After finding underground rivers sadly lacking in terror, I have modded in a few more denizens. Specifically, Giant Crabs, Giant Crayfish and Giant Lobsters. Now breaching the river in the wrong way results in a horde of pincer-snapping beasts taking my miners apart in bloody ways.
In this instance, I have a problem. I misaimed my breaching tunnel, which actually hit the river directly from below, flooding the tunnel. Fortunately the miners all escaped, and the beasties were all far enough away to not notice.
Unfortunately, there is a lot of breeding going on. Not just with my decapods, but the giant olms and toads. While this is reassuring since I know my goblin-pit-o-doom will be self-cleaning, it is making my attempts to harness the river... difficult. I have dropped a dam in near the source of the river, but the rest remains muddy and deadly.
Behold the waves of beasts in this two-level composite of the last two levels of the river. The one-level drop is marked with the red line. The lucky/unlucky breaching shaft is at the northern end.
(it uses the Mayday tileset, with custom adult and child models for the new creatures)
The issue is this: How the Pit can I clear this out?
-The critters are deadly enough to tear apart a tank, and crossbow bolts barely faze them.
-I have tried barraging them from a balcony, it does not work.
-I have an untapped magma pipe, but it is directly on the other side of the map, across two mountains and a valley.
-I would prefer to be able to harvest their hides and meat.
-I don't need any of these alive for breeding, as there is more than enough of each type in the dammed section, and in an underground pool.
How can I get out of this problem?
PS: They are still breeding.