[揽瓜阁精读] 5. Cod Fish

合成大wo瓜

1 cod fish基本情况。cod数量下降，人类采取很多措施弥补，得到的数据显示cod可以在繁殖并再次扩大数量。
2 kf 认为对cod数量恢复的预测是错的，cod不仅不会恢复，数量还会更加少。
3-4 kf解释原因。原来的预测不全面，cod吃饲料鱼，饲料鱼吃cod卵和幼虫。所以cod数量一旦上升，就会有饲料鱼吃cod的卵。一旦减少cod的数量，饲料鱼数量上升，cod数量会更少
5 如今饲料鱼因为自身数量上升竞争而导致数量下降，因此cod有更多机会顺利生长

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Mark一下！               

echoooo3333

5 cod fish
1 1990s cod是捕食者（猛），其消失导致好多prey boom泛滥 恢复方法：禁止捕捞cod并让它lay egg rebuild
2 5-6年的预测不对，六年过后毫无进展还降了
3 why：食物网不对，互吃（引出forage）：****成年cod 吃forage，forage吃 cod的卵和larvae
4 check+confirm forage对cod恢复的影响【过度捕捞之前，控制forage就不会吃edd，但捕捞降低cod之后，boom】
5 cod恢复增长的key：forage。如果cod恢复到原来的数量，可以keep forage down

Voracious 贪吃的devour 吞噬Unmolest不受干扰的 languished未取得进展 overfish过度捕捞

ninaninanina

一个现象；一种鱼数量减少很多，prey数量增长。为了让cod恢复以往，禁止钓这种鱼。预测说只要让这个鱼不受干扰就能够恢复以前的数量。

预计说5-6年能恢复，但是预计却错了，并没有恢复。反而出现新现象：一些物种却恢复了

为什么呢？因为没有考虑到这整个食物链是怎么运作的。成年的cod可以吃掉一些prey比如forage fish,但是f鱼会吃掉codde 鱼仔。

在cod没有被过度垂钓之前，数量还多的时候。还能一只f鱼的生长。以至于不会有人来吃鱼仔，但是当cod减少，f鱼就增多了，也就吃掉了很多c的鱼仔，所以即使没有人类掉c鱼，这个鱼也很难恢复。

直到现在，这个团队才看到一些c的恢复。因为f数量太多，自己超出了自己能够承受的范围。所以c才得以恢复，因为鱼仔不会被吃掉，会成年。如果c恢复到以前，f的数量会被下降很多。这个生态系统真的很复杂

结构：一个现象+一个措施
措施没有达到预期效果
探索原因
得出结论

常用：
The tables were turned
With their disappearance came a boom in their prey
Kept the forage fish in check
Put a dent in the cod population 改变影响
Have exploded to such high numbers that they are outstripping their own food supply
Have much better chance to reach adulthood
Return to their former levels

小卡lethe

【论点说明型】C鱼快挂了→为了解决 搞了个数学模型 然后限制渔业→结果发现没用 还更拉垮了→发现是这个模型的基础片面了 整个食物链一循环就不好使→但发现光禁打渔 f也会兴风作浪→但C少了f食物少了f也少了 所以C回升了→之后可能还会发生更多有意思的事儿
①        Key words: collapsed   ban cod fishing
【引出现象：Cod灭绝】Cod fish衰落→【进一步的结果】Cf捕食疯狂 数量衰减导致猎物疯涨(including小举例) →【寻找复生之法】限制甚至废除渔业→【解释原因-数学模型】如果不受干扰 会产蛋 迅速生长
②        Key words: wrong    no sign of recovery   languished
【However复生之法的后续】五六年 结果没用 没重回生机→【Instead更拉垮】没起色 更少了
③        Key words: food web
【找出拉垮原因】一开始预测的基础是C繁衍多快而非整个食物网→【进一步解释食物链循环】C吃c/s和其他鱼 这些鱼吃浮游动物 浮游又吃C的蛋和幼崽
④        Key words: unable to rebound
【其他无法复苏的原因】在cod过度捕捞前 捞走f小鱼 避免他们对于C鱼群体复苏的干扰→【进一步细化-反面情况-加强】开始捕捞 f小鱼暴增 吃C小鱼 没人打渔C也没法复活了
⑤        Key words: risen   complex
【延迟复苏的原因】降到1%时候回弹到30%→C太少 f小鱼崩溃→f小鱼减少  C的蛋和幼崽繁衍生长→【未来预测】能重回原先的数量 f小鱼数量会再↓→【留有余地】生态系统复杂 未来充满惊喜

Rhythmicic

dd

iririlua

Main Point: explains the missing link of an inaccurate prediction by presenting new information and logical connection

Structure:
Problem at hand: cod population collapse and the need to recover (P1)
Original Belief and Prediction:

• Belief: limiting fishing will naturally help the cod population recover (P1 last sentence)
• Prediction: 5-6 years the population will recover (P2 KF)
  

Prediction was incorrect: only considered production rate and did not factor in the whole food web (P3)
Missing Link: cod eats forage fish, which eats zooplanktons and eggs / larvae of cod. The high growth of forage fish cause more cod eggs and larvae being consumed. (P4)
Into the future: cod population has been rising (from 1% pre-collaspe level to 30%) mainly due to the lack of food supply for forage fish population given its previous fast growth. (P5)

XX829412

        • Cod fishe : collapsed in 1990
                ○ Boom in Prey: sprats,cepelin, lobster and crab
                ○ Strict limit on cod fishing
                ○ Prediction: rebuild in 5-6 years
                        § However: languished
                        § Why
                                □ Cod fish ↓→forager fish↑ →eggs and larvar of cod↓
                ○ Delayed recovery:1% →30%
                        § Forage fish : crash
                        § Cod eggs and larvae: reach adulthood

苏二在努力

P1 intro of cod fishers
in NA, cod fisheries collapsed
Voracious predator, prey eg. Sprates, capelins, young lobster, and snow crabs
To allow cod to recover, managers put strict limits on the cod fisheries or even banned
Mathematical model=>if the fish were left unmolested, the population recover

P2 predictions were wrong
KF: predication of the recovery 5-6 years
However, the prediction was wrong. After six years, no signal of recovery.
Instead, the population languished a few percent

P3 KF figured out the reason
Initial estimate: how fast cod reproduce, not on how the whole web is organized
Adult cod fed on sprats, capelins, and forage fish; forge fish eat eggs and larvae of cod

P4 explanation of reason
Before cod overfished: cod kept forage fish in check => small fish can not enough eggs and larvae to reduce cod population
Human lowers population of cod => tables turned
Forage fish boom => eat a substantial fraction of eggs and larvae
Even without human fishing, cod could not rebound

P5 KF sees the sign of delayed recovery
After falling to 1% of pre-crash level, cod rose to 30%
Key: KF said, forage fish exploded to such high numbers that outstripped their own food supply
Population of forage fish dropped=>larvae of cod better chance to reach adulthood
If cod return to their former level, they will able to keep the populations of their forage fish down once more
KF: that’s the trajectory, ecosystem is complex