首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 0 毫秒
1.
    
  1. Human impacts on marine ecosystems are increasing and the number of fish species listed in the Red List is constantly growing. In the Mediterranean Sea, seven of the 10 bony fishes defined as Threatened by the IUCN are known to be vocal, including the target species of this study: the shi drum (Umbrina cirrosa Linnaeus, 1758) and the brown meagre (Sciaena umbra Linnaeus, 1758). As a result, non-invasive passive acoustic monitoring (PAM) can be used to pinpoint their distribution at sea. However, for PAM to be effective, reliable acoustic discrimination is required because the sounds they emit during reproduction are remarkably similar (i.e. short broadband pulsed sounds).
  2. The shi drum and the brown meagre are closely related, elusive, vocal sciaenids, partially overlapping in their ecological niche. During summer 2019, three PAM surveys were conducted along the tidal inlets of the Venice lagoon (Italy). Here, the calls of both species have been recognized according to their temporal features: shi drum sounds were made up of a lower number of longer pulses with a different envelope, repeated at a lower rate than those of the brown meagre. Further, shi drum and brown meagre sounds of different origins (aquaculture and semi-natural conditions) were analysed and compared with those collected during the survey of the study area in order to validate the field collected data.
  3. Call discrimination allowed for a fine-scale species mapping, showing a partially overlapping distribution of the two species along the inlets. This is the first case in which two sciaenids have been documented to share their reproductive habitat in the Mediterranean Sea.
  4. This study demonstrates that it is feasible to acoustically monitor the target species even in those parts of the Mediterranean Sea where they co-exist. This, in its turn, could provide managers with the required data for effective conservation measures to be implemented.
  相似文献   

2.
    
  1. Marine protected areas (MPAs) and freshwater protected areas (FPAs), collectively aquatic protected areas (APAs), share many commonalities in their design, establishment, and management, suggesting great potential for sharing lessons learned. However, surprisingly little has been exchanged to date, and both realms of inquiry and practice have progressed mostly independent of each other.
  2. This paper builds on a session held at the 7th World Fisheries Congress in Busan, South Korea, in May 2016, which explored crossover lessons between marine and freshwater realms, and included case studies of four MPAs and five FPAs (or clusters of FPAs) from nine countries.
  3. This review uses the case studies to explore similarities, differences, and transferrable lessons between MPAs and FPAs under five themes: (1) ecological system; (2) establishment approaches; (3) effectiveness monitoring; (4) sustaining APAs; and (5) challenges and external threats.
  4. Ecological differences between marine and freshwater environments may necessitate different approaches for collecting species and habitat data to inform APA design, establishment and monitoring, but once collected, similar spatial ecological tools can be applied in both realms. In contrast, many similarities exist in the human dimension of both MPA and FPA establishment and management, highlighting clear opportunities for exchanging lessons related to stakeholder engagement and support, and for using similar socio‐economic and governance assessment methods to address data gaps in both realms.
  5. Regions that implement MPAs and FPAs could work together to address shared challenges, such as developing mechanisms for diversified and sustained funding, and employing integrated coastal/watershed management to address system‐level threats. Collaboration across realms could facilitate conservation of diadromous species in both marine and freshwater habitats.
  6. Continued exchange and increased collaboration would benefit both realms, and may be facilitated by defining shared terminology, holding cross‐disciplinary conferences or sessions, publishing inclusive papers, and proposing joint projects.
  相似文献   

3.
    
  1. Relatively little is known about seabird–fishery interactions (i.e. bycatch) for the U.S. North‐east and mid‐Atlantic, despite concerted efforts to document observed interactions since 1989.
  2. Fisheries observer data were used to estimate seabird–fishery interactions for 10 species and six gear types that operated within the US Northeast and mid‐Atlantic from 1996 to 2014.
  3. Hierarchical Bayes estimation was used and accounted for temporal, spatial, and operational considerations inherent in the data through post‐stratification.
  4. Over the 19‐year study period, 48 821 (coefficient of variation [CV] = 0.03) seabirds were estimated to have interacted with commercial fishing gear, resulting in an average of 2570 interactions per year.
  5. Trends in estimated interactions were explored using the marginal posterior distributions, with the majority of interactions pertaining to gillnets and shearwaters/fulmars.
  6. Comparison with previous work highlighted the need for consistency in data preparation, making it easier to compare relative trends in seabird bycatch estimates for the region.
  7. Future assessments should focus on providing context for the interaction estimates, so that population‐level impacts can be inferred and the necessary conservation measures enacted.
  相似文献   

4.
    
  1. In principle, the database generated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) offers an unparalleled opportunity to analyse trade in species of conservation concern.
  2. The value of the database is assessed in the context of trade in 47 species of seahorse (Hippocampus spp.), all of which are included on CITES Appendix II. This listing requires that all 180 Parties to CITES (member Parties) limit exports to levels that do not damage wild populations, ensure they are obtained legally, and report their trade to CITES.
  3. An evident need for greater universal compliance with CITES reporting requirements was identified. The most glaring problem was a substantial mismatch in species and volumes between export records and import records, indicating that neither dataset is complete nor reliable.
  4. The evaluation also showed that Parties should increase compliance with CITES requirements to record all trade shipments, provide units for exports (e.g. individuals, kilograms) and identify exported taxa to species, perhaps supported by automated checking of entries.
  5. The challenges with the CITES trade database were more evident for the global trade in dried seahorses than the smaller and more easily‐tracked trade in live seahorses. Nonetheless, CITES’ data from 2004–2011 revealed a seahorse trade involving millions of animals, tens of species, and scores of Parties.
  6. CITES data have also proven invaluable in supporting CITES reviews of how Parties are implementing the Convention for seahorses, and in generating consequent action for their conservation.
Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

5.
    
  1. Periodically harvested fisheries closures are widely implemented across the South Pacific as a conservation and fisheries management tool. There is a lack of information on the mechanisms and effectiveness of this management system in meeting fisheries and ecosystem sustainability goals.
  2. A before‐after‐control‐impact (BACI) pair design, was used to quantify flight initiation distance (FID), and biomass of two fishery‐target (Acanthuridae and Scaridae) and one non‐target (Chaetodontidae) families in two periodically harvested closures, two no‐take marine reserves, and two open fished areas, prior to and after harvest of the periodically harvested closures. Creel surveys were used to quantify catch per unit effort (CPUE) in open fishing grounds, and during the periodic harvests.
  3. Before harvest, FID of targeted families was higher in fished areas than periodically harvested areas. After harvest, Acanthuridae FID in periodically harvested closures increased significantly to beyond the maximum effective range of spearguns. Total biomass of fishes was lower in fished areas than areas under either type of management. Acanthuridae biomass in the periodically harvested closures was similar to fished areas, and lower than in the no‐take reserves. There was no difference post‐harvest for either total or Acanthuridae biomass.
  4. CPUE was higher for fishing trips inside the periodically harvested closures than regular fishing activities. Fishes were generally larger in catches from periodically harvested closures, but this was not sufficient to account for the increase in CPUE, particularly of the Acanthuridae, which were significantly more abundant in the harvest catch.
  5. When fishes are protected temporarily from fishing, their wariness decreases, which makes them more easily catchable when fishing is reinstated. This study shows that fish behavioural change is an important and overlooked benefit of periodically harvested closures. However, differences in the magnitude of behavioural changes between fishery‐target families may result in contrasting outcomes of periodically harvested management regimes.
Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

6.
    
  1. Coastal reefs are highly diverse marine ecosystems that in many regions suffer today from growing pressures by human activities. Among the most highly‐stressed are those found in the Levantine basin (south‐eastern Mediterranean Sea). The Levant represents the trailing‐edge of distribution of native species where they are exposed to the most extreme temperature and salinity conditions, and the region is also fast‐warming and exposed to a great many alien species and strong fishing pressure. In this study, the ecological state of reefs in the south‐eastern Levant was assessed quantitatively (including inside a small marine reserve) using current, extensive, survey data with reference to anecdotal historical information on their more pristine past.
  2. The results of very extensive subtidal community surveys that were conducted in north Israel indicate that reefs in this area are currently dominated by turf‐forming algae and aliens, and sustain low numbers of top predators. Specifically, it was found that on these Levant reefs: (1) commercial species represent a very small part of the fish assemblage (except inside the reserve); (2) alien species constitute a considerable portion (23–44%) of the fish assemblage (including in the reserve) and 95–99% of epi‐benthic molluscs, including inside the marine reserve; and (3) turf barrens are the dominant substrate cover, while cover of native brown algae canopy is limited to small patches occurring only during winter and spring.
  3. These findings suggest that the Levant reefs have been highly transformed by overfishing and alien invasions, and probably also climate change, and that even well managed marine reserves had little effect on alien species presence. From a biogeographic‐conservation perspective, as both warming and bioinvasions continue in the Mediterranean, it is expected that this degraded reef state will gradually advance westward. Alleviating fishing pressure with marine reserves might make the reefs more resilient to these regional pressures, but alien invaders will remain a dominant feature in the system. Therefore, a more realistic conservation target might be the preservation or restoration of ecosystem functions rather than the original native biodiversity.
  相似文献   

7.
  1. While the use of aquatic protected areas that exclude angling might be considered an evolutionarily enlightened management approach to dealing with fisheries‐induced evolution (FIE), there is little empirical data on the effectiveness of this approach at maintaining the diversity of phenotypic traits within protected areas.
  2. In species with paternal care, including largemouth bass (Micropterus salmoides), active nest‐guarding and aggression towards potential brood predators by males may render these individuals particularly vulnerable to capture by angling because of increased propensity to attack fishing lures/bait near their nests. Relative levels of aggression by these males during the parental care period correlates with their vulnerability to angling year round. Selective removal of more aggressive individuals by anglers should drive population‐average phenotypes towards lower levels of aggression.
  3. To assess the effectiveness of protected areas at mitigating FIE, the parental care behaviours of wild, free‐swimming male bass were compared during the early nesting period for bass within and outside protected areas in a lake in eastern Ontario. Nesting males within long‐standing aquatic protected areas closed to fishing for >70 years were more aggressive towards bluegill sunfish (Lepomis macrochirus), a potential nest predator, and patrolled larger areas around their nests compared with bass outside of sanctuaries. Males within protected areas were also more likely to strike at artificial fishing lures and were more prone to capture during angling events.
  4. Collectively, the findings suggest that the establishment of protected areas may promote phenotypic diversity such as more attentive and vigorous parental care, relative to areas open to angling. The extent to which this phenomenon occurs in other species and systems is likely to depend on the reproductive strategies of fish and their spatial ecology compared with protected area boundaries, and habitat quality within protected areas.
  相似文献   

8.
    
  1. The Adriatic Sea is one of the Mediterranean areas most heavily impacted by fishing and other human stressors. The northern part of the basin has been certified as an Important Marine Mammal Area because of the regular occurrence of common bottlenose dolphins, Tursiops truncatus.
  2. Boat surveys, totalling 76 days at sea and 10,711 km of navigation, were conducted between April 2018 and October 2019 to assess cetacean abundance within a 3,000-km2 area off Veneto, Italy. Bottlenose dolphins – the only marine mammal species observed – were encountered on 52 days and were tracked for 81 h and 26 min, resulting in 15,066 dorsal fin photographs of high quality and resolution.
  3. Various capture–recapture models were applied on individual photo-identification datasets. Model-based estimates indicate that approximately 600 individuals occurred within the study area during the sampling period in both years. Abundance varied monthly: minimum estimates were obtained in May 2018 (291 individuals; 95% CI 134–630) and May 2019 (121; 95% CI 20–721), whereas maximum estimates were obtained in September 2018 (385; 95% CI 310–477) and October 2019 (494; 95% CI 378–645).
  4. Evidence provided by this study can be used to complement and validate coarse ‘snapshot’ information from recent aerial surveys of the entire Adriatic Sea, and to enforce management action mandated by the European Community (EC) Habitats Directive and Marine Strategy Framework Directive, as well as guiding the EC’s Maritime Spatial Planning.
  相似文献   

9.
    
  1. Knowledge of vital data such as growth and age at maturity is necessary to develop effective management strategies for endangered species. The Critically Endangered flapper skate (Dipturus intermedius) is the largest skate in the North Atlantic and growth information, necessary to assess key life-history traits, populations’ growth rates and anticipate their response to management measures, is still lacking.
  2. While classical age estimation methods used in fish generally require the analysis of calcified structures, destructive methods are incompatible with conservation objectives for this species. Taking advantage of the high recreational value of the flapper skate, this study uses citizen-science data originating from photo-identification of trophy pictures and tag–recapture data supported by anglers to estimate growth in this Critically Endangered species. Using the growth increments measured between recapture events, an individual-based Von Bertalanffy growth model was fitted to the data using Bayesian inference.
  3. The results confirm that the flapper skate is a long-lived species with ages estimated as >40 years for the largest individuals captured. Despite this longevity, the model reveals a relatively fast initial growth but relatively late ages at maturity and significant sex-related differences in both growth rate and maximum size.
  4. These results suggest that population growth rate, and therefore recovery, might be much slower than previously reported. By using citizen science this study provides the necessary information to begin understanding population dynamics and monitor the recovery of an iconic Critically Endangered species.
  相似文献   

10.
    
  1. Publication is an important stage in the research process, but determining the impact of published research on environmental outcomes is a complex challenge that is seldom undertaken. In 2016, a published study used acoustic telemetry techniques and drift sampling to demonstrate that environmental flow releases triggered downstream spawning migrations by a threatened fish species, the Australian grayling (Prototroctes maraena). The study provided support for the use of these types of releases to mitigate some of the effects of river regulation on fishes.
  2. The impacts of this research and its publication in Aquatic Conservation: Marine and Freshwater Ecosystems were thoroughly reviewed to identify benefits to water managers, researchers, institutes, and the wider community.
  3. Five areas in which this research, and its publication, had a recognizable impact are enhanced confidence for water managers in undertaking actions; greater acceptance in the wider community of environmental flow releases; enhanced relationships among water managers; the credibility arising from the work being published in a peer‐reviewed journal; and setting a foundation for further evidence‐based management.
  相似文献   

11.
    
  1. Pelagic longline fisheries for relatively fecund tuna and tuna‐like species can have large adverse effects on incidentally caught species with low‐fecundity, including elasmobranchs.
  2. Analyses of observer programme data from the Fiji longline fishery from 2011 to 2014 were conducted to characterize the shark and ray catch composition and identify factors that significantly explained standardized catch rates. Catch data were fitted to generalized linear models to identify potentially significant explanatory variables.
  3. With a nominal catch rate of 0.610 elasmobranchs per 1000 hooks, a total of 27 species of elasmobranchs were captured, 48% of which are categorized as Threatened under the IUCN Red List. Sharks and rays made up 2.4% and 1.4%, respectively, of total fish catch. Blue sharks and pelagic stingrays accounted for 51% and 99% of caught sharks and rays, respectively.
  4. There was near elimination of ‘shark lines’, branchlines set at or near the sea surface via attachment directly to floats, after 2011.
  5. Of caught elasmobranchs, 35% were finned, 11% had the entire carcass retained, and the remainder was released alive or discarded dead. Finning of elasmobranchs listed in CITES Appendix II was not observed in 2014.
  6. There were significantly higher standardized shark and ray catch rates on narrower J‐shaped hooks than on wider circle hooks. Based on findings from previous studies on single factor effects of hook width and shape, the smaller minimum width of the J‐shaped hooks may have caused the higher shark and ray catch rates. For sharks, the effect of hook width may have exceeded the effect of hook shape, where small increases in shark catch rates have been observed on circle vs J‐shaped hooks.
  7. Shark and ray standardized catch rates were lowest in the latter half of the year. Focusing effort during the second half of the year could reduce elasmobranch catch rates.
Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

12.
    
  1. Mobulid rays are protected in New Zealand, but the spinetail devilray Mobula japanica is caught as bycatch in skipjack tuna purse seine fisheries.
  2. Between 2005 and 2014, rays were recorded in 8.2% of observed purse seine sets. Rays were caught during summer, with a ‘hotspot’ (24.3% of sets) near the shelf edge off North Island over seabed depths of 150–350 m. Rays were usually brailed aboard with the tuna catch from successful sets, but were often entangled in the bunt of the net during unsuccessful sets.
  3. Observers tagged nine rays with popup archival tags to obtain preliminary information on their post‐release survival, and spatial and vertical movements. Seven of the nine tags reported data, and four of those rays died within 2–4 days of release. All four rays that died had been brought aboard entangled in the bunt. The three surviving rays were all brailed aboard with the tuna catch.
  4. One surviving ray remained near New Zealand for 2.7 months during summer, and the other two migrated 1400–1800 km northward to tropical waters near Vanuatu and Fiji at minimum speeds of 47 and 63 km day?1 at the end of summer.
  5. Archive data from one ray showed that it made regular vertical movements of 25–100 m amplitude, but spent most of its time shallower than 50 m, more so during the night (89.6%) than the day (76.6%), and mainly experienced temperatures of 18?22 °C. Dives deeper than 200 m were usually made during the day or twilight.
  6. All three surviving rays typically moved between the surface and 200–300 m daily, and reached greatest depths of 649 m, 1000 m and 1112 m, respectively, substantially exceeding the previous depth record for this species of 445 m.
  7. Recommendations are made for reducing purse seine mortality of mobulid rays by avoiding areas of high ray abundance, avoiding setting on ray‐associated tuna schools, and adopting best‐practice methods of returning rays to the sea from the net or vessel.
Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

13.
    
  1. South Florida has a significant number of recreational anglers, and some shore-based fishing sites overlap with habitat for juvenile manta rays. Although manta rays are prohibited from harvest in Florida, they are frequently seen foul-hooked or entangled in fishing line.
  2. Recreational anglers (n = 198) were surveyed at piers and inlet jetties in Palm Beach County, Florida, USA to assess their knowledge of and actions and attitudes towards manta rays.
  3. Analysis of the responses revealed that while most anglers could identify a manta ray (66.7%) and expressed no interest in casting at (93.4%) or catching a manta ray (95.5%), they lacked knowledge about threats to mantas, as well as their conservation and protected status. Surveyed anglers overwhelmingly supported manta ray conservation (82.3%) and environmental protection (98.0%).
  4. Results indicate pier and inlet anglers are not using tackle strong enough to land a large ray to remove fishing gear, therefore it is recommended that outreach focuses on preventing recreational fishery interactions with manta rays, encouraging use of environmentally friendly tackle, and fostering engagement with anglers as citizen scientists.
  5. These results can inform the design of outreach materials aimed at closing knowledge gaps and encouraging best practices. Positive attitudes towards the environment and existing neutral behaviours towards manta rays indicate an opportunity to shift the behaviour of shore-based anglers in this area in support of manta ray conservation.
  相似文献   

14.
  1. Although it is widely recognized that protection may enhance size, abundance, and diversity of fish, its effect on spatial heterogeneity of fish assemblages and species turnover is still poorly understood.
  2. Here the effect of full protection within a Mediterranean marine protected area on β‐diversity patterns of fish assemblages along a depth gradient comparing a no‐take zone with multiple unprotected areas is explored. The no‐take zone showed significantly higher synecological parameters, higher β‐diversity among depths, and lower small‐scale heterogeneity of fish assemblages relative to unprotected areas.
  3. Such patterns might likely depend on the high level of fishing pressure outside the no‐take zone, as also abundance‐biomass curves seemed to indicate. Results suggested that full protection could play a role in maintaining high β‐diversity, thus reducing the fragility of marine communities and ecosystems, and spatial heterogeneity may represent a reliable predictor of how management actions could provide insurance against undesirable phase shifts.
  相似文献   

15.
    
  1. Following a shark attack, local governments often rapidly respond by implementing indiscriminate shark culls. These culls have been demonstrated to have substantial localized and adverse effects on a variety of marine organisms, and therefore there is an increasing need for an eco‐friendly alternative that maximizes both beachgoer and marine organismal safety.
  2. In response to such culls, the novel magnetic barrier technology, the Sharksafe Barrier was developed and rigorously tested on a variety of sharks implicated in shark attacks (e.g. bull sharks – Carcharhinus leucas and white sharks – Carcharodon carcharias). Although these studies exhibited promise in shark swim pattern manipulation and C. leucas exclusion, research was lacking in assessing if the technology could serve as an alternative to shark nets, or more specifically, if it could exclude motivated C. carcharias from bait.
  3. Using a 13 m × 13 m square exclusion zone, this study aimed to test the C. carcharias exclusion capabilities of the Sharksafe Barrier while additionally assessing the long‐term structural integrity of the system.
  4. After 34 trials and approximately 255 hours of total video collected over two years, data illustrate that all interacting C. carcharias were successfully excluded from the baited Sharksafe Barrier region, whereas teleosts and other small elasmobranch species were not. In addition, the long‐term deployment potential of this barrier system held promise owing to its ability to withstand harsh environmental conditions.
  5. Therefore, with the successful exclusion of a second large shark species, C. carcharias, from a baited region, continued long‐term research and implementation of this system at other locations should be considered to assess its viability and overall success as a bather and shark protection system.
  相似文献   

16.
    
  1. Marine conservation areas require high levels of compliance to meet conservation objectives, yet little research has assessed compliance quantitatively, especially for recreational fishers. Recreational fishers take 12% of global annual fish catches. With millions of people fishing from small boats, this fishing sector is hard to monitor, making accurate quantification of non‐compliance an urgent research priority.
  2. Shore‐based remote camera monitoring was tested for quantifying recreational non‐compliance in near‐shore, coastal rockfish conservation areas (RCAs) in the Salish Sea, Canada.
  3. Six high definition trail cameras were used to monitor 42 locations between July and August 2014.
  4. Seventy‐nine percent of monitored conservation area sites showed confirmed or probable fishing activity, with no significant difference in fishing effort inside and outside RCAs.
  5. Mixed effects generalized linear models were used to test environmental and geographic factors influencing compliance. Sites with greater depth had significantly higher fishing effort, which may imply high, barotrauma‐induced, rockfish mortality in RCA sites.
  6. Non‐compliance estimates were similar to aerial fly‐over compliance data from 2011, suggesting that trail camera monitoring may be an accurate and affordable alternative method of assessing non‐compliance in coastal conservation areas, especially for community‐based organizations wishing to monitor local waters.
  7. Widespread non‐compliance could compromise the ability of RCAs to protect and rebuild rockfish populations. Increased education, signage, and enforcement is likely to improve compliance.
  相似文献   

17.
    
  1. The purpose of this study was to investigate the effects of a circle hook ring on catch rates of target fish species and bycatch rates of sea turtles, elasmobranchs, and non‐commercial fish in a shallow‐set Italian swordfish longline fishery.
  2. Results were compared from 65 sets from six commercial fishing vessels totalling 50 800 hooks in which ringed and non‐ringed 16/0 circle hooks with a 10° offset were alternated along the length of the longline. In total, 464 individuals were caught in the 4 years of experiment, with swordfish (Xiphias gladius) comprising 83% of the total number of animals captured. Catch rates of targeted swordfish were significantly higher on ringed hooks (CPUEringed hooks = 8.465, CPUEnon‐ringed hooks = 6.654).
  3. Results indicate that ringed circle hooks captured significantly more small‐sized swordfish than non‐ringed circle hooks (27.7% vs. 19.5%, respectively).
  4. For species with sufficient sample sizes, the odds ratio (OR) of a capture was in favour of ringed hooks; significantly for swordfish (OR = 1.27 95%CI 1.04–1.57), and not significantly for bluefin tuna (Thunnus thynnus) (OR = 1.50, 95%CI 0.68–3.42) nor for pelagic stingray (Pteroplatytrigon violacea) (OR = 1.13, 95%CI 0.54–2.36). All six loggerhead turtles (Caretta caretta) and three of the four blue sharks (Prionace glauca) were captured on ringed hooks, however, the small sample sizes prevented meaningful statistical analysis.
  5. In summary, results from this study suggest that the addition of a ring to 16/0 circle hooks confers higher catchability for small‐sized commercial swordfish, and does not significantly reduce catch rate of bycatch species and protected species in a Mediterranean shallow pelagic longline fishery.
  6. These findings should motivate fisheries managers to consider factors in addition to hook shape when aiming to promote sustainable fishing practices. The presence of a ring has the potential to negate some conservation benefits.
Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

18.
    
  1. Sawfishes (Pristidae) are large shark‐like batoids (rays) that are among the most threatened of all marine fishes. While there is a broad consensus of severe sawfish declines globally, detailed status assessments for most of their vast circumtropical distribution do not exist. This paper reviews sawfishes of waters adjacent to the Arabian Peninsula, focusing on the Gulf. 1
  2. Until around the 1960s, sawfishes were abundant and widespread in the region, but since around the 1980s, they have been rarely recorded. Sawfishes can now be considered extinct as a functional component of coastal ecosystems, and may be close to being regionally extinct. This assessment is based on the overwhelming weight of evidence from diverse sources such as archaeological data, historical accounts, grey literature, personal communications and extensive fish surveys.
  3. Based on 176 individual records, Pristis zijsron was the most frequently recorded species, occurring in all regional seas. Anoxypristis cuspidata records were limited to the coasts of Iran, Pakistan, and Masirah Island (Oman). The first substantiated Pristis pristis records from the Arabian Peninsula are provided, and two records not identifiable to species do not exclude the possibility that Pristis clavata occurs in the region.
  4. Humans have used sawfishes as a food, oil, trade, and cultural resource for several thousands of years. Fins have been highly valued since at least the mid‐19th century.
  5. Based on recent and historical records, known biology, and marine conservation programmes for other species or habitats, priority areas for sawfish research and recovery programmes are the central southern Gulf; significant mangrove areas in Iran and the UAE; the Musandam Peninsula; and Masirah Island (Oman).
  6. Historical regional declines coincide with the widespread availability of nylon gillnets, to which sawfishes are disproportionately vulnerable. Any attempt at sawfish recovery must enforce strict controls on gillnetting, which could have significant benefits for other marine species of commercial and conservation interest.
Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

19.
    
  1. Manta and devil rays of the subfamily Mobulinae (mobulids) are rarely studied, large, pelagic elasmobranchs, with all eight of well‐evaluated species listed on the IUCN Red List as threatened or near threatened.
  2. Mobulids have life history characteristics (matrotrophic reproduction, extremely low fecundity, and delayed age of first reproduction) that make them exceptionally susceptible to overexploitation.
  3. Targeted and bycatch mortality from fisheries is a globally important and increasing threat, and targeted fisheries are incentivized by the high value of the global trade in mobulid gill plates.
  4. Fisheries bycatch of mobulids is substantial in tuna purse seine fisheries.
  5. Thirteen fisheries in 12 countries specifically targeting mobulids, and 30 fisheries in 23 countries with mobulid bycatch were identified.
  6. Aside from a few recently enacted national restrictions on capture, there is no comprehensive monitoring, assessment or control of mobulid fisheries or bycatch. Recent listing through the Convention on the International Trade in Endangered Species (CITES) may benefit mobulids of the genus Manta (manta rays), but none of the mobulids in the genus Mobula (devil rays) are protected.
  7. The relative economic costs of catch mitigation are minimal, particularly compared with a broad range of other, more complicated, marine conservation issues.
Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

20.
    
  1. Anecdotal evidence suggests that sharks are being targeted in the United Arab Emirates artisanal fishery. However, little information is available on this fishery and baseline information is essential for understanding its impact on shark populations in the Arabian/Persian Gulf, and for managing sharks in this region.
  2. The aim of this study was to investigate the artisanal shark fishery and gain an insight into the social, motivational and economic drivers behind it. Fishery characteristics were examined and the effect of fishing on local shark stocks assessed by interviewing Emirati fishermen across the country (n = 126).
  3. Sharks were found to be increasingly targeted owing to their high value in the global fin trade industry. The majority of fishermen (80%) confirmed that changes in species composition, abundance and sizes of sharks have been continuing for more than two decades, mainly because of overfishing, raising concerns about the sustainability of this fishery.
  4. Results suggest that sharks are likely to be overexploited and that management measures will need to take into account the precautionary principle. There is an urgent need to formulate long‐term and effective conservation and management plans to prevent further declines in a number of species.
  5. Additional efforts should be directed to quantify the ecological implications of the observed changes and determine if these are aggravated by the life‐history traits of the fished species. Such implications should be considered when assessing the sustainability of local fisheries.
  6. The data gathered can now serve as a reference to managers, fisheries scientists and other stakeholders to prioritize future research as well as lay foundations for the development and implementation of national management plans for the protection and conservation of sharks.
Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号