Fishy 3/25/20

Science with Richard Bleil

Recently a news story reported that trolling by commercial fishers produce as much greenhouse gas as air travel. It’s kind of an interesting revelation. Personally, I always thought of the fishing industry as relatively small, probably thanks to those shows surrounding small boats with four or give people. This must be a naïve opinion, though, since we are out fishing the ocean resources.

The question, then, is if we will be switching to farmed fishing. I suspect that far more of the fish in the market is from such farms than you might think. In Iowa, we had a shrimp farm just a few miles from where I was living, and I was living in the middle of nowhere. The town was painfully small, an hour away from any city of mentionable size at all, and difficult to reach since there were no major interstates that went near it. An hour of driving took you to an interstate, and yet, here we were…with a shrimp farm, a farm so popular, in fact, that more often than not they were sold out.

I love fish. That “fishy flavor” that so many people like to complain about always tasted good to me. On a drive back when there were insects in the country, I had a large accumulation of bugs on my windshield. I was rather surprised when I distinctly smelled fish on exiting the car. As it turns out, that “fishy flavor” occurs because fish eat a lot of insects. It’s not the fish itself, but rather their diet of bugs, so when you taste fish, you’re tasting the insects that they eat.

Animals are basically filtration systems of their diet. They eat whatever it is that of which their diet consists, extracting out the nutrients and minerals and incorporate them into their own muscles which is what we call “meat”. Insects produce the chemical “trimethyl amine”, the accumulation of which is what gives fish its characteristic smell and taste. In fish farms, they have to add this chemical to the water so the fish tastes wild since the fish food they are given is too “clean”. Trimethyl amine is a very simple organic compound, falling into the same class of compounds as “cadaverine” which gives that distinctive “death” smell of decaying human corpses (hence the name). Amines are often highly odoriferous and are also found in many pharmaceuticals. They are weak bases, so they react with weak acids to form salts. This is why so many drug names end in “.HCl”. These are all amine salts, reacted with hydrochloric acid so they are in their salt form. This salt form means the drugs won’t evaporate away as readily, producing longer shelf lives.

This is actually why we add lemon juice to fish. Lemon juice contains citric acid, and the acid reacts with the trimethyl amine to form trimethyl citrate salt. As a salt, the volatility is dramatically cut back, significantly reducing the dead bug smell. Many narcotics are also in the amine class of compounds. The term “free basing” refers to converting the narcotic salt back into the base form causing it to evaporate and become a gas. The drug user will then breathe in the gas.

So, what’s the point of all of this? Well, honestly, my mind is meandering, which often happens when I think about chemistry. Originally, I wanted to try to give the fish farm industry a boost. I think fishing will always be a great family activity (I was about to write father/son activity, but I know so very many women who truly love fishing that it’s not just sexist, but wildly inaccurate to boot). But I also know a lot of people who have some kind of objection with fish farming, although I honestly don’t understand why. If you get into a philosophical debate now with somebody badmouthing the fish farming industry, you can ask them how they like the taste of dead bugs. But I honestly would like to see the fish farming industry improve and give the fish in the oceans a chance to bounce back.

But then I start thinking about the compound classification, and all of the related compounds. Like barbituates, a class of amines created by Adolph von Bayer (yes, like the aspirin company). He named this new class of compounds after Barbara, which you might think is very sweet, but Barbara was not his wife. She was his mistress. And considering the way the word ends, apparently she was not a very good one.


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