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Catch-and-release fishing is supposed to be the best of both worlds: The anglers get the joy of a day spent on the water,
捕放式钓鱼法本应该是一种两全其美的方法：垂钓者在水上享受了一天的快乐，
and the fish gets to live another day. But sometimes, a hook will damage a fish's gills or esophagus and cause severe or even fatal bleeding.
而鱼又活了一天。但有时，鱼钩会伤害鱼的鳃或食道，导致严重甚至致命的出血。
For years, catch-and-release anglers have claimed that there's a straightforward solution to this:
多年来，捕放式垂钓者都声称，有一种简单的解决办法：
Just pour some soda on the fish to stop the bleeding and save its life.
只需要往鱼身上倒一些苏打水就能止血，拯救它的生命。
The idea was that the carbon dioxide in sodas constricted the blood vessels in the gills, thus stopping the bleeding.
这种方法认为，苏打水中的二氧化碳能够收缩鱼鳃中的血管，以到达止血效果。
But some biologists thought the idea sounded a little bit fishy. In a 2020 study, they decided to test this claim and figure things out for real.
但一些生物学家认为，这种想法听起来有点可疑。在2020年的一项研究中，他们决定对这种说法进行测试，把事情弄清楚。
In their study, the researchers got to do what I'm sure they spent all of grad school dreaming about:
在他们的研究中，研究人员做了他们在研究生院中一直梦想的事情：
They poured soda on bleeding fish. They tested Coca-Cola, Mountain Dew, and carbonated lake water and compared that to no treatment.
他们将苏打倒在了流血的鱼身上。他们用可乐、山露汽水以及含有二氧化碳的湖水，并将之与没有添加的湖水进行比较。
Alas, none of the drinks reduced the duration or intensity of bleeding. Technically, this study is a preprint,
没有一种饮料能减少出血的持续时间或强度。严格来讲，这项研究还只是预印本，
so it hasn't gone through the peer-review process yet, and corrections could turn up.
所以还没有进行同行评议，并且可能会有修正。
But at this point, it does seem to effectively debunk this idea. That said!
但在这一点上，它似乎有效地揭穿了这种想法。
In this process, the researchers did find clues about why so many people think this strategy works.
在这项过程中，研究人员确实发现了为什么这么多人认为这种方法有效的线索。
They noticed that while bleeding wasn't reduced overall, it would slow down for about 30 seconds.
他们注意到虽然总体上出血没有减少，但出血速度减慢了30秒左右。
Which might be as much time as an angler spends with their catch.
这可能是垂钓者花在鱼获上的时间。
Researchers think this happens because the carbon dioxide in the drinks causes bradycardia, or a very slow heart rate.
研究人员认为发生这种情况是因为，饮料中的二氧化碳导致心动过缓，即心率变得非常慢。
And if the heart slows down, blood is pumping more slowly through a fish's body, so it won't bleed as much.
如果心率减慢，鱼体内的血液流动就会变慢，所以它就不会流血太多。
At least, until its heart rate goes back up again. Now, heart rate wasn't specifically looked at in this study,
至少，直到它的心率再次回升前是这样，这项研究并没有特别关注心率，
but several previous papers have shown that when fish were briefly exposed to water with high CO2 levels, they had a substantial drop in heart rate.
但一些之前的论文已经表明，当鱼短暂暴露与高二氧化碳含量的水中时，它们的心率会大幅下降。
So there is support for this idea. Researchers think this drop is triggered by sensitive chemical receptors in the fish's gills.
所以这支持了这种观点。研究人员认为，是鱼鳃中的敏感的化学受体触发了这种心率下降。
That's based on things like how, when you sever the nerve that allows the gills to communicate with the rest of the body,
这种想法是基于，当你切断让鱼鳃和身体其余部分沟通的神经时，
fish no longer have this response to elevated CO2. But even though the how is clear, the why is another story.
鱼不再对高浓度二氧化碳有这种反应。但即便我们清楚这种情况如何产生，但却不知道为什么产生。
Despite decades of research, scientists still haven't conclusively demonstrated why this happens.
虽然进行了几十年的研究，但科学家们还没有最终证明为什么会发生这种情况。
One idea is that high carbon dioxide levels in water generally happen at the same time as low oxygen levels.
一种想法是，水中高含量二氧化碳通常与低氧含量同时发生。
And since the heart needs lots of oxygen to work, the bradycardia may help protect the heart muscle when there isn't as much oxygen available.
由于心脏需要大量氧气才能工作，那么在没有氧气的时候，心动过缓或许帮助保护了心肌。
Sadly, though, this still means there's no good evidence that pouring carbonated drinks on fish does them any good.
但这仍意味着没有充分的证据表明，给鱼倒碳酸饮料对它们有任何好处。
So if you've got a bleeding fish on your line, it's just going to be a rough day for that fish.
所以如果你钓的鱼流血了，那么对那条鱼来说，这将是艰难的一天。
But I guess you can console yourself with a nice, cold soda. If you have a science question for us, we would love to hear it.
但我猜你可以用一杯冰凉的苏打水来安慰自己。如果你有科学方面的问题，我们很乐意听到。
You can leave it in the comments below, or you can submit them through our Patron QQ inbox over at patreon.com/scishow.
你可以将问题留在下方评论中，或者通过patreon.com/scishow的QQ提交给我们。
And who knows: Your question might inspire our next episode. But in the meantime, thank you for watching this episode, too.
你的问题可能会启发我们的下一集，谁知道呢。但与此同时，谢谢观看本期节目。
