环境生态学---第二十章 收获理论
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第十四页，共30页。
T2 渔业(yúyè)和捕鲸业
要点
渔业
大洋(dàyáng)生产 力
海洋一直为我们(wǒ men)人类提供丰富的食物资源。现在全球渔获量
约1亿吨，其中一小部分并不直接被人类消费，而是用做 动物饲料。
与陆地系统相比，大洋是生产力很低的生境。大陆架生产力 较高，但全球单位公顷渔获量很低，部分是因为大洋区极低 的生产力，部分是由于渔获物处于食物链高营养级，其生产 效率很低。
第八页，共30页。
配额(pèi é)限制
在一定时期，可通过控制配额（收获对象生物量或个体数 量），限制收获。配额控制允许收获者在每一季节或每年收 走一定数量的猎物。配额限制通常应用于海洋渔业来获得 MSY，但成功例不多。这表明配额限制实际上很冒险，有可 能导致(dǎozhì)过捕，甚至种群灭绝。
第九页，共30页。
Related topics
Populations and population
Density and density
structure (H1)
dependence (H3)
Natality, mortality and Population dynamics –fluctuations,
growth (H2)
相关(xiāngguān) 主题
种群(zhǒnɡ qún)和种群(zhǒnɡ qún)结构（H1）
密度和密
度制约（H3）出生率、死亡率和种群增长（H2） 种群动
态——波
动、周期和混沌（H4）
第十三页，共30页。
T2 FISHING AND WHALING
Key Notes
Fisheries
The seas have historically provided a valuable food source to human populations. The current global fish catch is about 100 million tons, although a substantial minority of this is not used for direct human consumption, but as an animal feed source.
第六页，共30页。
第七页，共30页。
Quota limitation
Harvesting may be limited by controlling the quota (the biomass or number of individuals culled ) in a given period. Quota controls thus allow the harvesters to remove a fixed number of the prey species every season or year. Quota limi-tataion is commonly applied in marine fisheries to achieve a MSY with limited success. The theory demonstrates that quota-limitation is intrinsically risky and may cause overexploitation and even extinction of the harvested populations.
第十页，共30页。
努力(nǔ lì)限制
配额限制潜在的危险或通过导入努力(nǔ lì)限制来缓和。努 力(nǔ lì)限制具有明显的优点。因为当猎物种群数量减少时， 人们往往会通过更加努力(nǔ lì)来获限正在减少中的数量。
环境(huánjìng)波 动
利用种群增长模型预测被收获种群可获潜能的效果会受到 环境波动的严重影响。因为环境波动会影响种群的出生率 或死亡率。
的最大量——MSY。
第三页，共30页。
• 最大持续产量是在最大限度的开发、利用可再生资源 的同时，注意保护资源系统以维持最高再生能力的原则。 即所谓“青山常在、永续利用”原则。 如果把生物及其环境(huánjìng)作为一个整体当成一项 资源看待，只要开发利用适当，这项资源可以不断自 我更新，持续的向人类提供所需要的产量。但是，如 果在一定的时间和空间内人类取用可再生资源过量， 就会破坏资源的再生能力，造成资源衰竭。
第四页，共30页。
• 最大持续产量是20世纪(shìjì)30年代以来在渔 捞管理业中占重要地位的原理,如对世界上 产量最高的海鱼(秘鲁鳀)和最大海兽(蓝鲸) 资源的管理就以其为依据。
第五页，共30页。
• 确定最大持续产量的方法很多,最基础的是 根据(gēnjù)种群S-型增长原理而建立的模型来 估计,最后确定最大持续产量为种群环境容 纳量的1/2。
cycles and chaos (H4)
第十二页，共30页。
动态(dòngtài)库 模型
简单的模型不考虑种群的年龄结构，这使其预测能力有限， 因为死亡率与繁殖力都是与年龄相关的。收获个体通常都 是种群中体大、年高的个休，具有最高的繁殖潜能。精确 地考虑到不同年龄群出生率、生长和死亡率的动态库模型 对对象种群的预测效果更好。举例来说，考虑到不同年龄 群的动态库模型意味着可理论上检测海洋渔业中使用不同 大小网具的影响效果。
Effort limitation
The risk inherent in quota-limitation can be alleviated by adopting an approach of limiting effort. This has a clear advantage- as a prey species becomes rarer, more effort will be required to seek out and catch the diminishing numbers.
第十一页，共30页。
Dynamic pool models
Simple models do not consider the age structure of populations, which limits their predictive power, as the mortality rates and reproductive output of individuals is age-specific. Usually, the individuals harvested are the larger and older members of the population, which have the highest reproductive potential. Dynamic pool models explicitly consider the recruitment, growth and mortality of different age classes, allowing a better model of the population to be derived. This approach means that, for example, the impact of varying mesh size in a marine fishery can be tested theoretically.
第二页，共30页。
最大持续(chíxù) 产量
长期收获最大产量的一种方法是最大持续产量即MSY法。随着种群
密度在很低的基础上开始增加，出生率超过死亡率，种群的 净补充量增加。当种群密度达到最大环境容纳量时，死亡率 上升(shàngshēng)，出生率下降。因此最大净补充量发生在中 等密ቤተ መጻሕፍቲ ባይዱ、种群中存在许多繁殖个体、而种内竞争又相对较弱 的情况下。这一最大净补充量即为人们可长期从种群中收获
Ocean productivity
The open oceans are very unproductive habitats compared to terrestrial systems. Productivity is higher on the continental shelves, but the overall global fish catch represents a very low yield per hectare. This is partly because of the very low productivity of most of the ocean area, and partly because the harvest consists on animals high up the food chain, which have low production efficiencies.
Environmental fluctuation
The ability of models of population growth to predict the harvesting potential of a population is esverely compromised by environmental variation which may affect recruitment or mortality.
T1 收获 理论 (shōuhuò)
要点
收获(shōuhuò)目 标
为了使种群开发(kāifā)获得最大回报，管理应以使对象种群可长 期持续获得最大产量为目标。
第一页，共30页。
Maximum sustainable yield
One approach to deduce the maximum long-term yield is known as the maximum sustainable yield, or MSY approach. As a population increases in density from very low numbers, the birth rate outstrips the death rate, so the net recruitment(births-deaths) into the population rises. As the population density approaches the maximum the environment can support, the death rate increases and the birth rate falls. The maximum net recruitment therefore occurs at an intermediate density, when intraspecific competition is relatively low yet there are many reproductive individuals in the population. This maximum net recruitment is the maximum number that can be harvested from the population sustainably – the MSY.
dynamicpoolmodelsrelatedtopicspopulationsandpopulationdensityanddensitystructureh1dependenceh3natalitymortalityandpopulationdynamicsfluctuationsgrowthh2cyclesandchaosh4相关主题种群和种群结构h1密度和密度制约h3出生率死亡率和种群增长h2种群动态波动周期和混沌h4动态库模型简单的模型不考虑种群的年龄结构这使其预测能力有限因为死亡率与繁殖力都是与年龄相关的
第十五页，共30页。
第十六页，共30页。
The’ tragedy of the commons’
The hypothesis of ’ the commons’ suggests that a commonly shared resource (such as open oceans outside the control of national governments ) will tend go be overexploited by selfish individuals. Such behavior makes impossible any management to maximize long term yields, and will lead to population crashes and extinctions.
T2 渔业(yúyè)和捕鲸业
要点
渔业
大洋(dàyáng)生产 力
海洋一直为我们(wǒ men)人类提供丰富的食物资源。现在全球渔获量
约1亿吨，其中一小部分并不直接被人类消费，而是用做 动物饲料。
与陆地系统相比，大洋是生产力很低的生境。大陆架生产力 较高，但全球单位公顷渔获量很低，部分是因为大洋区极低 的生产力，部分是由于渔获物处于食物链高营养级，其生产 效率很低。
第八页，共30页。
配额(pèi é)限制
在一定时期，可通过控制配额（收获对象生物量或个体数 量），限制收获。配额控制允许收获者在每一季节或每年收 走一定数量的猎物。配额限制通常应用于海洋渔业来获得 MSY，但成功例不多。这表明配额限制实际上很冒险，有可 能导致(dǎozhì)过捕，甚至种群灭绝。
第九页，共30页。
Related topics
Populations and population
Density and density
structure (H1)
dependence (H3)
Natality, mortality and Population dynamics –fluctuations,
growth (H2)
相关(xiāngguān) 主题
种群(zhǒnɡ qún)和种群(zhǒnɡ qún)结构（H1）
密度和密
度制约（H3）出生率、死亡率和种群增长（H2） 种群动
态——波
动、周期和混沌（H4）
第十三页，共30页。
T2 FISHING AND WHALING
Key Notes
Fisheries
The seas have historically provided a valuable food source to human populations. The current global fish catch is about 100 million tons, although a substantial minority of this is not used for direct human consumption, but as an animal feed source.
第六页，共30页。
第七页，共30页。
Quota limitation
Harvesting may be limited by controlling the quota (the biomass or number of individuals culled ) in a given period. Quota controls thus allow the harvesters to remove a fixed number of the prey species every season or year. Quota limi-tataion is commonly applied in marine fisheries to achieve a MSY with limited success. The theory demonstrates that quota-limitation is intrinsically risky and may cause overexploitation and even extinction of the harvested populations.
第十页，共30页。
努力(nǔ lì)限制
配额限制潜在的危险或通过导入努力(nǔ lì)限制来缓和。努 力(nǔ lì)限制具有明显的优点。因为当猎物种群数量减少时， 人们往往会通过更加努力(nǔ lì)来获限正在减少中的数量。
环境(huánjìng)波 动
利用种群增长模型预测被收获种群可获潜能的效果会受到 环境波动的严重影响。因为环境波动会影响种群的出生率 或死亡率。
的最大量——MSY。
第三页，共30页。
• 最大持续产量是在最大限度的开发、利用可再生资源 的同时，注意保护资源系统以维持最高再生能力的原则。 即所谓“青山常在、永续利用”原则。 如果把生物及其环境(huánjìng)作为一个整体当成一项 资源看待，只要开发利用适当，这项资源可以不断自 我更新，持续的向人类提供所需要的产量。但是，如 果在一定的时间和空间内人类取用可再生资源过量， 就会破坏资源的再生能力，造成资源衰竭。
第四页，共30页。
• 最大持续产量是20世纪(shìjì)30年代以来在渔 捞管理业中占重要地位的原理,如对世界上 产量最高的海鱼(秘鲁鳀)和最大海兽(蓝鲸) 资源的管理就以其为依据。
第五页，共30页。
• 确定最大持续产量的方法很多,最基础的是 根据(gēnjù)种群S-型增长原理而建立的模型来 估计,最后确定最大持续产量为种群环境容 纳量的1/2。
cycles and chaos (H4)
第十二页，共30页。
动态(dòngtài)库 模型
简单的模型不考虑种群的年龄结构，这使其预测能力有限， 因为死亡率与繁殖力都是与年龄相关的。收获个体通常都 是种群中体大、年高的个休，具有最高的繁殖潜能。精确 地考虑到不同年龄群出生率、生长和死亡率的动态库模型 对对象种群的预测效果更好。举例来说，考虑到不同年龄 群的动态库模型意味着可理论上检测海洋渔业中使用不同 大小网具的影响效果。
Effort limitation
The risk inherent in quota-limitation can be alleviated by adopting an approach of limiting effort. This has a clear advantage- as a prey species becomes rarer, more effort will be required to seek out and catch the diminishing numbers.
第十一页，共30页。
Dynamic pool models
Simple models do not consider the age structure of populations, which limits their predictive power, as the mortality rates and reproductive output of individuals is age-specific. Usually, the individuals harvested are the larger and older members of the population, which have the highest reproductive potential. Dynamic pool models explicitly consider the recruitment, growth and mortality of different age classes, allowing a better model of the population to be derived. This approach means that, for example, the impact of varying mesh size in a marine fishery can be tested theoretically.
第二页，共30页。
最大持续(chíxù) 产量
长期收获最大产量的一种方法是最大持续产量即MSY法。随着种群
密度在很低的基础上开始增加，出生率超过死亡率，种群的 净补充量增加。当种群密度达到最大环境容纳量时，死亡率 上升(shàngshēng)，出生率下降。因此最大净补充量发生在中 等密ቤተ መጻሕፍቲ ባይዱ、种群中存在许多繁殖个体、而种内竞争又相对较弱 的情况下。这一最大净补充量即为人们可长期从种群中收获
Ocean productivity
The open oceans are very unproductive habitats compared to terrestrial systems. Productivity is higher on the continental shelves, but the overall global fish catch represents a very low yield per hectare. This is partly because of the very low productivity of most of the ocean area, and partly because the harvest consists on animals high up the food chain, which have low production efficiencies.
Environmental fluctuation
The ability of models of population growth to predict the harvesting potential of a population is esverely compromised by environmental variation which may affect recruitment or mortality.
T1 收获 理论 (shōuhuò)
要点
收获(shōuhuò)目 标
为了使种群开发(kāifā)获得最大回报，管理应以使对象种群可长 期持续获得最大产量为目标。
第一页，共30页。
Maximum sustainable yield
One approach to deduce the maximum long-term yield is known as the maximum sustainable yield, or MSY approach. As a population increases in density from very low numbers, the birth rate outstrips the death rate, so the net recruitment(births-deaths) into the population rises. As the population density approaches the maximum the environment can support, the death rate increases and the birth rate falls. The maximum net recruitment therefore occurs at an intermediate density, when intraspecific competition is relatively low yet there are many reproductive individuals in the population. This maximum net recruitment is the maximum number that can be harvested from the population sustainably – the MSY.
dynamicpoolmodelsrelatedtopicspopulationsandpopulationdensityanddensitystructureh1dependenceh3natalitymortalityandpopulationdynamicsfluctuationsgrowthh2cyclesandchaosh4相关主题种群和种群结构h1密度和密度制约h3出生率死亡率和种群增长h2种群动态波动周期和混沌h4动态库模型简单的模型不考虑种群的年龄结构这使其预测能力有限因为死亡率与繁殖力都是与年龄相关的
第十五页，共30页。
第十六页，共30页。
The’ tragedy of the commons’
The hypothesis of ’ the commons’ suggests that a commonly shared resource (such as open oceans outside the control of national governments ) will tend go be overexploited by selfish individuals. Such behavior makes impossible any management to maximize long term yields, and will lead to population crashes and extinctions.