Why can’t we just release a ton of fish fry to replenish populations?


We can breed fish by the thousands in farms, yet populations in the wild are dying out. Why can’t we just dump tons of fish fry/larvae into the waters they normally live in, and some will get eaten and some will live, and replenish the populations artificially? Fish aren’t particularly caring parents, so unlike releasing a bunch of lion cubs or something, it will resemble what happens in the environment.

Edit: I’m talking about overfishing specifically here, not climate change or natural diseases or whatever.

In: 5

Not all fish are easy to farm. Some need very specific conditions to grow. It might cost an unreasonable amount of money to farm some fish if the only intent is to repopulate.

It also matters *why* their population is dropping. If the problem is just some natural phenomenon, sure. If it’s overfishing then this could work with fishing restrictions in place. But what if the reason the population’s dropping is because a Samsung factory in Austin dumps a few hundred thousand gallons of chemicals into the water? We’d spend a lot of money farming fish just to dump them in poison water. It’s a waste of effort and just the cost of having an economy I guess.

Or what if the reason for depopulation is that climate change has made the conditions unfavorable? Again, we’d be raising a ton of babies just to kill them. We’d have to do something about climate change to fix it so they’re just going to have to go extinct.

This is also sidestepping that most of the time when we try to mess with ecosystems, there are side effects we couldn’t predict. The amount of plants, prey, and predators in a region is a delicate balance. Releasing thousands of new versions of any one of those could wreak havoc. Too many plants can accelerate algae growth and kill off the fish that normally feed on them. Too many prey fish eat up too much of the plants which can make conditions unfavorable. Too many predators eat up too many prey fish and create other problems.

So it’s better to not pollute, do something about environmental harm, and let nature heal itself than to fiddle with it. There are definitely some populations we replenish, but it’s a slow and careful process because we don’t want to shock ecosystems.

Because you need to make sure the fish have a high likelihood of survival if you’re going to waste your time growing them unless you want to spend all your time on the world’s most inefficient project to feed the local wildlife fish fry.

Restocking is a thing we do all the time, but it doesn’t work everywhere on all species.

One reason I haven’t seen mentioned yet is that nature abhors a vacuum, so when a species is over-fished, other fish species move in. If we deplete, then restock, baby fish of a species we want to catch and eat, we are just feeding this new dominant species we don’t want to catch and eat, for free.

Usually better to limit harvest, or shift what we harvest. Restocking can bolster natural production, not replace it.

This is done with trout and salmon, which are easy to raise in captivity. For example, California spawns a huge number of salmon and releases them as fingerlings to maintain salmon populations that can no longer reach most of their spawning habitat because of hydroelectric dams. Various other freshwater fish are stocked in rivers and lakes as well.

One thing to note is that these aren’t fry or larvae. It doesn’t make sense to release those because the enormous majority of them will die. You aren’t getting any benefit over a fish just spawning in the wild. Instead, by keeping the larvae in captivity you may have 90/100 survive to be released as juveniles instead of 1/100 released as larvae survive to be juveniles

But for most fish, even this just doesn’t really make sense. It’s _very_ difficult to raise most oceanic fish in captivity because of their tiny larvae which are challenging to feed. Freshwater fish are usually easier.

Another problem is that fish in the ocean are not confined to any particular location or national waters. So imagine you go through all the trouble and expense of replenishing fish populations….and fishermen from some other country come and get all the benefit. Who would be willing to put up the money for that? Especially when you compare it to the alternative of just farming the fish to adult size, ensuring that you get all the fish in the end that you spent all that money and effort raising. Fish farming, by the way, has been growing enormously for the past few decades.

You can also compare this to fish that are raised and stocked in freshwater ponds, rivers, and lakes….the fish stay in the body of water where you put them, and keeping them on a farm is pointless because the whole point is to have fish out there for people to go fishing. Of course, freshwater fish are widely farmed too, but that’s done by different people for different reasons.