清除淤泥，发现鱼类产卵的砾石层，找到合适的鲑鱼种类来重建种群是一项艰巨的任务。
Removing the mud, uncovering gravel beds where fish spawn, and finding suitable salmon types to rebuild the population is a daunting task.
有些热带鱼类产卵繁殖。
Some tropical fish reproduce themselves [their kind by laying eggs].
发现鱼卵及仔鱼共43个种，并且珠江口区域全年都有鱼类产卵。
Eggs and larvae found a total of 43 kinds, and the Pearl River estuary region are fish spawning year.
许多海洋鱼类是在淡水河里产卵的。
它们为鱼类和贝类提供产卵场所和营养物。
They provide spawning grounds and nutrients for fish and shellfish.
这些深海生态系统为鱼类以及其他生物提供生存，产卵以及繁殖的场所，也保护他们免受强流以及猎食者的袭击。
These deep ecosystems provide shelter, spawning and breeding areas for fishes and other creatures, as well as protection from strong currents and predators.
一旦这种动物死亡，礁石结构将会受侵蚀，作为鱼类至关紧要的产卵及进食的重要场所也不复存在。
Once the animals die, the rocky structures erode, depriving fish of vital spawning and feeding grounds.
石油泄漏会威胁到红树林和产卵的鱼类
用大坝阻断河流使得鱼类无法逆流而上去产卵，同时淤泥无法顺流而下去肥沃土地。
Blocking a river with a dam also blocks the movement of fish upstream to spawn and the movement of silt downstream to fertilise fields.
有些渔场在产卵季节被封闭（例如，为了鳕鱼产卵）；另一些鱼类孵化的渔场是永久禁入的。
Some grounds are closed during the spawning season (eg, for cod); others—nursery areas—are permanently off limits.
这表明本海区的鱼类的主要产卵季节是春季和夏季。
It shows that the main spawning season is in spring and summer.
这些深海生态系统为鱼类和其它生物提供生存、产卵、繁殖的场所，俄保护它们免遭大海流和猎食者的侵袭。
These deep sea ecosystems provide shelter, spawning and breeding areas for fish and other creatures, as well as protection from strong currents and predators.
虽然作为淡水鱼类，三文鱼大部分时间都生活在海洋里，它们只在产卵期间回到淡水中，这种生活习性被称为溯河产卵。
Salmon spawn in fresh water, but in many cases, the fish spend most of their lives at sea, returning to the rivers only to reproduce. This lifecycle is described as anadromous.
测定分析鱼类生殖力、产卵期、繁殖群体的年龄结构及产卵类型。
The spawning times, absolute fecundities, age structures of breeding population, and spawning types of fish were also studied.
某些热带鱼类靠产卵进行繁殖。
企鹅食用鱼类，大部分时间都生活在南极洲水中，但是在陆地上产卵以及养育小企鹅。
Penguins eat fish, and spend much of their lives in Antarctic waters, but lay eggs and raise their young on land.
其次如果我们仅拿走了大鱼 这就意味着同龄鱼类中的小鱼同时在产卵时体格更小 更可能活到产卵的时候。
Second, if we only remove the largest fish, that means fish that are smallfor their age and thus smaller when they first reproduce-are more likely to live long enough to make babies.
其次如果我们仅拿走了大鱼 这就意味着同龄鱼类中的小鱼同时在产卵时体格更小 更可能活到产卵的时候。
Second, if we only remove the largest fish, that means fish that are smallfor their age and thus smaller when they first reproduce-are more likely to live long enough to make babies.
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