Freshwater fish biodiversity in the Yangtze River basin of China: patterns, threats and conservation

We synthesized information on freshwater fish biodiversity in the Yangtze River basin. We documented 361 species and subspecies that had been recorded and described from the basin. Of these, 177 species are endemic. The basin is usually divided into three parts, i.e. the upper reaches, the middle reaches and the lower reaches. This study indicated that the three reaches approach was not supported by fish distribution patterns. Hydrological alterations are perhaps the largest threat to fish biodiversity in the basin. Fishes in the upper reaches will be seriously affected by the construction of the Three Gorges Dam and other dams, and action should be taken for priority conservation. The most immediate restoration need is reconnection of the Yangtze River with its lakes. The cluster of lakes in the Central Yangtze should be protected to maintain habitats for spawning, feeding and migration of migratory fishes. Our study indicates a need to identify areas of high fish biodiversity and to select nature reserves to mitigate the loss of fish biodiversity in the Yangtze River basin.     

长江口及其邻近海域渔业生物的群落结构特征

根据2006年6月、8月和10月对长江口及其邻近海域渔业生物的底拖网调查数据,对该海域渔业生物的群落结构特征进行了分析.调查中共捕获渔业生物207种,主要是以暖温性和暖水性的种类为主,冷温性种类细纹狮子鱼和黄鮟鱇等也出现在调查中并成为优势种.渔业生物的多样性有所升高,种类的更替加快,部分洄游种类已成为历史记录.经济价值低、个体小、年龄结构简单和营养层次低的类群在长江口及其邻近海域占据优势地位.调查捕获渔业生物的种类数明显高于20世纪80年代相应月份的种类数,但是渔业生物的渔获率和个体数仅占80年代调查的8%左右.渔获率比较高的区域主要分布在调查区域的北部、中部及河口区域,但是渔业生物的多样性指数分布与之相反,因此在具有相对均质高多样性的群落结构条件下很难维持高渔获率.     

我国湖泊与海水鱼类养殖的环境效应和基于生态系统的渔业管理

在我国,鱼类养殖是一项重要的商业活动。鱼类养殖在过去几十年的快速发展过程中,对水环境产生了重要影响。研究表明:鱼类养殖对养殖区鱼、浮游生物、水生植物群落结构和水质变化有重要影响。现在,几乎所有的鱼类养殖系统都在一定程度上受到了损害。随着人们环境保护意识的增强,鱼类养殖的环境效应和渔业管理问题已引起了社会的广泛关注,渔业管理不再仅仅是通过开发资源以获取最高产量。面临挑战,人们应该采取切实可行的步骤,从传统的渔业管理转变到基于生态系统的渔业管理,将渔业纳入生态系统管理以保障养殖业的可持续发展。     

赤水河鱼类资源的现状与保护

赤水河是长江上游右岸一级支流,为长江上游珍稀特有鱼类国家级自然保护区的重要组成部分。为了了解赤水河鱼类资源现状,于2007年4-10月在赤水河流域进行了鱼类资源调查。在干、支流共51个采样点采集了鱼类标本;对茅台镇、赤水市和合江县三个江段的渔获物进行了统计和分析。共采集到鱼类119种(亚种),隶属于5目16科75属。其中25种为该水域的新记录;34种为长江上游特有鱼类,尤其是宽唇华缨鱼(Sinocrossocheilus labiatus)仅分布于赤水河。在上、中、下游分别采集到鱼类36、61和100种。宽鳍鱲(Zacco platypus)、中华倒刺鲃(Spinibarbus sinensis)、光泽黄颡鱼(Pelteobagrus nitidus)、张氏(Hemiculter tchangi)和蛇鮈(Saurogobio dabryi)为赤水河中主要的经济鱼类,同时,各江段渔获物的组成也存在一定的差别。本研究表明,赤水河流域鱼类种类相对丰富,但过度捕捞和涉水活动导致鱼类资源出现了一定程度的衰减。     

长江江豚繁殖生物学研究概述

长江江豚,即江豚扬子亚种,是仅分布于长江及附属湖泊中的唯一江豚淡水亚种,也是3个江豚亚种中最濒危的一个亚种。本文概述了30 年来国内外关于长江江豚繁殖生物学方面的研究成果,主要从繁殖生态学、组织解剖学、生理学以及行为学等4 个方面阐述了长江江豚繁殖生物学研究现状,并对其中一些相互矛盾和有争议的问题进行了分析。探讨了今后研究中应注意的重点问题,力图为长江江豚的繁殖生物学研究指明方向,为早日实现长江江豚的人工繁殖奠定基础。
     

Fisheries management in practice: review of 13 commercially important fish stocks

This paper comparatively reviews several commercially important fish stocks, their state and their management in various regions of the world including Japanese anchovy, Bay of Biscay anchovy, North Sea sandeel, North Sea herring, Icelandic cod, Barents Sea cod, South African cape hakes, sockeye salmon, chinook salmon, southern bluefin tuna, Pacific halibut, Greenland halibut and Patagonian toothfish. The reviewed fish stocks are systemized in three categories: (1) stock properties and status; (2) management structure and objectives; and (3) management advice. We gather evidence to outline qualities of management regimes that are recommended and highlight those that most often fail. Robust management, biological limits (reference points), implementation and consensus are critical points that separate successful and unsuccessful management regimes. We evaluate each fish stock’s management performance relative to its management objectives and current conservation issues. Furthermore, we point out the importance of stakeholder involvement in fisheries management as well as the problems that international fisheries commissions face through examples from the case studies. Management successes tended to be single-nation and single-stock fisheries with capacity control and clear stakeholder involvement. Fisheries with fleet overcapacity, unclear objectives and illegal activity characterized the case studies with management problems.     

厚颌鲂(Megalobrama pellegrini)的繁殖生物学特征

从长江上游一级支流龙溪河收集了1382尾厚颌鲂开展繁殖生物学研究。结果表明,厚颌鲂繁殖期为4—7月份,盛期为4—5月份,在繁殖季节可借第二性征辨别性别。繁殖群体主要由2、3龄个体组成,总性比♀：♂=1：1．83。厚颌鲂2龄初次性成熟（♀：75％;♂：94．7％）,3龄个体全部成熟。最小性成熟雌性全长189．0mm,体长158．0mm,体重72．1g,成熟系数2．7％;雄性全长179．0mm,体长149．0mm,体重57．1g,成熟系数2．2％。厚颌鲂绝对怀卵量为（59587．22±59018）粒,相对怀卵量为（212．64±89．50）粒／g或（230．96±137．63）粒／mm,绝对怀卵量和相对怀卵量均在5龄大幅增长。比较繁殖力以3龄组最高,2、4、5龄组相近。集群繁殖需要18℃以上水温和其他一些生态因子刺激,亲鱼追逐约1h左右产卵。     

长江流域鸟类的初步分析

对长江流域范围内有关动物调查报告和研究资料进行全面、系统地收集和整理,建立了鸟类分布数据库,初步查明在长江流域分布的鸟类共有762种,隶属20目、66科、291属,约占全国鸟类种数的61．2％。其中拥有中国特有鸟及主要分布鸟类72种,国家一级重点保护动物26种,国家二级重点保护动物92种。     

长江中游鱼类资源量的估算

为了解长江中游的鱼类资源现状,于2018年5和6月以及9和10月在宜昌、石首、洪湖、武汉和湖口5个江段进行了渔获物调查工作。通过统计各江段的渔业捕捞情况,计算年捕捞量。用体长股分析方法,对铜鱼(Coreius heterodon)、鳊(Parabramis pekinensis)和瓦氏黄颡鱼(Tachysurus vachelli)的资源量进行估算,并以此推算各江段的鱼类总资源量。结果显示,宜昌江段的鱼类年总资源量1077.36 t,其中,铜鱼为623.25 t;石首江段的年总资源量为2190.74 t,铜鱼为698.19 t;洪湖江段的鱼类年总资源量为58.57 t,其中,瓦氏黄颡鱼为0.41 t;武汉江段的鱼类年总资源量1010.54 t,其中,鳊为148.65 t;湖口江段的年鱼类总资源量14.55 t,瓦氏黄颡鱼为0.032 t。估算结果可以为长江中游鱼类资源保护措施的制定提供数据参考。     

Fisheries enhancement and biodiversity assessment of fish,prawn and mud crab in Chilika lagoon through hydrological intervention

The degraded state of the fragile ecosystem of Chilika lagoon on the east coast of India caused by natural changes and anthropogenic pressure was in the process of restoration through an effective hydrological intervention during 2000 after thorough scientific investigation including EIA study. The rich fisheries of Chilika lagoon that support livelihood of 0.2 million local fisherfolk was in dwindling state during the eco-degradation phase. Studies on fisheries and fish biodiversity of the lagoon for 4 years before and 4 years after the intervention showed the stark and rapid recovery of fishery immediately after opening of the new mouth with sixfold increase in average annual landing. The average productivity (11.3 t km⁻²) and CPUE (6.2 kg boat-day⁻¹) during post intervention phase registered 528 and 464% increase, as compared to Pre-intervention years. In total, 277 species of fish and shell fish were documented as occurring in Chilika lagoon before the hydrological intervention. Inventory survey for fish and shell fish species diversity during and after hydrological intervention documented 68 and 97 species, respectively. New records of 56 species of fish and shell fish (7 freshwater, 20 brackishwater and 29 marine) were documented from Chilika lagoon after the hydrological intervention. Analysis of commercial catches showed that the migratory species contributed to the bulk of catches (75% by species and 68% by catch weight). Fish yield and biodiversity seemed to be very sensitive to salinity and hydrologic dynamics of the lagoon. Correlation analysis indicated inverse relationship between water transparency and fish catch (R ² = 0.715; d.f. = 25; P < 0.01). Positive correlation between salinity and prawn landing (R ² = 0.542; d.f. = 25; P < 0.01) and salinity and mud crab landing (R ² = 0.628; d.f. = 25; P < 0.001). Average salinity for the whole lagoon was significantly increased by 42.7% (P < 0.007) as compared to pre-intervention situation. Maintenance of estuarine character of Chilika’s ecosystem particularly the salinity gradient, un-hindered auto-recruitment of fish and shell fish and prevention of destructive fishing are the key factors for fisheries enhancement. Unless carefully planned conservation and regulation measures are ensured with the active participation of local communities during the early phase of restoration, the present scenario of fisheries enhancement may not sustain for longer time.     

长江经济带快速城镇化对耕地保护的影响

长江经济带建设作为我国三大发展战略之一,在快速推进城市化的同时,对耕地资源的影响是不容忽视的。土地快速城镇化对耕地的大量侵占是我国城市化面临的突出问题,而近些年长江流域及长江经济带的快速发展对耕地资源的影响尚缺乏全面系统的分析。基于中分遥感数据,将覆盖长江经济带与长江流域范围的156个地级市作为研究目标,从自然区位(上、中、下游)与城市规模(人口规模)相结合的角度分析了2000—2015年城镇化对耕地的影响,结果表明:(1) 2000—2015年,长江流域及长江经济带人工表面增加56.80%,耕地减少17.09%。其中,下游人工表面增加幅度最为明显,耕地减少也是最多的;(2)随着时间推移,长江流域及长江经济带城镇化对耕地的压力逐渐减弱,十五年间人工表面增长率从2733.75 km~2/a提高至2985.87 km~2/a,而耕地减少的速度从4439.94 km~2/a降低到3940.91 km~2/a,并且有大量旱田向水田转变;(3)位于不同流域且规模不同的城市,其人工表面的增加幅度以及对耕地的影响存在明显差异。例如,长江下游的中等城市人工表面15年间增加最多(增幅385.88%),同时耕地也损失最多;中游的大城市的人工表面增速最快,而上游则是巨大型城市,这种现象说明长江流域存在发展不协调的问题。长江流域及经济带未来城市优化布局不仅要充分考虑耕地保护问题,还要均衡不同规模城市的扩张速度,以及进一步提高开发用地的利用效率。     

Size-structural shifts reveal intensity of exploitation in coral reef fisheries

Fisheries exploitation represents a considerable threat to coral reef fish resources because even modest levels of extraction can alter ecological dynamics via shifts of stock size, species composition, and size-structure of the fish assemblage. Although species occupying higher trophic groups are known to suffer the majority of exploitative effects, changes in composition among lower trophic groups may be major, though are not frequently explored. Using size-based biomass spectrum analysis, we investigate the effects of fishing on the size-structure of coral reef fish assemblages spanning four geopolitical regions and determine if patterns of exploitation vary across trophic groups. Our analyses reveal striking evidence for the variety of effects fisheries exploitation can have on coral reef fish assemblages. When examining biomass spectra across the entire fish assemblage we found consistent evidence of size-specific exploitation, in which large-bodied individuals experience disproportionate reductions. The pattern was paralleled by and likely driven by, strongly size-specific reductions among top predators. In contrast, evidence of exploitation patterns was variable among lower trophic groups, in many cases including evidence of reductions across all size classes. The breadth of size classes and trophic groups that showed evidence of exploitation related positively to local human population density and diversity of fishing methods employed. Our findings highlight the complexity of coral reef fisheries and that the effects of exploitation on coral reefs can be realized throughout the entire fish assemblage, across multiple trophic groups and not solely restricted to large-bodied top-predators. Size-specific changes among fishes of lower trophic groups likely lead to altered ecological functioning of heavily exploited coral reefs. Together these findings reinforce the value of taking a multi-trophic group approach to monitoring and managing coral reef fisheries.     

Marine molecular biology: an emerging field of biological sciences

An appreciation of the potential applications of molecular biology is of growing importance in many areas of life sciences, including marine biology. During the past two decades, the development of sophisticated molecular technologies and instruments for biomedical research has resulted in significant advances in the biological sciences. However, the value of molecular techniques for addressing problems in marine biology has only recently begun to be cherished. It has been proven that the exploitation of molecular biological techniques will allow difficult research questions about marine organisms and ocean processes to be addressed. Marine molecular biology is a discipline, which strives to define and solve the problems regarding the sustainable exploration of marine life for human health and welfare, through the cooperation between scientists working in marine biology, molecular biology, microbiology and chemistry disciplines. Several success stories of the applications of molecular techniques in the field of marine biology are guiding further research in this area. In this review different molecular techniques are discussed, which have application in marine microbiology, marine invertebrate biology, marine ecology, marine natural products, material sciences, fisheries, conservation and bio-invasion etc. In summary, if marine biologists and molecular biologists continue to work towards strong partnership during the next decade and recognize intellectual and technological advantages and benefits of such partnership, an exciting new frontier of marine molecular biology will emerge in the future.     

长江下游近口段近岸鱼类群落多样性及潮汐强度的影响

为了解长江下游近口段近岸鱼类群落多样性及其潮汐的影响,于2016—2017年在靖江样点、2017—2018年在常熟样点分别进行连续4个季度的鱼类调查,同步收集潮汐强度数据。结果表明:靖江样点共监测到鱼类61种,隶属于9目18科47属,鲢(Hypophthalmichthys molitrix)、刀鲚(Coilia nasus)、贝氏?(Hemiculter bleekeri)、草鱼(Ctenopharyngodon idellus)、鳙(Aristichthys nobilis)为主要优势种;常熟样点共监测到鱼类41种,隶属于8目14科34属,鲢、中国花鲈(Lateolabrax maculatus)、鳙、鳊(Parabramis pekinensis)和鲫(Carassius auratus)为主要优势种;靖江样点Margalef指数、Shannon指数和Simpson指数均大于常熟样点,Pielou指数则小于常熟样点; SIMPER分析表明,靖江和常熟样点周年群落组成平均相似度分别为64.5%和64.7%,样点间平均相异度为61.1%;不同季节各潮汐周期内鱼类群落多样性相关分析结果...     

A fourteen-year overview of the fish assemblages and yield of the two oldest Algarve artificial reefs (southern Portugal)

Artificial reefs have been deployed worldwide for the last three decades in response to problems concerning coastal resources, ecosystems and fisheries. In many countries they have became important elements of integrated fisheries management plans. In Portugal two artificial reef systems (ARSs) were deployed by the Portuguese Institute of Marine Research (IPIMAR) in 1990, in the southern coast (Algarve). They were located off Faro and Olhão, over different sea-bottom types and located at different distances from the coastline. To analyse the effect of ARSs deployment on local fish assemblages and to evaluate their effectiveness in terms of mean fishing yields and mean number of species caught, fishing surveys have been conducted over 14 years (256 net sets) using a gillnet to sample the ARS of Faro and Olhão and respective control sites. The fishing yields from the ARs continually exceeded those from the control sites, in both the mean number of species caught and the mean CPUE in weight (1.8–2.6 times); both were higher at Faro. Moreover, the comparison between fish assemblages from the ARS and respective control sites showed that the deployment of the man-made structures did not change the composition of the fish assemblages caught by the gill nets, or the equilibrium of the community, since the relative proportion of the different functional groups of fish remained stable. The ARSs are a useful management tool on the Algarve coast, enhancing and diversifying the catches, thus contributing to improved local artisanal fisheries, which play a major role in this region.     

长江宜昌段鲢的繁殖生物学特征

2014年3月至2016年9月在长江中下游宜昌江段共收集鲢(Hypophthalmichthys molitrix)样本433尾,进行繁殖生物学研究。该江段鲢的繁殖时间为每年的5月下旬至8月上旬,以6~7月为盛产期。繁殖群体体长310~927 mm,体重600~17 090 g,由3~7龄共5个年龄组组成,3龄群体数量上占绝对优势,占繁殖群体的45.2%。雌雄性比为1.43︰1,雌雄群体间体长-体重关系存在显著性差异(0.01P0.05)。采用Logistic方程推算出初次性成熟雌性个体体长为482.3 mm,体重为2 206.7 g;初次性成熟雄性个体体长为484.0 mm,体重1 677.5 g。卵径(1.01±0.12)mm,大小分布呈单峰型,为单批产卵型鱼类。绝对繁殖力(477 662±9 631)粒,相对繁殖力为(93.38±5.92)粒/g,绝对繁殖力随着鱼体长、体重增长而增大。与其他地理种群相比较,宜昌江段鲢总体表现为卵径相对较小而繁殖力较大。     

广西十万大山地区的鱼类资源现状和保护对策

位于广西西南部的十万大山地区鱼类物种多样性丰富,分布于十万大山的野生鱼类以小型或中小型为主,缺乏经济价值高,产量大的种类,这是该地区野生鱼类资源的主要特点,目前资源量和鱼类物种丰富度都呈现出明显下降的趋势。这主要同有害的渔业生产方式和过密的捕捞强度,小水利设施及外来种的入侵有关。加强宣传力度和强化渔政管理,开发其它副业,拆除废弃的小水利工程,对人工养殖鱼种加强管理,以及开展入侵种对土著种影响的科学研究等是保护这一地区鱼类多样性的重要手段。     

插网网目尺寸及采样时间对潮沟游泳动物采样的影响

在长江河口九段沙盐沼湿地的一条潮沟中,我们比较了两种不同网目尺寸（4mm和8mm）的插网（fyke net）及日夜潮对游泳动物群落采样效率的影响。共捕获鱼类16种5476尾、虾2种4982只。采用方差分析、柯尔莫诺夫-斯米尔诺夫非参数检验法和无度量多维标定分析对两种网目插网的捕获效率,样品的体长分布,群落结构及日夜潮间的差异进行了分析。结果表明,网目尺寸对样品中游泳动物的物种数和鱼类的多度没有影响,但是小网目的插网对虾类有较高的捕获率。两种网目尺寸的插网均在夜潮中捕获较多的鱼类个体,但虾类在日潮捕获较多。在日潮中,网目尺寸对捕获物中五种优势游泳动物的体长分布无显著影响。在夜间,小网目的插网对斑尾复缎虎和脊尾白虾的较大个体具有较高的捕获率,但对较大个体鲅的捕获率不如大网目的插网。样品中游泳动物的群落组成在日夜潮间存在明显差异,大网目捕获物的样本间差异比小网目小。     

The case in international law for Canada's extension of fisheries jurisdiction beyond 200 miles

In March 1995, Canadian fisheries authorities boarded and arrested the Spanish fishing vessel, Estai, outside the Canadian 200‐mile zone on the Grand Banks, an event that served to focus world attention on a dispute that had its origins in the failure of the 1982 United Nations Convention on the Law of the Sea to implement an effective conservation and management regime for fish stocks on the high seas, particularly with respect to fish stocks that straddle coastal states’ exclusive economic zones. This article examines the origins of the dispute, including the allegations relating to overfishing of North Atlantic Fisheries Organization‐recommended quotas, the background to the vessel's arrest, and the subsequent confrontation that occurred, both at diplomatic levels and on the high seas, between Canada and the European Union. An analysis is made of the case in international law for Canada's extension of jurisdiction beyond 200 miles pursuant to the provisions of Section 5 of the Coastal Fisheries Protection Act. Finally, the article examines the implications of the recently concluded Agreement on the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks for disputes of the kind that arose in the present case.     

《分子生物学》研究性教学初探

当前高等学校教学改革的一个重要特点在于倡导进行研究性教学,研究性教学成为现代教学理念的构成要素,它是对传统的传递式——被动接受式的教育理念的革新。这种教学模式有利于培养学生研究能力,提升教学的有效性。从理论教学、问题情境教学、实验教学、科研成果的引入等4个方面阐述在《分子生物学》教学中如何运用研究性教学模式,贯穿研究性教学理念,有效培养学生的研究能力。