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1.
The eastern stock of Atlantic bluefin tuna (thunnus thynnus) was recently nominated for protection under the Convention on International Trade in Endangered Species of Flora and Fauna (CITES). That nomination failed, which leaves management of the heavily overfished stock in the hands of the International Commission for the Conservation of Atlantic Tunas (ICCAT). This paper reviews the history of ICCAT management of Atlantic bluefin tuna to show that (1) early elimination of competitive forces prevented agreement on management in keeping with scientific advice, resulting in the steep decline of the stock, (2) even just the threat of a CITES listing can provide temporary impetus for marked improvement in ICCAT management, and (3) long-term sustainable management by ICCAT will require continued economic and political pressure. 相似文献
2.
The current rate of shark global exploitation and mortality is arguably so high under current management regimes that unless a renewed initiative is undertaken some species of shark will become effectively extinct. Current efforts to sustainably manage shark mortality are driven primarily by domestic laws in a few countries, big international non-governmental organizations (BINGOs) promoting environmental laws in the countries or regions where they exist, a handful of regional fisheries management organizations (e.g., IATTC and ICCAT), and inter-governmental organizations such as CITES. The absence of enforcement capability is often argued as the critical component in the failure to protect sharks from overexploitation. The remedy advanced here goes far beyond the need for stepped up enforcement, and calls for the creation of an entirely new international management regime, the International Commission for the Conservation and Management of Sharks (ICCMS). Such an agency could learn from the experiences of management bodies tasked with conservation of species biologically similar to sharks, such as the International Whaling Commission (IWC), to improve its efficacy. Critics have identified many organizational flaws that reduced the IWC’s effectiveness during its earliest years. Some of those flaws are examined here and remedies are suggested that an ICCMS could use to create a more effective management regime. The life histories of elasmobranches and large whales are compared to illustrate their similarities as a biological foundation for the selection of the IWC as a model. 相似文献
3.
Organic contaminant and total mercury concentrations were compared in four species of lamniform sharks over several age classes to examine bioaccumulation patterns and gain insights into trophic ecology. Contaminants found in young of the year (YOY) sharks were assumed to be derived from maternal sources and used as a proxy to investigate factors that influence maternal offloading processes. YOY white (Carcharodon carcharias) and mako (Isurus oxyrinchus) sharks had comparable and significantly higher concentrations of PCBs, DDTs, pesticides, and mercury than YOY thresher (Alopias vulpinus) or salmon (Lamna ditropis) sharks. A significant positive relationship was found between YOY contaminant loads and maternal trophic position, suggesting that trophic ecology is one factor that plays an important role in maternal offloading. Differences in organic contaminant signatures and contaminant concentration magnitudes among species corroborated what is known about species habitat use and may be used to provide insights into the feeding ecology of these animals. 相似文献
4.
《Marine Policy》2015
Sharks are threatened from overfishing due to their life cycle biology, and unsustainably high catch rates to supply fins for shark fin soup. Canada, a leader in shark conservation uses numerous legislative tools to help conserve sharks. These tools include international treaty obligations under the Northeastern Atlantic Fisheries Organization [NAFO] and the International Commission for the Conservation of Atlantic Tuna [ICCAT], as well as national and provincial legislation including the Fisheries Act, Pacific and Atlantic Fisheries Regulations, and Coastal Fisheries Protection Act. Through the use of these legislative tools Canada has successfully banned shark finning in its waters, and implemented closed seasons, gear restrictions, and species restrictions to help manage shark populations. However, Canada still allows the sale of shark fin products locally, and allows the exportation of shark fins internationally. In order for Canada to maintain its leadership status Canada must increase legislative protection of sharks by following international best practices, and ban the sale and exportation of shark fin products. This would ensure that Canada does not play a role in global supply or demand of shark fins. Doing so would strengthen Canada's position as a leader in shark conservation, and improve the legislation currently used as a conservation tool. 相似文献
5.
《Marine Policy》2013
Leatherback turtles migrate across the jurisdictions of multiple sovereign states and present complex challenges to those responsible for their conservation. Concern for marine turtles has led to their protection under range state legislation and protective listing under a suite of multilateral environmental agreements. Evidence suggests that a distinct, reproductive sub-population of leatherback turtles is shared amongst a number of northern Caribbean range states, including the UK overseas territories (UKOTs) of Anguilla and the British Virgin Islands (BVI). The post-nesting movements of three female leatherbacks were tracked after they nested in Anguilla (n=1, tracked for 228 days) and the BVI (n=2, tracked for 12 and 13 days, respectively). These turtles used territories of multiple range states, with the leatherback tracked from Anguilla also migrating through high seas to foraging grounds in Canadian waters. In addition, a review of regional leatherback flipper tag return records helps define the range of this northern Caribbean nesting population (NCNP), which appears to be in recovery in some range states. While national legislation and conservation efforts appear to have contributed to these population recoveries, most relevant MEAs appear to have played little or no role. However, opportunities for constructive dialogue between NCNP range states exist under the Cartagena Convention the United Nations Convention on the Law of the Sea and the International Commission for the Conservation of Atlantic Tuna (ICCAT). UKOT conservation managers would, therefore, be justified in prioritising unilateral leatherback conservation action, and multilateral efforts through the Cartagena convention and regional fishery management mechanisms, over potentially costly accessions to additional MEAs. 相似文献
6.
Reliable age information is vital for effective fisheries management, yet age determinations are absent for many deepwater sharks as they cannot be aged using traditional methods of growth bands counts. An alternative approach to ageing using near infrared spectroscopy (NIRS) was investigated using dorsal fin spines, vertebrae and fin clips of three species of deepwater sharks. Ages were successfully estimated for the two dogfish, Squalus megalops and Squalus montalbani, and NIRS spectra were correlated with body size in the catshark, Asymbolus pallidus. Correlations between estimated-ages of the dogfish dorsal fin spines and their NIRS spectra were good, with S. megalops R2=0.82 and S. montalbani R2=0.73. NIRS spectra from S. megalops vertebrae and fin clips that have no visible growth bands were correlated with estimated-ages, with R2=0.89 and 0.76, respectively. NIRS has the capacity to non-lethally estimate ages from fin spines and fin clips, and thus could significantly reduce the numbers of sharks that need to be lethally sampled for ageing studies. The detection of ageing materials by NIRS in poorly calcified deepwater shark vertebrae could potentially enable ageing of this group of sharks that are vulnerable to exploitation. 相似文献
7.
Beach nets are preventative devices used to minimize interactions between potentially harmful sharks and unsuspecting swimmers. Quantitative studies demonstrated that beach nets drastically reduced local elasmobranch populations, as well as caused considerable bycatch mortality. For this experiment, a beach net-like device was constructed and the behaviors of six juvenile lemon sharks (Negaprion brevirostris) were analyzed. Induced by olfactory and gustatory cues, sharks were given the choice to swim through a magnetic or control opening in the net. In the first trial, all six sharks avoided the magnetic region and significantly preferred to swim through the control region of the fence. The magnetic stimulus no longer affected the swimming behavior of three sharks retested after resting 24 h. Results from the retested sharks were correlated with those from repeated tonic immobility trials, which demonstrated a linear decrease in sensitivity to repeated magnetic stimulation. This study serves as a baseline experiment demonstrating that permanent magnets may substantially decrease elasmobranch mortality within beach nets. 相似文献
8.
《Marine Policy》2013
Various species of sharks, skates, and rays continue to decline globally, demonstrating a greater need for effective conservation measures. In 1999 the Food and Agriculture Organization (FAO) developed comprehensive guidelines in its International Plan of Action for the Conservation and Management of Sharks (IPOA-sharks), which was followed by corresponding national plans in some nations. A case study of national implementation is presented here. Specifically, progress under Canada's National Plan of Action for Sharks (NPOA-sharks) is reviewed, against its stated goals, against Australia's NPOA, and against the original FAO guidelines. For comprehensiveness, additional management and conservation measures for sharks, as well as stakeholder input from the first Atlantic Shark Forum is provided. Although Canada is recognized as a leader in shark management, as it was one of the first countries to develop an NPOA, it has not effectively adopted the FAO's principles and guidelines. The plan lacks set timelines, priorities, and action plans to mitigate threats to sharks, and contains no performance indicators. Additionally, the plan neglects to identify priority species and engage stakeholders, and cannot be directly linked to management measures. To advance the revision of this plan (as well as other NPOAs), a stepwise process is recommended that includes (i) stakeholder engagement and development of a shark assessment report (SAR) (ii) addressing all IPOA objectives, while prioritizing issues arising from the SAR, and (iii) implementations of actions, targets, and timelines that are reviewed every four years. Key policy items to advance Canada's role in shark conservation and management are also presented. These include actions to improve data collection and research, management, and education, as well as coordination with stakeholders. In conclusion,major changes are needed to the existing NPOA to be fully effective and accountable. Likewise, the abovementioned measures may help guide more proactive plans in nations that have not yet established an NPOA. 相似文献
9.
《Marine Policy》2015
Gaining support for shark conservation has been extremely difficult due to the negative preconceived notions the general public holds toward sharks. In order to achieve public support for conservation initiatives the factors that will change an individual’s attitude and behavior toward sharks must first be determined. Using structured questionnaire interviews (n=186), indices were created that rated an individual’s knowledge, attitude, and potential behavior toward sharks and shark conservation. Generally public knowledge levels about sharks were low. However, people with more knowledge pertaining specifically about sharks had potential behaviors more supportive of their conservation. Therefore, it would seem that increases in public knowledge on sharks would help gain support for shark conservation. Males, members of environmental groups, and viewers of shark documentaries and “Shark Week” all showed significantly higher levels of knowledge about sharks. The media (such as “Shark Week” ) can play a significant role in promoting conservation, but unfortunately media coverage of sharks has been controversial recently with the airing of several non-factual, fake documentaries. To promote shark conservation the media’s message has to be unbiased, non-sensationalized, and accurate to ensure people are receiving the information necessary to build strong pro-shark conservation behaviors. 相似文献
10.
《African Journal of Marine Science》2013,35(2):255-261
Identifying nearshore waters that serve as important habitats for neonate and juvenile sharks is crucial for effective fisheries management. This study examined the abundance of neonate and juvenile dusky sharks Carcharhinus obscurus within the Port of Ngqura, on the south-east coast of South Africa, between September 2006 and August 2007 using a combination of shore-angling catches and mark-recapture data. During this period, the port was non-operational and still undergoing construction. A total of 480 dusky sharks, ranging in size from 50 to 123 cm (precaudal length), was captured. Catch per unit effort was greatest between October and February, peaking in November at 0.51 sharks angler–1 h–1. Of the 219 C. obscurus tagged and released during the study period, 37 (16.9%) were recaptured. Sharks were at liberty from 0 to 409 days with the majority (89.2%) recaptured within the port. Using a Jolly-Seber open population model, the abundance of sharks within the port was estimated at 552 (95% CI: 422–765). Annual apparent survival probability was 0.38 (95% CI: 0.30–0.46), with an average annual recapture probability of 0.28 (95% CI: 0.19–0.39). This study demonstrates that the Port of Ngqura is an important summer habitat and core activity zone for both neonate and juvenile dusky sharks. 相似文献
11.
Deep-water sharks are considered highly vulnerable species due to their life characteristics and very low recovery capacity against overfishing. However, there is still limited information on the ecology or population connectivity of these species. The aim of this study was to investigate if the species Centrophorus squamosus could make long displacements and thus confirm the existence of connectivity between different deep-water areas. In addition, the study was the first attempt to use tagging techniques on deep-water sharks, since it has never been undertaken before. Five C. squamosus were tagged with satellite tags (PAT) in the El Cachucho Marine Protected Area (Le Danois Bank) located in waters of the North of Spain, Cantabrian Sea (NE Atlantic). Data from four of these tags were recovered. One of the sharks travelled approximately 287 nm toward the north east (French continental shelf) hypothetically following the continental slope at a mean depth of 901±109 m for 45 days. Two other sharks spent almost 4 months traveling, in which time they moved 143 and 168 nm, respectively, to the west (Galician coast). Finally, another leafscale gulper shark travelled to the NW (Porcupine Bank) during a period of 3 months at a mean depth of 940±132 m. Depth and temperature preferences for all the sharks are discussed. Minimum and maximum depths recorded were 496 and 1848 m, respectively. The temperature range was between 6.2 and 11.4 °C, but the mean temperature was approximately 9.9±0.7 °C. The sharks made large vertical displacements throughout the water column with a mean daily depth range of 345±27 m. These preliminary results support the suggestion of a whole population in the NE Atlantic and confirm the capacity of this species to travel long distances. 相似文献
12.
Broad-scale movements (10s–100s km) of highly migratory species, such as sharks, present unique management challenges as fish migrate across international boundaries, thereby exposing them to different levels of anthropogenic pressure. Lemon sharks and blacktip sharks are well-studied throughout their range in the western North Atlantic, but broad-scale movements in the Caribbean region are largely unknown. Utilizing 10 years (2004–2014) of acoustic and conventional tagging data, this study presents the post-nursery movements of young of the year (YOY) and juvenile blacktip (n = 198) and lemon (n = 130) sharks tagged in the United States Virgin Islands (USVI). A total of five (2.5%) blacktip sharks were recaptured by recreational and commercial fishers in the greater Caribbean and as far north as the southeastern coast of the United States, moving between 2 and 2,200 km and crossing a minimum of six international boundaries. Of the acoustically tagged blacktip (n = 88) and lemon (n = 45) sharks, 28 (32%) and 16 (24%), respectively, were detected outside the boundaries of the nursery area in which they were tagged, dispersing throughout the USVI territory; blacktip sharks were acoustically detected beyond territorial waters as far as Florida, United States (1,881 km). Both species transited through local marine protected areas but did not establish residency resulting in little protection. This is the first study to examine connectivity between blacktip shark populations of the USVI and the east coast of the United States. 相似文献
13.
《Marine Policy》2014
In recent decades there has been steady progress towards a risk-based management approach for fisheries. An important first step in a risk analysis framework is scoping to identify, describe and catalog the sources of uncertainty that might have an impact on a fishery. This paper introduces a methodology based on a range of tools to formalize the process of elicitation of uncertainties, from both experts and stakeholders, for the International Commission for the Conservation of Atlantic Tunas (ICCAT). ICCAT is a regional fisheries management organization responsible for the conservation of tunas and other highly migratory fish in the Atlantic Ocean and its adjacent seas. The aim of the elicitation was to identify and prioritize uncertainties for inclusion in Operating Models for Management Strategy Evaluation (MSE). The tool presented in this paper supports the qualitative prioritization of uncertainties, while also visualizing the degree of consensus among stakeholders on particular issues. Perceptions of uncertainty in fisheries often vary widely among scientists, industry and other interest groups, so tools that can facilitate inclusion and representation of different opinions are useful where decision-making depends on broad agreement and more generally, where effective management depends on commitment from stakeholders. 相似文献
14.
《Marine Policy》2016
Social research can aid in understanding the behaviour of the general public or stakeholders towards natural resources. In the case of recreational fishing, social research aids in integrating anglers' knowledge and attitudes into management frameworks to increase the likelihood of the uptake of new management regulations. Tournament anglers were surveyed at game fishing competitions throughout New South Wales, Victoria, and South Australia between February 2012 and May 2013 to investigate their general beliefs around sharks and their behaviours when targeting pelagic sharks. Over half (55%) of the anglers interviewed practised catch and release of pelagic sharks. Of those, almost all (98%) asserted that they attempt to release sharks in good condition, but a large percentage of anglers (48%) did not use circle hooks that have been shown to increase post-release survival. Results showing some concordance between angler's beliefs and behaviours when targeting pelagic sharks suggest that anglers are cognisant of the functional role of sharks in the ecosystem and would be open to recommendations ensuring the long-term sustainability of recreational fisheries targeting pelagic sharks. 相似文献
15.
《Marine Policy》2017
Brazil currently ranks as the 11th producer and 1st importer of shark meat around the world. Data available from the FAO software FishStatJ along with data from regional sources, such as governmental bulletins, scientific papers, gray literature and internet were revisited to identify the main issues surrounding pelagic shark fisheries, trade and consumption in the largest country in South America. Among the main findings, it was noted that Brazil has not properly collected fishery statistics since 2007, that many species of threatened sharks are freely landed and traded even though it is prohibited by local legislation and/or international recommendations (regional fisheries management organizations). The blue shark (Prionace glauca) is the most frequently recorded shark in the official bulletins and is currently a locally targeted species. Additionally, the significant imports of this species from 23 other countries that also provide fins for Asia has drawn attention in recent decades. Regarding consumption, shark is considered to be low-value seafood compared to more common fish, such as groupers and snappers, and most Brazilians actually do not know that they are eating sharks. At present, the proportion of threatened elasmobranchs (in which sharks are included) in Brazil (33%, of 145 species) exceeds the global rate identified for the group (25%), and, until the present moment, no measure related to the management of species has been implemented. As advice, Brazil urgently needs to restructure its fishery information collection systems, management strategies and to tighten sanitary and labeling regulations for the marketing of fish. 相似文献
16.
The current study provides long-term catch rate and biological data for tiger sharks Galeocerdo cuvier caught in the KwaZulu-Natal bather protection programme. Between 1978 and 2014, 1 760 G. cuvier were caught in nets and between 2007 and 2014, 108 G. cuvier were caught on drumlines. Standardised catch rates increased significantly over time (p < 0.001) for both small (≤180 cm precaudal length, PCL) and large sharks (>180 cm). There was also a significant temporal increase in the mean size of sharks across gear types (p < 0.001). A quasi-Poisson generalised additive mixed model showed that the deployment of drumlines had no significant effect on the catch rate of sharks in nets. The nets, however, caught significantly larger sharks (mean 184.5 cm, SD 39) than did drumlines (mean 138.6 cm, SD 36.5; p < 0.001). The size frequency of the catch was unimodal and females significantly outnumbered males in both gear types. Few young-of-the-year (0.8%) or mature sharks (1.8%) were caught. Only 23 (4.7%) of the 486 sharks tagged and released were recaptured, with the majority (87.0%) of those recaptured <150 km from their original tagging locality. The results from this study suggest an increasing local population trend in G. cuvier along the KwaZulu-Natal coast. 相似文献
17.
Internationally, shark conservation is now being recognized as a major environmental challenge, but management efforts to halt the overexploitation of sharks have lagged behind. This review examines the state of knowledge for shark species in Canadian waters and analyzes the role of existing management and legislation in ensuring shark conservation. Despite Canada's early leadership, the present management framework reveals major shortcomings with regard to legal protection, bycatch and finning regulations. These problems are not unique to Canada but illustrate broader issues pertaining to the global management of endangered fish species. To strengthen the conservation and management of sharks, this paper recommends a set of key policies and management priorities, which exemplify proper precautionary management of endangered shark species in Canada and could serve as a blueprint for improving conservation efforts internationally. A structured approach for grading progress in shark conservation efforts against best practices is also presented and could be used as a goalpost elsewhere. 相似文献
18.
搁浅、误捕和救助记录是研究野生动物分布和获取其基本生物学数据的重要来源,尤其是对那些缺少系统性野外调查的物种。本研究收集了福建沿海2006—2019年间鲸鲨（Rhincodon typus）的搁浅、误捕和救助记录,初步探讨福建沿海鲸鲨的时空分布情况,并提出相应的保护对策。共收集福建沿海鲸鲨搁浅、误捕和救助记录30例,包括搁浅10例、误捕18例和救助2例,其中福州鲸鲨记录大部分在平潭岛附近,这可能与平潭海域上升流带来的丰富生物资源有关;所有记录中有28例（93.3%）发生在6—10月,表明夏秋季可能是鲸鲨在福建沿海活动的高峰期。此外,有体长记录的22条鲸鲨中,17条（77.3%）为幼年个体,可能是因为幼年鲸鲨偏好在高生产力的近岸海域聚集以获取充足的食物,因此也更容易搁浅或被误捕。较多的误捕记录（60.0％）提示渔业活动对鲸鲨有较大威胁。因此,建议建立全省甚至全国性的鲸鲨搁浅误捕数据库,进一步严格和规范渔业管理,改进渔具以降低误捕鲸鲨的概率,加强对公众（特别是渔民）的宣传教育,以更好地保护这一濒危物种。 相似文献
19.
《African Journal of Marine Science》2013,35(2):175-182
We present the first quantitative study of the occurrence, size and sex of white sharks Carcharodon carcharias at Bird Island, Algoa Bay. Twenty-two boat trips were made to Bird Island between November 2009 and October 2011 to chum for sharks. A total of 53 sharks was observed over the study period, ranging in size from 1.5 to 4.5 m total length (TL) and with the majority (60.3%) being <3 m TL. The sex ratio of sharks for which sex could be determined was not significantly different from unity. In both study years, sharks were present only in the winter between April and November with a maximum of 1.2 sharks sighted per hour. A zero-altered model, comprising a logistic regression to model presence/absence and a log-normal generalised linear model for abundance, showed that season explained the presence of sharks, peaking in mid-July, with abundance being significantly higher with higher barometric pressure. This study identified Bird Island as an important white shark aggregation site on the east coast of South Africa. These data are crucial not only to improve our understanding of white shark seasonal distribution and biology, but also for the long-term management and conservation of the species in South Africa. 相似文献
20.
《Marine Policy》2015
Conservation actions for sharks are hampered partly by the negative beliefs and inaccurate knowledge about them among the general public. This paper investigated the knowledge and attitude of residents and tourists towards shark species of Fernando de Noronha Archipelago, a marine protected area, and one of the major ecotourism destinations in Brazil. Findings showed that residents had a lower knowledge of sharks and less positive attitudes towards sharks than tourists. Even though residents did not see sharks as threats to humans and they were aware of the role of the archipelago as a shark nursery, they did not completely understand the sharks' ecological and economic importance. This distinction between residents' and tourists' perceptions of sharks demands different strategies to assure engagement in management and conservation policies relating to both groups. Management actions focusing on providing enjoyable experiences with sharks to residents and enhancing their participation in tourist activities related to sharks are presented. They would require innovative cooperation between scientific, management and environmental institutions to build initiatives aimed at increasing the knowledge and improving attitudes of residents towards shark conservation and to homogenise conservation values held by the entire public on the archipelago. 相似文献