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1.
渔获物平均营养级在渔业可持续性评价中的应用研究进展 总被引：1，自引：0，他引：1
高强度的捕捞努力量和渔业管理不力等因素导致全球范围内传统渔业资源的衰退,近年来渔获物平均营养级(MTL,mean trophic level)作为以生态系统为基础的渔业管理评价指标被普遍应用。本文在广泛收集国内外相关文献资料基础上,系统地介绍了MTL在渔业资源评价中的研究进展。已有研究显示,MTL能够利用已知渔获数据来分析,且参数化较为简便,在评价渔业可持续性中优势明显。受以渔获量作为生态系统指标、营养级(TL,trophic level)随体长的变化、渔获统计数据质量、低TL种类的过多捕捞和海域环境富营养化等因素的影响,在评估渔业资源利用状况时,需将MTL与剔除TL小于3.25物种下的3.25MTL、渔业均衡指数(FIB)等营养指标综合分析。此外,综合运用多指标,将营养指标与渔获组成、中上层鱼类与底层鱼类产量的比值、市场价格等指标结合分析,有助于掌握引起MTL变动的因素,更加全面地掌握捕捞活动下鱼类群落结构的实际变化状况。 相似文献
2.
Are the exploitation pressures on the Nile perch fisheries resources of Lake Victoria a cause for concern? 总被引：2，自引：0，他引：2
T. MATSUISHI L. MUHOOZI O. MKUMBO & Y. BUDEBA M. NJIRU A. ASILA & A. OTHINA I. G. COWX 《Fisheries Management and Ecology》2006,13(1):53-71
Abstract Lake Victoria is one of the African Great Lakes, and an important source of affordable protein food in the form of fish. It provides employment, income, and export earnings to the riparian communities. Despite this importance there are major concerns about the status and exploitation of the fisheries. This study assesses if current extraction rates/yield of Nile perch, Lates niloticus (L.), from Lake Victoria are sustainable for the foreseeable future. The paper reviews trends in catch and effort in the Nile perch fishery and models the expected scenarios using ECOPATH. The fishery exhibits, classic indicators of intensive fishing, erring towards overexploitation, including: (i) decline in total estimated catch of Nile perch in recent years from the peaks in the 1990s. This is coupled with a shift in contribution of catches from higher trophic level species (Nile perch) to lower trophic level (dagaa) species. (ii) Three major trends in the fishing effort are evident: (a) almost doubling of the number of fishers and fishing boats between 1990 and 2000, and the even greater expansion between 2000 and 2002; (b) a large scale increase in the number of gears operational in the lake; and (c) the propensity for use of ‘illegal’ gears. (iii) Catch‐per‐unit‐effort has declined from about 80 to 45 kg per boat day. (iv) Predictive modelling (ECOSIM) of the future of the Nile perch fisheries under a scenario of increased fishing effort suggests that the fisheries are unsustainable and will decline in the long term. It appears that the Nile perch stocks in the three riparian countries are under intense fishing pressure, and unless concerted action is taken, the potential for degradation of the resources is prevalent. In view of the importance of these fisheries, it is recommended that a precautionary approach to further intens‐ification of the fisheries is adopted until such time empirical evidence shows that the fisheries are capable of further expansion and intensification. The main options for management are devolvement of responsibilities for the fisheries to the communities, enforcement of existing regulations, improved monitoring and data collection processes, reducing post‐harvest losses and increasing the value of the products to the export market. 相似文献
3.
Abstract. Over the period 1966–1983 angling catches from the Penrhyncoch trout, Salmo trutta L., lakes in mid-Wales showed a steady decline while catches from the nearby Trisant lakes steadily increased. By the early-mid 1970s some of the Penrhyncoch lakes had ceased to exist as viable fisheries. The declining catches from many of the Penrhyncoch lakes appeared to be attributable to the recent acidification of the lakes which has led to a severe decline in the size of the native trout population and a high mortality among stocked hatchery-reared trout, Salmo trutta L. The increase in catches from the Trisant lakes appears to be due to a shift in angling pressure but the relatively high catches are a real reflection of high trout population densities in lakes unaffected by acidification. The average annual angling catch from the Penrhyncoch and Trisant lakes over 1966–1983 was 1·2 and 6·7 kg ha?l respectively. Catches per unit area from the Trisant lakes compare favourably with other much larger upland reservoirs. 相似文献
4.
The carrying capacity of marine shelf ecosystems in southern Brazil for harvestable species is analyzed by (1) quantifying the amount of available primary production appropriated by fisheries catches, (2) evaluating the trend in the mean trophic level of fisheries, and (3) simulating the ecosystem effects of “fishing down the food web” in an intensively exploited shelf region. Fisheries utilize ca. 27 and 53% of total primary production in the southern and south-eastern shelf regions, respectively. Regional variation in the carrying capacity appropriated by fisheries results from differences in the primary production, catch volume and trophic transfer efficiencies. Overall, fisheries landings do not display a trend of decreasing trophic level with time due to the collapse of the sardine fishery and the recent increasing of offshore fishing for higher trophic level species, mainly tunas and sharks. However, the simulations show that fishing down the food web through fisheries that target small pelagic planktivorous fishes, while at first increasing catches in intensively exploited regions, has the potential of decreasing yields, by interrupting major energy pathways to exploited, high-trophic level species. The consequences of these results to the design of precautionary measures for future fishing policies are discussed. 相似文献
5.
Hui Zhang Myounghee Kang Li Shen Jinming Wu Junyi Li Hao Du Chengyou Wang Haile Yang Qiong Zhou Zhigang Liu Harry Gorfine Qiwei Wei 《Fish and Fisheries》2020,21(3):601-620
Freshwater capture fisheries are globally essential for food security and aquatic biodiversity conservation. The Yangtze River Basin is the third longest and one of the most human‐influenced drainage basins worldwide. Since the founding of P. R. China in 1949, this large river system has suffered increasing human perturbation and its sustainable development is now severely challenged. Meta‐analysis showed that Yangtze River fisheries have experienced an extraordinary process of utilization–over‐exploitation–protection during the past 70 years, to an extent that other globally important rivers may never have encountered. Its fisheries appear to have collapsed over the past four decades, with yield decreasing to only 25% of an historical peak of 400,000 metric tonnes in the late 1950s. Endemic, migratory and rare fishes have been highly threatened with obvious changes in fish community structure and aquatic biodiversity. Anthropogenic activities, including impoundment of water in dams, discharge of pollutants and riverine modification for vessel navigation, have caused large decreases in fisheries yields. Projections from surplus production modelling showed potential for improvement under fishing ban scenarios, but without any prospect for full recovery to historical stock status. This study revealed that the change in fisheries resources was dominated by the social–ecological watershed system, and an integrated approach to river basin management is warranted. Better management of freshwater ecosystems to integrate food security with biodiversity conservation is urgently needed throughout the world, and the changes evident in the Yangtze River fish populations can serve as an informative global reference. 相似文献
6.
Olaf L.F. Weyl 《水产资源保护:海洋与淡水生态系统》2008,18(6):839-851
- 1. Lake Chicamba, Mozambique (19°08′S; 33°08′E) is a large (116 km2) impoundment in the headwaters of the Buzi River system, which was invaded by Oreochromis niloticus in 1996 from a small (<0.3 km2) upstream reservoir.
- 2. Experimental and artisanal catch data showed no O. niloticus until January 1996; after this O. niloticus was recorded in up to 83% of experimental seine net catches, 33% of experimental gill net catches, 43% of boat angling and 23% of shore angling catches, and in 48% of artisanal gill net catches.
- 3. During the period January to March 1997, O. niloticus mean (upper, lower 95% confidence interval) yields in the artisanal fishery were 5.2 (3.6, 7.0) t month?1.
- 4. The rapid invasion of this lake illustrates the significant invasion threat that small point‐sources of this species pose to southern African freshwater systems.
- 5. The study recommends: (1) that this species should not be used for aquaculture or fisheries enhancement in catchments that have not been invaded, and (2) that the eradication of potential point sources of O. niloticus in non‐invaded catchment systems should be considered.
7.
This study documented the history of lake fisheries in Kashmir, India, and estimated the trends in fish production using Kane's cross impact analysis (CIA) and stakeholders’ willingness to pay (WTP) for the restoration of the Schizothorax fisheries. Kane's CIA model for Lake Dal indicated a perceptible drop in Schizothorax production in the long run, and that the total catch is being maintained by an increasing contribution by carp. In Lake Wular, the CIA indicated that the size of the lake still offers scope for the co‐existence and growth of both Schizothorax as well as carp. A Classification and Regression Tree (CART) model was used to data mine multiple stakeholder responses to make a case for sustainable development of the Schizothorax fisheries in the lakes of Kashmir. The amount of time spent on the lakes to earn their livelihoods emerged as the single most important variable that determined WTP by stakeholders followed by income, type of stakeholder and age. The pruned tree gave the hierarchy of the variables that determined WTP. The results made a strong case for a concerted multi‐institutional action plan for the restoration of the Schizothorax fisheries in the lakes of Kashmir. 相似文献
8.
Abstract Artisanal fisheries are important socially, nutritionally and economically. Poverty is common in communities dependent on such fisheries, making sustainable management difficult. Poverty based on material style of life (MSL) was assessed, livelihoods surveyed and the relationship between these factors and fishery data collected using a fish landing study were examined. Species richness, diversity, size and mean trophic level of catches were determined for six fishing gears in an artisanal fishery in south-west Madagascar. There was little livelihood diversification and respondents were highly dependent on the fishery. No relationship was found between poverty and gear use. This suggests that poverty does not have a major impact on the nature of the fishery; however, this study was dominated by poor households, so it remains possible that communities with more variation in wealth might show differences in fishing methods according to this parameter. The fishery was heavily exploited with a predominance of small fish in the catches. Beach seines caught some of the smallest fish, overlapped in selectivity with gill nets and also had the highest catch per fishers. Thus, a reduction in the number of beach seines could help reduce the catch of small fish and the overlap in selectivity among gears. 相似文献
9.
东海带鱼渔获量变动原因分析 总被引：4，自引：0，他引：4
利用1951~1984年东海带鱼年渔获量和捕捞努力量资料,以及降雨、风速和海表温度等的时间系列,分析了带鱼渔获量年际变化与捕捞努力量及环境因素的关系,并建立了渔获量对捕捞努力量和环境变量的回归模型。带鱼渔获量随捕捞努力量的变化可用Fox模型拟合(R=0·89,P<0·01),1951~1974年期间,渔获量随着捕捞努力量的增长而不断提高,但自1974年后,随着捕捞努力量的持续增长,渔获量开始下降。排除捕捞效应后的带鱼渔获量波动还与环境因素显著相关,分析结果表明,长江流域和东海沿岸地区年降水量、渤海海域年均风速、长江口年均风速、黄海和东海海表温度(2月)、东海中部年平均海表温度及南部冬季月平均海表温度等环境因子都与之显著相关。包含捕捞努力量和环境变量的渔获量模型的回归系数为0·97,其置信水平达到99%以上。运用1951~1984年的回归模型对1985和1986年的渔获量作出了预测,其预测值与实际渔获量的相对误差均小于5%,验证了其可靠性。研究的结果表明,带鱼渔获量变动不仅与捕捞作用有关,同时还受环境因素的影响,是两者综合作用的结果。 相似文献
10.
Inland waters support the livelihoods of up to 820 million people and provide fisheries that make an essential contribution towards food security, particularly in the developing world where 90% of inland fisheries catch is consumed. Despite their importance, inland fisheries are overlooked in favour of other water use sectors deemed more economically important. Inland fisheries are also driven by external factors such as climate change and habitat loss, which impedes our ability to manage them sustainably. Using a river basin approach to allocate fish catch, we have provided an integrated picture of how different inland water bodies contribute to global inland fisheries catches. There is a substantial amount of information available on inland fisheries, but it has never been synthesised to build this global picture. Fishery statistics from river basins, lakes, floodplains, hydrobasins, and countries covering a time span from 1960–2018 were analysed. Collation of basin-scale fisheries statistics suggests a global inland catch of ≈17.4 million tonnes (PSE = ±3.93 million tonnes) in 2010, considerably more than the 10.8 million tonnes published by the United Nations Food and Agriculture Organization (FAO), but in line with estimates based on household consumption. The figure is considered a likely maximum due to recent reductions in catches because of closures, threats, and fisheries declines in the most productive fisheries. It is recommended that sentinel fisheries, which are important for food provision, employment, or where threats facing a fishery could cause a deterioration in catch, are identified to provide the baseline for a global monitoring programme. 相似文献
11.
基于Ecopath模型的长江口及毗邻水域生态系统结构和能量流动研究 总被引：7，自引：2，他引：5
根据2000年和2006年秋季长江口及毗邻水域渔业资源和生态环境调查数据,利用Ecopath with Ecosim软件,构建2个时期的长江口及毗邻水域生态能量通道模型,比较分析了三峡工程蓄水前后长江口及毗邻水域生态系统的结构和能量流动特征.模型包含鱼类、虾类、蟹类、头足类、浮游动物、浮游植物、底栖动物、碎屑等17个功能群,基本覆盖了能量流动的途径.分析结果表明,2006年秋季长江口及毗邻水域生态系统的总生物量、系统总流量比2000年秋季有所下降,碎屑链的重要性略有降低;由于低营养级层次渔获物数量的增加,渔获物平均营养级有所下降.2个时期长江口及毗邻水域生态系统的再循环率较低,仍有较高的剩余生产量有待利用,均处于不成熟的发育期. 相似文献
12.
Bin‐Song Jin Kirk O. Winemiller Bo Shao Ji‐Ke Si Jie‐Feng Jin Gang Ge 《Fisheries Management and Ecology》2019,26(2):131-140
The Yangtze River and its watershed have undergone vast changes resulting from centuries of human impacts, yet ecological knowledge of the system is limited. The seasonal variation and spatial variation of three sub‐lakes of Poyang Lake, a huge wetland in the middle Yangtze Basin, were investigated to examine how fish assemblages respond to seasonal hydrology and associated environmental conditions. In all three sub‐lakes, fish assemblage structure revealed strong variations associated with seasonal water level fluctuation. Fish species richness in all sub‐lakes was highest during the middle of the monsoon season and lowest during the dry season. Fish numerical abundance and biomass varied significantly, with several of the most common species having inconsistent patterns of seasonal variation among sub‐lakes. Fish assemblage structure was significantly associated with environmental gradients defined by water level, aquatic macrophyte coverage, conductivity and dissolved oxygen concentration. Assemblage composition in all three sub‐lakes underwent strongest shifts between December and April, the period when water levels were lowest and fishing has the greatest impact on fish stocks. Future impacts that change the hydrology of the middle Yangtze would alter the dynamics of habitat connectivity and affect environmental conditions and fish assemblages of the Poyang Lake wetland system. 相似文献
13.
G. De Graaf 《Fisheries Management and Ecology》2003,10(3):191-199
Floodplain fisheries were monitored from 1992 until 2000 in the Compartmentalization Pilot Project in Tangail, Bangladesh. In permanent floodplains about 165 ± 28 kg ha?1 of fish was caught annually. For seasonal floodplains, this figure was 83 ± 23 kg ha?1 yr?1. The fish catch exhibited a strong seasonal variation, with the highest catch in October, when the floodwater recedes towards the river, and the lowest catch during the dry season in April/May. The annual catch varied with the extent of flooding, with high catches in wet years and low catches in dry years. The extent of flooding was quantified through a Flood Index. Plotting the annual yields against this Flood Index provided a significant relation (P < 0.05), confirming the existence of a flood pulse. The fishing effort (f) and the catch‐per‐unit‐effort (CPUE) were significantly related (P < 0.05), whereby the fishing effort increased with increasing CPUE. The results are discussed within the frame of fisheries management in Bangladesh and highlight the need for long‐term data for proper evaluation of fisheries projects and the development of management schemes, and the difficulty of applying standard surplus production models in floodplain fisheries. 相似文献
14.
Leonardo Maia Durante Michael Peter Beentjes Stephen Richard Wing 《Fish and Fisheries》2020,21(4):813-830
New Zealand has led the world in restoration of marine fisheries since the introduction of the Quota Management System in 1986, but challenges remain in minimizing the ecosystem‐level effects of industrialized fishing. We analysed existing long‐term fisheries data sets from 1931 to 2015 in New Zealand to resolve trends in important ecological properties of major exploited fish communities. Increases in community dissimilarities of catch composition in 1931 and 1972, followed by increasing total landings, highlight major expansions of fishing grounds and exploited species during these periods. Mirroring global patterns, the remarkable rise in fishing power, demand and generation of new markets in New Zealand have all contributed to this expansion. Marine Trophic Indices (MTIs) of landings have decreased together with total catch after the year 2000, reflecting smaller catches with a higher composition of lower trophic‐level species in recent years. Differences in relative abundance of species estimated between fisheries‐dependent and fisheries‐independent data were observed, where high‐value species displayed better agreement in relative abundance between data sets. Despite being under a Quota Management System, temporal development of MTI values relative to the timing of industrial expansion of fisheries was remarkably similar to those observed in the North Sea and Brazil, with a single expansion and decline. MTI values presented better long‐term stability in the US fisheries analysed. Analysis of long‐term data and the development of well‐resolved ecological baselines will be the first step towards applying EBM to New Zealand fisheries, in keeping with global trends in fisheries management. 相似文献
15.
K. A. Young 《Fisheries Management and Ecology》2013,20(5):434-444
The debate over Atlantic salmon, Salmo salar L., stocking in Britain centres on the trade‐off between enhancing rod fisheries and harming wild populations. This article informs the debate by quantifying the relationship between stocking and angler catch statistics for 62 rivers over 15 years. After controlling for environmental factors affecting adult abundance, the 42 rivers with stocking had non‐significantly lower mean catch statistics than the 20 rivers without stocking. This difference increased with the age of stocked fish. Among stocked rivers, weak relationships between mean stocking effort and catch statistics also became more negative with the age of stocked fish. For stocked rivers, there was no evidence for a generally positive relationship between annual stocking efforts and catch statistics. Those rivers for which stocking appeared to improve annual rod catches tended to have lower than expected mean rod catches. The results suggest the damage inflicted on wild salmon populations by stocking is not balanced by detectable benefits to rod fisheries. 相似文献
16.
Between 1991 and 2000, angling associations on the tributaries of the River Hvítá leased net fishery rights in the Hvítá mainstem, with the aim of eliminating net fishery harvest and improving the rod catch. The rod catch and net catch in the Hvítá system were significantly correlated (r = 0.94; P < 0.001) over the 10‐year period prior to (1981–1990) closure of the net fishery. The rod fishery in the tributaries of the River Hvítá was also significantly correlated to the rod fishery in selected groups of rivers in west (r = 0.80; P < 0.01) and north (r = 0.73; P < 0.05) before the closure. Significant increases (P < 0.01) were observed in rod catches in the Hvítá tributaries between 1991 and 2000 after the closure, while rod catches in control regions decreased. Based on evaluation of rod catch trends before and after the closure, it was estimated that the net fishery lease increased rod catches in the tributaries between 1773 and 2175 fish (28–35%). The increase in rod catches also suggested that the rod fishery may be taking 39–52% of the estimated previous net catch. The high price paid annually for the net fishery lease just to eliminate net fishing (€135 000) reflects the high value of rod caught salmon compared with salmon caught by the net fishery. 相似文献
17.
Gear-based management of a tropical artisanal fishery based on species selectivity and capture size 总被引：3，自引：0，他引：3
The population density, species composition and lengths of fish landed by artisanal fishermen using six types of gear: large and small traps, gill nets, hand lines, spears and beach seines were studied in the multi‐species fishery of southern Kenya. Selectivity and catch composition among gears were determined by studying the species richness, diversity, size and mean trophic level of the catches for each gear type, to develop gear‐based management recommendations for this artisanal reef lagoon fishery. One hundred and sixty‐three reef and reef‐associated species from 37 families were recorded in the catch. Beach seines and small traps accounted for the highest number of fish landed (34–35 individuals per fisherman per day). These gears also caught smaller fish than big traps, spears and gill nets. Beach seines caught the highest number of species (14 ± 7 species per day) while most other gears caught four to five species per day with no differences between gears. Predatory species with a mean trophic level of 3.6 dominated catches from hand lines, while the mean trophic level of the other gears was low and ranged from 2.6 to 2.9 with no differences between the gears. The high diversity and small size of fish caught in beach seines indicates that its selectivity overlapped most with large traps and gill nets. Spears and small traps also showed high similarity in species selectivity and small traps captured the smaller mean size of fish, indicating that they are likely to pre‐empt the resource of spears. Large traps, hand lines and spears catch the largest individuals and the species composition of the catch differed sufficiently such that their selectivity should overlap the least and may, therefore, be the preferred mix of gears. The elimination or reduction of beach seines and small traps should reduce the catch of small fish and overlap in selectivity among the existing gears. 相似文献
18.
肖四海湖五种渔具的鳜渔获结构特征及其对鳜资源的影响 总被引：1，自引：1，他引：0
为评估不同渔具对鳜资源的影响,于2007年5月和12月对长江中游浅水湖泊肖四海湖刺网、延绳钓、网簖、电拖网和电捕仪5种渔具捕获的鳜渔获物结构特征进行了调查分析.结果发现,共采集鳜样本359尾,全长分布范围为92 ～600 mm,优势全长集中于251～350 mm;体质量分布范围为10～3 380 g,优势体质量集中于300 ～500 g.种群由5个年龄组构成,2～3龄为优势龄组,占总数的74.6％.刺网、延绳钓和网簖对鳜有较强的捕捞选择性,网目大小为80 mm和100 mm刺网的鳜渔获物中2龄及以上成熟个体占总数的93.3％,个体平均体质量466 g,“标鳜”(0.4 ～0.75 kg)个体占总数量的57.0％;延绳钓捕获的鳜渔获物中2龄及以上成熟个体占总数的86.9％,“标鳜”个体占总数量的43.5％;网簖捕获的鳜渔获物中90％以上为1龄的未成熟个体.电拖网和电捕仪捕获的鳜全长范围明显较大,其渔获物以1龄和2龄个体为主.综合分析表明,刺网适于作为鳜捕捞的主要渔具,延绳钓可以作为一种鳜捕捞的辅助渔具.网簖对鳜补充群体有较大危害,不适于作为鳜的捕捞网具.电拖网和电捕仪均属于违法渔具,对鳜资源危害巨大,应该加大监管力度,严禁使用. 相似文献
19.
N. G. Willoughby 《Aquaculture Research》1979,10(4):159-168
The subsistence and commercial fisheries of African rivers, floodplains and lakes are described in general terms. The problems in the management of these fisheries are thought to be more similar to those of the marine than the freshwater fisheries of Europe. Some of the problems peculiar to fisheries management in developing countries are discussed, including the difficulty of collecting reliable statistics and the unsuitability of many stock assessment models. The self-regulatory mechanisms in traditional fisheries are described briefly. The possibilities of discovering new fish stocks in swamps and lakes are considered, and the problems of licensing systems to maintain optimum yields discussed. Traditional and introduced methods of processing catches are described, and the future for African freshwater fisheries considered. 相似文献
20.
Wasted fishery resources: discarded by-catch in the USA 总被引：1，自引：0，他引：1
Fishery by‐catch, especially discarded by‐catch, is a serious problem in the world's oceans. Not only are the stocks of discarded species affected, but entire trophic webs and habitats may be disrupted at the ecosystem level. This paper reviews discarding in the marine fisheries of the USA; however, the type, diversity and regulatory mechanisms of the fisheries are similar to developed fisheries and management programmes throughout the world. We have compiled current estimates of discarded by‐catch for each major marine fishery in the USA using estimates from existing literature, both published and unpublished. We did not re‐estimate discards or discard rates from raw data, nor did we include data on protected species (turtles, mammals and birds) and so this study covers discarded by‐catch of finfish and fishable invertebrates. For some fisheries, additional calculations were required to transform number data into weight data, and typically length and weight composition data were used. Specific data for each fishery are referenced in Harrington et al. (Wasted Resources: Bycatch and discards in US Fisheries, Oceana, Washington, DC, 2005). Overall, our compiled estimates are that 1.06 million tonnes of fish were discarded and 3.7 million tonnes of fish were landed in USA marine fisheries in 2002. This amounts to a nationwide discard to landings ratio of 0.28, amongst the highest in the world. Regionally, the southeast had the largest discard to landings ratio (0.59), followed closely by the highly migratory species fisheries (0.52) and the northeast fisheries (0.49). The Alaskan and west coast fisheries had the lowest ratios (0.12 and 0.15 respectively). Shrimp fisheries in the southeast were the major contributors to the high discard rate in that region, with discard ratios of 4.56 (Gulf of Mexico) and 2.95 (South Atlantic). By‐catch and discarding is a major component of the impact of fisheries on marine ecosystems. There have been substantial efforts to reduce by‐catch in some fisheries, but broadly based programmes covering all fisheries are needed within the USA and around the world. In response to international agreements to improve fishery management, by‐catch and discard reduction must become a regular part of fishery management planning. 相似文献