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1.
This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific, the oceanic region centered on the eastern Pacific warm pool, but also including the equatorial cold tongue and equatorial current system, and summarizes what is known about oceanographic influences on seabirds and cetaceans there. The eastern tropical Pacific supports on the order of 50 species of seabirds and 30 species of cetaceans as regular residents; these include four endemic species, the world’s largest populations for several others, three endemic sub-species, and a multi-species community that is relatively unique to this ecosystem. Three of the meso-scale physical features of the region are particularly significant to seabirds and cetaceans: the Costa Rica Dome for blue whales and short-beaked common dolphins, the Equatorial Front for planktivorous seabirds, and the countercurrent thermocline ridge for flocking seabirds that associate with mixed-species schools of spotted and spinner dolphins and yellowfin tuna. A few qualitative studies of meso- to macro-scale distribution patterns have indicated that some seabirds and cetaceans have species-specific preferences for surface currents. More common are associations with distinct water masses; these relationships have been quantified for a number of species using several different analytical methods. The mechanisms underlying tropical species–habitat relationships are not well understood, in contrast to a number of higher-latitude systems. This may be due to the fact that physical variables have been used as proxies for prey abundance and distribution in species–habitat research in the eastern tropical Pacific.Though seasonal and interannual patterns tend to be complex, species–habitat relationships appear to remain relatively stable over time, and distribution patterns co-vary with patterns of preferred habitat for a number of species. The interactions between seasonal and interannual variation in oceanographic conditions with seasonal patterns in the biology of seabirds and cetaceans may account for some of the complexity in species–habitat relationship patterns.Little work has been done to investigate effects of El Niño-Southern Oscillation cycles on cetaceans, and results of the few studies focusing on oceanic seabirds are complex and not easy to interpret. Although much has been made of the detrimental effects of El Niño events on apex predators, more research is needed to understand the magnitude, and even direction, of these effects on seabirds and cetaceans in space and time. 相似文献
2.
《Marine Policy》2016
For decades, cetacean bycatch has been a major conservation and welfare concern in Europe, with high numbers of harbour porpoises, dolphins and whales continuing to die each year. Despite binding legal requirements to reduce bycatch, there has been limited effective monitoring or mitigation. Bycatch is also an important welfare issue. At this critical juncture, with discussion of incorporating monitoring and mitigation of bycatch of protected species in Europe into the Data Collection Framework and Technical Measures Framework taking place to help deliver the reformed Common Fisheries Policy (CFP), a clear, effective strategy could identify the steps that are required by all EU Member States to reduce bycatch towards zero. Here, implementation of current monitoring and mitigation obligations are reviewed. Recommendations are made for the provision of clear EU guidance in order to improve and unify population surveillance and bycatch monitoring, with enhanced implementation and enforcement from Member States. A more regionalised evidence-based approach to monitoring and mitigation is in line with the move to more regionalised management under the CFP, with Member States robustly showing that bycatch levels are decreasing over a set period of time (e.g. 5 years) by a specified amount. To this end, an EU Action Plan on Cetacean Bycatch, comparable to the existing 2012 Action Plan for reducing incidental catches of seabirds in fishing gear, might be beneficial and could ultimately form a model for an international Food and Agricultural Organisation (FAO) Cetacean Bycatch Reduction Action Plan. 相似文献
3.
《Marine Policy》2017
The International Whaling Commission's (IWC) Scientific Committee provides important advice to the IWC on a large variety of cetacean species, sub-species and populations and the issues affecting them. Cetaceans are facing increasing, non-whaling-related threats, and the Scientific Committee (SC), in accordance with the Commission's requests, has strengthened its conservation-oriented research work. A selection of the reports of the Scientific Committee from between 1986 and 2012 was assessed for its: (i) fundamental research; (ii) management; (iii) conservation; and (iv) administrative content, and to identify potential trends over time. Recommendations and their urgency were also examined, as implied from the language used by the SC in its reports. The analysis showed that the work of the Scientific Committee has increasingly been oriented towards conservation issues over the period reviewed, but at the same time this conservation work has received little funding. Increased support for conservation-related research projects is warranted to promote the long-term survival of cetaceans. Based on this review of the content and focus of the Committee reports, the analysis suggested that its issued advice be made clearer, whenever possible, and governments are urged to give due consideration to this science-based advice particularly when urgent conservation actions are needed. In addition, more consistent funding of the IWC's conservation-related research should be pursued to improve international conservation outputs regarding cetacean populations. 相似文献
4.
Geographical and temporal variation in levels of organochlorine contaminants in marine mammals 总被引：1，自引：0，他引：1
The interpretation of the spatial and temporal patterns of variation in organochlorine concentrations in marine mammal populations is complex because of the lack of wide-scale, long-term surveys. Therefore the results from several surveys must be combined and this causes undesired heterogeneity due to differences in the sampling and analytical techniques used and in the biological characteristics of the individuals sampled. Moreover, information is not homogeneously distributed in either space or in time. Most research is concentrated in western Europe, northern America and certain areas of Asia, while it is extremely limited or non-existent in Africa and most regions of the southern hemisphere. Marine mammals from the temperate fringe of the northern hemisphere, particularly fish-eating species which inhabit the mid-latitudes of Europe and North America, show the greatest organochlorine loads; noteworthy are the extremely high levels found in the Mediterranean Sea and certain locations on the western coasts of the United States. Concentrations in the tropical and equatorial fringe of the northern hemisphere and throughout the southern hemisphere are low or extremely low. The polar regions of both hemispheres showed the lowest concentrations of DDTs and PCBs, although levels of HCHs, chlordanes and HCB were moderate to high in the cold waters of the North Pacific. During recent decades, concentrations have tended to decrease in the regions where pollution was initially high but they have increased in regions located far from the pollution source as a consequence of atmospheric transport and redistribution. It is expected that the Arctic and, to a lesser extent, the Antarctic, will become major sinks for organochlorines in the future; this process may already be significant for some compounds such as HCB and HCHs. Effort should be devoted to both assessment of organochlorine trends in the now highly polluted populations of the temperate fringe of the northern hemisphere and to the implementation of long-term monitoring of marine mammal populations inhabiting polar regions. 相似文献
5.
Kajiwara N Watanabe M Tanabe S Nakamatsu K Amano M Miyazaki N 《Marine pollution bulletin》2002,44(10):1089-1099
Organochlorine compounds (OCs) such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane related compounds, hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), tris(4-chlorophenyl) methane (TCPMe) and tris(4-chlorophenyl) methanol were determined in the blubber of Dall's porpoises (Phocoenoides dalli) collected from Japanese coastal waters in 1998/1999. Among OCs analyzed, PCBs were the predominant contaminants with concentrations ranging from 1.5 to 39 microg/g on a wet weight basis. OCs concentrations were relatively low and less variable in mature females possibly due to the lactational excretion from their bodies, while in males the concentrations were increased with body length. Concentrations and compositions of DDTs and HCHs showed significant differences between the truei-type population off the Pacific coast of northern Japan and dalli-type from the Sea of Japan/Okhotsk, suggesting its usefulness to discriminate different populations. OCs levels detected in truei-type porpoises collected in 1998/1999 were lower than those collected in 1984, except TCPMe. On the other hand, except DDTs, the residue levels of other organochlorines in dalli-type porpoises showed no significant decrease since 1984. 相似文献
6.
Peter S. Ross Jay Barlow Thomas A. Jefferson Brendan E. Hickie Tatiana Lee Christina MacFarquhar E. Christien Parsons Kimberly N. Riehl Naomi A. Rose Elisabeth Slooten Chia-Yang Tsai John Y. Wang Andrew J. Wright Shih Chu Yang 《Marine Policy》2011
The adoption of endangered species laws in various nations has intensified efforts to better understand, and protect, at-risk species or populations, and their habitats. In many countries, delineating a portion of a species' habitat as particularly worthy of protection has become a mantra of these laws. Unfortunately, the laws themselves often provide scientists and managers with few, if any, guidelines for how to define such habitat. Conservationists and scientists may view protecting part of the habitat of an endangered species as an ineffectual compromise, while managers may be under pressure to allow a range of human activities within the species' habitat. In the case of small cetaceans, establishing boundaries for such areas can also be complicated by their mobility, the fluid nature of their environment, and the often ephemeral nature of their habitat features. The convergence of multiple human impacts in coastal waters around the world is impacting many small cetaceans (and other species) that rely on these areas for feeding, reproducing, and resting. The ten guiding principles presented here provide a means to characterize the habitat needs of small, at-risk cetaceans, and serve as a basis for the delineation of ‘priority habitat’ boundaries. This conceptual approach should facilitate a constructive discourse between scientists and managers engaged in efforts to recover endangered species. The degree to which the recovery of an at-risk species can be reconciled with sustainable economic activity will depend in part on how well these principles are incorporated into the delineation of priority habitat. 相似文献
7.
While climate change is expected to affect cetaceans primarily via loss of habitat and changes in prey availability, additional consequences may result from climate-driven shifts in human behaviors and economic activities. For example, increases in shipping, oil and gas exploration and fishing due to the loss of Arctic sea ice are highly likely to exacerbate acoustic disturbance, ship strikes, bycatch and prey depletion for Arctic cetaceans. In the tropics, climate change may result in increased hunting pressure on near-shore dolphins and whales off Asia, Latin America, Africa, and elsewhere as the availability of other marine resources diminishes. This study explores the range of potential consequences to cetaceans worldwide from predicted climate-driven shifts in human behavior, and evaluates the risks to particular species given their geographic ranges and habitat preferences. While concern about impacts of climate change on cetaceans has largely focused on polar species, the analysis presented here suggests tropical coastal and riverine cetaceans such as the Irawaddy dolphin, Indo-Pacific humpback dolphin, and finless porpoise are particularly vulnerable to those aspects of climate change that are mediated by changes in human behavior. Policy recommendations include the following: (1) information about cetacean populations should be incorporated into national, regional and international climate adaptation decisions wherever possible (for example, via GEF-sponsored adaptation initiatives); and (2) human-mediated impacts of climate change should be included in cetacean conservation and management plans, such as the management procedures of the International Whaling Commission (IWC), where possible. Because human responses to climate change are likely to evolve rapidly over the coming years and decades, it is important that local, regional and international cetacean conservation and management plans include regular reviews to allow them to adapt to new information. 相似文献
8.
Marine renewable energy is seen as an important component of the UK's future energy strategy and contribution to reducing the greenhouse gas emissions responsible for climate change. The UK aims to generate a total of 33 GW (gigawatts) of offshore wind energy. Its implementation strategy includes the development of ten offshore wind farms within Scottish territorial waters. In addition, between 1000 MW (megawatts) and 2600 MW of marine renewable energy generating capacity could be achieved in Scotland using wave and tidal power devices. However, there are negative environmental impacts associated with marine renewable energy. Intense noise is produced during pile driving, drilling and dredging operations with potential consequences for cetaceans. There are also increases in vessel activities during exploration, maintenance and construction with association risks of disturbance and collisions. Some underwater devices will be large and may be positioned in arrays across the habitats that cetaceans frequent. The consequences of encounters between cetaceans and such devices are as yet unknown. It is recommended that the Scottish Government complete full and transparent Marine Spatial Planning, including consideration of cumulative impacts, before moving to license appropriate sites. 相似文献
9.
The calibration of marine 14C dates requires the incorporation of regionally specific marine reservoir offsets known as ΔR, essential for accurate and meaningful inter-archive comparisons. Revised, regional ΔR (‘ΔRR’) values for the Barents Sea are presented for molluscs and cetaceans for the two latest iterations of the marine calibration curve, based on previously published pre-bomb live-collected and radiocarbon-dated samples (‘ΔRL’; molluscs: n = 16; cetaceans: n = 18). Molluscan ΔRR, determined for four broad regional oceanographic settings, are: western Svalbard (including Bjørnøya), −61 ± 37 14C yrs (Marine20), 94 ± 38 14C yrs (Marine13); Franz Josef Land, −277 ± 57 14C yrs (Marine20), −122 ± 38 14C yrs (Marine13); Novaya Zemlya, −156 ± 73 14C yrs (Marine20), 0 ± 76 14C yrs (Marine13); northern Norway, −86 ± 39 14C yrs (Marine20), 74 ± 24 14C yrs (Marine13). Molluscan ΔRR values are considered applicable to other marine carbonate materials (e.g., foraminifera, ostracods). Cetacean ΔRR are determined for toothed (n = 10) and baleen (n = 8) whales, and a combined toothed-baleen group (n = 18): toothed, −161 ± 41 14C yrs (Marine20), 1 ± 41 14C yrs (Marine13); baleen, −158 ± 43 14C yrs (Marine20), 8 ± 41 14C yrs (Marine13); combined baleen-toothed whales, −160 ± 41 14C yrs (Marine20), 4 ± 49 14C yrs (Marine13). Where identification and separation of baleen and toothed whales is impossible the combined ΔRR term may be used. However, we explicitly discourage the application of existing cetacean ΔRR terms to other marine mammals. Our new ΔRR values are applicable for as long as those broad oceanographic conditions (circulation and ventilation) have persisted, i.e., through the Holocene. We recommend using the latest iteration of the marine calibration curve, Marine20, which seems to better capture the time-variant nature of R compared to Marine13. More ΔRL datapoints for both molluscs and cetaceans would improve the accuracy and precision of ΔRR. In the meantime, our new ΔR terms facilitate the calibration of marine 14C dates across the region, paving the way for meaningful and accurate late Quaternary histories and inter-regional comparisons. 相似文献
10.
This article reviews the types and effectiveness of marine mammal mitigation measures used during some naval activities worldwide. The three main standard methods used to mitigate the potential impacts of naval sonar sound on marine mammals are (1) time/area planning (of exercises/active sonar use) to avoid marine mammals; (2) implementation of operational procedures (e.g. ‘soft start’ - where sound levels are gradually increased over time); and (3) monitoring of animals for the purpose of maintaining an ‘exclusion zone’ around the sound source. Suggestions towards a minimum worldwide mitigation standard are made. 相似文献