标准，并在实践中逐步接近ＩＳＯ标准或国际名牌产品标准，使渔具纤维材料性能有了较大的提高。本文通过对国内外渔具合成纤维材料强度性能的比较和分析，认为：（１）国产合成纤维长丝的有关性能与日本产品无显著差异；（２）国产ＰＡ胶丝性能普遍较好，并优于英国产品，而ＰＡ长丝捻线与国外产品尚有较大差距；（３）ＰＥ线产品性能普遍超过ＱＪ／ＣＮＦＣ０２９２标准，但仍低于ＳＣ１４１—８５标准要求；（４）国产ＰＡ长丝三股绳索性能与德国产品接近而高于日本产品；（５）ＰＥ和ＰＶＡ三股绳索性能仅略高于日本产品；（６）渔具新材料的研制及其在渔业中的开发应用与国外相比，尚有较大差距，应得到足够重视。 相似文献
17.
The aim of this paper is to compare the criteria for eco-labeling of wild-caught fish in the Norwegian eco-certified fisheries, and to study if these eco-labels affect the harvesting patterns of Norwegian fishermen. The eco-labels Marine Stewardship Council (MSC), KRAV and Friend of the Sea (FOS) as applied in 2009 were studied. In this study, the harvesting patterns are defined by using the following parameters: season, catch area, size of fishing vessel, gear type, bycatch, location of landing site and distance to the fishing ground. KRAV had more specific criteria than did MSC and FOS in specific fisheries regarding time of the fishing effort, catch area, size of fishing vessels, gear type (e.g. hook size, and the use of beam trawlers was not permitted) and distance to the fishing ground. The findings show that few of the eco-label requirements influenced these aspects in Norwegian fisheries. 相似文献
18.
《Marine Policy》2005,29(5):421-430
Discards refer to that part of the catch returned to the sea during fishing operations. This study assesses the consequences, causes, and potential solutions to the discard problem using the example of North Sea fisheries. Fishermen's immediate objectives during fishing operations and the low confidence in projected gains from discard reduction measures have promoted use of unselective trawls while the poor enforcement of the quota system has exacerbated discard quantities. It is concluded that a reduction in discard rates is required for a long-term solution to the ecological and economic costs of discarding and the development of fishing opportunity incentives can promote the use of more selective fishing techniques. 相似文献
19.
20.
《Marine Policy》2013
The performance of the EU long-term management plan for cod stocks, in force since 2009, is analysed focusing on the human and institutional factors. The plan operates through landings quotas (TACs) and effort restrictions following a Harvest Control Rule, and deploys a novel instrument allowing Member States to ‘buy back’ or increase fishing effort for fleet segments engaged in cod-avoidance measures. The stipulated fishing mortality reductions have not been achieved. On the positive side, the ‘buy-back’ instrument has led to increased uptake of selective gear and implementation of permanent and real-time temporary closures. On the negative side, ignoring the dimension of fishers as reactive agents in the design, the impact assessment, and the annual implementation of the measures has contributed to the failure to adequately implement the plan and achieve its objectives. The main problem is that the landings quotas taken in a mixed fishery did not limit catches because fishers were incentivised to continue fishing and discard overquota catch while quota for other species was available. The effort limitations intended to reduce this effect were insufficient to adequately limit fishing mortality in targeted fisheries, although fishers experienced them as prohibiting the full uptake of other quotas. Recommendations for future plans include (i) management through catch rather than landings quotas, (ii) the internalisation of the costs of exceeding quotas, (iii) use of more selective gear types, (iv) the development of appropriate metrics as a basis for regulatory measures and for evaluations, (v) participatory governance, (vi) fishery-based management, (vii) flexibility in fishing strategy at vessel level. 相似文献