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

Question

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

Answer 1

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.