Here’s an argument to the effect that there have been or will be ill effects from shutting down industries as described above:

The U.S. is in a place where it doesn’t have much relative advantage in trade, and so job growth has been largely in the non-tradable domestic sector. That is, many countries outside the U.S. enjoy absolute advantage (due to innovations in communication and transportation technologies, which effectively allow for labour arbitrage), and so the basis of mutually beneficial free trade doesn’t apply. One country gains a productive industry, while the workers in the U.S. transition to bartending, waitressing, health care, and so on.

While this is occurring, the U.S. economic “growth” is maintained by international loans, such as by the Chinese, Japanese, Saudis, and so on. If at some point further loans are cut off, the economy collapses on itself. That is, the decisions made a long time ago to specialize were in a different technological and political time, and have not made sense for some time.

Also, shutting down the fishing fleet has been done in many industries without ill effects. If there’s a trade disruption, however, watch out below. But long time ago the decision to specialize was made instead of “buying insurance” by having the capability of having a fishing fleet on standby.