Your solution needs to be extremely incentivized and also easy to enforce in those places of the world. “Banning” something will have a laughable impact and only affect people who never created the waste in the first place.
That also requires the government rather than industry to pay the cost of its regulations, and explicitly choose how to raise the money rather than implicitly taxing fishermen (and fish) without ever evaluating whether that is the optimal funding source.
Suppose they use plastic nets and that makes fishing less expensive, but they all do that and it's a commodity market so they don't get to keep any of that money, it just means that it reduces the price of fish.
Now we need them to use more expensive nets. If we put the cost of them on the fisherman, it raises the price of fish, a healthier source of protein than many of the alternatives (e.g. red meat), and raises the price of food in general. Not super great as an outcome.
If we put the cost of them on coal companies, it raises the price of coal. Coal has nothing to do with fishing net, but we're actually trying to discourage coal, so since taxing coal burning is better than taxing fish eating, that may be a better choice.
The other side of it is that people are extremely poor. Possibly negative net value, lots of debts and no other way to pay next months bills. These people are going to use whatever it takes to live, and authorities who try to enforce it will look like villains.