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1.
By reviewing the history of fishery exploitation in the coastal waters of west Canada and east Korea, related with contrasting life history strategies of the dominant species, the fishery management challenges that each country would face in the upcoming decades were outlined. In the ecosystem of the Canadian western coastal waters, the dominant oceanographic feature is the coastal upwelling domain off the west coast of Vancouver Island, the northernmost extent of the California Current System in the eastern North Pacific. In the marine ecosystem of the eastern coasts of Korea (the Japan/East Sea), a major oceanographic feature is the Tsushima Warm Current, a branch of the Kuroshio Current in the western North Pacific. Fishes in the Canadian ecosystem are dominated by demersal, long-lived species such as flatfish, rockfish, sablefish, and halibut. During summer, migratory pelagic species such as Pacific hake, Pacific salmon, and recently Pacific sardine, move into this area to feed. In the late 1970s, Canada declared jurisdiction for 200 miles from their coastline, and major fisheries species in Canadian waters have been managed with a quota system. The overall fishing intensity off the west coast of Vancouver Island has been relatively moderate compared to Korean waters. Fishes in the ecosystem of the eastern Korean waters are dominated by short-lived pelagic and demersal fish. Historically, Korea has shared marine resources in this area with neighbouring countries, but stock assessments and quotas have only recently (since the late-1990s) been implemented for some major species. In the Korean ecosystem, fisheries can be described as intensive, and many stocks have been rated as overfished. The two ecosystems responded differently to climate impacts such as regime shifts under different exploitation histories. In the future, both countries will face the challenge of global warming and subsequent impacts on ecosystems, necessitating developing adaptive fisheries management plans. The challenges will be contrasting for the two countries: Canada will need to conserve fish populations, while Korea will need to focus on rebuilding depleted fish populations.  相似文献   

2.
Japanese fisheries production in the Japan/East Sea between 1958 and 2003 increased to their peak (1.76 million tons) in the late 1980s and decreased abruptly with the collapse of Japanese sardine. Catch results for 58 fisheries and various environmental time-series data sets and community indices, including mean trophic level (MTL) and Simpson’s diversity index (DI), were used to investigate the impacts of fishing and climate changes on the structure of the fish community in the Tsushima warm current (TWC) region of the Japan/East Sea. The long-term trend in fisheries production was largely dependent on the Japanese sardine that, as a single species, contributed up to 60% of the total production in the Japanese waters of the Japan/East Sea during the late 1980s. Excluding Japanese sardine, production of the small pelagic species was higher during 1960s and 1990s but lower during 1970s and 1980s. This variation pattern generally corresponds with the trend in water temperature, warmer before early 1960s and after 1990s but colder during 1970s and 1980s. The warm-water, large predatory fishes and cold water demersal species show opposite responses to the water temperature in the TWC region, indicating the significant impact of oceanic conditions on fisheries production of the Japan/East Sea. Declines in demersal fishes and invertebrates during 1970s and 1980s suggested some impact of fishing. MTL and DI show a similar variation pattern: higher during 1960s and 1990s but lower during 1970s and 1980s. In particular, the sharp decline during the 1980s resulted from the abundant sardine catches, suggesting that dominant species have a large effect on the structure of the fish community in the Japan/East Sea. Principal component analysis for 58 time-series data sets of fisheries catches suggested that the fish community varied on inter-annual to inter-decadal scales; the abrupt changes that occurred in the mid-1970s and late 1980s seemed to correspond closely with the climatic regime shifts in the North Pacific. These results strongly suggest that the structure of the fish community in the Japan/East Sea was largely affected by climatic and oceanic regime shifts rather than by fishing. There is no evidence showing “fishing down food webs” in the Japan/East Sea. However, in addition to the impacts of abrupt shifts that occurred in the late 1980s, the large predatory and demersal fishes seem to be facing stronger fishing pressure with the collapse of the Japanese sardine.  相似文献   

3.
We compiled and analyzed past time-series data to evaluate changes in oceanographic conditions and marine ecosystems near the Ieodo ocean research station (IORS) in the East China Sea (N 31°15??C33°45??, E 124°15??C127°45??) in relation to longterm changes in climate and global warming. The environment data we used was a depth-specific time-series of temperature and salinity for the water columns at 175 fixed stations along 22 oceanographic lines in Korean waters, based on bimonthly measurements since 1961 taken by the National Fisheries Research & Development Institute. As an indicator for the ecosystem status of the waters off Ieodo, we analyzed species composition in biomass of fishes caught by Korean fishing vessels in the waters near the IORS (1984?C2010) and summarized the data in relation to the environmental changes using canonical correspondence analysis (CCA). To detect step changes in the time-series of environmental factors, we applied a sequential t-test analysis of regime shift. Correspondence analysis detected a major shift in fish assemblage structure between 1990 and 1993: the dominant species was filefish during 1981?C1992, but chub mackerel during 1992?C2007. This shift in fish assemblage structure seemed to be related to the well-established 1989 regime shift in the North Pacific, which was confirmed again with respect to temperature in the Yellow Sea and the Korea Strait (but not in the waters off the IORS). In overall from 1984 to 2010, salinity was more important than water temperature in CCA, implying that the fluctuation of the Tsushima warm current is a most important force driving the long-term changes in fish assemblage structure in the waters off the IORS. Further multidisciplinary researches are required to identify oceanographic and biological processes that link climate-driven physical changes to fish recruitment and habitat range fluctuations.  相似文献   

4.
Evidence supports the hypothesis that two climatic regime shifts in the North Pacific and the Japan/East Sea, have affected the dynamics of the marine ecosystem and fisheries resources from 1960 to 2000. Changes in both mixed layer depth (MLD) and primary production were detected in the Japan/East Sea after 1976. The 1976 regime shift appears to have caused the biomass replacement with changes in catch production of major exploited fisheries resources, including Pacific saury, Pacific sardine and filefish. Both fisheries yield and fish distribution are reflected in these decadal fluctuations. In the 1960s and 1990s, common squid dominated the catches whereas in the 1970s and 1980s, it was replaced by walleye pollock. In the post-1988 regime shift, the distribution of horse mackerel shifted westward and southward and its distributional overlap with common mackerel decreased. The habitat of Pacific sardine also shifted away from mackerel habitats during this period. To evaluate changes in the organization and structure of the ecosystem in the Japan/East Sea, a mass-balanced model, Ecopath, was employed. Based on two mass-balanced models, representing before (1970–75) and after (1978–84) the 1976 regime shift, the weighted mean trophic level of catch increased from 3.09 before to 3.28 after. Total biomass of species groups in the Japan/East Sea ecosystem increased by 15% and total catch production increased by 48% due to the 1976 regime shift. The largest changes occurred at mid-trophic levels, occupied by fishes and cephalopods. The dominant predatory species shifted from cephalopods to walleye pollock due to the 1976 regime shift. It is concluded that the climatic regime shifts caused changes in the structure of the ecosystem and the roles of major species, as well as, large variations in biomass and production of fisheries resources.  相似文献   

5.
This study uses a comparative approach to examine responses of marine ecosystems to climatic regime shifts. The three seas surrounding the Korean peninsula, the Japan/East Sea, the East China Sea and the Yellow Sea represent three contiguous but distinct ecosystems. Sampling has been carried out by the National Fisheries Research and Development Institute of South Korea since 1965, using the same methods in all three seas. Sampling was generally synoptic. Amplitude time series of 1st EOF modes for temperature, salinity, zooplankton biomass and concentrations of four major zooplankton taxa were used to determine whether the three marine ecosystems respond in a similar manner to climate variations. Temporal patterns of the variables were strongly similar among the three seas at decadal time scales, but very weakly similar at interannual scales. All three seas responded to a climatic regime shift that occurred in 1989. Temperature, zooplankton biomass and copepod concentrations increased in the late 1980s or early 1990s in all three seas. Concentrations of amphipods, chaetognaths and euphausiids also increased in the Japan/East Sea and the East China Sea, but not the Yellow Sea. The Yellow Sea ecosystem differs strongly from the other two seas, and water exchange between the Yellow Sea and the East China Sea is much weaker than that between the East China Sea and Japan/East Sea. Spatial patterns of zooplankton determined by the EOF analysis were closely related to currents and fronts in each of the three seas.  相似文献   

6.
The Bering Sea is a high-latitude, semi-enclosed sea that supports extensive fish, seabird, marine mammal, and invertebrate populations and some of the world's most productive fisheries. The region consists of several distinct biomes that have undergone wide-scale population variation, in part due to fisheries, but also in part due to the effects of interannual and decadal-scale climatic variation. While recent decades of ocean observation have highlighted possible links between climate and species fluctuations, mechanisms linking climate and population fluctuations are only beginning to be understood. Here, we examine the food webs of Bering Sea ecosystems with particular reference to some key shifts in widely distributed, abundant fish populations and their links with climate variation. Both climate variability and fisheries have substantially altered the Bering Sea ecosystem in the past, but their relative importance in shaping the current ecosystem state remains uncertain.  相似文献   

7.
Past studies suggested that a basin-wide regime shift occurred in 1988–1989, impacting marine ecosystem and fish assemblages in the western North Pacific. However, the detailed mechanisms involved in this phenomenon are still yet unclear. In the Ulleung basin of the East Sea, filefish, anchovy and sardine dominated the commercial fish catches in 1986–1992, but thereafter common squid comprised > 60% of the total catch in 1993–2010. To illuminate the mechanisms causing this dramatic shift in dominant fisheries species, I related changes in depth-specific oceanographic conditions from 0 to 500 m to inter-annual changes in the fish assemblage structure from 1986 to 2010. In the upper layer of 50–100 m depths, water temperature suddenly increased in 1987–1989, and consequently warm-water epi-pelagic species (anchovy, chub mackerel, and common squid) became dominant, while sardine, relatively cold-water epi-pelagic species, nearly disappeared. An annual index of the volume transport by the Korea Strait Bottom Cold Water, originating from the deep water of the Ulleung Basin, displayed a sudden intensification in 1992–1993, accompanied by decreased water temperature and increased water density in the deep water and replacement of dominant bentho-pelagic species from filefish, warm-water species, to herring and cod, cold-water species. The results suggest that climate-driven oceanic changes and the subsequent ecological impacts can occur asynchronously, often with time lags of several years, between the upper and the deep layer, and between epi-pelagic and deepwater fish assemblages.  相似文献   

8.
The Barents Sea ecosystem, one of the most productive and commercially important ecosystems in the world, has experienced major fluctuations in species abundance the past five decades. Likely causes are natural variability, climate change, overfishing and predator–prey interactions. In this study, we use an age-length structured multi-species model (Gadget, Globally applicable Area-Disaggregated General Ecosystem Toolbox) to analyse the historic population dynamics of major fish and marine mammal species in the Barents Sea. The model was used to examine possible effects of a number of plausible biological and fisheries scenarios. The results suggest that changes in cod mortality from fishing or cod cannibalism levels have the largest effect on the ecosystem, while changes to the capelin fishery have had only minor effects. Alternate whale migration scenarios had only a moderate impact on the modelled ecosystem. Indirect effects are seen to be important, with cod fishing pressure, cod cannibalism and whale predation on cod having an indirect impact on capelin, emphasising the importance of multi-species modelling in understanding and managing ecosystems. Models such as the one presented here provide one step towards an ecosystem-based approach to fisheries management.  相似文献   

9.
Fisheries management in European waters is gradually moving from a single-species perspective towards a more holistic ecosystem approach to management (EAM), acknowledging the need to take all ecosystem components into account. Prerequisite within an EAM is the need for management processes that directly influence the ecological effects of fishing, such as the mortality of target and non-target species. Up until recently, placing limits on the quantities of fish that can be landed, through the imposition of annual total allowable catches (TACs) for the target species, has been the principal management mechanism employed. However, pressure on non-target components of marine ecosystems is more closely linked to prevailing levels of fishing activity, so only if TACs are closely related to subsequent fishing effort will TAC management serve to control the broader ecosystem impacts of fishing. We show that in the mixed fisheries that characterise the North Sea, the linkage between variation in TAC and the resulting fishing effort is in fact generally weak. Reliance solely on TACs to regulate fishing activity is therefore unlikely to mitigate the impacts of fishing on non-target species. Consequently, we conclude that the relationship between TACs and effort is insufficient for TACs to be used as the principal management tool within an EAM. The implications, and some alternatives, for fisheries management are discussed.  相似文献   

10.
舟山近海棘头梅童鱼群体遗传多样性微卫星DNA分析   总被引：5，自引：0，他引：5  
应用6对可在棘头梅童鱼（Collichthy lucidels）中扩增的大黄鱼（Pseudosciaena Crocea）微卫星引物对浙江舟山近海的棘头梅童鱼群体进行PCR扩增,变性聚丙烯酰胺凝胶电泳分析扩增产物.6对引物在群体中共扩增出46个等位基因,平均每个位点得到5.308 0个有效等位基因,各位点的PIC值为0.412 6~0.893 5（平均值0.670 8）,PC1C4和PC8F5为中度多态性位点,PC4H12、PC5E11、PC10F10及PC10G6为高度多态性位点,这些位点可以做为棘头梅童鱼群体遗传学研究的有效的分子遗传标记.6个位点的连锁分析显示,各位点间不存在明显的连锁关系.各位点在群体中的观测杂合度（Ho）为0.454 5~0.916 7（平均值0.659 1）,期望杂合度（He）为0.468 0~0.901 9（平均值0.699 7）,与其他海水鱼类比较,浙江近海的棘头梅童鱼群体遗传多样性偏低.对各位点进行Hardy-Weinberg平衡检测表明,PC4H12、PC10F10及PC10G6位点的等位基因频率偏离了平衡,综合现有的资源调查资料,遗传多样性的降低与近年来棘头梅童鱼资源的下降有关.  相似文献   

11.
东海区海洋捕捞渔获物的营养级变化研究   总被引：4，自引：0，他引：4  
根据东海区主要海洋渔业公司1950～1995年分品种渔获物产量的统计数据，分析了东海区渔获物营养级的变化过程，用平均营养级指数来评估东海区海洋渔业资源的开发利用状况。结果表明，经过几十年的捕捞开发，东海区渔获物的平均营养级已从1965年的3．5下降到1990年的2．8，自1974年后海区的产量主要依靠捕捞低营养级品种如马面鲍等而获得。东海区海洋捕捞渔获物营养级结构已经发生了变化，1974年后捕捞主要在低营养级品种内进行。另外还描述了东海区带鱼等品种的种群内部结构小型化、低龄化现象。  相似文献   

12.
This paper describes the main features of the Icelandic marine ecosystem and its response to climate variations during the 20th century. The physical oceanographic character and faunal composition in the southern and western parts of the Icelandic marine ecosystem are different from those in the northern and the eastern areas. The former areas are more or less continuously bathed by warm and saline Atlantic water while the latter are more variable and influenced by Atlantic, Arctic and even Polar water masses to different degrees. Mean annual primary production is higher in the Atlantic water than in the more variable waters north and east of Iceland, and higher closer to land than farther offshore. Similarly, zooplankton production is generally higher in the Atlantic water than in the waters north and east of Iceland. The main spawning grounds of most of the exploited fish stocks are in the Atlantic water south of the country while nursery grounds are off the north coast. In the recent years the total catch of fish and invertebrates has been in the range of 1.6–2.4 million ton. Capelin (Mallotus villosus) is the most important pelagic stock and cod (Gadus morhua) is by far the most important demersal fish stock. Whales are an important component of the Icelandic marine ecosystem, and Icelandic waters are an important habitat for some of the largest seabird populations in the Northeast Atlantic.In the waters to the north and east of Iceland, available information suggests the existence of a simple bottom-up controlled food chain from phytoplankton through Calanus, capelin and to cod. Less is known about the structure of the more complex southern part of the ecosystem. The Icelandic marine ecosystem is highly sensitive to climate variations as demonstrated by abundance and distribution changes of many species during the warm period in the 1930s, the cold period in the late 1960s and warming observed during the recent years. Some of these are highlighted in the paper.  相似文献   

13.
The Canadian Beaufort Sea is one of the last places on Earth that has not experienced large-scale commercial fisheries. The aboriginal people of the western Canadian Arctic, the Inuvialuit, have become increasingly concerned about the potential effects of large-scale commercial operations on key subsistence species of fish and marine mammals and the marine ecosystem upon which they depend. A 1984 comprehensive land settlement agreement (treaty) between Canada and the Inuvialuit established a co-management regime for limited aspects of fish and marine mammal resource management, and gave the Inuvialuit rights to subsistence fisheries and existing commercial fisheries but no preference for new commercial fisheries. The Fisheries Joint Management Committee (the fisheries co-management body), the Canada Department of Fisheries and Oceans, the Inuvialuit Regional Corporation and the Inuvialuit Game Council have developed an integrated fisheries management framework agreement for the review and assessment of any proposed commercial fisheries within the Canadian Beaufort Sea. The agreement provides clarity and transparency for decision making and strengthens the protection of fish stocks. The development of the framework depended upon a history of cooperation between the parties and a bridging initiative by the Fisheries Joint Management Committee and an NGO that brought together the Inuvialuit and the government.  相似文献   

14.
The rock bream, Oplegnathus fasciatus, is a common rocky reef game fish in East Asia and recently has become an aquaculture species. Despite its commercial importance, the population genetic structure of this fish species remains poorly understood. In this study, 163 specimens were collected from 6 localities along the coastal waters of Korea and China and their genetic variation was analyzed with mtDNA COI sequences. A total of 34 polymorphic sites were detected which determined 30 haplotypes. The genetic pattern reveals a low level of nucleotide diversity (0.04 ± 0.003) but a high level of haplotype diversity (0.83 ± 0.02). The 30 haplotypes are divided into two major genealogical clades: one that consists of only Zhoushan (ZS, East China Sea) specific haplotypes from the southern East China Sea and the other that consists of the remaining haplotypes from the northern East China Sea, Yellow Sea, Korea Strait, and East Sea/Sea of Japan. The two clades are separated by approximately 330~435 kyBP. Analyses of AMOVA and Fst show a significant population differentiation between the ZS sample and the other ones, corroborating separation of the two genealogical clades. Larval dispersal and the fresh Yangtze River plume are invoked as the main determining factors for this population genetic structure of O. fasciatus. Neutrality tests and mismatch distribution analyses indicate late Pleistocene population expansion along the coastal waters of Korea and China approximately 133–183 kyBP during which there were periodic cycles of glaciations and deglaciations. Such population information needs to be taken into account when stock enhancement and conservation measures are implemented for this fisheries species.  相似文献   

15.
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16.
The hake resource is the most important commercial fish species in the demersal sector of Namibia's fisheries, both in terms of annual catch and contribution to Gross Domestic Product (GDP). The fishery now spans four decades. In the 1960s and 1970s, hake were exploited heavily by mainly foreign fleets, total catches peaking at more than 800 000 tons in 1972. The first control measures, the use of a minimum mesh size of 110 mm and the allocation of quotas to each member country participating in the hake fishery, were implemented by the International Commission for the Southeast Atlantic Fisheries in 1975. In 1990, the Namibian Government took action to control fishing activities in Namibian waters, and the enactment of its Fisheries Policy (1991) and Sea Fisheries Act of 1992 provided for the control measures to be taken. The conservative management strategy adopted between 1990 and 1993 resulted in gradual increase in hake biomass, but thereafter the stock declined. The hake fishery is currently managed on the basis of a total allowable catch that takes into consideration the rate of increase or decrease in the size of the resource. Since 1990, the demersal trawl fishery has accounted for approximately 90% of the total hake catch. The resource is subjected to both directed fishing and bycatch, the latter taken in directed fisheries for species such as horse mackerel, monkfish and sole.  相似文献   

17.
Whitespotted conger Conger myriaster is a commercially important species in the seas around China, Korea and Japan. The coastal waters of China serve as an important feeding ground for congers, but the spatio-temporal variations in the fishery and biological characteristics of the population have been rarely evaluated and less well understood in this area. We studied the growth, spawning and feeding characteristics of C. myriaster on the basis of samples collected from October 2016 to April 2017 in the Yellow Sea and East China Sea. A total of 529 specimens were collected, with ages ranging from 1 to 6 years and total length ranging from 132 mm to 834 mm.The parameters of von Bertalanffy growth equation L_∞ and k were 1 026 mm and 0.226 a~(–1), respectively; the sex ratio was 88:0(female: male) in the East China Sea and 2.67:1 in the South Yellow Sea; the development stage of ovary ranged from peri-nucleolus stage to secondary yolk globule stage, and the testis of two males was at midmeiotic stage; Crustacean was the major prey for conger of small length, and food source shift to fish with somatic growth. The results showed substantial differences from previous studies in Japan and Korean waters, as well as from China seas in the 1980 s, suggesting potential spatiotemporal changes in the biological characteristics of C.myriaster. This study may improve current understanding of the fishery biology of C. myriaster in the Yellow Sea and East China Sea.  相似文献   

18.
The purpose of this article is to analyze the legal status of fisheries in the East China Sea (ECS) pursuant to these fisheries agreements, focusing on the legal issues of the Current Fishing Pattern Zone (CFPZ) which is provided for in the Fisheries Agreement between Korea and China. The CFPZ is a zone or area in which Korean and Chinese fishing patterns that existed before the agreement are respected. Although the legal status of fisheries in the CFPZ appears to be very simple, it is in fact very complex due to the overlapping jurisdictions of Korea, China and Japan. Therefore, the fisheries regime is rather vulnerable with the possibility of increasing legal conflicts. However, it is noteworthy that fisheries conflicts come up rarely in these relevant waters. This article explores the bilateral fisheries agreements and EEZ laws of the respective states, and thereafter deals with the legal issues that arise in the execution of these agreements regarding the area of overlapping waters.  相似文献   

19.
本文为“中国长臂虾亚科研究”的第二部分,包括长臂虾属(Palaemon)、白虾属(Exopalaemon)、小长臂虾属( Palaemonetes)和细腕竏属(Leptocarpus),共计18种。其中有2新种,1新亚种,2新记录。 本文第一部分已报告沼虾属(Macrobrachium)21种,瘦虾属(Leander)2种,拟瘦虾属(Leandrites)1种。(此处増补图23,图24)全文共计7属42种。沼虾属种类多、数量大,在淡水(包括半咸水)虾类捕捞和养殖中都占很重要地位。第二部分的18种,绝大部分都有经济价值,有的在动物地理学上有重要意义。长臂虾属10个种都是沿岸浅海常见种,其中条纹长臂虾(P. paucidens)是北太平洋温带种,仅见于黄海、渤海和日本北部。葛氏长臂虾(P. graver)是中国北部(黄海和东海西部)和朝鲜的地方性特有种,数量很大,但不见于日本沿岸;新种细指长臂虾P. tenuidactylus仅见于华北、华东的河口半成水域;估计这个种在朝鲜沿岸也会有分布,后者也可能是黄海、东海的地方性特有种。巨齿长臂虾P. macrodactylus也属这一类型,但见于日本沿岸。在中国近海,葛氏长臂虾是该属中最重要的经济种(在东海西部水深70-80m以内的陆架区广泛分布)。洁白长臂虾P. concinnus、广东长臂虾P. guangdongensis、太平长臂虾P.pacificus仅见于东海和南海以南的温暖浅海,不见于长江口以北;太平长臂虾广分布到夏威夷群岛,是分布最广者。锯齿长臂虾P. serrifer广泛分布于印度洋和西太平洋的潮间带,但数量不大。白背长臂虾 P. sewelli 分布于印度至广东的暧海低盐水域。白虾属4种都是重要经济种,脊尾白虾 Exopalaemon carinicauda 广分布于华北和华东的低盐浅海,大河口附近产量极大;东方白虾 E. orientis 则仅见于东南沿海,也有经济价值;安氏白虾 E. annandalei 局限于河口半咸水和淡水中,长江口产量很大;秀丽白虹 E.modestus 是广泛分布于华东、华北和东北淡水湖泊及河流中的经济种。  相似文献   

20.
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