I am looking for a short story
"Between the Dark and the Daylight" by Algis Budrys, first published (as by "David C. Hodgkins") in Infinity Science Fiction, October 1958, available at the Internet Archive.
and anthology / anthologies containing it.
The ISFDB bibliography page for this stories lists several anthologies and Budrys collections in which it appeared. You may have read it in The Best Science Fiction Stories published by Hamlyn in 1977.
A multi generation ship
"The Expedition Charter was written four hundred years ago, a thousand lightyears away. The men who drew it up are dust. The men who signed it are dust."
"You're in the direct line of descent from the first Captain."
"Then you're recognizing me as a hereditary monarch, Falconer. I don't see the basis of your complaint."
Seens they got there by FTL ship rather than a generation ship, but they have been living on the planet for generations.
has landed on a planet with very hostile inhabitants on it.
"There is nothing in this world that loves us. There is nothing in this would that can even tolerate us. Generations of us have lived in this stone trap because not one of us—not even I—could live in the ecology of this planet. It was never made for men. Men could not have evolved on it. It would have killed them when they crawled from the sea, killed them when they tried to breathe its atmosphere, killed them when they tried to walk on its surface, and when they tried to take a share of food away from the animals that could evolve here. We are a blot and an abomination upon it. We are weak, loathesome grubs on its iron face. And the animals know us for what we are. They may even guess what we have spent generations in becoming, but it doesn't matter whether they do or not—they hate us, and they won't stop trying to kill us.
The aliens are chipping away at the hull of the ship with primitive instruments.
Conducted by the substance of the dome, there was a constant chip, chip, chip coming from somewhere, together with a heartless gnawing sound that filled everyone's head as though they were all biting on sandpaper.
The leaders of the space ship decide to breed aggressive children to counter the aliens.
"They're our children too!"
"All right, then, be proud of them. Tomorrow they go outside, and there'll be men out on the face of this world at last. Your flesh, your blood, and they'll take this world away from the storms and the animals. That's what we've spent all this time for. That's what generations of us have huddled in here for, hanging on for this day. What more do you want?"
They know that this is suicidal as the children will be so aggressive that they will kill the parental generation.
There was a new sound echoing through the dome. "Now they don't need us to let them out, anymore." There was a quick, sharp, deep hammering from outside—mechanical, purposeful, tireless. "That . . . that may be Donel now."